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Nov. 12, 1946.--
2,410,981
W. R. KOCH
SUPER-REGENERATIVE RECEIVER CIRCUIT
Filed June 25 ,
1942
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Patented Nov. 12, 1946
Z,4i',981
UNITED STATES PATENT OFFICE
2,410,981
SUPERREGENERATIVE RECEIVER CIRCUITS
Winfield R. Koch, Haddonfield, N. J., assignor to
Radio Corporation of America, a corporation of
Delaware
Application June 25, 1942, Serial No. 448,340
16 Claims.
(Cl. Z50-20)
1
2
My present invention relates to super-regener
ative receiver systems, and more particularly to
receivers of the latter type utilizing self-quench
ing action.
Super-regenerative receivers of the self
quenching oscillator type are Well known, Usu
carrier energy or frequency modulated carrier
energy; variations in quench frequency being
translated into variable uni-directional currents
which correspond to, and follow, the modulation
which originally existed lon the received carrier.
Another important .object of this invention is
ally in such types of receivers the super-regen
erative detector includes in its signal input circuit
a resistor-condenser network which functions to
to provide a novel method of improving the mod
ulation signal voltage output of a super-regener
ative detector by taking advantage of the fact
provide the interruption, or quenching, action at 10 that the quench frequency is a function of Vap
a super-audible frequency. In such a super-re
plied signal amplitude variation, and quench fre
generative detector of the self-quenching type
quency variations being subjected to a discrimi
the quenching action causes a change in average
nator network thereby greatly to increase the
plate current depending upon the amplitude of
variations in modulation signal output current
the signal carrier. Amplitude modulation of the
for given received signals.
carrier causes the average plate current value to
Another object of the invention is to provide a
follow at the modulation frequency. On the
super-regenerative receiverl employing ,a self
other hand where frequency modulated carrier
quenching oscillator whose signal input circuit is
energy (FM) is received, the input circuit of the
of the loop type; there being employed a quench
detector is somewhat mistuned from the center
frequency detector having a discriminator input
frequency of the applied FM signals thereby
circuit to derive modulation signal frequency
transforming the FM signal energy to corre
from variations in quench frequency caused by
sponding amplitude modulated carrier energy
signal amplitude variation.
_
(AM). Thereafter, the transformed amplitude
Still another object of the invention may be
modulated carrier energy causes the average 25 stated to reside in the provision of a novel method
value of the plate current of the super-regener
of receiving radio signals whether of the FM type
ative detector tube to follow at the modulation
or AM type, which method 'comprises generating
oscillations at the frequency of the received car
rier, `quenching the generated oscillations at a
. frequency.
Usually there is a utilized a counter type of re
sistor-condenser network in the plate circuit of
the super-regenerative detector. The modula
predetermined super-audible frequency thereby
to provide high selectivity and gain, deriving from
the quenching of the oscillations at carrier fre
tion signal voltage is developed by the integrat
ing action of the resistor-condenser network.
quency additional currents in the quench fre
However, the sensitivity of such a detection cir
quency range whose frequency varies in accord
cuit is relatively small, and, hence, there is rela 35 ance with amplitude variations of the signal cartively inefdcient production of modulation signal
rier, and translating frequency variations of the
voltage. Furthermore, considerable noise is pro
quench frequency currents into amplitude varia
duced between station channels.
tions of the last named currents, and rectifying
I have discovered that the quenching frequency
the amplitude variations to produce modulation
in a Super-regenerative detector of the self
quenching type is dependent to al substantial ex
tent upon the applied signal amplitude. I have
found that variations in the received signal am
Dlitude can be made to cause substantial varia
tions in quench frequency, and that such varia
tions in quench frequency can be subjected to
discriminator action thereby greatly to improve
the modulation signal voltage output and greatly
to reduce the noise sensitivity when tuning be
tween station channels.
It can be stated, then, that itis one of the main
objects of my present invention to provide a
40
signal currents therefrom.
Still other objects of the invention are to im
prove generally the simplicity and efficiency of
super-regenerative receivers, and more particu
larly to provide super-regenerative receivers of
the self-quenching type which are not only re
liable in operation, but are economically manu
factured and assembled~
The novel features which I believe to be char
acteristic of my invention are set forth in par
50 ticularity in the appended claims; the invention
itself, however, as to both its organization and
method of operation will best be understood by
reference to the following description taken in
super-regenerative detector circuit of the self
quenching type7 and upon whose tuned input cir
connection with the drawing in which I have in- .
cuit may be applied either amplitude modulated 55 dicated diagrammatically several circuit organi
2,410,981
3
zations whereby my invention may be carried into
effect.
In the drawing:
Fig. l shows a super-regenerative receiver em
bodying the invention,
Fig. 2 shows the response characteristic of the
loop input circuit of the receiver,
Fig. 3 shows the response curve of the quench
detector input circuit,
be assumed that network 6-1 is chosen so that
the quench frequency FQ is 40 kilocycles (kd).
This means that the regenerative feedback to
loop circuit I is permitted to occur to an extent
such that the circuit is beyond the point of oscil
lation when regenerative feedback is interrupted.
The oscillations are, of course, of carrier fre
quency. The interruption proceeds at a super
audible rate, with the result that maximum gain
and selectivity is secured in circuit 2--I.
Fig. 4 shows a modified form of the invention, 10
Fig. 5 shows the response curve of the quench
detector input circuit of the receiver shownin
Fig. 4.
Net
work 6_1 might consist of an 82 mmf. (micro
microfarads) capacitor and a 330,000 ohm re»
sistor.
In Fig. 2 I have shown in a purely qualitative
One of the important advantages of the pres
manner
the response curve of loop circuit I--2.
ent invention is that the super-regenerative re 15 It will be clearly understood that this curve does
ceiver circuits employed may be arranged within
not depict the actual characteristic, but merely
a compact casing which is so small that it may
is illustrative. For AM signal reception the var
readily be fitted into the vest pocket of the user.
iable capacitor 2 is adjusted so that at ea'ch sta
For this purpose miniature type of tubes are em
tion reception channel, circuit I-2 will be accu
ployed, and the energizing direct current sources
rately tuned to the desired signal-modulated car
are of the miniature long-life battery type- The
rier frequency. This, of course, will be the mid
reproducer may be of the crystal type, and is
band frequency of the station. Hence, in Fig. 2
preferably of the type used in deaf-aid equipment.
there is shown the fact that the tuning adjust
Referring to Fig. 1, the transmitted modulated
of the loop is at the peak of the response
carrier energy is picked up by a tunable loop cir 25 ment
curve for AM signal reception. In such case, I
cuit which comprises a loop I shunted by tuning
have found that- there flows in the plate circuit
condenser 2. It is preferred that the loop I be
of tube 3 a current whose magnitude is a func
wound within the casing of the receiver. The
tion of the quench frequency. I have, also, found
tuning condenser 2 is to be understood as con
that the quench frequency is proportional in mag
structed and designed so as to tune the loop cir
nitude to the carrier amplitude. Hence, the
‘cuit over a relatively wide carrier range. The low
stronger the signal received the higher becomes
potential side of condenser 2 may be grounded.
the quench frequency. The variable plate cur
It is to be understood that the receiver may be
used for receiving FM signal energy, or it may
rents of tube 3 actually vary in frequency in ac
with the signal amplitude at grid 5.
be used to receive AM signals. Preferably, recep 35 cordance
Since the signal amplitude at grid 5 is a function
tion in the FM band of 42 to 50 megacycles (mc.)
of the modulation applied to the carrier at the
is preferred. It is to be clearly understood that
transmitter,
it follows that the frequency varia
, by choosing the constants properly the loop cir
tions of the quench frequency current flowing in
cuit may be designed to be tuned over any desired
the plate circuit of tube 3 is a function of the
range of station channels. The tube 3 shown is 40 modulation existing on the carrier at grid 5. The
one of the pentode type, and has its cathode 4
carrier currents existing in the plate circuit of
connected to an intermediate point on loop I.
tube 3 are not used. For FM reception these cur
'I_‘he control grid 5 is connected to the high po
rents are mostly at the natural frequency of cir
tential side of the loop I by a capacitor B, the
cuit I-2. In any case the carrier currents are
resistor 'I connecting the grid side of capacitor `Ii
to ground. The plate 8 of tube 3 is’connected to a
point of proper positive potential by the primary
bypassed to ground. Capacitor II’ bypasses car
rier currents in winding 9.
In accordance with one of the objects of my invention, the frequency variations of the quench
Screengrid II and plate 8 have applied to them 50 frequency currents flowing in the plate circuit of
tube 3 are augmented by a, discriminator action
the positive potential from the direct current
following. the plate circuit of tube 3. To secure
source which is not shown. The suppressor grid
this augmented action, circuit I2-I3 is pref
is established at ground potential. The screen
erably adjusted to a frequency such that in the
grid I I is bypassed to ground by capacitor I I’.
of received. carrier energy the circuit
A‘The secondary winding I2 of transformer I0 55 absence
I2-I3 is tuned to any frequency along the round
has shunted across it a capacitor I3. Circuit
top of the response curve shown in Fig. 3. The
I2----I3 is resonated to substantially the quench
curve of Fig. 3 is the response curve of the quench
frequency FQ. Diode I4 has its anode I5 con
detector input circuit I2-I3. Here, again, it is
nected to the high potential side of winding I2,
while the cathode IB is returned to ground 60 not intended that the curve represent the actual
characteristic. It is merely illustrative in nature.
through resistor I 1. The latter is shunted by ca
In Fig. 3 it is shown that in the absence of re
pacitor I8. The modulation signal voltage, which
ceived carrier energy circuit I2-I 3 is tuned sub
may be in the audio frequency range, is taken
stantially to FQ. This means that the quench
off from the cathode end of resistor I'I. The mod
ulation signal voltage may be amplified in one or 65 frequency currents, in the absence of received car
rier energy, have a frequency substantially coin
more stages of modulation signal amplification,
ciding with the frequency of circuit I2--I3, and
and the amplified signals will` then be reproduced.
this frequency is at the peak of the response curve
Considering, ñrst, the action of the self~quench-
windings of transformer I0. The screen grid II
is connected to the lower end of winding 9.
- ing oscillator which comprises tube 3 and its as
- of circuit I 2-I 3.
When modulated carrier energy is received the
sociated circuits,'it is pointed out that network 70 quench
frequency currents applied to circuit
6-1 has its time constant so chosen that the
oscillations produced’b'y virtue of the connection
of cathode '4 to an intermediate point on loop I
I2-I 3 increase in frequency, because the stronger
the received signal amplitude the higher will be
the quench frequency. I have shown an inter
will be quenched, or interrupted, at a predeter
mined super-audible rate. For> example, let it 75 mediate point along the slope of the 'response
5
2,410,981
6
curve as being the center point about which the
quench frequency- currents vary in frequency
under the influence of the signal ampliture varia
tions.~ It will be recognized that this is a fre
quency discriminating action wherein highly mag- r Ul
niñed amplitude variation currents are derived
from frequency deviations of the same currents
.about a center frequency point. In this way, the
variations in frequency in the plate circuit of tube
3 are transformed into magnified corresponding 10
amplitude variations. These amplitude varia
tions are then rectified by diode lll. The rectified
voltage Variations across resistor I7 are a faith
ful reproduction of the modulation originally ex
load resistor 5|. It will be understood'that in
place of a single rectifier 50, or single rectiñer I4
in Fig. l, there may fbe utilized the balanced rec
tiñers known in FM detection circuits. For eX
ample, there may be employed discriminator-rec
tiiier networks of the type shown by S. W, Seeley
in U. S. Patent 2,121,103 granted June 21, 1938;
or a discriminator-rectifler of'the type shown by
J. D. Reid in U. S. Patent 2,279,506, granted April
14, 1942.
There could also be used an FM de
tector of the type using oppositely mistuned cir
cuits with a balanced detector of the type shown
by G. Mountjoy, U. S. Patent 2,280,530, granted
April 2l, 1942.
isting on the carrier at grid 5. It will now be seen 15
For FM signal reception the variable capacitor
that tube 3 and its circuits function as a device
2 of Fig. l will be adjusted as shown in Fig. 2, so
for converting the amplitude variations of the re
that the center frequency of the FM signal energy
ceived signal to frequency variation of quench
will fall on one side or the other of the peak of
currents appearing in the plate circuit of tube 3.
the response curve of the loop circuit. As is well
It is, of course, possible to use any discrimi 20 known, such mistuning results in transformation
nator device in place of circuit |2-l3. vThose
of the received FM energy into corresponding AM
skilled in the art are fully acquainted with the
various types of frequencyy discriminators that
signal energy.
The transformed AM signal
energy is then treated in the same manner as
may be employed instead of the simple tuned cir
has been described previously for AM signal re
cuit |2-|3. Any circuit which has a sloping out 25 ception. In this case the tube 3 (or tube 2D) acts
put voltage vs. frequency input characteristic may
as a super-regenerative “trans-modulator.”
`be utilized to transform the quench current fre
To recapitulate the important features of this
quency variations into corresponding amplitude
invention, I have provided a discriminator cir
Variations. It is also possible to amplify the
cuit following the self-quenching oscillator, which
quench frequency current prior to discrimination. 30 discriminator circuit transforms small changes in
In Fig. 4 there is shown a modification wherein
quench frequency into large changes of quench
rthe self-quenching circuit employs a tube 20 of
current amplitude thereby giving a large modula
the triode type whose cathode is grounded. The
tion signal voltage output from the following rec
loop '2l is shunted by the tuning capacitor 22.
tifier. Furthermore, by using a tuned circuit as
The quenching network comprises capacitor 23 35 a discriminator large voltages can be developed
and grid resistor 24. The plate 25 provides the
and applied to the subsequent rectiñer. The cir
regenerative feedback, as at M, by virtue of a loop
cuit therefore exhibits greater sensitivity than
section 26 in the plate circuit. The positive po
the usual super-regenerative circuit. Either side
tential is applied to plate 25 through a plate re
of the response curve shown in Fig. 3, or Fig. 5,
sistor 21, whose lowerend is bypassed to ground. 40 can be used. In addition, however, by setting
A quench amplifier 30 has its input .grid 3| cou
the quench discriminator circuit frequency to a
pled by capacitor 32 to the upper end of plate
slightly lower frequency than the quench ‘fre
resistor 21, the grid end of capacitor 32 being re
quency when receiving a signal, the well known
turned to ground through a resistor. The quench
background noise of a super-regenerative re
amplifier tube 30 prevents the discriminator cir
ceiver, in the absence of signals, can be greatly
cuit from stabilizing the quench frequency. There
reduced.
is a tendency on the part of the discriminator cir
The quench frequency in the absence of signals
cuit to stabilize the quench frequency currents
will be somewhat lower, and practically at the
and thereby prevent the desired frequency varia
tions in the quench currents. The coupling net- , top cf the response curve of the quench current
discriminator circuit. Variations of quench fre
work between tubes 20 and 30 is designed to trans
quency in such case then produce practically no
fer the 40 kc. quench currents.
change in amplitude, because of the round top
The discriminator in this case comprises a
portion of the selectivity curve. However, When
transformer 4€! whose primary and secondary
windings are each shunted by respective tuning ..
condensers. Each of the primary and secondary
circuits are tuned, in the absence of received car
signals are received they cause an increase in the
average quench frequency so that the resulting
quench voltage has considerable amplitude varia
tion by virtue of operation along the high fre
rier energy, substantially .to the quench frequency.
quency side of the response curve. The quench
The transformer ¿i0 is so constructed, and has its
current discriminator circuit tuning for maxi
primary and secondary circuits so co-upled,l that ec mum audio output is not generally the same as
it has a substantially fiat-topped response curve
for minimum noise-signal noise. Hence, the dis
as shown in the response curve illustrated in Fig.
criminator circuit should be -set for whichever
5. The sides of the response curve are relatively
improvement is desired. Of course, either of
steep. Hence, when modulated carrier energy is
tubes 3 or 20 may be preceded by an amplifier to
received operation will be had along the steep (i5 prevent radiation. The circuits shown may be
slope of the curve thereby to give increased am
plitude variations for the same frequency devia
. tions of the quench current.
The rectiñer 50 is used to rectify the ampli
tude-variable quench current. In this case the
anode of diode 50 is connected to the high poten
tial side of the secondary circuit of transformer 40.
The load resistor 5l is connected between the low_
employed as the I. F. ampliñer and detector of a
superheterodyne receiver, for the same reason.
While I have indicated and described several
systems for carrying my invention into effect, it
will be apparent to one skilled in the art that
my invention is by no means limited to the par
ticular organizations shown and described, but
that many modifications may be made without
departing from the scope of my invention, as set
potential side and ground, and the modulation
signal voltage is taken «olf from the upper end of 75 forth in the appended claims.
"
2,410,981
7
8
of the oscillation-s at a super-modulation rate,
What I claim is:
selection
of currents of said interruption fre
1. A method of receiving modulated carrier
quency,
subjection
of the selected currents to
wave energy which comprises regenerating the
frequency discrimination, and rectification of the
energy to a high degree, interrupting the re
currents.
generation at a predetermined frequency thereby 5 resulting
9. A method of receiving angular velocity
to provide interruption current Whose frequency
modulated carrier wave energy which comprises
is a function of the amplitude modulation of said
regenerating the energy to a high degree, inter
carrier energy, transforming the interruption
rupting the regeneration at a predetermined fre
current frequency variations by frequency dis
quency, transforming by frequency discrimination
10
crimination into corresponding amplitude varia
resulting interruption current frequency varia
tions, and deriving signal voltages from the re
tions into corresponding amplitude variations,
sulting amplitude variable interruption current
and deriving from the resulting interruption cur
corresponding to the modulation on the received
rent of varia-’ble amplitude voltages corresponding
carrier.
to the modulation on the received carrier.
2. In a system for receiving modulated carrier
Wave energy, a regenerative amplifier tube pro
vided with a carrier wave energy input circuit
tuned substantially to a desired carrier frequency,
means in the input circuit of said tube for pro
viding self-quenching oscillations at a super
10. In a system for receiving frequency modu
lated 4carrier Wave energy, a tube provided with
a carrier wave energy input circuit tuned sub
stantially to a desired carrier frequency, said
input circuit acting like a sloping filter, means
in the input circuit of said tube for providing
audible frequency, means coupled to the output
self-quenching oscillations at a super-audible
circuit of said tube for translating frequency de
frequency, means for regenerating the input cir
viations of quench current into corresponding
cuit, means coupled to the output circuit of said
amplitude variations, and means for rectifying
tube for translating frequency deviations of
the amplitude variable quench current so pro 25 quench current into corresponding amplitude
duced.
variations, and means for rectifying quench cur
3. In a super-regenerative receiving system,
. rent so produced.
ì
means for regenerating received modulated car
11. In a super-regenerative receiving system,
rier Wave energy, means for interrupting the re
generation at a super-audible frequency, means 30 means for regenerating received modulated car
rier Wave energy to the point of oscillation, means
producing interruption currents of variable fre
for interrupting the regeneration at a super
quency which correspond to the modulation on
audible frequency, means producing interruption
the received carrier energy, and frequency dis
currents of variable frequency which correspond
crimination means for producing corresponding
the modulation on the received carrier energy,
amplitude variations of the interruption currents. 35 to
and a sloping ñlter means for producing corre
4. In a method of receiving frequency modu
sponding amplitude variations of the interruption
lated carrier Wave energy in a super-regenerative
currents.
‘
receiving system, translating the received energy
12. In a method of receiving modulated carrier
into corresponding amplitude modulated carrier
Wave energy in a super-regenerative receiving
wave energy, regenerating the translated energy, 40 system, regenerating the energy to the point of
quenching the regeneration at a super-audible
oscillation, quenching the regeneration at a
frequency, deriving quench current variable in
super-audible frequency, deriving quench current
frequency in accordance with original modulation
variable in frequency in accordance with original
of the received carrier energy, translating the
45 modulation of the received carrier energy, trans
frequency variations of the quench current into
lating the frequency variations of the quench
corresponding amplitude variations, and detect
currents into corresponding amplitude variations,
ing said translated amplitude variations.
and detecting said amplitude variations.
5. In a super-regenerative receiving system, a
13. In a super-regenerative receiving system, a
self-quenching oscillator circuit having a tuned
input circuit resonated to substantially a desired 50 self-quenching oscillator circuit having a tuned
vinput circuit resonated to substantially a desired
carrier frequency, means in circuit with the input
circuit for producing quenching action at a
super-audible frequency thereby to provide
quench currents whose frequency is a function
carrier frequency, means in circuit with the input
circuit for producing quenching action at a super
audible frequency thereby to provide quench cur
55 rents Whose frequency is a function of the modu
of the modulation on the received carrier, means
lation on the received carrier, means for ampli
for amplifying the quench current, and frequency
fying the quench current, and a tuned circuit
responsive means, responsive to said variable fre
discriminator means, responsive to said variable
quency quench currents, for providing voltage
frequency quench currents, for providing voltage
corresponding to the modulation originally ap 60 corresponding to the modulation originally ap
plied to the received carrier.
plied to the received carrier.
6. A method of receiving radio signals in a
14. In combination with a self-quenching oscil
self-interrupted oscillator system, which in
lator of the super-regenerative type provided with
cludes applying said signals to said system, sep
tunable loop input circuit, a quench current
arating out current of the interruption frequency, 65 adetector
provided with a resonant input circuit
and detecting said separated current subsequent
tuned to the quench frequency in the absence of
to separation.
received modulated carrier energy, and means
7. A method of receiving radio signals which
transferring frequency-variable quench currents
includes self-quenching super-regenerative de
from the oscillator to said input circuit.
tection of said signals, selection of quench-fre
l5. In combination with a self-quenching oscil
quency currents, and frequency discrimination 70 lator
of the super-regenerative type provided with
and subsequent rectification of said currents.
a
tunable
loop input circuit, a quench current
8. A method of receiving radio signals in an
oscillating system including application of said ,detector provided with a resonant input circuit
tuned to the quench frequency in the absence of
signals to a circuit oscillating at approximately
75
received modulated carrier energy, and means
the same frequency as the signals, interruption
2,410,981
transferring frequency-variable quench currents
from the oscillator to said input circuit, said Iast
means comprising a, quench current ampliñer
which prevents said detector input circuit from
stabilizing the frequency of the quench currents.
16. In a, compact type of receiver of the type
comprising a super-regenerative detector tube
having a tunable loop input circuit, and means
10
in the input circuit to provide self-quenching ’
action; the improvement which comprises a rec
tiñer provided with a frequency discriminator
input circuit, and means for transmitting to the
discrimínator input circuit quench currents of
variable frequency developed in the detector tube
output.
WINFIEID R. KOCH.
Disclaimer
2,410,981._W¿n7îeld R. Koo/L, Haddonüeli'N. J. VlSUPERREGMIEPATIVE RE
CEIVER CIRCUITS. Patent dated Nov. 12, 1946. Disclaimer ñled Mar.
13, 19,51, by the assignee, Badia Corporation 0f Amev‘z'ca.
--`Hereïoy enters this disclaimer t0 claims 1_, 2», 3, 6, 7, and 8 of said patent».
[Oyjïcz'al Gazette April 24, 1951.]
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