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Nov. 5, 1946.
2,410,736
D. B. HOISI'NGTON
PULSE-MODULATED WAVE-SIGNAL RECEIVER
Filed Aug. 15, 1944
3 Sheets-Sheet 1
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6E53198. 0:
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DAVID
INVENTOR
B. HOISINGTON
Nov. 5, 1946.
D. B. HOISINGTON
2,410,736
PULSE-MODULATED WAVE-SIGNAL RECEIVER
Filed Aug. 15, 1944
3 Sheets-Sheet 2
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Nov. 5, 1946.
2,410,736
D. B. HOISIYNGT'ON
PULSE-MODULATED WAVE-SIGNAL RECEIVER
Filed Aug.‘ 15, 1944
' s sheets-sheet 3
Patented Nov. 5, 1946
; 2,410,730
UNITEIS STATES PATENT OFFICE‘
2,410,736
PULSE-MODULATED _WAVE-SIGNAI_4
RECEIVER
David B. Hoisington, Little Neck, N. Y., assignor,
by'mesne assignments, to Hazeltine Research,
Inc., Chicago, 111., a corporation of Illinois
Application August 15, 1944, Serial No. 549,616
13 Claims. (c1. 250-20)
2
This invention relates, in general, to a receiver
for deriving desired modulation components of
a received pulse-modulated carrier-frequency
wave signal. It is particularly directedto such
that both received signals are faithfully trans
lated to the second detector. For this condition
the aforementioned prior art receiver produces a
a receiver which is subject to receive an inter
the'output circuit of the second detector, con-~
taining the desired modulation components and
having a carrier frequency equal to the di?er
heterodyne-component pulse-modulated signal in
fering continuous- wave signal concurrently with
and having a different carrier frequency than
the desired pulse-modulated signal. While the
ence between the carrier frequencies of the re
invention is subject to a variety of applications,
ceived pulse-modulated and continuous-wave
it is especially suited for inclusion in the receiver 10 signals. For the most part, at the operating
portion of a radio-locator or direction-?nder sys
frequencies of such a system, the carrier fre
tem and will be described in that connection.
quency of this heterodyne-component signal falls
Direction-?nder systems of the prior art hav
outside of the narrow pass band of the succeed
ing a receiver of the superheterodyne type and
ing receiver stages and thus is effectively lost,
the effects thereon of an interfering continuous 15 even though this ‘heterodyne-component signal
wave signal will ?rst be considered. It is to be
includes a major portion of the energy content of
noted at the outset that such a system is usually
the translated signals corresponding to the modu
operated in the ultra-high portion of the fre
lation components desired. Further, such prior
quency spectrum because of the present alloca
art arrangements do not include means for de
tion of available radio-frequency channels and 20 riving the desired modulation components of the
also to take advantage of improved directivity
heterodyne-component signal should its carrier
possible at ultra-high frequencies. , Since allow
frequency be such as to be translated by the
ance must be made for drifts in the operating
narrow-band stages succeeding the second de
frequency of the heterodyne oscillator and in the
tector. It will be appreciated that this operat
carrier frequency of the transmitted signal, at 26 ing limitation may likewise be undesirable in
least the initial stages of such receivers are re
quired to have a wide pass band to assure‘ re
many installations.
ception of the desired direction-?nder signals.
At the same time, this band-width characteristic
renders the receiver subject to interfering sig
nals of a correspondingly wide range.
30
When
the interfering signal has a high intensity, com‘
pared with that of a desired pulse-modulated
direction-?nder signal, it causes overloading or
blocking in many of the prior art receivers to 35
such an extent that the pulse-modulated signal
is not translated. In other words, the desired
direction-?nder signal is lost under the stated
condition. Obviously, this is an undesired lim
itation.
40
In certain other'prior art receivers of the type
under consideration the band width is mate
rially reduced in stages following the second de
tector. The change in band width is desired to
increase the signal-to-noise ratio of the receiver 45
but impedes efficient operation in the presence
of strong interference. Usually the band width
of the stages following the second detector of
such a receiver‘is selected to be only as wide as
required to translate the desired vmodulation 50
components of a received pulse-modulated di
rection-?nder signal. Assume astrong inter
fering continuous-Wave signal to be received con
‘
It is, therefore, an object of the invention to
provide an improved receiver for deriving de
sired modulation components of a received pulse
modulated carrier-frequency wave signal and
which avoids one or more of the above-mentioned
limitations of prior art arrangements.
It is another object of the invention to provide
an improved receiver for deriving desired modu
lation components of a received pulse-modulated
carrier-frequency wave signal even in the pres
ence of a strong interfering wave signal received
concurrently therewith and having a carrier fre
quency different than that of the pulse-modu
lated signal.
‘In accordance with the invention, a receiver
for deriving desired modulation components of a
received pulse-modulated carrier-frequency wave
signal but subject to receive concurrently there
with an interfering wave ‘signal of different fre
quency than the carrier frequency of the pulse
modulated signal comprises a ?rst signal-trans
lating means including selector circuits for
translating both of the received signals. The
?rst signal-translating means also includes de
tecting means effective in the absence of the
interfering wave signal to derive the desired mod
ulation components of the pulse-modulated sig
nal and effective in the presence of the inter
currently with the pulse-modulated ‘signal and
.also assume the design of the receiver to be such 55 fering signal with high intensity to derive from
3
9,410,730‘
4
the received signals of a heterodyne-component
pulse-modulated signal having modulation com
ponents corresponding to the desired components.
The receiver is provided with a second signal
translating means coupled to the afore-men
tioned detecting means and including selector
circuits for translating both the desired modu
lation components and the heterodyne-compo
nent pulse-modulated signal. A rectifying means
is included in the second signal-translating
means e?ectlve to derive the desired modulation
28 and a series-tuned circuit provided byvan ad
iustable inductor 2t and a condenser 25, the
tuned circuit being coupled to the input elec
trodes of tube 20 by way of a resistor 26. An op
erating bias for tube 20 is supplied by a cathodebiasing resistor 21. A parallel-tuned circuit is
coupled to the anode electrode of'tube 20 and
components from the heterodyne-componeht
pulse-modulated signal. Additionally, the re
28 and associated stray capacitances.
includes an adjustable inductor 28 which is
tuned by a condenser 29, shown in broken-line
construction since it may be comprised in whole
or in part of the inherent capacitance of inductor
Tuned
circuit 28, 28 is damped by a resistor 30.
ceiver is provided with means, coupled to the
The second ‘intermediate-frequency ampli?er
second signal-translating means, for supplying 15 stage is coupled to the output circuit of tube 20
the desired modulation components to a utiliz
through a coupling condenser 3|. This stage is
ing device.
similar to the preceding one, having a damped
For a better understanding of the present in
tuned circuit coupled to the output circuit of its
vention, together with other and further objects
amplifying tube ‘ii. The tuned circuit consists
thereof, reference is had to the following de 20 of an adjustable inductor 32, a condenser 33, and
scription taken in connection with the accom
a resistor 34. A positive potential is applied to
panying drawings, and its scope will be pointed
the input electrode of tube 2| through a bleeder
out in the appended claims.
network including resistors 35 and 36 coupled to
Referring to the drawings, Fig. 1 is a schematic
a voltage source, indicated +3. The cathode
representation of a pulse-modulated signal re 25 bias resistor 31 of this stage has a high value,
ceiver in accordance with the invention; Figs. 2,
for a purpose to be described hereinafter. The
3 and 4 individually comprise a series of graphs
?nal stage of the intermediate-frequency am,
utilized in explaining the operation of the Fig.
pli?er, including tube 22, is substantially the
1 arrangement under several different operating
same as the second stage and corresponding
conditions; and Fig. 5 is a schematic representa 30 components are identi?ed by like reference nu
tion of a modi?ed pulse-modulated signal receiver
merals primed.
embodying the invention.
Suitable operating potentials are applied to
Referring now more particularly to Fig. 1 of
the several stages from the source indicated +B.
the drawings, the arrangement there represented
A variable resistor 38 is included as a common
may be considered as constituting the receiver 36 element in the anode-cathode circuits of. the am
portion of a direction-?nder system in which
direction-?nding information is translated by
way of pulse-modulated carrier-frequency wave
signals. Accordingly, the receiver is adapted to
plifying stages of unit M to adjust the cathode
bias of the several tubes. thereby to provide a
gain control. Additional gain control is aiforded
by an adjustable resistor 89 coupled between
derive desired modulation components of a re 40 source +3 and the cathode electrodes of tubes
ceived pulse-modulated carrier-frequency wave
2| and 22 through resistors 40 and ii, respec
signal for application to a utilizing device but is
tively.
also subject to receive concurrently therewith an
The described tuned circuits of the intermedi
interfering wave signal of different frequency
ate-frequency ampli?er constitute selector cir
than the carrier frequency of the received pulse
5 cuits. The circuits are stagger-tuned in conven
modulated signal. As illustrated, the receiver
tional manner and the damping provided is such
comprises an antenna system I0, I l for intercept
that the circuits have a band-pass characteristic
ing pulse-modulated carrier-frequency wave sig
substantially as wide as that of units l2 and ii.
nals and for applying such signals to a ?rst sig
That is, the selector circuits permit the received
nal-translating means coupled to the antenna 50 signals to be translated faithfully through the
system.
intermediate-frequency stages.
The ?rst signal-translating means comprises
The detector ii of the described signal-trans
a radio-frequency ampli?er I2 of one or more
lating means comprises means effective in the.
absence of an interfering wave signal to derive
stages to which are coupled, in cascade, an
oscillator-modulator l3, an intermediate-fre 55 desired modulation components of a received
quency ampli?er l4, described more particularly
pulse-modulated wave signal and effective in the
presence of an interfering wave signal of high
hereinafter, and a detecting means i6. Units l2
intensity to derive from the received signals a
and I3, shown in block form, may be of any con
heterodyne-component pulse-modulated signal
ventional construction and design. The heter
odyning oscillator of unit it in the usual case 80 having modulation components corresponding to
the desired components of the received pulse
will have a tendency to drift,‘ that is, its operat
modulated signal. This detector is coupled to the
ing frequency will tend to vary over a predeter
last stage of the intermediate-frequency am
mined range of frequencies. Therefore, units l2
pli?er through a coupling condenser 45 and in
and i3 are preferably selected to have a corre
cludes a diode detector 48 having a load circuit
spondingly wide band-pass characteristic so as to
comprising a resistor l1 and an intermediate-fre
allow for such instability or frequency shifts of
quency choke 48.
the heterodyning oscillator as well as shifts of
The receiver of Fig. 1 includes a second signal
the carrier frequency of signals to be received.
translating means, this second signal-translat—
The intermediate-frequency ampli?er i4 is
shown as a three-stage ampli?er, although as 70 ing means having an input circuit coupled to de
tector l5. This last-named means includes se
many stages of ampli?cation may be utilized as
lector circuits having a band-pass charactereistic
desired. In the illustrated arrangement. the
substantially as wide as that of the ?rst signal
stages include pentode-type amplifying tubes 20,
translating means for translating both the de
2i and 22. The ?rst stage is coupled to oscil
lator-modulator it through a coupling condenser 75 sired modulation components and the heter
2,410,786
5
6
.
odyne-component pulse-modulated signal de
given direction from its reference level. - That is,
rived in the load circuit of detector l5 under
various operating conditions. The second sig
nal-translating means includes an ampli?er 50
having a pair of cathode-coupled amplifying 5
tubes 5| and 52. The output signal of detector,
I5 is applied to the input circuit of tube 5|
through a coupling condenser 53 and an inductor
54. Inductor 54 resonates with the input capac
itance of tube 5| to maintain high-frequency 10
?delity in the translating arrangement under
consideration. Additionally, inductor 54 is self
resonant at the mid-frequency of intermediate
repeated device 16A is effective to repeat only sig
nal variations of positive polarity. The system
also includes a second repeater device, section
frequency ampli?er N to isolate intermediate
frequency signals from the second signal-trans
16B of tube ‘I6, biased so as to be responsive to
bidirectional amplitude variations, or variations
of positive and negative polarity, of the applied
signal from its reference level. Input and output
circuits are provided for the repeater devices, in‘
cluding an impedance which is common to the
output circuit of the ?rst device and to the input
circuit of the second device. This impedance is
shown as series-connected cathode resistors 18
and 19 and is such that signal variations in the
15
?rst device 16A tend to effect opposing signal
lating means under consideration. The cathode
electrodes of tubes 5| and 52 are coupled through
a T-type network including resistors 55, 56 and,
51. With this circuit arrangement, tube 52 con
stitutes a cathode-driven ampli?er. A source of 20
space current, indicated +B, is connected with
the anode electrodes of tubes 5| and'52, as shown,
and a positive potential is applied to the con
trol electrodes thereof through a bleeder network
of resistors 58, 59 and 60. The components of the 25
described T network are selected of such value
that tubes 5| and 52 have the desired effective
variations in the second device 16B. The system
has means, comprising a coupling condenser 80,
for applying the signal output. of limiter section
613 with a given phase and given intensity to
the input circuit of ?rst device 16A. The system
likewise has means, comprising a coupling con
denser 8| connected to a tap on the anode re
sistor l2 of limiter section 613, for applying the
signal output of section 613 with the same phase
but with substantially less than the aforesaid
given intensity tothe input circuit of second de
vice '|6B. Preferably, the tap of resistor 12 is so
operating bias.
'
adjusted that the signal is applied to repeater de
A limiter 65 is coupled in cascade with tube 52
vice 163 with less than one-half the intensity of
through a condenser 66. The limiter 55 is similar 80 the signal as applied to repeater device 61A.
to unit 5|) in that it contains a pair of cathode
Finally, the system includes means, comprising a
coupled electron-discharge repeater devices, il
connection 82, coupled to the output circuit of
lustrated as individual sections of a duo-triode 61
the second repeater device for deriving an output
having a common cathode resistor’ 68. The anode
signal from the system having amplitude varia
electrodes of each section of tube 61 connect with" 35 tions which are determined by the variations of
a source of space current +3 and a positive po
the applied signal but which are unidirectional
tential is applied to the control electrodes of each
with respect to a reference amplitude level corre
section through a network of resistors 69, ‘I0 and
sponding to the reference level of the applied
signal. A detailed description of ‘unit 15 is con
‘II, The resistor elements 68-", inclusive, are
proportioned to establish such operating biases on 40 tained in the above-mentioned copending appli
the control electrodes of the sections of tubes 61
that the ?rst section 61A eifects limiting of strong
cation.
_
The receiver of Fig. 1 further includes means
applied signal variations of negative polarity,
coupled to the signal-translating means compris
while limiting of strong signal variations of posi
ing units 50, 65 and 15 for supplying the desired
tive polarity is accomplshed in the remaning sec 45 modulation components to a utilizing device.
tion 613. This limiting action in each instance is
This means is provided by a cathode follower in
obtained by the sections being driven to anode
cluding a pentode-type tube 90. The cathode fol
current cutoff by the signal variations limited in \ lower is coupled to the output circuit of second
the particular section.
repeater device 163 through connection 82 and
The second signal-translating means also in 50 a coupling condenser 9|._ A source of space cur
cludes a rectifying means 15 which effectively
rent, indicated +B, is connected with anode elec
comprises a full-wave recti?er for deriving the
trode of tube 90. The desired modulation com
desired modulation components from the hetero
dyne-co-mponent pulse-modulated signal ob
ponents of the received pulse-modulated signal
are derived across a cathode impedance 92 and
tained from detector |5 in the presence of a re-_ 55 supplied to an output terminal 93 to which a suita
ceived pulse-modulated signal and a strong in
ble utilizing device (not shown) may be connected.
terfering continuous-wave signal of different fre
The anode resistor 83 of repeater 16B and the in
quency than the carrier frequency of the pulse
herent capacitance of its anode circuit, repre
modulated signal. This rectifying means is sub
sented by broken-line condenser 84, effectively
stantially the same as the signal-translating sys 60 constitute a low-pass ?lter in the input circuit of
tem forming the subject matter of applicant’s
cathode follower 90 so that substantially only the
copending application, Serial No. 549,615, ?led
desired modulation components are translated
concurrently herewith and assigned to the same
therethrough to output terminal 93. In other
assignee as the present invention.
words, while the selector circuits of the several '
The arrangement of unit 15 is described in the 55 stages of the described receiver from the antenna
copending application as a signal-translating
system H), H to cathode follower 90 have wide
system for translating 3, signal which may include
band-pass characteristics, the ?nal stage 90 has
bidirectional amplitude variations ‘with respect to
a narrow pass band, being only as wide as re
a reference amplitude level. Brie?y, the sys
quired to translate the desired modulation com
tem comprises a ?rst repeater device including 70 ponents. This reduction in band width at the
section 16A of a duo-triode 16. This section is
?nal stage of the receiver enhances the signal
biased substantially to anode current cutoff by
to-noise ratio.
virtue of a stabilizing circuit including a diode
In considering the operation of the described
11, so that it is responsive substantially only to
arrangement, reference is made to the series of
amplitude variations of an applied signal in a. 75 graphs of Fig. 2. These graphs illustrate the
‘2,410,788
a
operation for the condition in which the desired
pulse-modulated direction-?nder signal alone ‘is
intercepted by antenna system 10, H. A single
pulse of the received signal is represented by
curve a.
r
s
from intermodulation of the pulse-modulated and
interfering signals. It has a frequency corre
sponding to the di?erence in the carrier fre
quencies of these received signals but has a rela
The received signal is ‘translated 5 tively low intensity compared with the detected
pulse-modulated signal. The ripple component
through units I! to IE, inclusive, in accordance
with conventional heterodyne operation, and the
detected modulation components thereof appear
is effectively removed through the limiting action
of section "A of unit 65 so that the signal ap
in the output circuit of detector IS with the wave
plied to unit 15, as represented by curve d', is
form of curve b. The derived output signal, after 10 substantially the same as that obtained in the
amplification in unit 50, is translated through
limiter 65 where the ?rst section 61A limits the
signal at-the limiting‘level represented by hori
zontal line c of Fig. 2. The output signal of the
limiter, full-line curve d, is a unidirectional sig 15
presence of the pulse-modulated signal alone.‘
Consequently, the output signal of detector ‘ll,
curve It’, and that delivered to terminal ll cor
respond to thoseobtained for the ?rst-mentioned
operating condition.
nal having’ only amplitude variations of negative
Beforeconsidering the over-all response of the
polarity from a reference amplitude level, indi
cated e1. This output signal of limiter 65 is
receiver to a pulse-modulated signal and a strong
applied through condenser 80 to the input circuit
of ?rst repeater device "A of unit ‘Ill with a
given phase and full intensity. The same signal
is applied with the like phase but with less than
half intensity through condenser 8| to the input
circuit of second repeater device "B. The ap
interfering continuous-wave signal received con
currently therewith, mention should be made of
20 the function of the biasing circuits of the
'_ second and third intermediate-frequency ampli
fier stages described above. While a positive po
tential is applied to the control electrodes of
tubes 2| and 22, the cathode resistors 31 and 31' of
plied signal, having only amplitude variations of 25 these stages are selected of such value that the
negative polarity,'is not translated by ?rst re
e?ective grid bias operates the tubes close to
peater device "A. However, the second repeater,
anode current cuto?’. Due to the curvature of
functioning in a manner analogous to a con
the characteristic curves of tubes II and 22 at
ventional triode ampli?er, translates the signal
the selected operating point, any signal voltage
of less than half intensity to the output circuit 30 on the input electrodes tends to increase the
of detector 15 where it appears with the wave
average space current since positive half cycles
form of curve It. This signal has unidirectional
‘of the applied signal increase the space current
amplitude variations determined by the ampli
more than negative half cycles decrease it. Due
tude variations of the applied signal, curve d, but
to the positive voltage on the control electrodes
of positive polarity with respect to a reference .35 and due to the large cathode resistors, a small
amplitude level as corresponding to the reference
level er of the applied signal. The desired modu
change in the space current produces a relatively
large change in the operating bias. High-in
tensity continuous-wave signals move the operat
15 are selected in the input circuit of cathode
ing point beyond anode current cuto?’ so that
follower so and supplied to output terminal 53 40 such high-intensity signals may be accommodated
for utilization. By stating that the reference
without overloading the intermediate-frequency
level e: of the output signal of unit 15 corresponds
stages on the positivesignal peaks. For this
to the reference level er of the signal applied
reason, high-intensity interfering signals do not
thereto is meant that the amplitude level of the
produce such over-loading as would cause the
output signal has the value e: when the applied 45 desired pulse-modulated signal received concur
signal has its reference amplitude value e1.
rently therewith to be e?ectively lost.
From the foregoing description it will be ap
The graphs of Fig. 4 indicate the over-all‘
parent that when the pulse-modulated signal
receiver response when the interfering continu
alone is received, the arrangement of Fig. 1 func
ous-wave signal is of high intensity as compared
tions as a conventional superheterodyne receiver, 50 with that of the pulse-modulated signal. These
deriving the desired modulation components in
graphs correspond with those of Fig. 3 and are
the second detector l5 and translating these
identi?ed by similar reference characters double
components after suitable ampli?cation in the
primed.
succeeding signal stages 50, 65 and 1'5 to output
It will be seen that for such operating condi
terminal 93.
55 tions, the output signal of the detector l5, curve
lation components of this outputvsignal of unit
Consider now the operation of the receiver
when an interfering continuous-wave signal of
1)", comprises a substantial direct current com
ponent and a heterodyne-component pulse-modu
relatively low intensity is received concurrently
lated signal having modulation components cor
with the pulse-modulated direction-?nder signal.
responding to the desired components of the re
The response of the receiver for this condition is 60 ceived pulse-modulation signal and having a car
represented by the graphs of Fig. 3. The curve a
rier-frequency equal to the di?erence between
represents the pulse-modulated signal and curve I
the carrier frequencies of the received signals.
represents an interfering continuous-wave signal
In other words, the detected modulation com
having a carrier frequency different from that
ponents derived directly through detection of the
of the pulse-modulated signal but included with
received pulse-modulated signal are overwhelmed
in the pass band of units l0—ll, inclusive. For
by the heterodyne-component signal resulting
this condition, both signals are translated to de
from the intermodulation of the received pulse
tector II in view of the wide band-pass charac
modulated and continuous-wave signals. Since
teristics of the preceding stages. The output sig
capacitive coupling is utilized between the second
nal of the detector, as shown by curve 12', con 70 detector I5 and ampli?er 50, the direct current
tains a low-intensity direct current component,
component of the detector output signal is lost
the detected modulation components of the re
and the signal of curve b” is applied to unit 50
ceived pulse-modulated signal and a superposed
as a pure alternating current signal. Both the
ripple component g. The ripple component rep
positive and negative amplitude variations of this
resents a heterodyne-component signal resulting 76 signal are limited in unit 65, as indicated by limit
9,410,786
ing levels 0 and c' of Fig. 4. The resulting signal
nel is characterized by a band-pass character‘
istic such as to translate substantially only the
desired modulation components of the received
output of the limiter is represented by full-line
curve d". It has bidirectional amplitude varia
tions from a reference level e1" corresponding to
the alternating current axis of the heterodyne
pulse-modulated direction-?nder signal.
The
other channel is generally similar to the described
second signal-translating means of the Fig. l
arrangement, having a relatively wide band-pass
component pulse-modulated signal. The limited
signal is translated by detector 16, appearing in
the output circuit thereof with the wave form of
characteristic. ' In particular, this channel com
curve h". The translated signal has amplitude
prises a unit 50 which here designates both‘ the
variations which are determined by the bidirec 10 wide-band ampli?er 50 and limiter 05 of the
tional amplitude variations of the limited signal
Fig. 1 arrangement. This channel also includes
of curve d" but which are unidirectional with
the full-wave recti?er ‘I5 and its'band-pass char
respect to a reference amplitude level ea" corre
acteristic is such that the channel is effective
sponding to the reference level er" of the limited
to translate any heterodyne-component pulse
signal. From a comparison of curves (1" and h" 15 modulated signal derived in detector I5 in the
it will be evident that the unit ‘I5 functions as a
presence of both a pulse-modulated signal and a
full-wave recti?er. The speci?c operation of unit
strong interfering continuous-wave signal, as
15 in this respect is completely described in the
described above. Preferably, the pass band of
above-mentioned copending application.
this second channel comprising units 50 and ‘I5
While the output signal of curve h" includes 20 is such as to translate substantially only such
the desired modulation components of the received
heterodyne-component pulse-modulated signals
pulse-modulated signal, it also contains a com
of detector I5. The desired modulation com
ponent having twice the frequency of the heter
ponents derived from the heterodyne-component
odyne-component pulse-modulated signal ob
signal in recti?er ‘I5 are supplied to the narrow
tained from detector I5. This high-frequency 25 band ampli?er 90 which may comprise a cathode
component. as‘ well as others not desired to be uti
follower arranged to translate substantially only
lized, are effectively eliminated by the ?lter 83, 84
the desired modulation components, as in the
in the input circuit of cathode follower 90. There
Fig. 1 arrangement.
fore, the signal delivered to output terminal 93
The modi?ed receiver also includes means cou
for application to the utilizing device again con 30 pled to the described pair of parallel-connected
tains substantially only the desired modulation
channels for supplying the desired modulation
components of the received pulse-modulated di
components to the utilizing device. This means
rection-?nder signal.
. g
*
is provided by an output terminal 93 to which
In order to simplify the description, the re
the ?rst channel is coupled through a condenser
sponse of the receiver has been considered only 85 IOI, while the second channel is coupled there
for the condition in which a given interfering
to through ampli?er 90 and a condenser 92.
signal of high intensity is received concurrently
with the desired pulse-modulated signal. How
In general, the two channels coupled to detec-l
tor I5 will not be used simultaneously and, there
fore, the arrangement is Provided with an ampli
ever, it will be clear that an interfering signal
having a carrier frequency within a range of fre
quencies corresponding to the pass band of the
tude-selective means responsive to an interfering
wave signal of high intensity for disabling the
receiver may be translated simultaneously with
?rst-described channel. This means, as repre
sented, includes a relay I02 of well-known con
a desired pulse-modulated signal. For this rea
son, the resulting heterodyne-component pulse
modulated signal derived in detector I5 may like
struction connected in the output circuit of de
An armature I05 normally connects
45 tector l5.
wise have a carrier component within a corre
sponding frequency range. I Since the pass band
the ?rst channel, including narrow-band ampli
?er I00, to the output circuit of detector I5
of the second signal-translating means comprised
through a condenser I04 and normally closed
of units 50, 65 and ‘I5 is as wide as that of the
contact I03. In its alternate position the arma
preceding stages, any such heterodyneecomponent 50 ture disables the ?rst channel and connects the
signal is translated thereby to derive the desired
second channel to the output circuit of detector
modulation components in the described manner.
l5 through condenser 53 and the remaining relay
In one embodiment of the invention found to
contact I 06.
have practical utility, the receiver had the fol
The operation of the Fig. 5 arrangement will
55 be apparent from the preceding discussion.
lowing characteristics:
Brie?y, when a pulse-modulated direction-?nder
Pass band of units IZ-I 5, inclusive
signal alone is received, the desired modulation
megacycles__
4
Pass band of units 50, 65 and ‘I5 ____ __do____
Pass band of cathode follower 90
4
Mid-frequency of radio-frequency stages
'
components are derived in- detector.I5 and ap
plied through normally closed contact I03 and
kilocycles__ 200 60 narrow-band ampli?er I00 ‘to output terminal
megacycles__ 172
93.
However, when a strong interfering con
tinuous-wave signal is simultaneously received,
the average current in the output circuit of de
tector I5 has such value that relay I02 is ener
65 gized and connects the output circuit of the de
The receiver arrangement of Fig. 5 is generally
tector with the alternate parallel-connected sig
similar to that of Fig. 1 and corresponding com
nal-translating channel. For this condition, the
ponents thereof are identi?ed by the same refer
desired modulation components are derived in
Mid-intermediate frequency _______ __do____ 11
Pulse-repetition frequency_______ _‘_cycles__ 400
ence numerals, with exceptions as noted herein
full-wave recti?er ‘I5 and applied through nar- .
after. In the Fig. 5 modi?cation the second 70 row-band ampli?er 90 and condenser 92 to out
signal-translating means coupled to detector I5
effectively comprises a pair of parallel-connected
signal-translating channels. One such channel
comprises a narrow-band ampli?er I00 which
may be of conventional construction. This chan 75
put terminal 93.
It is well known that a pulse-modulated signal
of the type represented by the curves of Figs. 2,
3 and 4 contains, at least theoretically, an in
?nite series of frequency components.
These
2,410,?”
11
components require an unusually wide band-pass
characteristic if the signal is to be translated
with no distortion. Such ?delity, however, is
seldom required and in the usual installation only
a selected portion of those components are uti
lized in the receiver.‘ The expression “desired
modulation components," as used throughout
this speci?cation, is intended to include such
a selection of the frequency components of a
received pulse-modulated signal.
While the invention has been particularly de
scribed in connection with a receiver of the su
perheterodyne type, it will be understood that
this is not a necessary limitation, It will" be ob
vious to those skilled in the art that the inven
tion may likewise be applied to other receivers,
for example, the tuned radio-frequency type.
lector circuits for translating said desired modu
lation components and said heterodyne-compo
nent pulse-modulated signal, rectifying means
included in said second signal-translating means
eifective to derive said desired modulation com
ponents from said heterodyne-component pulse
modulated signal, and means coupled to said sec
ond signal-translating means for supplying said
desired modulation components to a utilizing
10 device.
2. A receiver for deriving desired modulation
components of a received pulse-modulated car
rier-frequency wave signal but subject to receive
concurrently therewith an interfering wave signal
15 of different frequency than the carrier frequency
of said pulse-modulated signal comprising, a ?rst
signal-translating means including selector cir
cuits for translating both of said received signals,
detecting means included in said ?rst signal
In discussing the receiver response in the pres
ence of an interfering continuous-wave signal
of high intensity with reference to, and of a car 20 translating means effective in the absence of said
interfering wave signal to derive said desired
rier frequency different than, the received pulse
modulation components of said pulse-modulated
modulated signal, it was shown that a hetero
dyne-component pulse-modulated signal is pro
signal and effective in the presence of said inter
fering signal with high intensity to derive from
duced which includes the desired modulation
components. This same general operation pre 25 said received signals a heterodyne-component
pulse-modulated signal having modulation com
vails whether the interfering signal is a continu
ponents corresponding to said desired compo
ous—wave signal in a strict sense of the term or
nents and having a carrier frequency equal to
is a keyed continuous-wave signal having a long
the difference between the carrier frequencies of
‘duty cycle with reference to the pulse duration
said received wave signals, a second signal
of the received direction-?nder signal. Also,
translating means coupled to said detecting means
substantially the same result is obtained when
and including selector circuits for translating said
the continuous-wave signal has a sinusoidal or
desired modulation components and said hetero
other modulation at a frequency which is low
with reference to the period of the received
pulses.
dyne-component pulse-modulated signal, recti
35 fying means included in said second signal
translating means eii'ective to derive said desired
modulation components from said heterodyne
component pulse-modulated signal, and means
dyne-component pulse-modulated signal, is dis
coupled to said second signal-translating means
closed as a full-wave recti?er. This represents
the preferred embodiment of the invention, in 40 for supplying said desired modulation compo
nents to a utilizing device.
creasing the energy level of the desired modula-'
3. A receiver for deriving desired modulation
tion components to a value comparable to that
components of a received pulse-modulated car
obtained when the pulse-modulated signal is re
rier-frequency wave signal but subject to receive
ceived with no interference. It will be under
The recti?er ‘l5, utilized in deriving the de
sired modulation components from the hetero
si'ood that a half-wave recti?er may be em
concurrently therewith an interfering wave sig
nal of different frequency than the carrier fre
quency of said pulse-modulated signal comprising,
While there have been described what are at
a ?rst signal-translating means including selector
present considered to be the preferred embodi
circuits for translating both of said received sig
ments of this invention, it will be obvious to
those skilled in the art that various changes and 50 nals, detecting means included in said ?rst signal
translating means effective in the absence of said
modi?cations may be made therein without de
interfering wave signal to derive said desired
parting from the invention, and it is, therefore,
modulation components of said pulse-modulated
aimed in the appended claims to cover all such
signal and effective in the presence of said inter
changes and modi?cations as fall within the true
fering signal with high intensity to derive from
spirit and scope of the invention.
said received signals a heterodyne-component
What is claimed .is:
pulse-modulated signal having modulation com
l. A receiver for deriving desired modulation
ponents corresponding to said desired compo
components of a received pulse-modulated car
nents, a second signal-translating means coupled
rier-frequency wave signal but subiect to receive
concurrently therewith an interfering wave sig 60 to said detecting means and including selector cir
cuits for translating said desired modulation com
nal of diiferent frequency than the carrier fre
ponents and said heterodyne-component pulse
quency of said pulse-modulated signal compris
modulated signal, full-wave rectifying means in
ing, a ?rst signal-translating means including se
cluded in said second signal-translating means
lector circuits for translating both of said re
ceived signals, detecting means included in said 65 effective to derive said desired modulation com
ponents from said heterodyne-component pulse
?rst signal-translating means effective in the ab
modulated signal, and means coupled to said sec
sence of said interfering wave signal to derive
ond signal-translating means for supplying said
said desired modulation components of said pulse
desired modulation components to a utilizing
modulated signal and effective in the presence of
said interfering signal with high intensity to de 70 device.
4. A receiver for deriving desired modulation
rive from said received signals a heterodyne
ployed. if desired.
component pulse-modulated signal having modu
lation components corresponding to said desired
components, a second signal-translating means
coupled to said detecting means and including se
components of a received pulse-modulated car
rier-frequency wave signal comprising, a ?rst sig
nal-translating means including selector circuits
76 for translating said pulse-modulated signal and
9,410,786
13
-
having a band-pass characteristic effective to
translate a predetermined range of frequencies
such that said receiver is subject to receive con
,
‘
14
said desired modulation components of said
pulse-modulated signal and effective in the pres
ence of said interfering signal with high intensity
currently with said pulse-modulated signal in
to derive from said received signals a heterodyne
terfering wave signals having carrier frequencies 5 component pulse-modulated signal having mod
within a band of frequencies substantially as wide
ulation components corresponding to said desired
as said predetermined range, detecting means in
cluded in said ?rst signal-translating means ef
fective in the absence of an interfering wave signal
components, a second signal-translating means
coupled to said detecting means and including
selector circuits for translating said desired mod
ulation components and said heterodyne-com
to derive said desired modulation components of
said pulse-modulated signal and e?ective in the
presence of an interfering signal with high inten
sity to derive from said received signals a hetero
ponent pulse-modulated signal, rectifying means
included in said second signal-translating means
dyne-component pulse-modulated signal having
ponents from said heterodyne-component pulse
effective to derive said desired modulation com
modulation components corresponding to said de 15 modulated signal, and means coupled to said ‘
sired components and having a carrier frequency
second signal-translating means including a low
within a band of frequencies substantially of the
pass ?lterfor supplying substantially only said
width of said predetermined range, a second sig
desired modulation components to a utilizing de
nal-translating means coupled to said detecting
vice.
means and including selector circuits having a 20
'7. A receiver for deriving desided modulation
band-pass characteristic substantially as wide as
components of a received pulse-modulated car
that of said ?rst signal-translating means for
rier-frequency wave signal but subject to receive
translating said desired modulation components
concurrently therewith an interfering wave sig
and heterodynel-component pulse-modulated sig
nal of different frequency than the carrier fre
nals derived in said detecting means in the pres 25 quency of said pulse-modulated signal compris
ence of said pulse-modulated signal and an in
ing, a ?rst signal-translating means including
terfering signal of high intensity, rectifying
selector circuits for translating both of said re
means included in said second signal-translating
ceived signals, detecting means included in said
means effective to derive said desired modulation
?rst signal-translating means effective in the ab
components from said heterodyne-component 30 sence of said interfering wave signal to derive
pulse-modulated signal, and means coupled to
said desired modulation components of said
said second signal-translating means for supply
pulse-modulated signal and effective in the pres
ing said desired modulation components to a util
ence of said interfering signal with high intensity
izing device.
to derive from said received signal a heterodyne
5. A receiver for deriving desired modulation 35 component pulse-modulated signal having mod
components of a received pulse-modulated car
ulation components corresponding to said desired
rier-frequency wave signal but subject to receive
components, a second signal-translating means
concurrently therewith an interfering wave sig
coupled to said detecting means and including
nal of different frequency than the carrier fre
selector circuits for translating said desired mod.
quency of said pulse-modulated signal compris 40 ulation components and said heterodyne-com
ing, a ?rst signal-translating means including
ponent pulse-modulated signal, means included‘
selector circuits for translating both of said re
in said second signal-translating means for lim-'
ceived signals, detecting means included in said
iting the maximum amplitudes of said desired ?rst signal-translating means effective in the ab
modulation components and said heterodyne
sence of said interfering wave signal ‘to derive 45 component pulse-modulated signal to a predeter
said desired modulation components of said
mined value, rectifying means coupled to said
pulse-modulated signal and effective in the pres
limiting means for deriving said desired modula
ence of said interfering signal with high intensity
to derive from said received signals a heterodyne
component pulse-modulated signal having mod
tion components from said heterodyne-com
ponent pulse-modulated signal, and means cou
50 pied to said second signal-translating means for
supplying said desired modulation components to
ulation components corresponding to said de
a utilizing device.
sired components, a second signal-translating
means coupled to said detecting means and in
8. A receiver for deriving desired, modulation
cluding selector circuits for translating said de
components of a received pulse-modulated car
sired modulation components and said heter 55 rier-frequency wave signal but subject to receive
odyne-component pulse-modulated signal, rec
concurrently therewith an interfering wave sig
tifying means included in said second signal
nal of different frequency than the carrier fre
translating means effective to derive said de
quency of said pulse-modulated signal compris
sired modulation components from said heter
ing, a ?rst signal-translating means including
odyne-component pulse-modulated signal, and 60 selector circuits for translating both of said re
means coupled to said second signal-translating
means for supplying substantially only said de
sired modulation components to a utilizing de
vice.
ceived signals, detecting means included in said
?rst signal-translating means effective in the
absence of said interfering wave signal to derive
said desired modulation components of said
I 6. A receiver for deriving desired modulation 65 pulse-modulated signal and effective in the pres
components of a received pulse-modulated car
ence of said interfering signal with high intensity
rier-frequency wave signal but subject to receive
to derive from said received signals a heterodyne
concurrently therewith an interfering wave sig
component pulse-modulated signal having mod
nal of different frequency than the carrier fre
ulation components corresponding to said desired
quency of said pulse-modulated signal compris 70 components, a second signal-translating means
ing, a ?rst'signal-translating means including
coupled to said detecting means and including
selector circuits for translating both of said re
ceived signals, detecting means included in said
?rst signal-translating means effective in the
selector circuits for translating said desired mod
ulation components and said heterodyne-com
ponent pulse-modulated signal, means included
absence of said interfering wave signal to derive 75 in said second signal-translating means compris
9,410,786
-
ing a pair of cathode-coupled electron-discharge
16
mg a band-pass characteristic‘ substantially of
repeater devices for limiting the maximum am
plitude of said desired modulation components
and said heterodyne-component pulse-mod
ulated signal to a predetermined value, rectify
ing means coupled to said limiting means for
the width of that of said first signal-translating
means to translate substantially only heterodyne
component pulse-modulated signals derived in
vice.
gal‘: desired modulation components to a utilizing
said detecting means in the presence of said
pulse-modulated signal and an interfering signal
deriving said desired modulation components
of high intensity, rectifying means included in
from said heterodyne-component pulse-mod
said other channel e?ective to derive said desired
ulated signal, and means coupled to said second
modulation components from said heterodyne
signal-translating means for supplying said de 10 component pulse-modulated signal, and means
sired modulation components to a} utilizing de
coupled to said pair of channels for supplying
4
~
9. A receiver for deriving desired modulation
e
components of a received pulse-modulated car
rier-frequency wave signal but subject to receive
ce.
11. A receiver for deriving desired modulation
components of a received pulse-modulated car
concurrently therewith an interfering wave sig
rier-frequency wave signal but subject to receive
nal of different frequency than the carrier fre
‘concurrently therewith an interfering wave signal
quency of said pulse-modulated signal compris
of different frequency than the carrier frequency
ing, a first signal-translatingmeans including se
of said pulse-modulated signal comprising, a first
lector circuitsfor translating both of said re
signal-translating means including selector cir
ceived signals, detecting means included in said
cuits for translating both of said received signals,
first signal-translating means effective in the
detecting means included in said first signal
absence of said interfering wave signal to derive
translating means e?ective in the absence of said
said desired modulation components of said
interfering wave signal to derive said desired mod
pulse-modulated signal and effective in the pres 25 ulation components of said pulse-modulated sig
ence of said interfering signal with high inten
nal and effective in'the presence of said interfer
sity to derive from said received signals a heter-_
ing signal with high intensity to derive from said
odyne-ccmponent pulse-modulated signal having
received signals a heterodyne-component pulse
modulation components corresponding to said de
modulated signal having modulation components
sired components, a second signal-translating 30 corresponding to said desired components, a sec
means coupled to said detecting means and effec
ond signal-translating means coupled to said de
tively comprising a pair of parallel-connected sig
tecting means and e?'ectively comprising a pair of
parallel-connected signal-translating channels,
nal-translating channels, one of said channels
having a band-pass characteristic effective to
one of said channels having a band-pass charac
35 teristic effective to translate substantially only
tion components and the other of said channels
said desired signal components and the other of
having 'a band-pass characteristic effective to
said channels having a band-pass characteristic
translate said heterodyne-component pulse-mod
effective to translate said heterodyne-component
ulated signal, rectifying means included in said
pulse-modulated signal, rectifying means included
other channel effective to derive said desired 40 in said other channel effective to derive ‘said de
modulation components from said heterodyne
sired modulation components from said hetero
component pulse-modulated signal, and means
dyne-component pulse-modulated signal, means
coupled to said pair of channels for supplying
coupled to said pair of channels for supplying said
translate substantially only saiddesired modula
said desired modulation components to a utilizing
device.
desired modulation components to a. utilizing de
vice, and means for selectively disabling one of
said pair of channels.
12. A receiver for deriving desired modulation
components of a received pulse-modulated car
rier-frequency wave signal but subject to receive
concurrently therewith an interfering wave sig
.
10. A receiver for deriving desired modulation
components of a received pulse-modulated car
rier-frequency wave signal comprising, a ?rst
signal-translating means including selector cir
cuits for translating said pulse-modulated sig
nal and having a band-pass characteristic effec
_ nal of different frequency than the carrier fre
tive to translate a predetermined range of fre
quencies such that said receiver is subject to re
quency of said pulse-modulated signal compris
ing, a ?rst signal-translating means including
selector circuits for translating both of said re
ceived signals, detecting means included in said
?rst signal-translating means e?ective in the ab
sence of said interfering wave signal to derive said
desired modulation components of said pulse
modulated signal and effective in the presence of
said interfering signal with high intensity to de
rive from said received signals a heterodyne-com
ceive concurrently with said pulse-modulated sig
nal interfering wave signals having carrier fre
quencies within a band of frequencies substan
tially as wide as said predetermined range, de
tecting means included in said iirst-signal-trans
lating means effective in the absence of an inter
fering wave signal to derive said desired modu
lation components of said pulse-modulated signal
ponent pulse-modulated signal having modulation
and effective in the presence of an interfering
signal with high intensity to derive from said
received signals a heterodyne-component .pulse
modulated signal having modulation components
corresponding to said desired components and
having a carrier frequency'within a band of fre
quencies substantially of the width of .said pre
components corresponding to said desired compo
nents, a second signal-translating means cou
65
pled to said detecting means and effectively com
prising a pair. of parallel-connected signal-trans
lating channels, one of said channels having a
band-pass characteristic effective to translate
determined range, a second signal-translating
substantially only said desired signal components
means coupled to said detecting means and ef 70 and the other of said channels having a, band-pass
fectively comprising a pair of parallel-connected
characteristic e?‘ective to translate said hetero
signal-translating channels, one of said channels
having a band-pass characteristic effective to
translate substantially only said desired signal
' components and the other of said channels hav
dyne-component pulse-modulated signal, rectify
ing means included in said other channel effective
to derive said desired modulation components
75 from said heterodyne-component pulse-modu
17
2,410,786
lated signal, means coupled to said pair of chan
nels for supplying said desired modulation com
ponents to a utilizing device, and means respon
sive to said interfering wave signal for disabling
said one of said channels.
13. A receiver for deriving desired modulation
components of a received pulse-modulated car
rier-frequency wave signal but subject to receive
concurrently therewith an interfering _wave signal
of different frequency than the carrier frequency
of said pulse-modulated signal comprising, a ?rst
signal-translating means including selector cir
cuits for translating both 'of said received signals,
detecting means included in said ?rst signal
translating means e?ective in the absence of said
interfering wave signal to derive said desired mod
ulation components of said pulse-modulated sig
nal and effective in the presence of said interfer
18
modulated signal having modulation components
corresponding to said desired components, a sec
ond signal-translating means coupled to said de
tecting means and e?ectively comprising a pair
vof parallel-connected signal-translating chan
nels, one of said channels having a band-pass
characteristic e?'ective to translate substantially
only said desired signal components and the other
of said channels having a band-pass characteristic
e?‘ective to translate said heterodyne-component
pulse-modulated signal, rectifying means included
in said other channel effective to derive said de
sired modulation components from said hetero
dyne-component pulse-modulated signal, means
coupled to said pair of channels for supplying
said desired modulation components to a utilizing
device, and amplitude~selective means responsive
to said interfering wave signal of high intensity
ing signal with high intensity to derive from said
for disabling said one of said channels.
.received signals a heterodyne-component pulse 20
DAVID B. HOISINGTON.
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