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Патент USA US2405238

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Aug. 6, 1946.
s. w. sEELl-:Y
2,495,238
POSITION DETERMIÑING SYSTEM
Filed April 1s, 1940
e sheets-sheet 1
»Stuart ‘l/V.' «Seeleyl
Aug. 6, 1946.
2,405,238
s. w. s'EELEY
POSITION DETERMINING SYSTEM
Filed April 13, 1940
6 Sheets-Sheet 2
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Aug. 6, 1946.
2,405,238
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POSITION DETERMINING SYSTEM
Filed April 13, 1940
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2,405,238
POSITION DETERMINING SYSTEM
Filed April 15, 19470
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Aug. 6. 1946.
s. w. sEELEY
2,405,233
POSITION DETERMINING SYSTEM
Filed April 15, 1940
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PòsITloN DETERMINING SYSTEM
Filed April 13, 1940
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Patented Aug. 6, 1946
2,405,238
UNITED STATES PATENT oFFlcE
2,405,238
,
POSITION DETEBMINING SYS‘TEM
Stuart W. Seeley, Roslyn, N. Y., assignor to Radio
Corporation of America, a. corporation of Dela
Ware
" Application Aprilia, 1940, serial NBL 329.434
1s claims. (ci. 25o-1)
l
This invention relates to a system and method
for accurately determining the instantaneous
' position of a movableobject with respect to one
or more reference points whose locations are
known. More particularly, it relates to a radio
control system whereby a movable object may
be guided directly to_ the location of a predeter
mined objective.
By the term “movable object” is herein meant
any aircraft, ship, submarine, motor vehicle or
the like. The invention is particularly useful for
directing the night of an airplane to a position
directly above a predetermined objective such as
an airport, city, crossroad, bridge, or the like,
and such a particular application will be herein
described, although it is to be understood that
the invention is nowise limited to the particular
arrangement described.
Aircraft position locating systems are known
2
ference by other transmissions. At the same
time, the nature of the transmission is such that
it preserves substantially complete secrecy, thus
making it impossible for unauthorized listeners
to utilize any signals radiated from the airplane
or the control station which may be intercepted.
A further object of the present invention is to
provide a system which is not dependent `for its
operation upon the relative amplitudes of the
transmitted or received signals but merely upon
the presence or absence of a signal. So far as is
known most of the systems of the prior art oper
ate in conjunction with overlapping directional
ilelds which are alternately keyed, the “on course”
indication being a function of the relative am
plitudes of the two iields. T'he position indicators
of the prior art generally utilize directional loop
antennas for the successive determination of the
bearing of the airplane with respect to two or
in which directional bearings of two or more 20 more ground stations. The present system dif
ground stations `are successively, or simultane
fers from the known prior art in that it depends
ously taken from an airplane. By drawing lines
for its operation upon the invariable velocity of
on a map having angles which correspond to the
propagation of radiant energy. As a result, the
bearings of known ground stations and which
accuracy of the present system exceeds that of
pass through the points on the map correspond 25 all known prior systems.
ing to the location of the ground stations, the po
A still further object of this invention is to
sition of the airplane may be determined by the
provide a position determining system for air
point at which the lines intersect. Systems are
planes and the like, in which the distance from
also known by means of which such bearingsA are
the airplane to two or more ground stations is
automatically taken and recorded so as to pro
accurately determined, as distinguished from
vide a continuous indication of the location of
known systems in which the angular bearing of
the airplane with respect to predetermined ground
stations. Such directional bearings, however,
are subject to substantial errors due to “night
effect” and other causes, as is well known. It is
the principal object of this invention to provide
a position determining system for movable ob
the ground'station is determined.
A still further object of this invention is to
provide a visual indicator for airplanes, and the
like, which may be preset to guide the plane to a
predetermined objective, the indicator being pro
vided with an objective index and one or more
jects Which is free from the errors of the known
variable indexes which correspond to the position
systems and which is sufficiently accurate to in
dicate the location of the object with respect to 40 of the plane at any time. 'I'he airplane is then
guided along a path which causes the variable in
a given _point or points within an error of a few
dex or indexes to approach the objective index,
hundred feet, even where the reference points or
and finally to coincide therewith. At such time
ground stations are several hundred miles dis
the pilot of the airplane knows that he has
tant. Another object of this invention is to ac
reached his objective and may then prepare to
complish the foregoing result in such a manner
land or accomplish any other mission which has
as to provide the navigator, or an aircraft, for
been assigned to him.
example. with a continuous visual or semipic
A still further object of this invention is to
torial indication of his distance from the known
provide a simple, adjacent, easily installed, and
control points, and from a third point which is
substantially fool-proof form of guiding or posi
to be the objective of his flight.
tion ñnding system by means of which it is pos
A further object of this invention is to accom
sible to locate the position of an aircraft in space
plish the foregoing results in such a manner that
in a plane which is either parallel to or normal to
the system is substantially free from interfer
the surface of the earth, as well as to determine
ence due to static and other electrical disturb
ances, and likewise substantially free from inter 55 the instantaneous location 'in space of an air
I
2,405,988
.
craft, or the like, relative to a predetermined or
-4
.
splitter; Figure 9 is the circuit diagram of a Duke
- selected objective.
selector; Figure 10 is a diagram illustrating the
The foregoing and other objects of this'inven
operation of the step selector of Fig. 9; Figure 11
tion are accomplished by a system in’which a' plu
_ is the circui-t diagram of a clipper tube; Figure 12
rality of'ground stations are provided, which for 5 is the circuit diagram of a keying tube; Figure 13
convenience are herein termed the “primary con..is a diagram _illustrating the' input' and output
trol station” and the “secondarycontrol station.” ' voltages of the keying tube; Figure 14 is the cir
The locations of these control stations are. _fixed
cuit diagram of a phase reverser and clipper; Fig
relative to each other and are accuratelyknown.
ure 15 -is the circuit diagram of a vtime delay net- '
'I'he control stations may be located at permanent
work; Figure 16 is the circuit diagram o1' a com
installations, or they may be located vin trucks orv
mutatorgïand _Figure 17 is the circuit diagram of
other vehicles so as'to be movable to any locationsV - _» an impulse transmitter;
as conditions change. V'li’he control stations may
VThe present invention has a wide variety of
evenbe located in balloons suspended above the - applications, other than the embodiment herein
earth at predetermined locations and heights, or 15 illustrated. It should be clearly understood,
- the control stations may be located _in ships at sea ~ therefore, that anyassumptions made are only
whose positions are accuratelyA known.
Still i'ur- v
>for the purpose of illustration and are not in
ther ?the control' stations may -even be located'
tendedl in any manner to limit the -scope of the
beneath the surface of the earth òr beneath the
present invention. Referring vto Fig. 1, the view
water, or any combination of the above may be
ing screen 2| of a cathode ray tube is illustrated.
used. VIt is to be understood, however. the loca so By suitable apparatus which will be hereinafter
tions of the control stations remain ilxed during
described, a series of ten horizontal lines are
any given night. _
Y
‘ traced acrossthe face of the screen by suitably
The equipment which is utilized at »each control
deilecting the electron beam. The general nature
station includes means for reradiating a pulse of
ofthe beam deflection is such that it is caused to
radio frequency energy. The term "reradia ” is
Vmove horizontally from lef-t to right at a uniform
intended to include reflection as well as actual re
rate in a given time and then to return lfrom
ception and retransmission. The preferred ar
_ right to left in a very much shorterv time to begin
rangement consists of a receiver and a transmit
tracing the second horizontal line in a similar
manner. In each case the return time vof the
beam is made as rapid as possible, and the time
required for returning the beam to its starting
position is usually of theorder of 2 percent of the
time required to trace one line. In this manner
ter. The receiver operates to receive the radio
frequency transmissions from the guided aircraft.
It is connected to the transmitter, and modulates
the same, which reradiates the received wave at a
slightly different radio frequency. In order to
distinguish one ground station from». another the 35 the beam successively traces the tenhorizontal
transmitter frequencies at each station are dif
lines moving in each case from left to right in a `
l ferent.
The equipment required on the movable
time, which for the sake of illustration, may be
object includes a pair of receivers responsive to
the ground station transmitters and a transmit
assumed to be $50.000 of a second.
At the same
time the beam=deflects vertically, in steps or lin
- ter of the impulse type which is well _known in the 40 early with respect to time, so as to move the
art. Such a transmitter radiates an ’extremelybeam from the ñrst’line to the tenth line -in a
short pulse of radio frequency energy,‘the dura- ~ -period approximately equal to 1,4„000 of a second.
tion of the pulse being considerably less -than the y „As before, the beam is returned from the bottom
time required for the wave of radiant energy to ' Aof «the screen to its initial position very rapidly so
travel from the aircraft to the ground station _and 45 that substantially no time~ is' lost between the
return to the aircraft. By measuring Vthe time completion ofthe tenth line and the start of the
required for each impulse to be radiated‘i'rom the
firstV line.
airplane and received again, the actual .distance ‘_ i
of the aircraft from each of the control'stations
may be determined. It will be appreciated that
this information is all that is necessary -to d_etei'- ;
mine the position of the aircraft-,with
to
the two ground stations. l In'the case Voil* _theindi- Y
'
'
'
'
_ It will be appreciated that the beam traces ten
` lcomplete lines, or one frame at the rate of 3,000
frames persecond. Since a radio wave is known
> to travel _at the rate of 300,000,000 meters per sec
_ ond, it will be appreciated that a pulse of radio
ï energy will >travel a distance of 10,000 meters
cator system herein described, it is not necessary
througlispace during the time required for the
for the pilot to make any c_alculationsin ilying -55 beam -to trace each horizontal line. If it now be
to a predetermined objective, while at thesam'e
time, his distance from the control stations'and
from the objective is continuously
indi- _
_assumed that the several line traces produced by
' the cathode ray beam upon the luminescent view
ing target 2l o_f the `cathode ray tube cover an
_ area of approximately 4 inches square, it will at
This invention
be better understood -from ‘60` once become evident that during the time the
the following description when considered- in` con
cathodel ray beam has moved along one line of
‘ nection with the accompanying' drawingsand its _‘ the screen a distance of 1 inch, a radio wave will
scope is indicated by the appended claims.
._
-travel_approximately 2500 meters through space.
Referring to the drawings, Figure 1 is a sketch
It is realized that this ligure is only approximate,
indicating the cathode ray indicator located .in 65 since it does not take into consideration the small
the movable object; Figure 1a is a sketch similar
to Figure 1; Figure 2 is a sketch illustrating the ‘
general system; Figure 3 is a block diagram of the
cathode ray indicator system which is provided ‘in
the aircraft; Figure 4 is the wiring diagram of a
frequency counter; Figure 5 is an explanatory
diagram relating to the operation of the frequency
counter; Figure 6 is a wiring diagram of differen
tiator; Figure 7 is the circuit of a saw-tooth dis
charge tube; Figure 8 is the circuit of avphase
period of time required for the return of the
cathode ray beam. In order to simplify the ex
planation, however, this return time will be neg
lected, but -it is to be understood that actualâ cal
culations utilizing this instrument must include a
consideration of the return time.
In accordance with the basic conception of this
invention a short pulse of- radio energy is trans
mitted from the aircraft at a time To. This im
Pllliie is utilized to initiate the scanning cycle of
2,405,288
6
the cathode ray beam. Thus, the left hand end
-of the ilrst scanning line corresponds to the time
To at which the first impulse is radiated. Re
such a system is entirely practical, it has the dis
advantage that it is necessary to align two vari
able index marks with two ilxed index marks
ferring now to Figs. 1a and 2, it will be seen that
the impulse travels from the aircraft 23, is re
ceived by the receiver 25 at the primary control
which may be and usually are located at diilerent
the receiver 35 which is located on the aircraft.
cathode ray beam to provide a mark at the instant
points on the cathode ray screen. ' Accordingly,
a preferred system is herein provided by means
of which only one objective index is required even
station, reradiated from the transmitter 21 and
though the distance from the objective to the pri
received back at the aircraft on a receiver 29.
mary control station diñers considerably from the
The received impulse is then applied to the cath'
ode ray screen so as to produce a small upward 10 distance to the secondary control station.
The preferred method of providing the ñxed
deiiection P in the scanning beam or to vary its
objective index will now be described. It will be
intensity in accordance with well known prac
apparent that the time distance from the pri
tice. The elapsed time is, of course, a measure
mary control station to the objective can readily
of the total distance through which the impulse
be calculated, taking into consideration the known
has traveled, plus some fixed time intervals which
delays of the equipment. Assuming that the
are a function of the circuit characteristics of the
objective is further from the primary control sta
receivers and transmitters utilized and which may
tion than from the secondary control station, the
be accurately predetermined. During this elapsed
time the cathode ray beam has traversed a num
time distance from the primary control station is
ber of horizontal line traces and is, for example, 20 first determined. It is apparent that a mark
could be placed over the scanning line correspond
traversing the eighth line at the instant the re
ing to the calculated time distance. This would
ceived impulse de?lects the cathode ray beam to
not produce a very accurate determination, how
form a position index mark P.
ever, since any change in the position of the lines
At the Same -time the transmitted impulse will
would cause a corresponding error. It is desirable,
be received by the receiver 3| of the secondary
therefore, to include the objective index in the
control station, reradiated on a diiîerent fre
scanning line itself by suitably defiecting the
quency by transmitter 33 and received again by
corresponding to the precalculated time distance.
One method of accomplishing this is to delay a,
pulse initiated at the time the radiated pulse was
transmitted by a period equal to the calculated
deñects the beam downwardly to produce the
time distance. This, however, would require a.
time delay network of proportions which would
position index S illustratedin Fig. la. It has
been assumed in this instance that the aircraft »: be prohibitive in an aircraft. Consequently, pro
vision is made for deriving a pulse which occurs
is at the particular moment slightly nearer the
a known interval after the transmission of the
secondary control station than the primary con
radiated pulse, the known interval being approxi
trol station, so that the position index S from the
mately the desired time distance. This approxi
latter station is received before the position index
P has been received from the primary control. 40 mate timing pulse may then be corrected and
utilized to provide the objective index marker.
station.
Alternatively a series of fixed timing indexes may
It thus becomes apparent that the distance of
be provided, one of the timing indexes being se
the aircraft from the two control stations may be
lected as the objective index by suitable marking
determined by measuring the position of the im
and the exact calibration eiîected by shifting the
pulses P and S along the scanning lines. Specific
time relation of the radiated impulse with respect
objects of this invention, however, make possible
'I'he resultant impulse is also utilized to deflect
the cathode ray beam in a vertical direction, but
in order to distinguish this impulse from the one
previously received it may be phased so that it
a far more accurate determination than would be
to the timing impulses or vice versa. The latter
possible by the suggested measurement, and in
arrangement is preferred and is described here
inafter.
Each line of Fig. l is seen to be divided into
ñve equal time periods by means of small index
marks which occur at regular time intervals and
which represent successive time periods of
addition, a system is provided by means of which
the pilot may fly to a predetermined objective
without having to actually measure the position
of the received position index pulses along the
scanning lines, or to make any calculations what
soever. In accordance with this modification of
the invention a pair of objective indexes OP and
OS are provided which represent the destination
of the aircraft. That is, the pilot is merely re
quired to ny the aircraft until the variable posi
tion indexes P and S coincide with the respective
'objective index, at which time he knows that he
Vhas reached his objective and is within a few
,hundred yards of his destination.
Before the aircraft takes ofi for any given flight
to reach a particular destination it is, of course,
necessary to calculate the time distance of the
objective from each of the given control stations.
Now the time distance from the objective to the
primary control station is not necessarily equal to
the time distance from the objective to the sec
ondary H“control station. Nor is it desirable to
provide two objective indexes corresponding to
the two separate distances, since the pilot must
then align the position index P with the objective
index OP, and also align the position index S
with the corresponding objective index OS. While
1/isaouo second. These timing indexes not only
v
make possible more accurate measurements along
the ilne in case the system is to be used for the
calculation of the distance of the aircraft from
two control stations, but also are the source of
the objective index which was referred to above.
In accordance with the preferred system, as
suming the calculated time distance falls between
the 38th and 39th timing index, in the 8th line,
the timing index which is the ñrst to occur after
the calculated time distance, i. e., number 39, is
marked by means of a suitable mark O which
may be placed upon the glass face of the cathode
ray screen.
In order to calibrate the device for
distances intermediate the times represented by
successive marking impulses, the transmitted im
pulse itself is then delayed by a calculated amount
so that the received impulse coincides with the
selected marking index O at the calculated time.
It now becomes necessary to consider the fact
that the calculated time distance from the objec
tive to the secondary control station is not nec
17
'
'i
8
the»
¿s that from the obiecuve to
the primary control station. In this case a sec
ond _impulse is radiated from the aircraft trans
_Y ning frame will be applied to the cathode ray
screemthe following nine scanning frames being
suppressed.' This selecting mechanism is also
provided with means for deiïnitely determining
._which» one of the group of ten frames is being
mitter at a subsequent time which is so calcu- .
lated 'that .itwill arrive back at .the receiver at
y y the same'mstant that the erst transmitted im
" pulse returns from the primary- control station
when-"the'aircraft is directlyover its objective.
`
viewed'.
»
-
Y
'
f ‘_The objective» index0 may, for example, occur
~_during'the ñfth scanning frame if the distance
„the primary control station to the objec
-is'accomplishe'd by utilizing one of thein- ` , l>>'from
`dexing impulses Ít'ogenerate a secondtransmitted` .l0 tifeis s_ußiciently great. ' The pilot, however, be
impulse ata known time interval after the trans-` 1_. ' _- ing' desirous Vof indicating his approximate dis
mission of the iirst'impulse to the .primary ycon- "
tancev from the control station at all times, will
__first select `the first scanning trame and follow
its
X appearing
locationV on
-at the
thetime
_fourth
interval
scanning
represented'
line is 'se
by "theposition jindex P representing his distance
»from thezprimary control station along the var
lected and utilized to release'an impulsefrom ' 'ious'lines o1' the' ?rst scanning frame. As his
the aircrafttransmitter. As before, corrections`
_
_
distance increases the point P will move of! the
fortime- intervalsless than the period between 'v 'fright-hand -end voi! the tenth' line and will no
successive timing index pulses may be made ,by -_ _ ‘_ longer appear until he operates the selector mech
delaying the transmission lof thepulse cori-_e-anismjand applies the second scanning frame
sponding. to the selected.> timing pulsesby
.tothe cathode ray indicator. The variable in
trolstation. For example, the -indexing impulse
_ amount equal to the desired correction.
'
-dex_ P will thenappear on the ñrst scanning
line and'will move successively down to the tenth
line as his distance from the primary control
station increases. This process will then be con
It will now be appreciated th'atit is necessary:
to provide means for preventing thenrst im
pulse from deilecting the Acathode ray after re
' transmission by thesecondary control station and.
tinued _until he reaches the general vicinity oi
thev objective,- at which time .the objective index
ilecting the cathode ray'afterretransmission by ' 1 VO in'the fifth scanning frame will appear.
the `primary control station. »Itthis werefnot 1“ _Y Since it is desirable to simultaneously indicate
done, four impulseswouldbeïobserved onthe ' ` ¿fthe distance' of the aircraft from the secondary
first
cathode
to beray
transmitted
screen _instead
totheofprimaryjcontrolsta
two since the pulsey’ `'coi'itrolstation,_it is preferable to follow a course
which' lis generally equi-distant from the' two con
tion would als'obeß` repeated 4back from thesec- _ _ trollstations. The pilot will thus be able to ob
ondary'» control'?station.- lllllçewise,___.-the»` secondi .ïï'servehis relative _position with respect to the two
transmitted
would befrepeated _back from _ _.fcontrolstations at all times.- However, this will
for preventing the subsequentimpulse i'romA de
both'. control- stations.. Consequently, it is .pro-_ - _Y _' not always be the case, sinceas pointed out above,
» posed to synchronously commutatethe two. re- _. y V_separately timed pulses are radiated for >the two
vceivers and the circuit connecting ythe successive' ' __i-:control stations to'compensate for-the difference
in distance between the objective and the control
which
modulating
is relatively
impulses
small
to the
with-respect
transmitter
to at.
thetime
a vrate
stations. » 'If 'the discrepancy is great enough, it
being measured so" that one or more pulses are'
may-be necessary to alternately select one scan
sent vto andl received-from the primary `control f-~_ ningl frame and then th'e other in order to check
y station andthen _for 'a successive interval one or
his relative'gdistance `from the two control sta
more pulses varesent to and received _from lthe
tions. Alternatively during the initial part of the
secondary control station.' 'I'herate of commu
‘ flight, it-may be desirable to'radiate but a single
tation, however, kisY preferably suilicient> to v.pro-_. __» `pulse and'receive it from both control stations
vide persistence -of vision on vthe cathode ray*- »
screen so that both pulses are apparently simul
taneously received.
'
u
'
-_
i _ *_
simultaneously 'inforder to provide a more accu
` `i'ateindication of his general~ position with re
, spect to the control stations.
.
-Before taking up the _discussion’oi' the partic- '
‘ ,
One switch is pro
vided-forf'eifectively removing the commutator _
ular apparatus and accomplishing the above de
»- H5, _and another rswitch is provided'ior discon
scribed results, Vit is desirablertov consider-*means ._ -
nectingthe second modulating impulse from th'e
transmitter.- Suitable switching arrangements
for extending the' range of the device beyond that .
which would be attained by the time interval rep-
_ tol vaccomplish this are fprovided.
resented «by the ten scanning"- lines. Since the
scanning pattern is repeated successively at a
rate of 3,000` complete frames of ten lines each
tem may thenvbe switched in so that the single
_-objective.index, properly compensated for the
relativeV distances to the two control stations, is
per second, it will be appreciated thatiI the dis.'
- tance from the aircraft to either control station
is sufficiently great, i. e., in exces’s'of 100,000 me- `
Upon ap
_proaclii'ng- the objective the doubleimpulse sys
’
_. utilized. l
»
'
5A_ ’speciflcjembodiment of‘this invention will
ters, the retransmitted impulse will not :arrive-
vnow be described by referring to lF’ig. 3 Awhich‘ il
lustrates in'block diagramform the apparatus
.position index YP wereto appear on theflrst 'scan- 1 ljivhich'is 'installed in the aircraft to accomplish
' during the ñrst 'scanning'peri'od` '_I‘hat is, ifvthe
ning Vline this might indicate either>> that- the. air
craft was very- near ~the ' primaryv >controlstation
or at such a distance that the received impulse
was not in fact on the first scanningline buton I
the eleventh scanning line which coincides there
with.- `In order to ascertain inïwhich complete
scanning frame the received impulse has been
' _received asystem has been provided which per»- '
mits the selection of any one of ten complete>
frames.
'I'hat is, when the aircraft is within a `
certain .distance of the control station the instru
mentwill be adjusted so that only the ñrst scan
_
‘
the -above-described results. . Reference numeral`36 _indicates an oscillator,
the frequency of-which is accurately maintained
vat a `constantvalue which, for the sake of illus
tration, .is assumed to be .150 kc. The accuracy
.of the instrument depends directly upon th'e sta
bility of this oscillator, and it should, therefore,
be suitably 'controlled by means of a piezo-electric
. element or the like.
The oscillator output is ap
plied-to thecontrol elementv of a counter 31 which
may be a device similar to that described in Brit
ish Patent 471,731, of December 4, _1935, which
2,405,238
effectively divides the oscillator frequency to one
iifth its previous value somewhat in the manner
of a multivibrator. The difference between the
10
marks or timing index pulses are produced along
the ten scanning lines as indicated in Fig. l.
Since these impulses are derived directly from the
counter and a multivibrator is essentially that
the latter has an oscillatory period of its own
while the former responds only to some prede
main oscillator 3B their timing is extremely ac
curate.
It has been pointed out above that a complete
termined fraction of the frequency of the applied
scanning cycle comprises ten complete frames
make available voltage impulses of varying char
first frame. 'I'his impulse is indicated in Fig. 1
by the first impulse in the first line winch occurs
at time To. It will be appreciated, therefore, that
it will be necessary to select one particular pulse
from the large number of pulses which occur dur
ing the period and use it to initiate the scanning
each of which in turn contain ten horizontal
voltage. The actual circuit of the counter 31 is
scanning lines. It has also been pointed out that
illustrated in Fig. 4 which will be described here
inafter. It will be noted th'at three output ter 10 the ñrst transmitted impulse is derived from
the first-timing pulse of the first line and the
minals are provided. These output terminals
acteristics which are ~indicated by the curves
shown immediately adjacent the
conductors .
which are connected to the three terminals.
The number 3 terminal, hereinafter described,
provides a series of impulses whichoccur at, one
cycle as well as to time the transmitted pulse.
iifth’ the frequency of the oscillator 36, that is,
It will also be appreciated that but one pulse
the time between successive impulses is equal
to $60,000 of a second. These impulses are applied 20 should be radiated during the period covered by
the complete scanning cycle of ten frames. In
to a diñerentiator 39, the function of which is to
' order to accomplish this, the No. 3 output of the
decrease the duration of each impulse so that it
counter 49 is connected to the control input of a
will more accurately determine the operating time
similar 10-to-1 counter 58. The No. 2 output ter-_
of a saw-tooth discharge tube which is represent
ed by reference numeral 4I. The differentiator 25 minal of the counter 58 then provides a step volt
age of the type illustrated by the small diagram
circuit is illustrated in Fig. 6 and is hereinafter
adjacent connecting lead 59. This voltage in
described. The saw-tooth discharge tube is il
creases in ten equal steps from a given starting
lustrated in Fig. '1, and provides a saw-tooth out
point and then suddenly returns to the original
put voltage in the well-known manner. This
point
at a time interval which is equal to 1/soo,ooo
30
voltage is applied to a phase splitter 43 illustrated
K of a second. ’I'he 300 cycle step voltage which is
in detail in fFig. 8 which provides as its output
so obtained is applied to the input of a differ
balanced saw-tooth voltages for energizing a
entiator and a clipper tube 6| the circuit of
push-pull deflection amplifier 45, which is a con
which is illustrated in Fig. 6. The function of
ventional ampliñer, the output of which' is con
tube is to produce a positive impulse corre
nected between the horizontal deiiecting elec 35 this
sponding to the return time of the step voltage,
“ trodes of a cathode ray tube 41.
the frequency of the impulses being, as a result,
The number 3 output terminal of the five-to
300 cycles per second. The output of the differ-`
one counter 31 is also connected to the control
entiator and clipper is connected to the No. 2
input circuit of a similar 10-to-1 counter indi
terminal of a keying tube 63 which is illus
cated by reference numeral 49. The No. 2 out 40 input
trated in detail in Fig. 12. The phase reversing
put terminal of the counter 49 is a step voltage
ampliñer 55 is connected to the No. 1 input of the
of the type indicated by the small curves adja
cent connecting lead 5l which applies the output
voltage ofthe counter 49 to an ampliñer 53. The
amplifier is connected to one of the vertical de 45
iiecting electrodes of the` cathode r y tube 41.
As a result, a vertical deiiecting pote `tial is ap
plied to the tube 41 which increases in ten equal
steps, each step occurring at a time interval of
1/30,0n0 of a second. The complete cycle of ten 50
steps is obviously accomplished in a time interval
of ï/aooo of a second. As a result, the cathode ray
beam is caused to move horizontally across the
luminescent screen in 1/30,000 of a second at which
keying tube 63.
l
The function of the keying tube is to pass cur
rent only at such time as there is present on its
input circuits a positive impulse from the phase
_reversing amplifier and a similar impulse from
the diß‘erentiator 6|. Since the 3 kc. counter 49
supplies the vertical deilecting voltage for the
cathode ray tube 41, it will be recognized that
the impulse derived from the step output of the
0.3 kc. counter 58 occurs at the instant the cath
ode ray beam has completed its entire scanning
cycle of vten complete frames. Consequently, the
time it is returned to its original starting point 55 resulting impulse which is produced by the diifer
entiator GI-is concurrent with the No. l impulse
but one line lower, and th‘e second line is then
of the scanning cycle. ‘The circuit constants are
scanned. Alternatively, the vertical deflecting
adjusted so that the duration of the derived im
voltage may be derived from a saw-tooth dis
pulse
is short enough to exclude the No. 2 input
charge tube which produces a deilecting voltage
occurs 1/15u,uou of a second later.
similar to that applied to the horizontal deflect 60 which
The output of the keying tube is a negative
ing electrodes, but in such a case the lines will
impulse having a small peak corresponding to
not be horizontal but will slope downwardly, as is
the selected timing impulse. This impulse is ap
well known.
plied to a reverser and clipper tube 65 the cir
The No. 1 output terminal of the 5-to-1 counter
31 is connected to a phase reversing amplifier 55 65 cuit of which is illustrated in detail in Fig. 14
The function of this tube is to eliminate the low
the output of which is a unipotential voltage com
frequency keying impulse and to obtain only the
prising a series of pulses separated by intervals of
selected timing impulse as illustrated in the
1,650,000 of a second. The phase reversing ampli
small curve adjacent the reverser and clipper
fier is merely a conventional amplifier, and its
purpose is to invert the negative impulses which 70 tube 65. 'I'he output of this tube is then applied
to a delay network 61 which may be, for ex
are produced by the counter 31 so that they will
ample, of the series inductance-shunt capaci
have the proper polarity. The output of the am
tance
type illustrated in Fig. 15. 'I‘he delay net
plifier 55 is connected by means of a switch 51
work is designed to have a total time shift at
to the remaining vertical deilecting electrode of
least equal to the time period between adjacent
th'e cathode ray tube 41. As a result, small 75
2,405,288
lll
.
timing impulses. This period is approximately
equal to 1/15o,ono of a second or '7 microseconds.
The delay network is preferably made adjust
able, and is calibrated in terms of the total delay
produced. By suitably adjusting the delay net
12
in time with every fifth timing impulse, and which
may be made to coincide with the initiating im- '
pulse, or with any desired successive impulse by
means of the pulse selector 13.
.
A similar system is utilized to select the de
work, the time of transmission of the radiated
sired line of the scanning frame; that is, a sec
impulse with respect to the time at which the
ond line selector 8| is connected to the No. 2
scanning cycle is initiated is adjusted so that
or step voltage outputof the 3 kc. counter 49.
the calibrated time distance from the primary
The line selector 8l is connected to a third key
control station to the objective, based on the total 10 ing tube 83 through a clipper tube 85. The op
path of transmission and the known constant de
eration of these elements is identical to that of
lay, will coincide with one of the timing impulses
the corresponding elements described. immedi
in the desired frame which most nearly corre
ately above. In this case, however, the line se
sponds to the objective distance.
.
lector is adjusted to select the desired one of
The output of the time delay network $1 is 15 ten steps, rather than one of five, as in the pre
applied to an ultra high frequency transmitter
ceding case. As before, the control impulse from
69 through a commutator device 1t. The trans
the line selector is of insuiiicient accuracy to be
mitter itself is an impulse transmitter and may,
utilized alone, so that it is combined with the
for example, be of the type illustrated in Fig. 17.
selected- pulse from the reverser and clipper 19 in
The commutator 1l may be mechanically or elec 20 keying tube 83 the output of which is again passed
trically operated, as desired, and preferably takes
through a reverser and clipper 81 which removes
the form illustrated in Fig. 16. The function of
the control impulse and permits only the accu
the commutator 1l is to apply the selected control
rately timed impulse to pass. By suitably adjust
impulse to modulate the impulse transmitter 69
ing
the line selector 8i, it is, therefore, possible
in alternation with other control impulses which 25 to obtain
an impulse which corresponds in time
are utilized in a manner which will hereinafter
to the selected impulse X but which is repeated
be described.
during each of the ten scanning frames which
As indicated above, it is impractical to obtain
constitute a complete scanning cycle. The ñnal
` the impulse which is to be used to key the trans
step, consequently, is to select the desired frame
mitter to radiate a wave to the secondary con 30 period, and this is accomplished, as before, by
trol station by delaying the initial selected im-V
a frame selector 89 which is coupled to the No. 2
pulse, since the required delay period would be
output of the 0.3 kc. counter 58. The output of
excessive. It, therefore, becomes necessary to
the frame selector is connected to a fourth key
select another particular timing pulse `which may
ing tube 9| through a clipper tube 93, the output
occur in any line of any of the ten frames. As 35
of the keying tube being connected, as before, to a
suming that it is desired to select impulse X from
reverser and clipper tube 95 which in turn applies
line t of the first frame, as indicated in Fig. 1,
the selected pulse to a. delay network 91, 'I'he
a selector system is required by means of which
output of the delay network is applied to the com
it is possible to select, ñrst, the first, second, third,
mutator 1I and is, accordingly, applied to control
fourth, or fifth timing impulse, the third .being 40 the
transmitter 69 along with the ñrst derived
selected in the present example, then to select
impulse from delay network 61 at alternate in
the particular scanning line in which the desired
tervals.
impulse lies, that is, the fourth, and finally to
The selector system so far described thus makes
select the oney of the ten frames in which the de
sired pulse occurs.
The first portion of this se
lector system comprises `a pulse selector 13 the
output of which is connected to the No. 2 output
terminal of the 30 kc. counter 31. The circuit dia
gram of a suitable pulse selector is illustrated in
it possible to select any one of the 500 timing
pulses which occur during each complete scan
ning cycle. Thus, it is possible to select the de
sired frame, the desired scanning line of the
frame, and the particular pulse in the selected
line. In practice, the device is adjusted to direct
Fig. 9, which will be later described. The func 50 the aircraft to a particular objective by deter
tion of the pulse selector is to derive a, short pulse
mining the time distance from the primary
whose duration includes the interval between
ground station to the objective, assuming that
successive steps of the 30 kc. step voltage pro
this distance is longer than the distance from the
duced by counter 31. The pulse selector- is pro
secondary control station to the objective. As
vided with a manual adjustment by means of 55 sume that the time-distance from the primary
which any one of the ñve steps may be selected
ground station to the objective is less than in
at will. 'I'he impulse which is so derived is passed ` dicated by the indexing pulse O of Fig. 1 and
through a limiter or clipper tube 15 the circuit
greater than the next preceding or 38th index
diagram oi’` which is illustrated in'li‘ig.I 11. The
pulse. ’I'he time-distance difference between
function of this tube is to produce an essentially 60 ing
the indexing pulse O and the actual time-dis
square positive impulse the time duration of which
tance is obtained by delaying the first transmitted
includes one of the ñve equal steps of the 30
pulse an amount suflicient to compensate for
kc. voltage, and, consequently, it will be appre
the said time-distance difference and for any‘
ciated that this impulse coincides with every fifth
other compensation required. Next determine the
timing impulse. However, this square impulse
time-distance from the secondary ground sta
is not of sufficient accuracy to utilize by itself, so
tion to the objective. Use the indexing pulse O
that it is necessary to combine it with a timing
impulse from the phase reversing amplifier 55
in a keying tube 11 similar to that discussed pre
viously.
The output of the keying tube is ap
plied to a phase reverser and Aclipper tube 19
which removes the control and passes only the
selected timing impulse. There is thus obtained
to represent the objective and measure from O to
wards To a time-distance equal to the time-dis
tance from the secondary ground station to the
objective to determine the nearest timing impulse.
This particular impulse is then selected by adjust
ing the selecting system, is compensated by the ad
justable delay network 91 (if compensation is re
at the output of the reverser and clipper 19 an
quired) and is utilized to initiate the second im
accurately timed short impulse which corresponds 75 pulse
from the transmitter which is received and
2,405,238
13
14
retransmitted by the secondary ground station.
and antenna system broadly tuned to include
'I'he received pulses are indicated as P and S. As
the aircraft or other vehicle is directed toward
signals from both of the control station trans
mitters. The output of the first receiver |09 is
the objective, the indications P and S approach
the index O. When the indications P and S coin
cide with the index O, the coincident indications
,
connected through a phase reverser || 3 to a com
mutator || 5. The output of the second receiver
||| is connected directly to the commutator | I5.
The commutator is synchronously operated from
show that aircraft should be at the objective.
It is apparent that some system must be pro
a commutator control voltage source | |1 with the
vided for indicating which of the various pulses,
commutator 1|. lAs a result, the outputs of the
lines and frames have in fact been selected. Such 10 ñrst and second receivers are alternately con
an indicator is provided by an auxiliary cathode
nected to one of the vertical deflecting plates of
the cathode ray tube 41. As pointed out above,
ray tube 99 which may be a small 2-inch tube, or
this permits the signals from the two ground sta
the like. The 300 cycle step wave output of the
tions to be alternately received. The phase re
0.3 kc. counter 50 is applied to the vertical de
verser ||3 inverts the phase of the voltage from
flecting electrode of the auxiliary cathode ray
one of the receivers so that the variable indexing
tube 99. The 3000 cycle step wave output of the
impulse S, for example, may be distinguished
3.0 kc. counter 49 is applied to the horizontal de
from“ the variable indexing impulse P.
ñecting electrode. Consequently, a series of ten
I have thus described the general system by
lines is produced similar to the ten lines of the
means of which a preferred embodiment of my
main cathode ray tube 41. The No. 2 output of
invention may be carried into practice. As to
the 0.3 kc. counter 58 is also applied to another
the specific details of the various elements which
frame selector |0|, which is identical to those
have been schematically indicated in Fig. 3, it is
previously described. Its output is connected, as
to be understood that there are many diiïerent
usual, through a Clipper tube |03 which in turn is
systems which may be utilized. However, in order
coupled to the control grid |05 of the cathode
to fully describe an operative system, an illustra
ray tube 41. This 'control grid is normally given a
tive embodiment of each of the elements which
are not well known to those skilled in the art will
negative bias so that the cathode ray beam is
extinguished until such time as a positive impulse
is applied from the output of the clipper tube |03.
now be described.
The time duration _of this impulse corresponds to 30 Referring to Figs. 4 and 5, I have illustrated a
frequency counter of the type described in the
the time period required to complete one. scan
British Patent 471,731, previously mentioned.
ning frame; that is, 1fáooo of a second, Conse
Sine wave input is applied through a limiting
quently, the cathode ray screen remains dark
resistor to the grid of a tube ||9, the plate cir
during a period corresponding to nine scanning
frames.
35
The output of the clipper |03 is also applied
to a phase reverser |01 which in turn is coupled
to the control grid of the auxiliary cathode ray
tube 99. 'I‘his control grid is normally biased so
that the cathode ray beam is operative, but, due 40
to the phase reverser |01 when an impulse is ap
`
plied to the main cathode ray tube to produce a
frame, the same impulse is applied to the aux
iliary cathode ray tube to extinguish it for a cor
responding period.
Now the vertical scanning
period is l/áoo of a second. If an impulse of
M4000 of a second is applied to bias off the tube, it
is apparent that one of the ten lines will be re
moved. It will, therefore, be an easy matter to
cuit of which is energized from a suitable source
of D.-C, voltage through a resistor |2| and a
peaking inductor |23~ The plate is also coupled
through a small capacitor |25 to the cathode of
a diode rectifier |21 and the anode of a second
diode rectifier |29.
The anode of the ñrst diode rectiñer |21 is con
nected to output terminal No. l and is also con
nected to ground through a resistor |3I. The
cathode of diode |29 is connected to ground
through a large capacitor |33, to the grid of a
cathode follower tube |35, and through an in--
ductor |31 to the grid of an output tube |39.
Output terminal No. 2 of the frequency counter
is connected to the cathode of the cathode fol
count the remaining lines in order to determine 50 lower tube |35. Output terminal No. 3 is con
nected to the anode of the output tube |39. The
which line has been selected. The number of
output circuit of this tube also includes an in
the line selected, as indicated on the auxiliary
ductor |4| which is coupled so as to produce a
cathode ray tube, corresponds to the frame which
regenerative feedback to the grid circuit inductor
is applied to the main cathode ray tube 41; that
` is, if an observation of the auxiliary cathode ray 55 |31- A positive bias is applied to the cathode
of the output tube |39 by means of a voltage di
tube indicates that the third line is missing, it
vider |43.
‘
may be established that the frame selector |0|
Input tube I I9 is normally drawing plate cur
has been adjusted to select the third frame. The
rent. As its grid becomes negative during each
operation of the line and pulse selectors may be
checked by utilizing switch 51 which in its “check 60 cycle of applied voltage, its plate voltage becomes
more positive, thus causing a small constant
position" connects the ñnally selected keying im
charging current to flow through capacitor |25
pulse from the output of the reverser and clipper
and diode |29 into capacitor |33. The 'capacity
95 to one of the vertical defiecting electrodes,
of capacitor |25 is quite small with respect to
while removing the superimposed timing im
pulses. It is apparent that the position of the 65 that of the capacitor |33 so that the total charge
received by the latter capacitor is not suñlcient to
selected impulse should coincide with the position
charge the capacitor up to its full capacity. The
of one of the timing impulses on the cathode ray
voltage across the large capacitor |33 conse
screen. Thus, by operating the switch 51, noting
quently takes the form of the step wave illus
the position of the single selected impulse which
will appear in the “check position”, and return 70 trated in Fig. 5. A similar output voltage is then
applied to output terminal No. 2 by means of the
ing the switch to its normal position, the line and
cathode follower tube |35.
number of the selected pulse may be determined.
When the applied voltage causes the grid of
The two receivers |09 and || I are also included
the input tube to become positive, the plate volt
in the aircraft equipment. These receivers may
be separate or they may have a common input 75 age decreases, as is well known. This causes a
l' ne ative-
u amas@
*vis
ulse t`o be applied to the cathodeoi' the .
.f
'Y
'
resistor lll may be included in the grid; circuit. .
diogde lz'lpand current vflows through resistor> |3|,_¿ ' Output
is taken 'from a capacitor- I“ coupled tof
producinga negative pulse at output terminal No.
its anode. -Q'I‘he amplitude of the applied step .
2, lasjillu'strated in `li‘lg. 5.. 'A similar _negative> voltage is selected so that the increase for anyv _
pulse is produced each time the grid exceedsl the - given step exceeds the voltage necessary to cause
cut-oif-ïvalue of the _input tube.. However, dur- - Y the tube to pass from plate current cut-oir. to
ln'g this ' interval. v,capacitor m l maintains its`
zerobias, as is indicated in Fig. 10;V that is, the » ' >chargasince it is now yisolated by rectifier |25.
cut-0l! point fOr the tube is determined by-ßd
As >a-result,-ea.ch reversal of the applied voltage
Justment
of the potentiometer |55.v lThis value is ,
causes the charge in the capacitor |33 to be in
to slightlvexceed the
voltage‘ffor >
~reased until ilnally at some predetermined’volt j set
any given step, s'o that, when‘the 4voltage rises _
z ge .the negative'bias which is normally applied .
for.- the nextsucceeding step,.the_tube will draw . Y
, a.l large plate currentvand its plate vvoltage will ,
to the output tube |39l is overcome. l When this
occurs, the beginning plate current' produces-a
regenerative feedback voltage on the grid which
bstenceuy- lewr _v_elaej..
'rapidly
It; will bedecreaseto
appreciated_a
that. _vby adjusting thepof '
accelerates the tube to plate current saturationin; ' -'~
¿'»tentiometer |65, -plate‘ .current .may be
_ .l
veryrapid‘time. Grid current ilowsin' tl_1ej.9ut-¿A Íj'ilow
at a time' periQd’corresponding' to`-any de-` 1_ ;
put tube vand rapidly discharges capacitor_.|l.l,._1_ __
at which .pointlthe -charging cycle-begins again. „_ '
The voltageîappearing vat output terminal No. l3 ~
one
of the- severalsteps., v'_I'he output‘volt
v
agel of the pulse selector is also ill
.
_
@trawl-»1n
»
10, and is lscenic be adifferentlal voltage
consists -of .a rapid -negative pulse corresponding» _
to maximum plate current followed- by asmall
.»
Y.> -which
currentbecomes
increases.
suddenly
and thenegative
plate voltage
-whenthe
decr.
plate '_ 1 " ’
reactive positi've ` pulse. It will be appreciated ._
, The
then
output
slowly
ofrises
the _again
pulse selector‘is
to its steady
appliedto>
state. ç j ‘
that. when plate saturation'is reached, the phase ,_ ‘ .and
of the feedback voltageis reversed'.` The gridjof
the` output tube rapidly becomes more negative lThis
~a. clipper-tube tube
includes
which'isa> gridillustrated resistor-"Illv
in Fig. 1_1. ‘ _
and control by t,he ñxed negative bias -is reestab-"Qî- ; through‘which the negative pulse produced by the' "
lished. The point at which the condenserA i3d-'is
y. pulse selector is applied to a tube |13. y The amf
' discharged is determined by the adjustment volf` ‘ '1
‘1
'
plitude of the applied pulse is preferably sum-_-
the voltage divider |43.
vcient >to cause’the grid voltage to exceed -the cut_-' '
To operate as a 5--to-1 frequency counter, the '
_oil value. l_As a result, the peak amplitude- of the?
fixed bias applied _to output tube is 'adjusted
to a value suihcient to cause the-tube'to become'> 1 output voltage is limited in a manner illustrated
in the small curve above the output terminal'ofw--'„'_„
triggered at theñfth step, as indicatedin Fig. 5. , -.f _Fig.
11.
At the same time, the polarityvof the’l
In order to operate as a 10-to-1 frequency coun-- '
ter, it is merely necessary to increase the iìxed -' bias which is `applied to the output Ltube so that
. it will _betriggered into action when the tenth
_
charging impulse is applied to capacitor> |33.
Fig. 6 is a diil'erentiator whichis merely an `am ' .
pliñer in which the input capacitance and grid
resistance are so selected thatthe amplifieratube
|45 responds to rapid changes in the potential of _
the applied voltage. In order to prevent thehigh ' '
frequency components of the »applied .pulses from -
-sponding to the increase in voltage at ,theselected>
step and whose duration is'suii‘lcient to include- a E; ‘
period up to but exclusive of the next succeeding '_
step.
noted
Referringthat the
for_output
a moment
of theto-clipper
Fig. 3„tube
itwill
is ap->
be Y Y»
vplied to a keying tube which has two input >ter-'A
l
the remaining terminal beingenergized-
being attenuated,_ the plate circuit of the ampli
-‘
by an indexing impulse corresponding tothe orig- . . .
fier includes a compensating ret/ttorY |41
nected inshunt with a- resistor |49.y
vpulse
rectangular
tube comprises
is inverted,
forma'sowhich
positive
thatthe
starts
pulse
output
atofaof
substantially
time
the clipper"
ccrre--- ~`
con-
v
The saw-tooth >discharge tube illustrated vfv'in 'l
Fig. 7 includes fai capacitance-resistance*input
coupling system Aand a thermio'nic'tube v|5|,"thel
- inal oscillator frequency.
_
Such a keying tubeis
"
v illustrated in Fig. 12, and the applied voltages ; f
1 are indicated in the sketch illustrated vin Fig. 1_3" ‘
to »which reference is now made.'A 'I‘he- k
plate circuit of'which is energized by a source 'of , ltube,_f0r example, is a vtulle |15 of the “6L7" type
D.~C. potential through a high resistance |55. " having a pair of grids which> are'connected re-'»`
Spectively to the No. 1 input and the No. 2 input I
A small capacitor |55 is connected across the platey
terminals.
The output of the keying tube is. de~ .
circuit resistor |53.V -In operation, the' capacitor
rived-from the plate circuit >which is' energized
|55 is slowly charged through resistor Í|53Í`at a _
through a series impedance.- In the absence of
rate which is`«substantially'linear over a small
range.
Aty predetermined intervals, _ determined . an applied grid voltage, the tube isbiasedjte a
by the applied impulses, the anode-cathode> iin-_> »substantially low valueof plate current. Short'` »
pedance of the tube |5|- becomes very low-ïand‘ ‘ _impulses of the type produced by the No. 1 out-. ` '
put of- the counter tubes are applied to the No. _.1discharges the_ condenser.`
_
'I'he saw-tooth out'-A ' ._
arid. The substantially rectangularv impulsev ,
put
small
voltage
curve which
directlyis above
produced
the isoutput
illustrated
terminal;V
>in >the'9
from the- clipper. tube
applied _to .the No. 24.
Fig. 8 illustrates a phase splitter, and comprises ' -grid. 'I_'he resultant output voltage illustrated inle tnermiometube |51 the output voltage `of which l’ y
_ i negative
vages
Fig. 13
and>
isoutputimpulse
comprisesfa
a combination
substantially
havinga
of the two
small
rectangular.v
input
negative>
volt- '_ ._
` is divided between> the, anode and `cathode
>ciiitsiizhat is, resistors |59 andV IBI >of'equal-fiin
pedance are connected in the cathode and >al'iod'e
circuits of the tube, respectively; balanced output
being taken from the anode and cathode elecf',
,'-peak'at
applied'to
its a
'minimum
phase reverser
point.. and
Thisclipper
voltagesuch
is’then.
asl -'.
that illustrated in Fig. Maand to" _which refer-#- f_i
trodes. '
v_enceisnowmada
- The' phase reversing section
`~
, " of , this
device
Y l `
in-v
A
The pulse selector illustrated in Fig. 9 comprises 'Y
coupled.coupled
amplifier
tube |11,
al the
capacity-resistance
plate circuit of which‘is
to .
a
potentiometer
thermionic tube
|65 |83
for which
applying
is provided
an adjustable
with-a f .' vcludes
a.
biased
ampliiler
tube
|18
ofthe
cathode
fol
positive voltage to its cathod . A series limiting
._
-zs lower type.. output is tekenrrom the cathode _
2,405,238
across a cathode resistor IBI, and a ñxed posi
tive bias is applied to the cathode by means of
a potentiometer |83. As a result, the combined
keying impulse and timing impulse A produced
by the keying tube is inverted by the first ampli
18
receiving and reradiating said pulses at said con
trol stations, receiving said reradiated pulses at
said object, producing a ñrst indication corre
sponding to the time period required for a pulse
to travel from said predetermined objective to
one of said control stations and back, producing
a second indication corresponding to the time pe
trated at B in the small diagram of Fig. 14.
riod required for a pulse to travel from said mov
The horizontal section of the keying impulse B
able object to the other of said control stations
corresponds to the cut-oiî bias of the output tube
|19. This is accomplished by a suitably adjusted 10 and back, and comparing said ñrst and second
indications with a distance indication which is a
potentiometer |83. As a result, all the timing
time function of said known distance to deter
impulses, except that one which coincides with
mine when said object has reached said prede
the keying impulse, are eliminated by the ñrst re
termined objective.
verser and clipper. In addition, the keying im
2. In the guiding of a movable object to a pre
pulse itself is eliminated, since the output of the 15
determined point which is a known distance from
clipper tube responds only to potentials in excess
of the peak potential of the keying voltage. As ,Y two control stations having Vknown locations, the
method which comprises radiating pulses of ra
a result, a single impulse C is selected which cor
dio energy from said movable object, receiving
responds in time with the impulse produced by
the pulse selector.
20 and reradiating said pulses at said control sta
tions, receiving said reradiated pulses at said ob
Fig. 15 represents an adjustable time delay
ject, producing one indication corresponding to
network suitable for use'in connection' with this
the time period required for a pulse to travel from
invention and comprises a series of inductors L
fier tube |11 to produce a wave of the type illus
A
said predetermined objective to one of said con
manner. The operation of this network is con 25 trol stations and back, producing another indica
tion corresponding to the time period required
ventional and need not be described in detail.
for a pulse to travel from said movable object to
Fig. 16 represents an electronic commutator
the other of said control stations and back, pro
suitable for use in connection with this inven
ducing as a function of time a third indication
tion. The commutator includes a pair of double
grid thermionic tubes, of the 6L? type, for ex 30 corresponding to said known distance, and uti
lizing said iirst and second indications by com
ample, |85 and |81. Input No. 1, from the delay
` and capacitors C connected in the well-known
network 6l of Fig. 3, for example, is coupled to
one grid of the first tube |85. Input No. 2, from
the delay network Sl of Fig. 3, for example, is
parison with said third indication to determine
when said object has reached said predetermined
point.
3. In the guiding of a movable object to a pre
connected to the corresponding grid of the sec 35
determined point which is a known distance from
ond tube |87. An alternating voltage is applied
a control station at a known location, the meth
in phase opposition from a suitable source of
od which includes radiating successive short pulses
A.-C. voltage through a switch |88 in the re
maining grids of the two tubes.
The output
anodes are connected in parallel and suitably
energized by a source of positive potential. Op
erating the switch |88 removes the A.-C. control
voltage so that both tubes are simultaneously
operative, and the commutating action sus
pended.
,
In operation, the applied A.-C. control voltage
causes the two tubes to become alternatively con
ductive s`o that the voltages applied to the re
spective input circuits are alternately amplified
and connected to the output terminal.
Fig, 17 illustrates an impulse transmitter of
the type suitable for use 'in connection with this
invention. Since the radiated pulses are of ex
tremely short duration, it is possible to operate
the tube at a severe overload for such a short
interval. A small tube may be utilized to radiate
a pulse of large amplitude, since the tube is
actuallyin operation only an extremely small
portion of the total time. Consequently, a volt
of radio frequency energy from said movable ob
ject, receiving and reradiating said pulses at said
control station, receiving said reradiated pulses
at said object, the time length of said pulses
being small with respect to the time required for
each pulse to travel from and to said object, and
the interval between successive pulses being
greater than said time so that each pulse is ra
diated and received before the next succeeding
pulse is radiated, producing as a function of time
one indication corresponding to the calculated
time period required for a pulse to travel from
said predetermined point to said control station
and back, producing a second indication corre
sponding to the time period required for a pu1se
to travel from said movable object to said con
trol station and back, the relative displacement
of said first and second indications being a meas
ure of the distance of said object from said pre
determined objective.
4. In the guiding of a movable object to a pre
determined point which is a known distance from
age supply source |89 is provided which sup
two control stations at known locations, the meth
plies, for example, 10,000 volts at 1 m. a. This
od which includes radiating successive short
voltage is applied to the anode of an oscillator
pulses of radio frequency energy from said mov
tube |9| which is connected in a conventional
able object, receiving and reradiating said pulses
oscillator circuit. However, the oscillator grid
is normally biased to cut-oir so that the tube is 65 at said control stations, receiving said reradiated
pulses at said object, the time length of said pulses
inactive until such time as a suitable positive
being small with respect to the time required for
pulse is applied to its grid through input terminal
each pulse to travel from and to said object, and
|93. As a result, a short impulse of large ampli
the interval between successive pulses being
tude is radiated from the antenna |95.
I claim as my invention:
70 greater than said time so that each pulse is ra
diated and received before the next succeeding
1. The method of directing a movable object
pulse is radiated, producing as a function of time
to a predetermined objective which ls a known
an objective index corresponding to the time pe
distance from two control stations which are at
riod required for a pulse to travel from said pre
known locations, which comprises radiating
pulses of radio energy from said movable object, 75 determined objective to the most distant control
19
2,4%,238
station, timing the transmission of the second of
said successive radiated pulses with respect to
20
tance of said object from said control stations,
whereby the distance of said object from s eb
jective may be determined.
ences in distance between said objective and said
8. In a system for directing a movable object
two control stations, and utilizing said received
to a predetermined objective which is located at
reradiated pulses to produce position indexes cor
known distances from two control stations the
responding to the time periods required for said
combination of means for radiating a succession
pulses to travel from said object to respective
of pulses of radio frequency energy from said ob
control stations and back, the relative displace
means located at each of said control sta
ment of said objective index and said position 10 ject,
tions for receiving and reradiating said pulses,
indexes being a measure of the distance or said
means for separately receiving at said object the
object from its objective.
pulses
reradiated from said two control stations,
5. The method of indicating the position of a
a
cathode
ray tube eiîectively connected to said
movable object with respect to a predetermined
receiving means and including ray deflecting
objective the location of which is known with 15' means for> producing a time measuring trace, and
respect to the locations of a pair of control sta
means including said cathode ray tube for meas
tions which comprises, radiating a, first series of
uring the time required for pulses transmitted
pulses of radio frequency energy from said ob
said object to 'be reradiated and returned
ject, receiving and reradiating said pulses at the from
to said object, and means for producing an ob
control station furthest from said objective, ra 20 jective index on said cathode ray trace, said in
diating alternately? pulses of a second series, re
dex corresponding to the time interval required
ceiving and reradiating said second series of
for a pulse to travel from the location of said ob
pulses from the control station nearest said ob
jective to one of said control stations and back.
jective, the time period between corresponding
9. A system for -indicating the position of a
pulses of said iirst and second series being equal 25. movable object with respect to a predetermined
to the difference in the time required for the
objective, said objective being a known distance
pulses of said iirst and second series to travel
from two contro1 stations which'includes means
from said objective to respective control stations
for radiating a pulse of radio frequency energy
and back, receiving said reradiated pulses at said
from
said object, means located at said control
object, producing an objective index correspond 30 stations
for receiving and reradiating said pulse,
ing to the time period required for a pulse to
means for separately receiving said reradiated
travel from said predetermined objective to said
pulses. time measuring means, means for pro
furthest control station, and utilizing said re
ducing predetermined timing indications on said
ceived pulses to produce position indexes corre
time measuring means correspondingl to the times
sponding to the position of the said object with 35 required for a pulse to travel from Athe location of
- respect to said control stations.
said objective to said control stations and back.
6. The method of indicating the position of a
and means for producing indications on said time
movable object with respect to a predeterminedl
measuring means corresponding to the time in
objective the location of which isv known with
tervals required for a pulse to travel from said
respect to the location of a pair 0f contl‘ûl Sta 40 object to said contro1 stations and back, the dif
tions which comprises radiating a ñrst series of
ference between corresponding indications being
pulses of radio frequency energy from said ob
a measure of the distance of said object from its
’ the ñrst radiated pulse to compensate for diiIer
ject, receiving and reradiating said pulses at the
objective.
contro1 station furthest from said objective, ra
10. A system for directing a movable object to
diating alternately pulses of a second series, re 45 a predetermined objective which is located at
ceiving and reradiating said second series of -pulses
known distances from a pair of control stations
from the contro1 station nearest said objective,
which includes in combination means for radiat
the time period between corresponding pulses of
ing
a first series of pulses from said object, means
said ñrst and second series being equal to the
receiving and reradiating said pulses from
diiference in the time required for the pulses of 50 for
one oi.'v said control stations. means for receiving
said first and'second series to travel from said
said ñrst series of reradiated pulses at said ob
objective to respective contro1 stationsv and back,
ject, means for radiating a second series of pulses
receiving said reradiated pulses at said object,
from said object, the pulses of said ñrst and sec
producing a. cathode ray beam, deiiecting said
ond series being radiated alternately, means for
beam to produce a known time trace, producing 55 receiving and reradiating the pulses of said sec
on said trace an objective index, the position of
ond lseries at the other of said control stations,
which corresponds to the time distance from said
means for receiving said second series of reradi
objective to said furthest station and back, and
ated pulses -at said object, indicating means kre
utilizing said received pulses to produce position
sponsive to said reradiated pulses and including
indexes ‘on said trace, the position of said indexes 60 said receiving means for producing position in
corresponding to the instantaneous position of
dex marks corresponding to the times saldre
said object with respect to said control stations.
radiated pulses return to said object, and means
7. In the navigation of a movable object to a
for applying as a junction of time an objective
predetermined objective which is a known dis
index mark on said indicating means, the arrival
tance from two contro1 stations. the method which 65 of said object at the location of said objective
includes radiating a succession of discrete pulses
being determined by the coincidence of said ob
of radio frequency energy from said object, 're
jective mark and said position index marks.
ceiving and reradiating said pulses at said con
11. A device of the character described in claim
trol stations, receiving said reradiated pulses at
10 in which the time period between correspond
said object, establishing electrically in accordance 70 ing pulses of said ñrst and second series of pulses
with a time function an objective index corre
spending to the calculated time for a pulse to`
travel from said objective to one of said contro1
is equal to the difference in the time required for
a pulse to travel from said objective to respective
control stations and backto said objective.
stations, and utilizing said received pulses to pro
12. A device of the ~character described in claimduce indications of the instantaneous time dis- 75`10 in which said indicating means comprises a
t
2,405,238
21
cathode ray tube having beam deiiecting means
for producing a line trace, the position of said
index mark along said line trace being a measure
of the relative time sequence of said marks.
13. A device of the character described in claim
10 in which said indicating means comprises a
cathode ray tube having beam deñecting means
for producing a plurality ‘of separate linear traces,
said traces being drawn in time sequence, the
position of said index marks along said line traces 10
being a measure of the time sequence of the re
ception of said reradiated pulses.
14. In a device of the character described, a
22
-said control stations distinctive pulses received
from said object, a cathode ray tube mounted in
said object, scanning means for producing line
traces on said cathode ray tube, and means con
nected to said cathode ray tube and separately
responsive to the reception of said distinctive re
radiated pulses for producing index marks on said
traces, the positions of said index marks along
said lines being measures of the transit time of
said pulses.
15. A device of the character described in claim
14 which includes, in addition, means for Vpro
ducing as a function of time an Aobjective index
on one of said line traces, the position of said
movable object, means for radiating a succession
of pulses of radio energy from said object, at 15 objective index being indicative of the destination
` rof said object.
least two control stations Whose locations are
STUART W. SEELEY.
known, means for receiving and reradiating from
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