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Патент USA US2406468

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altars
Patented Aug. 27, 1946
UNITE
STATES PATENT OFFICE
2,406,468
DIRECTION-INDICATING ‘SYSTEM
Bernard D. Loughlin, Bayside, N. Y., assignor, by
mesne assignments, to Hazeltine Research, Inc.,
Chicago, 111., a corporation of Illinois
Application September 15, 1944, Serial No. 554,231
26 Glaims. (Cl. 250—11)
l
an aid in the navigation of a mobile craft and,
ating with high power gain, and additionally per
mits a transponder type of operation. In the lat
ter mode of operation, the process by which direc—
particularly, to such systems of the radiant-sig
nal type which utilize spaced antennas.
The majority of the prior art systems for air
craft navigation are of the complementary-signal
tion is determined is initiated by an interrogat
ing signal which is transmitted from the direc
hon-indicating station to the station which radi
ates the wave signals used in providing the direc
The present invention relates to direction-indi
cating systems of the type adapted for use as
tion indication. The interrogating signals when
class or the equisignal-locus class used with pre
received by the latter station initiate and control
determined de?ned courses. These systems may
be considered direction-indicating systems in the lo its operation so that direction-indicating wave
signals are radiated only when required, thus
limited sense that the de?ned courses have pre
minimizing possible interference on adjacent
determined ?xed directional relations to a terres
transmitting channels used for other purposes
and increasing the element of secrecy which is
A more general form of direction-indicating
system used largely for marine navigation is the 15 of importance in military applications.
It is an object of the present invention to pro
radio direction-indicating system which employs
vide an improved direction-indicating device and
amcvable directive antenna, usually of the loop
system which is free from one or more of the
or Adcock type, by which to ascertain the direc
above-mentioned disadvantages and limitations
tion of a transmitting station from the craft.
trially located radiating system.
Two such stations widely spaced furnish su?i
of prior art systems.
It is also an object of the invention to provide
an improved direction-indicating device and sys
tem which does not require the use of directional
Where compass bearings are not available or can
antennas.
not be relied upon, at least three widely spaced 25 It is a further object of the present invention
to provide an improved direction-indicating de
stations are necessary for the ascertainment of
cient information with the aid of a compass for
an ascertainment of position without ambiguity,
by calculation. or by some plotting process.
position. This last-mentioned system has the
disadvantage that it not only requires at least
two ‘and possibly three widely spaced transmit
ting systems, but also that it is in general not
adapted rapidly and easily to provide desired
direction indications.
_ Other prior art systems have numerous disad
vice and system which affords omnidirectional
indications of direction without ambiguity.
It is also an object of the present invention
to provide a direction-indicating device and sys
tem which has one or more of the desirable char
acteristics mentioned above.
In'accordance with the invention there is pro
vantages and limitations by virtue primarily of
the fact that they depend upon the intensity of
vided, in a radiant-energy system of the type
which effects the translation of diretcion-indica
received wave-signal energy to provide direction
indications. Thus, any factor affecting wave-sigl
tive modulation signals at least one of which is
of pulse wave form over at least two space paths
extending between an antenna of one antenna
nal intensity, such as unevenness of the terrain
surrounding the transmitting antennas or atmos
pheric fading, seriously impairs the accuracy of
such systems. Accuracy of indication may like
wise be impaired by changes of the relative in
tensities or phases of the wave signals applied
tov the transmitting antenna systems or by rela
tive changes of the amplitudes or phases of mod
ulating signals.
'
It would be desirable that direction indications
through 360 degrees, and without ambiguity, be
system and individual spaced antennas of another
antenna system, a direction-indicating device for
indicating with relation to a predetermined ref
erence plane the direction of one of the antenna
systems ‘relative to the other. This device com
prises means for receiving the modulation signal
of pulse wave form translated over one of the
space paths and means responsive to the modu~
lation signal translated over the other of the
space paths for providing a reference signal of
saw-tooth wave form having a characteristic
provided by the use of only one station of ?xed
location. It would further be desirable that the 50 which varies‘ with time. The device includes
means responsive to the aforesaid received modu
system be one of the pulse-modulation type which
has the important advantages that it permits the
transmitting equipment of the system to operate
with high peak-power outputs greatly exceeding
its average power-output capabilities, thus oper
lation signal of pulse wave form for evaluating
the reference signal to derive therefrom a con
trol signal having a characteristic varying with
. the relative lengths of the aforesaid space paths,
2,406,468
3
I and means responsive to the control signal for
indicating the aforesaid direction.
-
For a better-understanding of the present in
vention, together with other and further objects
thereof, reference is had to the following descrip
4
modulation components thereof for developing a
reference signal having a characteristic which
varies with time.
For this purpose there are
provided two receivers 20, 2| adapted to receive
signals from transmitters H and [2, respectively,
tion taken in connection with the accompanying
drawings, and its scope will be pointed out in
and hereinafter referred to as the "east and west
receivers.” Each receiver. is provided with a suit
the appended claims.
'
able antenna circuit, as by coupling to a common
Referring now to the drawings, Fig. 1 is a cir
antenna 22. Receiver 20 may include one or
cuit diagram, partly schematic, of a complete 10 more stages of radio-frequency ampli?cation, a
direction-indicating system embodying the pres
ent invention; Figs 3 and 5 are circuit diagrams,
partly schematic, of complete direction-indicat
ing systems embodying different modi?ed forms
of the invention; while Figs. 2, 4, 6 and 7 com
prise curves used as an aid in explaining the
operation of the several embodiments of Figs. 1,
3 and 5.
Referring now more particularly to Fig. 1 of
detector for deriving the modulation components
of a received wave signal, and one or more stages
of ampli?cation for amplifying the signal of
periodic-pulse wave form derived by the detector.
15 There is also included at one or more points along
the signal translating channel of this receiver at
least one stage which functions as a limiter to
limit to a substantially constant value the pulse
amplitude of the periodic-pulse signal developed
the drawings, there is represented a complete 20 in the output circuit of the receiver. The output
direction-indicating system embodying the pres
circuit of receiver 20 is coupled to an input cir
ent invention in a particular form suitable for
providing an indication of direction with relation
cuit of a saw-tooth signal generator 23. Saw
tooth generator 23 is adapted to generate a ref
to a predetermined reference plane of longitude
erence signal which has a characteristic which
which is coincident with a ?xed terrestrially po 25 varies with time and, preferably, one the am
sitioned antenna system of the indicating sys
tem. . This
arrangement
thus
provides
azi
muthal indications. It will be understood, how
plitude of which varies linearly with time, such
as a linear saw-tooth signal.
Receiver 2! is es
sentially similar to receiver 20 and hasits output
ever, that the invention is not so limited and the
circuit coupled to a similar saw-tooth generator
reference plane may if desired be a horizontal 30 24. Saw-tooth generators 23, 24 are so intercon
one in which case the indications then involve the
nected, in a manner presently to be explained in
aspect of elevational direction. The direction
greater detail, as to permit the generation of a
indicating system includes a pair of transmitters
reference signal only by that one of the saw-tooth
H and I2, for generating and transmitting in
generators associated with the receiver which re
dividual ones of a ?rst pair of distinguishable 35 ceives the ?rst signal to arrive from the pair of
wave signals modulated by individual modulating
signals having a, determinable time relation
therebetween, and a second pair of transmitters
i 3 and M, for similarly generating and transmit
ting individual ones of a second pair of wave
signals modulated by individual modulating sig
nals having a determinable time relation there
transmitters ll, i2, the other saw-tooth gener
ator being effectively de-energized upon the ini
tiation of this reference signal by the one gen
erator.
rIfhe means for developing the above-mentioned
?rst control signal from the wave signals of the
east and west antennas l5 and "5 also comprises
means responsive to the other of the signals re
between. Each of transmitters ll, l2, l3 or M
is provided with a respective antenna system 15,
ceived from this pair of antennas for evaluating
i6, I‘! or 18, the antennas being positioned in 45 the reference signal to derive therefrom a con
spaced pairs on individual axes of a system of
trol signal having a value dependent upon the
Cartesian coordinates. The antennas are pref
relative times of reception of the modulation
erably located at the four cardinal points of the
components of these wave signals. This means
compass and equidistant from the origin of the
comprises an evaluating or sampling circuit 25,
Cartesian coordinate system so that the direction 50 the detailed arrangement of which will be con
indications provided by the system become azi
sidered hereinafter, having a ?rst input circuit
muthal indications and will be hereinafter re
coupled to an output circuit of saw-tooth gener
ferred'to as such. Transmitters ll, l2, l3 and I4
ator 23 and a second input circuit coupled to an
may be of conventional design, and preferably are
output circuit of receiver 2|. To provide bidi
of the pulse-modulation type having individual 55 rectional azimuth indications, the last-mentioned
carrier-wave frequencies. A pulse generator I9,
means also includes an evaluating 0r sampling
for generating a signal of periodic-pulse wave
form, has an output circuit connected to a mod
ulation input circuit of each of the transmitters.
It will be understood that the elements H-l9,
inclusive, are normally terrestrially located, and
that the portion of the system presently to. be
described comprises a direction-indicating de
vice which normally is associated with a craft the
azimuth of which is to be determined.
The direction-indicating device includes means
for receiving wave signals from a ?rst two of the
spaced antennas, for example, the east and west
antennas l 5, i ii for developing a ?rst control sig
nal having a value dependent upon the relative
times of reception of the modulation components
of the wave signals from these ?rst two antennas.
More particularly, this means comprises means
for receiving the ?rst of these signals to arrive
circuit 26, which is similar in structure, func
tion and arrangement to sampling circuit 25,
having a ?rst input circuit coupled to the output
circuit of the saw-tooth generator 24 and a sec
ond input circuit coupled to an output circuit of
the receiver 20.
The direction-indicating device additionally
includes
means
for
receiving
wave
signals
radiated from a second two of the antennas, for
example the north and south antennas l1, H3, in
a different line than the ?rst two antennas for
developing a second control signal having a value
dependent upon the relative times of reception
70 of the modulation components of the wave sig
nals from the second two antennas.
This means
comprises two receivers 21, 28 adapted to re
ceive individual wave signals from transmitters
M, [3, respectively, and two saw-tooth signal
at the indicating device and responsive to the 75 generators with two sampling circuits indicated
2,406,468
5
generally as a unit 29, arranged in the same
manner as the east-west system already de
scribed. Receivers 2'! and 28 differ from each
other and from receivers 20 and 2! in operat
ing frequency but are otherwise similar in struc
indicated as -C’. Another control electrode of
tube 49 is negatively biased by a source —C
through resistor 50. The screen grid of tube 49
is supplied with an appropriate operating poten
ture and function to the latter.
of tube 49 is ‘connected through a resistor 5| t0
the source of potential +B. The last-mentioned
control electrode of tube 49 is coupled through
tial from a source indicated as +Sc. The anode
The unit 29 is
shown in detail as representative of the circuit
arrangement of the generators 23, 24, the
a condenser 52 to an output circuit of receiver
samplers 25 and 26, and their connections to
10 28. The anode of tube 49 is by-passed to ground
their associated receivers.
by a condenser 53 and is coupled to one of the
Neglecting for the moment a consideration
vertical de?ecting plates of cathode-ray tube 30.
of the detailed description of those elements of
All elements in cascade with receiver 28 have
the north-south
, cm which are indicated as
the same reference numerals primed as those
the unit 29 and cons‘ ering further the direction
employed in describing the corresponding ele
indicating device as a whole, the direction
ments in cascade with receiver 21, and essentially
indicating device includes signal-display means
are the same in structure, function and circuit
comprising preferably a cathode-ray tube 30 and
appropriate operating potential sources 3| and n arrangement. The anode of tube 49’ is con
nected to the other’ vertical deflecting plate of
32 therefor.
The cathode-ray tube 30 includes means re
20 cathode-ray tube 30 and the ?rst control elec
trode of tube 49’ is coupled to an output circuit
of receiver 21. Tubes 34 and 3d’ are provided
with a common cathode resistor 54, for a purpose
sponsive to the above~'nentioned ?rst control
signal for determining the indications of the dis
play means in one coordinate direction. For this
purpose there is provided a pair of deflecting
electrodes in cathode-ray tube 30, for example
its horizontal beam-deflecting plates, connected
in balanced relationship to the output circuits of
to be described hereinafter.
A common source
sampling circuits 25, 2'6. Similarly the tube 36
of bias potental 42 is provided for the control
electrodes of tubes 34 and 35’.
Reference is made to Fig. 2 for an explana
tion of the operation of the Fig. 1 arrangement.
includes means responsive to the above-men
At time t1, which may be considered as the start
of an illustrative cycle of operation of the direc
tioned second control signal for determining the
tion—indicating system, transmitters H, l2, l3
indications of the display means in another co
ordinate direction. This means comprises a
second pair of beam-deflecting electrodes in
cathode-ray tube til, for example its vertical de
?eeting plates, connected in balanced relation
ship to the output circuits of the sampling cir
and M are modulated by a pulse generated by
the generator I9 simultaneously to radiate pulse
signals distinguishable in frequency. Assume
_ that the receiving equipment is in the southeast
quadrant and consider for the moment only the
signals from transmitters i4 and i3, hereinafter
referred to as “south” and “north” signals, repre
sented by curve A of Fig. 2. These signals are
cuits included within the unit 29.
It will be understood that the use of the terms
“?rst control signal” and “second control signal”
is intended for the purpose of distinguishing the
control signals and is not intended necessarily
to indicate time sequence.
Considering now the detailed description of
the two saw-tooth generators and samplers of
unit 29, the output circuit of the receiver 21 is
intercepted by antenna 22 and applied to re
ceivers 2‘! and 23 where they are selectively re
ceived. It is assumed that the distance from
the antennas to the indicating device is so great
that the convergence of the paths of signal travel
; from antennas l1 and I8 to antenna 22 may be
neglected. Under the assumed conditions, the
signals received from the north and south trans
mitters i3 and M by the north and south re
ceivers 28 and 2'! are spaced in time at the time
coupled through a condenser 33 to a control
electrode of a tube 3/5, preferably a triode, com
prising the ?rst tube of a conventional univi~
brator. The univibrator comprises two similar
of reception by the determinable time relation
tubes 33 and 35, each of which has its output
ship
circuit coupled through one of the condensers 36
or 31 to the input circuit of the other. Each of
the tubes 30}, 35 is provided with its respective
t=kd sin a
grid-leak resistor 36, 39 and its respective load
resistor 130, Al and both are provided with a com
mon source of space current, indicated as +B.
The tube 34 is biased from a source 42 to a nor
mally nonconductive operating condition.
d is the distance between antennas I‘! and I8,
55 a is the angle formed by a line drawn from
The
second tube 35 is so biased as to be normally eon
ductive.
,
The signal output of the univibrator just de
(1)
where
60
antenna 22 to the mid-point of the line
between antennas l5 and I B, and
is is a constant related to the wave-signal velocity
and the units of measurement selected.
Similarly, the signals received from transmit
ters H and 12 by the east and west receivers 20
scribed is used to develop a saw-tooth reference
and 2| are spaced in time at the time of reception
signal of the type mentioned above. For this
by the determinable time relation
purpose, the control electrode of tube 35 is cou
pled to the control electrode of a triode 153 in 65
t’=kd cos a
(2)
cluded in a saw-tooth generator. Tube 43 is
provided with anode potential by connection to
The system has such operation that the con
source +B through resistor M and has its out
trol signals which are applied to the cathode-ray
put circuit connected across a condenser 45.
tube 30 have values varying with the signal time
The saw-tooth signal just mentioned is cou
pled to an input circuit of a sampling circuit.
differentials kd cos a and led sin (1 thus to pro
vide azimuth or direction indications through a
Speci?cally, the anode of tube 43 is coupled
through a condenser 46 and grid-leak resistor 41
360-degree angle and without ambiguity.
to a control electrode of a tube 119. This elec'
trode is normally biased negatively from a source
from the south transmitter It is the ?rst one
Under the assumed conditions, the wave signal
to arrive at the direction-indicating device, for
2,406,468
example at instant t2 as shown by curve B.
This wave signal is selectively received by re
denser 45 increases substantially linearly with
time, whereby there is generated across the con
denser a reference signal having a linear saw
tooth characteristic, as represented by curve C
of Fig. 2. This reference signal is applied to a
control electrode of tube 43. The latter does not
ceiver 21, and the pulse-modulation components
thereof are derived and applied with positive
polarity to the control electrode of the ?rst uni
vibrator tube 34. Tube 34, which normally is
maintained in a nonconductive condition by the
repeat the reference signal, however, since it is
bias of the battery 42, thereupon becomes con
maintained
at anode-current cutoff by the bias
ductive and applies an ampli?ed potential of
negative polarity to the control electrode of the 10 -C applied to another of its control electrodes.
The time constant of the circuit comprising re
second univibrator tube 35 to render it less con
sistor 443 and condenser 45 is long compared-to
ductive. This potential is ampli?ed in tube 35
the
duration of this univibrator pulse and is of
to produce in its anode circuit a potential of
such a value that the amplitude of the saw-tooth
positive polarity which is regeneratively fed back
through condenser 36 to the input of tube 34 15 reference signal permits tube 59 to operate with
in a linear portion of its characteristic.
in phase with the pulse-modulation components
Assume now that the wave signal from the
applied thereto, thereby cumulating the poten
north transmitter 13 is received by receiver’ 28
tials tending to render tube 34 fully conductive
at time is,
2. There is then derived in the
and tube 35 non-conductive. This cumulative ' output
circuit
of
the latter, and applied with pos
action proceeds rapidly and tube 35 therefore 20
itive polarity both to the univ‘ibrator tube 34’ and
is sharply cut off and becomes nonconductive at
to another control electrode of tube 49, a signal
instant t2. Tube 35 is maintained in a non
of pulse wave form. This signal is not e?ective
conductive state for a predetermined period by
to render the univibrator tube 34’ conductive,
a negative potential drop developed across re
sistor 39 by the discharge of condenser 37 25 however, since the potential drop produced across
cathode resistor 54 when tube 34 became con
through tube 34, condenser 31 having previously
ductive at time t2 renders the cathode of tube 34'
been charged from the source +B through the
resistors 39 and 40.
positive and is effective to block or disable the
As soon as tube 35 is
saw-tooth generator, comprising tubes 34’, 35'
rendered nonconductive, condenser 35 begins to
and 43', associated with receiver 28. Thus it will
charge from the source +B through resistors
38 and 4! thus to develop a positive potential 30 be seen that only the ?rst received signal is
across the grid resistor 38 of tube 34 which
tends to maintain the latter tube in its conduc
tive state.
After a predetermined interval, condenser 31 35
will have suihciently discharged that the poten
tial developed across the resistor 39 and applied
to the control electrode of tube 35 is insufficient
to maintain this tube biased below anode-current
cutolT. Tube 35 thereupon becomes conductive
and produces in its output circuit a potential of
negative polarity which is applied through con
denser 36 to the control electrode of tube 314.
This potential is ampli?ed in tube 34 and regen
eratively fed back in positive polarity through
condenser 31 to the control electrode of tube
35, thereby cumulating the potentials tending
utilized to derive a reference signal, as illustrat
ed by curve C of Fig. 2. The pulse signal of re
ceiver 218 is, however, effective to render tube 49
conductive thus to derive in its output a control
signal having an amplitude varying with the am
plitude which the reference signal represented
by curve C, and which is applied to the other con
trol electrode of tube 45, has at this time. The
signal thus applied to tube 43 from receiver 28
is limited to a substantially constant amplitude
by the limiting stage or stages of receiver 23 and
effectively evaluates the saw~tooth reference sig
nal applied to this tube from the tube 43. Since
45
the amplitude of the reference signal increases
linearly with time, and since the interval tz-tz
between the signals received by receivers 2‘! and
28 is equal to Icd sin a, it will be apparent that the
to render tube 35 fully conductive and tube 34
result
of the evaluation by tube 45 of the refer
nonconductive. As before, this cumulative
ence signal is to derive a control signal having a
action proceeds rapidly and tube 35 is therefore
Value proportional to Ted sin a. This signal is ap
sharply cut on and tube 34 sharply returned to
plied
to the vertical deflecting electrodes of the
its normally nonconductive condition. Tube 35
cathode-ray tube 35 and is effective to supply a
thereafter remains conductive, since its control
displacement component to the electron beam
electrode and cathode are at the same potential,
until another pulse is applied from the receiver 55 thereof proportional to lcd sin 66, thus to deter
mine the indications of the cathode~ray tube in
21 to tube 34 to initiate another cycle of the
one coordinate direction.
operation described.
While the operation described thus far has
By a proper selection of the circuit constants
considered only one pulse of the signals of trans
of the univibrator, there is produced across the
mitters I3 and M, it will be understood that these
grid resistor 39 of tube 35 a negative potential of
approximately rectangular-pulse wave form hav 60 signals are of the periodic-pulse type so that the
control signal developed by tube 49 essentially is
ing a duration at least substantially as long as
formed by a large number of repeated cycles of
the maximum difference ever encountered be
tween the times of arrival of the signals from
the operation described.
The time constant of
the circuit comprising condenser 53 and resistor
transmitters l4 and I3.
5! is so selected as to be long compared to the
The control pulse thus generated at the con
repetition rate of the signals of transmitters l3
trol electrode of tube 35 is applied to the con—
and i4 so that a substantially unidirectional p0
trol electrode of tube 43 to render it nonconduc
tential is applied to the vertical deflecting elec
tive during the period of the control pulse. Con
trodes of tube 3!].
denser 45, which was previously charged to the
In like manner, wave signals from the east
potential existing across tube 43 when it was in 70
and west transmitters H and 42 are selectively
its conductive state, is now charged from source
received by receivers 29 and 2!. Under the as
+B through resistor 44 to a higher potential.
sumed conditions, the signal of the transmitter
The values of the resistor 44 and condenser 45
are so chosen that the potential across the con
H is received ?rst and causes the generator 23
to generate a saw~tooth signal and to block or
2,406,468
10
effectively deenergize the generator 24. The sig
and a pair of east-west transmitters, indicated
nal of the transmitter I2 is received later in point
of time and is applied to the sampler 25 to de
as a unit 56. The ?rst unit 55 includes a trans
mitter 51 having a modulation input circuit cou
pled through a delay network 59 to an output
circuit of a generator 58 which generates a sig
nal of periodic-pulse wave form. This signal of
velop in the output circuit thereof a second con
trol signal having a value dependent upon and
proportional to the relative times of reception of
the modulation components of wave signals re
ceived from transmitters H and I2. This control
signal is applied by sampler 25 to the horizontal
de?ecting electrodes of tube 35 and is effective
to produce a component of displacement on the
electron beam thereof proportional to led cos 0.,
thus to determine the indications of the cathode
pulse wave form preferably amplitude-modulates
the wave signal generated by the transmitter 51
to provide a pulse-modulated wave signal. The
unit 55 also includes a transmitter 66 having a
signal generator coupled to an output circuit of
the pulse generator 58 for synchronized opera
tion therewith and adapted to generate a pc
riodic signal of saw-tooth wave form and of saw
ray tube in another coordinate direction.
7 The two control signals simultaneously de?ect 15 tooth duration- at least twice as long as the time
of wave-signal travel between the antenna sys- "
the beam of tube 39 so that there appears on the
tems I7, l8». This saw-tooth signal is applied
?uorescent screen thereof a luminous spot the
to a modulator of transmitter 60 to frequency
angular position of which indicates the azimuth
modulate the carrier wave generated in the lat
of the indicating device with relation to the sev
eral antennas Iii-i8, inclusive. The screen of 20 ter. The east-west transmitters of unit 56 com
prise elements similar in structure, function and
tube 36 may therefore be calibrated in terms of
arrangement to those of unit 55, either trans
azimuth.
mitter of the former being frequency-modulated
It will further be apparent that when the di
rection-indicating device is in the northeast
by the saw-tooth signal.
The transmitters of
quadrant with relation to the spaced antennas a 25 units 55 and 56 are provided with individual an
control signal is applied from the output circuit
of tube 49' to the vertical de?ecting electrodes
tennas l5, I6, H and I8, disposed as in the Fig. 1
system.
The Fig. 3 system has a direction-indicating
of tube 39 and is effective to produce a vertical
device which includes means for receiving wave
component or“ de?ection of the electron beam
thereof
a direction opposite to that hereinbe 30 signals radiated from a ?rst two of the antennas,
fore described.
Further, when the indicating
for example the north-south antennas ll, l8, for
device is in the southwest quadrant, a control
developing a ?rst control signal. This means is
signal is applied by sampler 26 to the horizontal
de?ecting electrodes of tube 35, thus to produce
a horizontal component of de?ection opposite to
indicated as a unit ‘ti and includes means for re
that previously described.
ceiving the amplitude-modulated wave signal and
responsive to the modulation components there
of for‘ evaluating the reference signal to derive
From the above description of the Fig. 1 ar
rangement, it will be apparent that the direc
tion-indicating system is a radiant~energy sys
tem of the type Which effects the translation of
directiondndicative modulation signals, at least
one of which is of pulse wave form, over at least
two space paths extending between an antenna
22 of one antenna system and individual spaced
ceiving the frequency-modulated wave signal for
developing a reference signal and means for re
therefrom a control signal having a characteris
tic varying with the relative times of reception
of the modulation components of the received
wave signals. The reference-signal developing
means comprises a frequency-modulation receiver
62 which includes a conventional limiting system
antennas iii-l8, inclusive, of another antenna 45 and a balanced frequency detector for deriving
in the output circuit thereof a reference signal
system. It will further be evident that the di
having an amplitude varying with the instan
rection-indicating device of the invention indi
taneous frequency of the received frequency
cates the azimuth or direction of one of the an
modulated wave signal considered with reference
tenna systems relative to the other. The re
ceivers Ell, 2|, 2? and 28 of the direction-indicat 50 to the ,mean frequency thereof and having a
polarity dependent upon whether the instanta
ing device comprise means for receiving the mod
neous frequency of the wave signal is greater or
ulation signal of pulse wave form translated over
less than its mean frequency. An ampli?er 63
one of the space paths, the saw-tooth generators
has an input circuit coupled to an output circuit
23, 2a and the corresponding generators of unit
29 comprise means responsive to the modula 55 of the frequency-modulation receiver 52. The
output circuit of ampli?er 63 is coupled, through
tion signal translated over the other of the space
the condenser 46, to a control electrode of sam
paths for providing a reference signal of saw
pling tube 49, whereby the reference signal is ap
tooth wave form having a characteristic which
plied to the latter.
varies with time, and the samplers 25, 26 and cor
The sampling signal means includes a receiver
responding samplers of unit 29 comprise means 60
48 adapted to receive the amplitude-modulated
responsive to the received pulse-modulation sig
wave signal from transmitter 5‘! and to derive
nal for evaluating this reference signal to derive
therefrom the modulation components compris
therefrom a control signal having a characteris
ing the sampling signal of periodic-pulse wave
tic varying with the relative lengths of the space
paths. The cathode-ray tube 39 comprises means 65 form. This receiver includes a limiting system
effective to limit the amplitude of the latter sig
responsive to the control signal for indicating the
nal to a substantially constant value independ
azimuth of one of the antenna systems relative
ently of the intensity, over the normal range
to the other.
thereof to be expected in practice, of the wave
A direction-indicating system which permits a
somewhat simpli?ed form of direction-indicat 70 signal received by. the receiver 48. An output
circuit of receiver $8 is coupled to another con
ing device is shown in Fig. 3. This system is es
trol element of tube 49, whereby there is derived
sentially similar to the Fig. 1 system and similar
in the output of the tube a control signal having
elements are designated by similar reference nu
a value dependent upon the relative times of re
merals. The Fig. 3 system includes a pair of
north-south transmitters, indicated as a unit 55, 75 ception of the modulation components of the
2,406,468
12
wave signals from transmitters 5? and 6% The
by the receiver 48 at some later time, for example
anode of tube 139 is connected to one of the ver
vat time ts, which is displaced from time is by an
amount dependent upon the relative spacing d
ofvthe antennas ll, I8 and the direction of the
de?ecting electrode in the present arrangement 5 direction-indicating device with relation to these
is connected through a centering potentiometer
antennas. The time interval ts-ts thus is pro
R. to an energizing source indicated as +B.
portional to lcd sin a. The modulation compo
As-will be explained in greater detail herein
nents of this received wave signal are derived to
tical de?ecting electrodes of the cathode-ray tube
3i? as in the Fig. 1 system, but the other vertical
after, the unidirectional centering biases applied
to the deflecting electrodes of the cathode-ray
tube 353 de?ect the beam thereof to one side of
the center of the screen of tube 39 in the absence
provide in the output circuit of receiver 48 a
sampling signal of substantially constant am
plitude established by the limiting system of the
receiver 68 and thus an amplitude independent
of the intensity of, the received wave signal.
This signal is applied through condenser 52 to
another control electrode of sampler tube 49,
of any received wave signals. If such de?ected
‘position of the beam were to produce an indica
tion on, the screen of tube 30, the indication thus '
provided would be a false indication of direction.
whereby the sampling process occurs as 7 de
To- avoid this undesirable condition of operation,
,there is provided a diode recti?er device 61 having
its
anode ' and
cathode
elements
scribed in connection with the Fig. 1 embodi
ment. The control signal produced in the out
put of tube 49 and applied to the vertical de
?ecting electrodes of the signal-display means
connected
through a load resistor 68 to individual terminals
of a resistor 66 which is coupled through con
densers E5, 10 to an output circuit of receiver 48.
The load resistor 68 has connected in shunt there
to a condenser 69 and this resistor and condenser
are serially included in the intensity-control elec
thus has a value varying with 70d sin a.
Similarly, wave signals from the east and west
transmitters of unit 56 are utilized in the east
and west receivers of unit 64 to develop a con
trol-signal having a value which varies with kd
cos a. -This signal is applied to the horizontal
trode circuit of ‘the cathode-ray tube 30. The 7di
ode recti?er 61 is so poled that an electron beam
can be developed in tube 30 only while wave sig
de?ecting electrodes of cathode-ray tube, 30.
The two control signals thus applied to the de
?ecting electrodes of tube 30 provide the desired
direction indication, as in the Fig. 1 arrange
nals arereceived by the receiver 48.
I The Fig. 3, system also includes means for re
.ceiving signals radiated from a second two an
ments
ftennas, namely the east ward antennas l5, l6,
__for developing a second control signal having a
v
cathode-ray beam of tube 30 is vertically cen
.value dependent upon the relative times of recep
tered on the screen of the latter at a time when
tion of the modulation components of the east
west wave signals.
the signal of saw-tooth wave form applied to tube
439 has zero amplitude during, each pulse applied
,tcthis tube from the output circuit of receiver
138; that is, when the direction-indicating device
This means is indicated as
"a unit 64 and comprises the same circuit elements
and circuit arrangement as the unit 6|. The
voutput circuit of the unit 84 is coupled to one of
is due east or west of the antennas I1, I8.
the horizontal de?ecting electrodes of the cath- .
'ode-ray tube 36, the other horizontal electrode being energized from a potential source indi
cated at +3 through a centering potentiom
ieter R’.
.
7
The potentiometer R is so adjusted that the
The
potentiometer R’ is similarly adjusted horizon
tally to center the cathode-ray beam of tube 30
when the direction-indicating device is due north
or south of the antennas l5, l6.
.
The unidirectional centering potentials ap
-
anReference
explanation
is made
of the
to operation
the curvesofof the
Fig.Fig.
4 for3 '
‘ embodiment.
One cycle of the saw-tooth signal
:of transmitter 50 is represented by curve D and.
is shown as being initiated at time i1 by the action
plied to the de?ecting electrodesrof thecathode
ray'tube sojaue'to the adjustments of the poten
ticmeters R and R’ last mentioned, cause the
of, pulse generator 58 and as having a saw-tooth _-.
vduration at least Zkd long. The pulse signal of
generator 58 also is also applied through a delay
network 59, having a time delay equal to led, to
the transmitter 51. The pulse of this signal
cathode-ray beam of tube 30 to have a normal
‘deflection to one side of the center of the screen
of tube 30 during intervals when no wave sig
nals are received. The intensity-control electrode
,of tube 30 consequently is biased by the biasing
source 32 to space current cutoif so that no elec
trons impact the screen of this tube in the ab
which initiated the saw-tooth cycle of curve D is p. '
thus applied to the latter unit at time t2 as rep
resented by curve E. Assume now that the di
sence of received wave signals.
Upon the receipt
of wave signals, however, the signal of periodic
pulse wave form which is developed in the output
circuit of the receiver 48 is applied to the diode
rection-indicating device is in the southeast
quadrant with relation to the transmitting an
tenna system. As indicated by curve F, the saw
recti?er device 61.
tooth modulated wave signal of transmitter 60 ‘
‘unidirectional control potential which is applied
with positive polarity to the intensity-control
‘electrode of cathode-ray tube 30 to bias this elec
arrives at antenna 22 at time t4 and is applied to
receiver 62, which derives in its output circuit a
‘reference signal, represented by curve H, having
1 an, amplitude varying linearly with the frequency
vof the received wave signal, and independently of
'the intensity of the latter, and a polarity depend
ent upon the deviation of frequency above or
vbelow its mean frequency. This reference signal
The latter derives across
its load resistor 68 from this applied signal a
trode su?iciently positive that electrons are per
65 mitted to'flow from the cathode of tube 3K] to its
?uorescent screen. The values of the resistor
68 and condenser 69 are so selected that their
time constant is suinciently long effectively to
provide peak rectification of the periodic-pulse
‘has zero amplitude at instant is. The reference ,
‘signal thus derived is applied through ampli?er '
I63 and coupling, condenser 4'5 to a control elec
signal applied to the diode 61. It will thus be
apparent that indications are provided by the
trode of the sampler tube 49.
Under the assumed conditions, the pulse-mod
"pulated Wave signal from transmitter 51 is received
vwave signals are received, thus to avoid any
vfalse direction indications which otherwise would
75
cathode-ray tube 30 only during intervals when
be produced in the absence of the control cir
'
2,406,468
1.3
cuit comprising the diode recti?er 6‘! and its
associated circuit components.
A direction-indicating system which embodies
a modi?ed form of direction-indicating device
of the present invention is shown in Fig. 5. This
system is essentially similar to the Fig. 3 system
and similar elements are designated by similar
reference numerals. The Fig. 5 system includes
14
signal. This. means comprises a beat-frequency
detector 80' having an input circuit coupled to
the antenna 84 and tuned to receive the wave
signals of both of the transmitters ‘I2 and 13.
Coupled to the output circuit of the detector 50',
in the order named, are an ampli?er and limiter
8|’, a frequency detector 82’ and an ampli?er
and integrating network 83’ generally similar in
structure, arrangement and function to the
three spaced antennas ‘M, 15 and ‘it. The an
corresponding elements 8l-83, inclusive, here
tennas ‘i4 and ‘I5 constitute the north-south 10 inbefore described. The output circuit of the
antennas'while the antennas ‘l6 and ‘15 are posi
integrating network 83' is coupled to the hori
tioned on a line normal to that of the antennas
zontal beam-de?ecting electrodes of tube 39.
‘M, 15 and constitute the east-west antennas.
Reference is made to the curves of Figs. 6 and '7
The system includes two transmitters ‘I I, ‘#3 ‘each
for an explanation of the operation of the sys
15
having a modulation input circuit coupled
tem just ‘described. Thefrequency character
through a respective delay network‘ ‘l8, ‘F9 to e istic of the wave signal of transmitter ‘12 for sev
an output circuit of a synchronizing-signal gen
eral cycles of the saw-tooth modulation signal
erator ‘H, which preferably generates a signal
thereof is represented by curve I, Fig. 6. In re
of periodic-pulse wave form. The latter signal
to a pulse generated by generator ‘H, a
amplitude-modulates the wave signals generated 20 sponse
cycle of the saw-tooth modulation signal is gen
by transmitters ‘H, T3. Each of the transmitters
‘H, ‘(3 has an output circuit coupled to a respec
tive one of the antennas ‘M, ‘H5. The system also
includes a transmitter ‘l2 having a modulation
erated in transmitter 12 and frequency-modulates
the wave signal thereof over a frequency range
fs-fe.
The saw-tooth modulating signal has a
saw-tooth duration equal to at least twice the
signal generator coupled to an‘ output circuit of 25 time of wave-signal travel between the antennas
the’ synchronizing-signal generator ‘H for syn
chronized operation therewith and adapted to
‘M, ‘E5. The pulse generated by generator 11 is
translated through delay network ‘I8 and ampli
tude-modulates the wave signal of transmitter
‘H, which has a frequency fa, as represented by
30
this signal is at least twice as long as the time
curve J. The value of delay provided by the net
of wave-signal travel between either of the pairs
work ‘58 is preferably so chosen that the pulse
generate a periodic signal of saw-tooth wave
form. The duration of each saw-tooth cycle of
of‘ antennas ‘l5, ‘M or ‘I5, 15. The saw-tooth
signal is applied to a modulator included in
transmitter ‘I2 to frequency-modulate the carrier
Wave generated in the latter. Frequency~modu
lation transmitter ‘12 has’ an output circuit cou
modulation occurs at an instant 259 which is later
than the initiation at time is of a cycle of the
35 signal of saw-tooth wave form, the time delay
t8—t9 being equal to the time of signal travel be
tween antennas ‘M, ‘L5. The signal of pulse wave
form generated by the generator TI is applied in
similar manner through the delay network ‘l9,
pled to antenna ‘15. It will be understood that
those portions of the Fig. 5 system heretofore
described are normally terrestrially located and
having the same value of delay as the network
that the remaining portion of the system pres 40 ‘F8, to a modulation circuit of the transmitter 13
ently to be described is normally associated
where the wave signal of frequency f1 generated
with the craft whose direction is to be deter
by transmitter ‘I3 is amplitude-modulated by the
mined.
pulse signal, as indicated by curve K.
The Fig. 5 system includes a direction—indicat
The Wave signals of transmitters ‘I I, ‘l2, ‘13 are
45
ing device which includes means for receiving
radiated from antennas ‘M, 15 and ‘I6, respec
wave signals from a ?rst two of the antennas
tively, and are propagated through space to the
for example, the north-south antennas ‘M, ‘15,
antenna 84 where they are received and applied
for providing a ?rst control signal. This means
to beat-frequency detectors 80 and 80'.
includes means for receiving one of the wave
Consider for the moment only the operation of
signals to provide a reference signal having a 50 the detector 88 and the circuit elements in cas
characteristic which varies with time and
cade therewith. The tuned input circuit of this
means for mixing therewith-the other received
detector has a pass band sufficiently broad to in
wave‘ signal to derive a beat-frequency signal.
clude the frequency fs and the frequency range
For this purpose there is provided a beat-fre
55 fs-fa, inclusive, but includes a wave-signal trap
quency detector 80 which has an input circuit
or ?lter circuit which enables the detector to re
coupled to the antenna 84 and tuned to receive
ject or be unresponsive to the frequency 3‘? of the
the wave signals of both of the transmitters ‘H
transmitter 13. The wave signal received from
and 12 but to reject the wave signal of the trans
transmitter ‘I2 provides in detector 80 a reference
mitter 13 as by the provision in the input circuit
signal the frequency of which varies over the fre
60
of unit 80 of a wave trap or wave-rejection ?lter
quency range fs-J‘s as indicated by graph L of
circuit. The detector 80 has an output circuit
Fig. 7. There is also received by the detector 80
coupled through a beat-frequency ampli?er and
a pulse-modulated wave signal radiated from an
limiter 8| to an input circuit of a frequency
tenna 14 and having a frequency fa. Assume now
detector 82. The detector 82 is responsive to
that the direction-indicating device is located at
the beat-frequency signal for deriving therefrom 65 some point equidistant from antennas ‘l4 and 15.
a control signal having an amplitude varying
Under this assumed condition of operation, the
with the frequency thereof. Detector 82 has an
phase relationships of the modulation compo;
output circuit coupled through an ampli?er and
nents of the pulse-modulated wave signal from
integrating network 83 to the vertical beam
70 antenna ‘M with respect to the modulation com
de?ecting electrodes of cathode-ray tube til.
ponents of the frequency-modulated wave signal
The direction-indicating device also includes
radiated from antenna 75 are the same upon re
means for receiving‘wave signals radiated from
ception at the direction-indicating device as at
a second two of the spaced antennas, for ex
the time of radiation since the times of signal
ample the east-west antennas ‘I6, ‘I5, and re
travel of the two wave signals are equal. The
75
sponsive thereto for providing a second control
2,406,468
"15
reference signal and the pulse-modulated signal
are combined in detector 80 to derive a beat-fre
quency signal of periodic-pulse wave form having
a difference frequency in", Fig. 7. This beat-fre
quency signal has its amplitude limited by the lim
iter of unit 8| to reduce the undesirable effect of
changes of intensity of the received wave signals
due to atmospheric fading and the like. The lim
16
under the last-assumed condition of operation,
frequency detector 82 applies through unit 83 a
signal which is characteristic of the south posi
tion and is effective to produce a downward de
?ection of the beam of tube 30 in the vertical
direction.
At all assumed positions in the northerly
quadrants, the beat-frequency signal derived
ited beat-frequency signal is then ampli?ed by
by the detector 80 has a frequency between f0”
the ampli?er of unit 8| and applied to frequency 10 and f4, depending upon the direction of the in
detector 82, which has a band-pass characteristic,
dicating device with respect to the spaced an
of width f3—f4, centered on the frequency in" and
tennas 14, 15. Similarly, at all points in the
which develops in the output circuit thereof a
southerly quadrants the beat-frequency signal
control signal having a characteristic, for exam
has a frequency between )‘3 and in" dependent
ple an amplitude, varying with the deviation of
upon the same factor. The control signal de
the. frequency of the beat-frequency signal from 15 rived from this beat-frequency signal thus has
the mean frequency f0". Frequency detector 82
a polarity and amplitude indicative of direction
produces no output signal for the mean fre
quency fa",of course, since it is centered on this
with relation to the antennas 14, ‘I5.
7
The operation of the units 80'-83', inclusive, is
frequency. :For the condition of operation here
20 similar to that described in connection with the
tofore assumed, no potential is translated through
ampli?er and integrating network 83 to the verti
cal de?ecting electrodes of tube 43 so that the
units 80-83, inclusive. The pass band of the
tuned input circuit of the detector 80’ includes
the frequency f7 and the frequency range fs-fe,
luminous spot thereof is not de?ected in the verti
inclusive. The reference signal radiatedfrom
cal direction.
25 antenna 15, and having a frequency range fs-fc,
.Assume now that the position of the direction
is evaluated by the wave signal of frequency f’! ‘
indicating device is moved into the northeast
from antenna 16 to develop in theroutput circuit
quadrant. For this assumed condition of opera
of the detector 80’a beat-frequency signal hav
tion, the antenna 14 is then closer to the indicat
ing a frequency within the range from ii to f2,
ing device than is the antenna 75 and the time 30 It will be evident that frequency fl is charac
of signal travel of the wave signals from antenna
teristic of an assumed West position of the direc
15.is longer than that from antenna 14.
The
tion indicating device and that f2 is characteristic
of an assumed east position. The‘ particular
comes effective to phase-delay the modulation
frequency of this signal depends, of course, upon
components of the frequency-modulation wave
35 the direction of the indicating device with re
signal radiated from antenna 15 with respect to
spect to the antennas 75, ‘I6. Discriminator _8,2'
the modulation components of the pulse-modu
has a linear-response characteristic over the fre
lated‘wave signal radiated from antenna 14. For
quency range fi-f2 and is so tuned as to produce
the condition that the indicating device is due
a control signal having zero amplitude in re
north of the antennas ‘l4, 15, this phase delay is 40 sponse to a beat-frequency signal having a fre
equal to kd which is the maximum phase dis
quency f0’ characteristic of an assumed position
placement occasioned by the antenna spacing.
of the direction-indicating device due north or
Under this last-assumed condition, the reference
south of the antennas 15, 1G and thus equidistant
signal and the pulse-modulation signal are com
therefrom. The control signal under consider
bined in detector 80 to derive a beat-frequency 4:5 ation has a negative polarity and a maximum
spacing between the antennas 14 and ‘i5 now be
signal having a periodic-pulse wave form and a
amplitude for an assumed west position of the
difference frequency of fe—-f5, or f4. Frequency
indicating device and has a positive polarity and
maximum amplitude for an assumed east posi
as shown by curve M'and provides a signal of
The control signal from the output of wfre
positive polarity for any input signal within the 50 tion.
quency detector 82' is applied‘ through ampli?er
frequency range between f0" and f4. Thebeat
and integrating network 83' to the horiiontal
frequency signal of frequency f4 produces in the
beam-de?ecting
electrodes of tube 30 to deter
output, of frequency detector 82 a control signal
mine
the
indications
thereof in another co
of maximum amplitude and‘: positive polarity
ordinate direction. The resultant de?ection of
which is characteristic of the north position. 55 the cathode-ray beam of tube 30 under control
This signal is applied through the unit 83 to the
of the control, signals developed by units 80-83,
vertical de?ecting electrodes of tube 30 to pro
detector 82 has a linear-response characteristic
inclusive “and 80'-83’, inclusive, thus provides
duce a maximum upward deflection of thevbeam
thereof in the vertical direction.
without ambiguity in indication of the direction
of the indicating device with relation to the an
tenna system 14, 75 and 76 as in the Fig. 3 em
the direction-indicating device is moved into 60 bodiment.
.
the southeast quadrant. In this case, the an
While
there
have
been
described
What
are
at
tenna spacing d is effective to phase-delay the
present considered to be the preferred embodi
modulation components of the pulse-modulated
ments of this invention, it will be obvious to those
wave'signal from antenna 14 with respect to the 65 skilled
in the art that various changes and modi
modulation components of the frequency-modu
?cations
may be made therein without departing
lated wave signal from antenna 75. The refer
1 Assume on the other hand that the position of
ence, signal and pulse-modulated signal are com
bined in detector 8!] to derive a beat-frequency
signal which, for the condition that the indicat
from the invention, and it is, therefore, aimed
to cover all such changes and modi?cations as
fall within the true spirit and scope of the in
ing device is due south of ‘the antenna '24, 15, 70
has a difference frequency of fe-fc or f3.
Fre- ‘
quency detector 32 produces in the output circuit
thereof a control signal of negative polarity for
any input signal within the range fs-fo". Thus
.
'
'
vention.
V
'7 What is claimed is:
'_
i
a
1
.
- 1. In a radiant-energy system of the type
which effects the translation of direction-indica
tive modulation signals at least one of. which is
of pulse wave form over at least two space paths
’.,.
2,406,468
17
extending between an antenna of one antenna
system and individual spaced antennas of an
18
erence plane the direction of one of said antenna
systems relative to the other comprising, means
responsive to the pulse-modulation signal trans
other antenna system, a direction-indicating de
lated over the shorter of said space paths for de
vice for indicating with relation to a predeter
veloping a reference signal having a characteris
mined reference plane the direction of one of
tic which varies with time, means responsive to
said antenna systems relative to the other com
the pulse-modulation signal translated over the
prising, means for receiving said modulation
longer of said space paths for evaluating said
signal of pulse wave form translated over one of
reference signal to derive therefrom a control
said space paths, means responsive to the modu
lation signal translated over the other of said 10 signal having a characteristic varying with the
relative lengths of said space paths, and means
space paths for providing a reference signal of
responsive to said control signal for indicating
saw-tooth wave form having a characteristic
said direction.
which varies with time, means responsive to said
. In a radiant-energy system of the type
received modulation signal of pulse wave form
which
e?ects the translation of a pulse-modula
15
for evaluating said reference signal to derive
tion signal over at least two space paths extend
therefrom a control signal having a character
ing between an antenna of one antenna system
istic varying with the relative lengths of said
and individual spaced antennas of another an
space paths, and means responsive to said con
tenna system, a direction-indicating device for in
trol signal for indicating said direction.
2. In a radiant-energy system of the type 20 dicating with relation to a predetermined refer
ence plane the direction of one of said antenna
which eifects the translation of direction-indic
systems relative to the other comprising, means
ative modulation signals at least one of which
responsive to the pulse-modulation signal trans
is of pulse wave form over at least two space
lated over the shorter of said space paths for
paths extending between an antenna of one an
developing a reference signal of saw-tooth wave
tenna system and individual spaced antennas of
form having an amplitude which varies with
another antenna system, a direction-indicating
time,
means responsive to the pulse-modulation
device for indicating with relation to a predeter
signal translated over the longer of said space
mined reference plane the direction of one of
paths for evaluating said reference signal to
said antenna systems relative to the other com
prising, means for receiving said modulation sig 30 derive therefrom a control signal having a char
acteristic varying with the relative lengths of said
of pulse wave form translated over one of said
space paths, and means responsive to said control
space paths, means responsive to the modula
signal for indicating said direction.
t‘cn signal translated over the other of said space
6. In a radiant-energy system of the type
paths for providing a reference signal of saw
which
effects the translation of a pulse-modula
tooth wave form having a characteristic which 35
tion signal over at least two space paths extend
varies with time over an interval related to the
ing between an antenna of one antenna system
spacing of said spaced antennas, means respon
and individual spaced antennas of another an
sive to said received modulation signal of pulse
tenna system, a direction-indicating device for
wave form for evaluating said reference signal
to derive therefrom a control signal having ‘a 40 indicating with relation to a predetermined ref
erence plane the direction of one of said antenna
characteristic varying with the relative lengths
systems relative to the other comprising, means
of said space paths, and means responsive to said
I control signal for indicating said direction.
responsive to the pulse-modulation signal trans
lated over the shorter of said space paths for de
3. In a radiant-energy system of the type
which effects the translation of direction-indic 45 veloping a reference signal of saw-tooth wave
form having a saw-tooth duration related to the
ativeinodulation signals at least one of which
spacing of said spaced antennas, means respon
is of pulse wave form over at least two space
paths extending between an antenna of one an
sive to the pulse-modulation signal translated
over the longer of said space paths for evaluating
another antenna system, a direction-indicating 50 said reference signal to derive therefrom a con
trol signal having a characteristic varying with
device for indicating with relation to a predeter
the relative lengths of said space paths, and
mined reference plane the direction of one of
means responsive to said control signal for in
said antenna systems relative to the other com
dicating said direction.
prising, means for receiving said modulation sig
'7. In a radiant-energy system of the type
nal of pulse wave form translated over one of 55
which effects the translation of a pulse-modula
said space paths, means responsive to the mod
tion signal over at least two space paths extend
ulation signal translated over the other of said
ing between an antenna of one antenna system
space paths for providing a reference signal of
and individual spaced antennas of another an
saw-tooth wave form having a characteristic
which varies linearly with time over an interval 60 tenna system, a direction-indicating device for in
dicating with relation to a predetermined refer
related to the spacing of said spaced antennas,
ence plane the direction of one of said antenna
means responsive to said received modulation
systems relative to the other comprising, means
signal of pulse wave form for evaluating said
responsive to the pulse-modulation signal trans
reference signal to derive therefrom a control
signal having a characteristic varying with the 65 lated over the shorter of said space paths for de
veloping a. reference signal having a characteris
relative lengths of said space paths, and means
tic which varies with time, means responsive to
responsive to said control signal for indicating
the pulse-modulation signal translated over the
said direction.
longer of said space paths for evaluating said
4. In a radiant-energy system of the type
reference
signal to derive therefrom a control
which effects the translation of a pulse-modula 70
signal having a characteristic varying with the
ticn signal over at least two space paths extend
relative lengths of said space paths, said last
ing between an antenna of one antenna system
named means including a vacuum tube having a
individual spaced antennas of another an
?rst control electrode coupled to said reference
tenna system, a direction-indicating device for
indicating with relation to a predetermined ref 75 signal developing means and a second control
tenna system and individual spaced antennas of
‘l3?
electrode to which is applied said last-mentioned
pulse-modulation signal, and means responsive
to said control signal for indicating said direc
‘20
11.‘ In a radiant-energy system‘ of the type
which eifects the translation of a ?rst wave signal
frequency-modulated with a signal of saw-tooth
tion.
wave form and of a‘ second Wave signal modulated
8. In a radiant-energy system of the type which
with a signal of pulse wave form over individual
effects the translation of a pair of distinctive
space paths extending between an antenna of
pulse-modulation signals over individual ones of
one antenna system and individual spaced anten
at least two space paths extending between an
nas of another antenna system, a direction-indi
antenna of one antenna system and individual
cating device for indicating with relation to a
spaced antennas of another antenna system, a 10 predetermined reference plane the direction of
direction—indicating device for indicating with re
one of said antenna systems relative to the other
lation to a predetermined reference plane the di
comprising, means for receiving said ?rst wave
rection of one of said antenna systems relative
ignal and for deriving therefrom a reference sig
to the other comprising, a plurality of reference
nal of saw-tooth wave form, means for receiving
signal developing means normally responsive to
said second wave signal and responsive thereto
individual ones of said pulse-modulation signals
for evaluating said reference signal to derive
for developing individual reference signals each
therefrom a control signal having a character
having a characteristic which varies with time,
istic varying with the frequency of said ?rst wave
means responsive to the development of a refer
signal during the pulse intervalof said second
ence signal by the one of said reference-signal de 2.0 wave signal, and means responsive to said con
veloping means which is responsive to the modu
trol signal for indicating said direction.
lation signal translated over the shorter of said
12. In a radiant-energy system of the type
space paths for de-energizing the other of said
which effects the translation of a ?rst wave sig
reference-signal developing means, means re
nal frequency-modulated with a signal of saw
sponsive to the pulse-modulation signal trans
tooth wave form and of a second wave signal
modulated with a signal of pulse wave form over
individual space paths extending between an an
lated over the longer of said space paths for eval
uating the reference signal developed by the re
sponsive reference-signal developing means to de
tenna of one antenna system and individual
spaced antennas of another antenna system, a di
rection-indicating device for indicating with re
lation to a predetermined reference plane the
direction of one of said antenna systems relative
to the other comprising, means for receiving said
?rst wave signal to provide a reference signal
having a characteristic which varies with time
rive therefrom a control signal having a charac
teristic varying with the relative lengths of said
space paths, and means responsive to said con
trol signal for indicating said direction.
9. In a radiant-energy system of the type which
effects the translation of a first wave signal fre
quency-modulated with a signal of saw-tooth
wave‘ form and of a second wave signal modulated
with a signal of pulse wave form over individual
space paths extending between an antenna of one
antenna system and individual spaced antennas
of another antenna system, a direction-indicating
device for indicating with relation to a predeter
mined reference plane the direction of one of said
and for receiving and hetrodyning therewith said
second wave signal to derive therefrom a beat
frequency signal having a frequency varying with
the frequency of said ?rst received wave signal
during the pulse interval of said second received
wave signal, means responsive to said beat-fre
quency signal for deriving therefrom a control
signal having an amplitude varying with the fre
quency of said beat-frequency signal, and means
'. responsive to said control signal for indicating
said direction;
13. In a direction-indicating system of the type
including at least one transmitter and a pair of
spaced antennas'for transmitting individual ones
antenna systemsrelative to the other comprising,
means for receiving said ?rst wave signal to pro
vide a reference signal having a characteristic
which varies with time, means for receiving said
second‘wave signal and responsive thereto for
evaluating said reference signal to derive there
from a control signal having a characteristic
varying with the frequency of said ?rst wave sig
nal during the pulse interval of said second wave
signal, and means responsive to said control sig
. of a pair of wave signals modulated by individual
modulation signals having a determinable time
relation therebetween and at least one of which
has a pulse wave form, a direction-indicating de
vice for receiving said wave signals to indicate
with relation to a predetermined reference plane
its direction with respect to said antennas com
prising, means for receiving the one of said wave
signals which is modulated by the modulation
signal ‘of pulse wave form, means for receiving
nal for indicating said direction.
10. In a radiant-energy system of they type
which effects the translation of a ?rst wave sig
nal frequency-modulated with a signal of saw
tooth wave form and of a second wave signal mod
ulated with a signal of pulse wave form over in
dividual space paths extending between an an_
tenna of one antenna system and individual 60 the other of said wave signals to provide a ref
spaced antennas of another antenna system, a di
erence signal having a characteristic which varies
rection-indicating device for indicating with rela
with time, means responsive to said one received
tion to a predetermined reference plane the di
signal for evaluating said reference signal to de
rection of one of said antenna systems relative to
rive therefrom a control signal having a charac
the 'other‘i'comprising‘, means for receiving said
teristic varying with the relative times of recep
tion of the modulation components of said wave
signals, and means responsive to said control sig
nal for indicatingsaid direction.
14. In a direction-indicating system of the type
including at least one transmitter and a pair of
spaced antennas for transmitting individual ones
?rst wave signal to provide a reference signal
having a characteristic which varies with time,
means for receiving said second wave signal and
responsive to the modulation components thereof
for evaluating said reference signal to derive
therefrom a control signal having a characteristic
varying with the frequency of said ?rst wave sig
nal during the pulse interval of said second wave
signal, andmeans responsive to said control sig
nal for indicating said directions
a
,
of a pair of distinguishable wave signals modu
lated'by individual modulation signals having a
determinable time relation therebetween and at
75
leastv one of which has a pulse wave form, a
2,406,468
21
direction-indicating device for receiving said
wave signals to indicate with relation to a pre
determined reference plane its direction with re
spect to said antennas comprising, means for se
lectively receiving the one of said Wave signals
which is modulated by the modulation signal of
pulse Wave form, means for selectively receiving
the other of said wave signals to provide a ref
erence signal having a characteristic which varies
with time, means responsive to said one received
signal for evaluating said reference signal to de
rive therefrom a control signal having a char
acteristic varying with the relative times of re
22
whereby the de?ected position of said beam pro
vides without ambiguity an indication of said
direction.
17. In a radiant-energy system of the type
which effects the translation of pulse-modula
tion signals over at least two pairs of space paths
extending between an antenna of one antenna
system and individual pairs of spaced antennas
of another antenna system, a direction-indicat
ing device for indicating with relation to a pre
determined reference plane the direction of one
of said antenna systems relative to the other com
prising, means responsive to the pulse-modula
tion signal translated over the shorter space path
ception of the modulation components of said
wave signals, and means responsive to said con 15 of each pair thereof for developing individual
reference signals each having a characteristic
trol signal for'iiid'ié'ating said direction.
which varies with time, means responsive to the
pulse-modulation signal translated over the long
er space path of each pair thereof for evaluating
tive modulation signals at least one of which is
of pulse wave form over at least two pairs of 20 the reference signal developed for the other path
of said each pair to derive therefrom individual
space paths extending between an antenna of
control signals each having a characteristic vary
one antenna system and individual pairs of
ing with the relative lengths of the space paths
spaced antennas of another antenna system, a
of said each pair of space paths, and signal-dis
direction-indicating device for indicating with
play
means responsive jointly to said control sig
relation to a predetermined reference plane the
nals for indicating in two coordinate directions
direction of one of said antenna systems rela
and without ambiguity said direction.
tive to the other comprising, means for receiving
18. In a direction-indicating system of the type
said modulation signal of pulse wave form trans
15. In a radiant-energy system of the type
which effects the translation of direction-indica
lated over one space path of each pair thereof,
means responsive to the modulation signal trans
lated over the other space path of each pair there
of for providing individual reference signals of
saw-tooth wave form each having a character
istic which varies with time, means responsive to
the modulation signal received over said one space
path of each pair thereof for evaluating said
reference signal provided for the other path of
including at least one transmitter and at least
three antennas spaced in nonlinear relationship
for transmitting individual ones of a plurality of
wave signals modulated by individual modulation
signals having a determinable time relation
therebetween, a direction-indicating device for
receiving said wave signals to indicate with rela
tion to a predetermined reference plane its direc
tion with respect to said antennas comprising,
means for receiving wave signals radiated from a
said each pair to derive therefrom individual con
?rst two of said antennas to provide a first con
trol signals each having a characteristic varying
trol signal having a characteristic varying with
40
with the relative lengths of the space paths of
the relative times of reception of the modulation
said each pair of space paths, and signal-display
components of said Wave signals, means for re
means responsive jointly to said control signals
ceiving wave signals radiated from a second two
for indicating in two coordinate directions and
of said antennas in a different line than said ?rst
without ambiguity said direction.
two antennas to provide a second control signal
16. In a radiant-energy system of the type
having a characteristic varying with the relative
which effects the translation of direction-indica
times of reception of the modulation components
tive modulation signals at least one of which is
of
said last-named wave signals, and signal dis
of pulse wave form over at least two pairs of
play means responsive to said ?rst control signal
space paths extending between an antenna of
for determining the indications thereof in one
one antenna system and individual pairs of
coordinate direction and simultaneously respon
spaced antennas of another antenna system, a
sive
to said second control signal for determining
direction-indicating device for indicating with
the indications thereof in another coordinate di
relation to a predetermined reference plane the
rection, thereby to provide without ambiguity in
direction of one of said antenna systems relative
dications of said direction.
to the other comprising, means for receiving said ‘
19. In a direction-indicating system of the type
modulation signal of pulse wave form translated
including at least one transmitter and at least
over one space path of each pair thereof, means
three antennas spaced in nonlinear relationship
responsive to the modulation signal translated
for transmitting individual ones of a plurality of
over the other space path of each pair thereof
wave signals modulated by individual modulation
for providing individual reference signals of saw
signals having a determinable time relation
tooth wave form each having a characteristic
therebetween, a direction-indicating device for
which varies with time, means responsive to the
receiving said wave signals to indicate with rela
modulation signal received over said one space
tion to a predetermined reference plane its direc
path of each pair thereof for evaluating said ref
tion with respect to said antennas comprising,
erence signal provided for the other path of said
means for receiving wave signals radiated from
each pair to derive therefrom individual control
a ?rst two of said antennas to provide a ?rst con
signals each having a characteristic varying with
trol signal having a characteristic varying with’
the relative lengths of the space paths of said
the relative times of reception of the modulation
each pair of space paths, and a cathode-ray tube
components of said wave signals, means for re
responsive to one of said control signals for de
ceiving wave signals radiated from a second two
?eeting the cathode-ray beam thereof in one co
of said antennas in a different line than said ?rst
ordinate direction and simultaneously responsive
two antennas to provide a second control signal
to the other of said control signals for de?ect
having a characteristic varying with the relative
ing the cathode-ray beam of said tube in another
75 times of reception of the modulation components
coordinate direction normal tosaidr?rst direction,
2,406,468
23
of. said ‘last-named wave si'gnals,.and a cathode
ray tube including means responsive to the ?rst
control signal for de?ecting the electron beam
thereof in one coordinate direction and simul
taneously responsive .to the second control signal
for de?ecting said electronbeam in another coor
dinate direction, whereby the de?ected position
of said beam provides without ambiguity an in
dication of said direction.
I
_ 20. .In a direction-indicating system of the type
includingat least one transmitter and atleast
three antennas spaced in nonlinear relationship
for transmitting individual ones of a plurality of
Wave signals modulated by individual modulation
signals having a determinable time relation
24
' 22. A direction-indicatingsystem comprising,
a pair of antenna systems remotely spaced from
one another and at least one of which includes
spaced antennas, means coupled toone of said
antenna systems for effecting the translation of
a pulse-modulated Wave signal over at least two
space paths extending between an antenna of one
antenna system andindividual spaced antennas
of another antenna system, means coupled tothe
other of said antenna systems and responsive to
the Wave signal translated over the shorter of said
space paths for developing a reference signal hav
ing a characteristic which varies with vtime, means
coupled to said other antenna system and respon
15 sive to the modulation signal translated over the
therebetween, a direction-indicating device for
longer of said space paths for evaluating said ref;
receiving said Wave signals to indicate with rela
erence signal to derive therefrom a control sig
tion to a predetermined reference plane its direc
nal having a characteristic varying with the rel
tion with respect to said antennas comprising,
ative lengths of said'space paths,_and means vre
means for receiving one of a ?rst Pair of said
sponsive to said control signal for indicating with
wave signals radiated from a ?rst pair, of said
relation to a predetermined reference plane the
antennas to provide a ?rst reference signal hav
direction of one of said antenna systems relative
ing-y a characteristic whichv varies with time,
to the other. 7
‘
r
means for receiving the other of said ?rst pair
23. A direction-indicating system comprising,
ofv wave signals and responsive to the modulation 25 means for providing two wave signals, means for
components thereof for evaluating said ?rst ref
modulating said wave signals with individual
erence signalto provide a ?rst control signal hav
modulation signals having a determinable time’
ing- a characteristic varying with the relative
relation therebetween, at least one of said mod
times of reception of the modulation components
ulating signals having a pulse wave form, a pair
of said ?rst pair of wave signals, means for re
of spaced antennas coupled to said ?rst-men
ceiving one of a second pair of wave signals radi
tioned means for radiating individual ones of said
ated from a second pairof said antennas in a
modulated wave signals, means for receiving the
different line than said ?rst pair to provide a
one of said wave signals which is modulated by
second reference signal having a characteristic
said one modulation signal of pulse wave form,
which varies with time, means for receiving the 9 means for receiving the other of said wave signals
other of said second pair of wave signals and re
and responsive to the modulation components
sponsive to the modulation components thereof
thereof to provide a reference signal having a
for evaluating said ‘second reference signal to
characteristic which varies with time, means re
sponsive to the modulation components of said
teristic varying with the relative times of recep 40 one received signal for evaluating said reference
tion of the modulation components of said second
signal to derive therefrom a control signal hav
pair of wave signals, and signal-display means
ing'a
characteristic dependent upon the relative
responsive to said ?rst control signal for provid
times of reception of the modulation components
ing an indication in one coordinate direction and
of said wave signals, and means responsive to
simultaneously responsive to said second control
said control signa1 for indicating with relation
signal for providing an indication in another co
to a predetermined reference plane the direc
ordinate direction, whereby said indication in
tion of said receiving means relative to said an
said coordinate directions provides without. am-.
‘tennas.
provide a second control signal having a charac
biguity indications of said direction.
~
21. A direction-indicating system comprising,
a pair of antenna systems remotely spaced from
one another and at least one of which includes
spaced antennas, means coupled to one of said
antenna systems for effecting the translation of
direction-indicative modulated wave signals at
least one of which is a ‘pulse-modulated wave
signal over at least two space paths extending
between an antenna of one antenna system and
individual spaced antennas of anotherantenna
system, means coupled to the other of said an
tenna systems for receiving said pulse-modulated
wave signal translated over one of said space
paths, means coupled to said other antenna sys
tem for receiving the wave signal translated over
the other of said space paths for providing a
reference signal of saw-tooth wave form having
a characteristic which varies with time, means
responsive to said received pulse-modulated wave
signal for evaluating said reference signal to
derive therefrom a control signal having a char‘
acteristic varying with the relative lengths of said
space paths, and means responsive to said con
trol signal for indicating with relation to a prede
termined reference plane the direction of one of
said antenna systems relative to the other.
24. A direction-indicating system comprising,
means for providing two wave signals, means
for modulating said wave signals with individual
modulating signals having pulse wave forms and
a determinable time relation therebetween, a pair
of- spaced antennas coupled to said ?rst-men
tioned means for radiating individual ones of said
, modulated wave signals, means for-receiving the '
one of said wave signals ?rst to arrive at said
indicating device and responsive to the modula
tion components thereof for developing a refer
ence signal having a characteristic which varies
with time, means for receiving the other of said
wave. signals and responsive to the modulation
components thereof for evaluating said reference
signal to derive therefrom a control signal hav
ing a characteristic varying with the relative
times of reception of the modulation components
of vsaid wave signals, and means responsive to said
control signal for indicating with relationrto a
predetermined reference-plane the direction of
said receiving means relative to said antennas.
25. A direction-indicating system comprising,
means for providing two wave signals, means for
frequency-modulating one of said wave signals
with‘ a signal of saw-tooth'wave form and for
75 modulating the other of said wave signals with a
2,406,468
25
26
signal of pulse wave form having a determinable
signals, means for frequency-modulating one of
said wave signals with a signal of saw-tooth wave
form having a saw-tooth duration at least twice
time relation with respect to said saw-tooth sig
nal, a pair of spaced antennas coupled to said
?rst-mentioned means for radiating individual
ones of said modulated wave signals, means for
receiving the one of said signals which is modu
lated by said modulation signal of pulse wave
form, means for receiving the other of said wave
signals and responsive to the modulation com
ponents thereof for providing a reference signal
having a characteristic which varies with time,
means responsive to the modulation components
of said one received wave signal for evaluating
said reference signal to derive therefrom a control
as long as the time of wave-signal travel between
said spaced antennas, means for modulating the
other of said wave signals with a signal of pulse
wave form having each pulse thereof delayed in
time from the initiation of a corresponding cycle
of said signal of saw-tooth wave form by the time
of wave-signal travel between said spaced anten
nas, means for receiving said frequency-modulat
ed Wave signal to provide a reference signal hav
ing a characteristic which varies with time, means
for receiving said other wave signal and respon
signal having a characteristic varying with the 15 sive to the modulation components thereof for
evaluating said reference signal to derive there
frequency of said other received wave signal dur
from a control signal having a characteristic de
ing the pulse interval of said one received wave
signal, and means responsive to said control sig
pendent upon the relative times of reception of
the modulation components of said wave signals,
nal for indicating with relation to a predeter
mined reference plane the direction of said receiv 20 and means responsive to said control signal for
indicating with relation to a predetermined ref
ing means relative to said antennas.
26. A direction-dndicating system comprising,
erence plane the direction of said receiving means
relative to said antennas.
means for providing two wave signals, a pair of
spaced antennas coupled to said ?rst-mentioned
means for radiating individual ones of said wave 25
BERNARD D. LOUGHLIN.
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