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Патент USA US2125953

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‘Aug, *1'1“ 193-.
Filed May 28, 1957
2 sheets-sheet 2
Patent-ed Aug. 9, 1938
Rudolf Prochnow, Berlin, ‘Germany, assignor to
Telefunken Gesellschaft fur Drahtlose Tele
graphic in. b. IL, Berlin, Germany, a ‘corpora/
tion of Germany
Application May 28, 1937, Serial No. 145,196
In Germany March 16, 1936 .
4 Claims. (Cl. 250-8)
The general aim to simplify the operation of ible only if reception of telegraphic signals is
effected by sonic (audio frequency) modulation
commercial receiver apparatus involves the prob
lem to make the change from reception of tele ' of the ?rst heterodyne of a superheterodyne re
graphic signals to telephonic signal reception ceiver apparatus. However, it is possible in this
case to ?lter this note so that the change mecha
5 automatic. It has been suggested in the prior
nism will not res‘pondto the said modulation fre-y
art to utilize for the said change the direct cur
rent component resulting‘ from the recti?cation
, Now, the invention shall be explained in more
of the incoming radio frequency signals by feed
ing the direct current voltage produced by the detail by reference to the accompanying draw
ings which show the radio frequency ampli?er 10
10 carrier wave to a time~lag relay which responds
only to impulses of long duration. Inasmuch as ?rst detector and initial intermediate frequency
ampli?ers, of a heterodyne receiver dia‘gram
in telegraphic work the direct current component
matically, that is, by rectangles and then shows
varies at the rhythm and rate of the signals be
tween, zero and maximum, whereas it is constant the elements starting from the second interme
diate frequency ampli?er tube in detail.
15 in the reception of telephonic signals the relay
In the plate circuit of the intermediate fre
responds only to telephone signal reception, and
disconnects the heterodyne employed in the re
ception of telegraphic signals.
However, this method involves a number of
20 troublesome disadvantages.
The change, as will
be noted, is a function of the telegraphing speed.
If the signals are of long duration it may happen
that the automatic device disconnects the hetero
dyne although no modulated signals (telephony)
are present. This is due to the fact that the
time-lag of the relay cannot be pushed to any
desired limit. ‘Moreover, in. the case of trans
mitters comprising means insuring automatic
blocking of the carrier between words (quiescent
aerial radiation) the time lapses of telephonic
signals are liable to have only the length of a
somewhat long telegraphic signal. It will be seen
therefrom that the change is apt to be attended
with inaccuracies and defects in systems of the
said sort.
quency amplifier tube H] of Fig. 1 is included a
circuit I tuned to the intermediate frequency,
and furthermore, an audio frequency coupler
transformer 2. If the grid biasing voltage for IE!
is properly chosen, this stage acts as a radio fre
quency ampli?er and a recti?er. In coupling re
lation' with the tuning circuit l is the second
heterodyne oscillator tube 20 which is fed with
plate potential by way of the resting contact 22 25
of magnet relay 3. Mixing of the incoming
wave, 1. e., the intermediate frequency output of
III, and the auxiliary wave supplied by 20, is ef
fected in the recti?er circuit 4. The heterodyne
voltage transformed in. the circuit is so chosen
that it will not contribute any appreciable amount
to thevolume control potential. The regulation
voltage, on the contrary, is a function of the am
plitude of the receiver input potential. Such
musical telegraphic signals, according to this in
vention, is so designed that automatic change in
connections is accomplished by the aid of recti
?ed telephony modulation.
telegraphic signals as may be received produce, 35
when beat with oscillations from the second heter
odyne 2i), beat notes which are fed by way of the
audio frequency ampli?er 30 to the headphones.
Across the output terminals of the audio fre
quency coupler 2, on the other hand, an alter 40
nating voltage will exist only in case of telephonic
In describing my invention more in detail refer
ence will be made to Figures 1 to 3 of the draw";
ings, each of which show a different embodiment
45 of my receiver with the control means which puts
reception. This voltage is then ampli?ed by
audio frequency ampli?er i0, is then recti?ed by
full-wave recti?er 50 and then fed to the relay 3.
It will be clear that the second heterodyne 20 can 45
be disconnected by the relay only in case of te
ation, depending on the type of signal received.
This scheme insures another advantage in that,
lephony signals. The receiver is always ready to
receive telegraphic signals, and it is changed over
under certain circumstances, a distinct relay may
be dispensed with if the heterodyne is caused to
in case modulated signals are coming in.
In order to obviate the said defects, a receiver
for selective reception of telephonic and non
the continuous wave oscillator in or out of oper
break off directly by the recti?ed audio frequency
According to another object of the invention, 50
the relay is to be dispensed with as shown in Fig.
voltage, as shall be shown in more detail further
below by reference to Fig. 2. There results the
2. In this arrangement the alternating poten
tial furnished from the audio frequency ampli
further advantage that also musical telegraphy
?er is recti?ed and is used as a counter-voltage
55 signals may be picked up without a heterodyne
so that there results a clean note.
Modulation must be derived from the receiver,
of course, at a point where the heterodyne fre
quency required for the reception of telegraphic
signa1$ has not yet been added. This will be feas
for a glow tube 8. The output of 50 supplies volt 55
age to a resistor 6!] in the direct current circuit of
8. The resistor 60 is poled to oppose the poten
tial supplied by the direct current circuit to 8.
The glow tube circuit is a voltage divider for the
screen grid potential of the second heterodyne 20 60
and supplies the plate potential also.‘ When the
audio frequency voltage supplied by 2, 40 and 50
frequency energy is derived, a'recti?er having an
input coupled to said output, said recti?er having
has attained a certain value in the presence of
an. output, an ampli?er circuit having input elec
small or no telephony modulations on the received" *1 trodes and having output electrodes coupled to a
wave, the said glow tube is caused to go out,jand , "utilization circuit, a second recti?er coupling the
the second heterodyne 20 has no screen grid‘ori input of said ampli?er to the output of said ?rst
plate potential. By this means aclean-cut and "recti?er, a local oscillator coupled to said ?rst
smooth instantaneous circuitchange isisecured.v ' recti?er to impress thereon oscillations to be beat
It may be mentioned that the audio ,frequency. > with the intermediate frequency wave energy
10 ampli?er stage 40 in a re?ex circuit scheme may '
whenlthe received wave is modulated by non 1O
be combined with the preceding stages of the musical telegraphy ‘signals, said oscillator being
receiver equipment. All that is'necessary is to, irrnormally operative, and additional rectifying
make sure that this tube will not be a?ected by
the automatic volume control regulation, otherr
wise it will not operate to cause the receiver to
respond to telegraphy except in the presence of
Another circuit organization is shown in Fig. 3.
Inthis scheme the voltage arising across the cou
20 pler 2 in the presence of telephonic’ signals is rec
ti?ed and is used in the form of a negative grid
bias for the power tube 30 of the audio frequency
ampli?er; The plate circuit of the said ‘power
tube moreover contains, in addition to the out-1
25 put coupler 6, also a relay 3_ which responds to'a
change of the plate current of about 2 milliamps.
In case of telegraphy signals, the power tube 30
operates only with a very low negative biasing
voltage. This is readily possible since distortions
are immaterial.
In the presence of modulated
signals the power’tube will be more strongly biased
so that the incidentally caused change in the plate
current disconnects the plate circuit of the sec
ond heterodyne 20 bythe action of relay 3.
In conclusion, certain phenomena shall be dis
cussed which are liable to endanger satisfactory
operation of the scheme. Roaring noises, which
are likely to arise in receivers of high sensitiveness
and which, so far as their action is concerned,
40 are similar to the modulation of a signal may
cause the automatic mechanism to respond unless
precautionary steps are taken. It is suggested to
tune the audio frequency coupler 2 to around 1000
cycles with the consequence that the high fre
_ quencies are suppressed.
The incoming signals, moreover, must have a
certain amplitude in order that the automatic de
vice may be operated. It will be readily under
stood that unduly feeble signals will lead to fail
501 ure of the automatic device so much less fre
quently, the steeper the regulation characteristic
of the volume control means.
I claim:
means excited by energy from the output of said
?rst recti?er for rendering said oscillator inopera
tive when said received wave energy is modulated 15
by telephony ‘signals.
3. In a system for receiving wave energy modu
lated by telephony signals or by non-musical tele
graphy signals, a demodulator of the heterodyne
type'including a source of' oscillations and- a ?rst 20
detector excited by received wave energy and by
oscillations from said source of oscillators, means
for deriving from said detector the beat frequency
produced by beating said received wave energy
with said oscillations, a beat frequency ampli?er 25
tube having input and output electrodes, means
for impressing said beat frequency on said input
electrodes, means‘ for biasing the electrodes of said
tube to produce plate recti?cation in said tube, an
output circuit connected with said output elec 30
trodes, a utilization circuit coupled by a recti?er
to said output circuit, an additional recti?er of
the full wave type having input electrodes cou
pled to said output circuit and having output elec
trodes connected in a relay circuit, an additional
oscillator coupled to said output circuit to supply
oscillations thereto, and means connecting said
relay with a circuit of said additional oscillator
to render'the same inoperative when said received
wave energy is modulated by telephony signals.
4. In a system for receiving wave energy modu
lated by telephony signals or by non-musical
telegraphy signals, a local oscillator, a ?rst de
tector, means for impressing oscillations from said
oscillator on said ?rst detector and wave energy
to be demodulated on said ?rst detector, an out
put circuit coupled with said ?rst detector, said
output circuit being responsive to the beat fre
quency between said wave energy and said oscil
lations from said local oscillator, a beat fre
quency ampli?er and recti?er of the electron dis
chargetube type having a control grid coupled
1. In a receiving system to be used for the re
ception of telegraphy or telephony signals, a wave
ampli?er and recti?er, means for impressing said
signals on said ampli?er, a utilization circuit re
sponsive to wave energy coupled to the output
of said recti?er, a local oscillator coupled to said
60 wave ampli?er and recti?er and normally'opera
tive to impress beating oscillations thereon when
continuous wave energy is impressed on said am
pli?er, the resulting beat note being impressed on
said utilization circuit, and additional means cou
pled'to' said' recti?er and associated with said os
cillator for rendering ‘said oscillator inoperative
when signal modulated waves are impressed on
said'wave amplifying means.
> 2. In a system for the reception of Wave energy
modulated by ' telephony signals or by non
mus'ic'al telegraphy signals, wave receiving ampli
fying and demodulating means of the heterodyne
type having an'input on which the wave energy is
impressedand an output from which intermediate
with said output circuit and having an anode
connected in an alternating current output cir
cuit, means for biasing the electrodes of said dis
charge tube to produce plate recti?cation there
in, a utilization circuit, an electron discharge tube
ampli?er having an anode coupled to said utiliza
tion circuit and having a control electrode, a
recti?er coupling said controlling electrode to said 60
second named output circuit, means in said sec
ond named output circuit responsive only to cur
rent components resulting from the recti?cation
of wave energy modulated by telephony signals
in said ampli?er and recti?er, a third recti?er
coupling said last named circuit to the control
electrode of said electron discharge tube ampli
?er, a local oscillator coupled to said second
named output circuit, and a relay coupling the
anode of said electrondischarge tube ampli?er to
a circuit of said local oscillator to control the
operativeness thereof.
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