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Патент USA US2112446

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March 29, 1938.
c. PELMULDER ET Al.
2,112,446
MEANS FOR REMOTE TUNING OF RADIO RECEIVERS
Filed Deo. 8, 1936
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Patented Mar. 29, 1938
2,112,446
UNITED STATES PATENT OFFICE
2,112,446
MEANS FOR REMOTE TUNING 0F RADIO
RECEIVERS
Chester Pelmulder, San Francisco, and Hans 0.
Storm, Palo Alto, Calif., assignors to Globe
Wireless Ltd., San Francisco, Calif., a corpo
ration of Nevada
Application December 8, 1936, Serial No. 114,782
7 Claims.
Our invention relates to a means and method
for the supervisory tuning of radio receivers from
a transcribing station located at a distance from
a radio receiver, and more particularly to a sys
tem which employs a single telephone pair simul
taneously energized for supervisory tuning and
for transmission of the radio signals. It is par
ticularly adapted for use when a transcribing sta
tion is located at such a distance from the re
10 ceiver that the greatest possible economy in the
use of connecting wires must be obtained.
Among the objects of our invention are: To
utilize a single telephone pair between a tran
scribing station and a radio receiving station for
1 the simultaneous transmission of the radio sig
nals to the transcribing station and tuning control
impulses from the transcribing station; to provide
a means and method of controlling the tuning of
a remote radio receiver over a standard telephone
20 line; to provide a means and method of control
ling the tuning of a remote radio receiver by im
pulses carried by the same telephone pair that
carry the received signals to the transcribing sta
tion; to provide a means and method of sending
25 radio signals and tuning control impulses over a
single telephone pair wherein only the audio-fre
quency rights are available; and to provide a
means and method of utilizing an existing com
mon power source for the control of a radio re
30 ceiver situated at a distance from a transcribing
station.
Our invention possesses numerous other ob
jects and features of advantage, some of which,
together with the foregoing, will be set forth in the
35 following description of specific apparatus em
bodying and utilizing our novel method. It is
therefore to be understood that our method is ap
plicable to other apparatus, and that we do not
limit ourselves, in any way, to the apparatus of
(Cl. 171-97)
a downtown location where messages received
may be quickly and efliciently dispatched to their
addressees`
It is also obvious that in such an ar
rangement the greatest possible economy in the
use of connecting wires must be obtained, and,
for example, it is common practice to utilize a
standard telephone connection between the re
ceiving station and the transcribing station, the
signals passing through the telephone switch~
board system exactly as do telephone conversa
tions. Under these circumstances the use of a
standard telephone pair on which audio frequency
rights only are available would be much cheaper
than the use of special circuits.
The main difficulty, however, in transcribing
signals coming to a transcribing station’ through
a telephone pair from a remote receiver lies in
the fact that the radio signals to be received may
accidentally or purposefully vary somewhat from
time to time in frequency, and if an oscillating 20
radio receiver is utilized the local oscillator will
also vary somewhat in frequency.
It is, therefore, of great advantage that the
transcribing operator should have a supervisory
control of the tuning of the receiver in order that 25
the signal volume be maintained by retuning as
oscillator or signal frequencies change. It is also
at times desirable to vary the output frequency of
_an oscillating receiver to avoid interfering sig
nals or to meet the personal differences in the 30
hearing of various operators. Modern receivers
and transmitters do not diverge widely from that
frequency to which they are adjusted, and it is
obvious, therefore, that a large latitude in tuning
supervision is not necessary.
Ordinarily, such supervisory tuning would have
to be exercised over a separate circuit than that
used for the reception of the signals. Such dupli
cation of connections, however, is expensive, and
40 the present application, as we may adopt vari
our present invention allows both the tuning su
ous other apparatus embodiments, utilizing the
method, within the scope of the appended claims.
The figure is. adiagram showing a preferred cir~
cuit for the practice of our invention, the diagram
45 being reduced to lowest terms and being shown
without such accessories as switches, fuses, limit
pervision impulses and the signal impulses to pass
simultaneously, without interference, through the
same telephone pair, thus greatly reducing the
expense and allowing the operator at the tran
scribing station to control at all times the tuning 45
of the receiver giving forth the signals to which
he is listening.
inasmuch as ordinary telephone pairs are de
signed to carry audio impulses only, We prefer to
utilize, for tuning control power, commercial al 50
ing resistors, meters, spark Suppressors, power
factor correction condensers, or repeaters which
might be required on longer lines.
It> often occurs that a radio receiving station
is located on the outskirts of a city, or beyond, in
order to reduce interference to a minimum and
in order to obtain proper directional characteris
tics of the receiver antenna system. It is often
advantageous to transmit the received signals to
40
ternating current which is taken from the same
alternating current power system that supplies
the receiving station, and since the frequency of
this alternating current in the power system is
usually 6G’ cycles per second, and the received 55
2
2,112,446
signals are usually on the order of 1000 cycles per
second, it is obvious that they may be passed over
an ordinary telephone pair without interference
with central station equipment or change of cen
tral station design.
on the same pair. Output leads 46 from the re
ceiver I lead to the hybrid coil assembly, one of
them being connected directly to the line and the
other to an intermediate point in the hybrid coil
Referring directly to the drawing for a more de
tailed description, a radio receiver I, having a
use in this service.
split symmetrical main tuning condenser 2, bal
anced with respect to ground, is further provided
10 with a split remote control band spread condenser
2' of relatively smaller capacitance, in parallel
with the main tuning condenser, and with a split
remote control condenser 3 of relatively larger
capacitance, connected in series between the two
15 sections of condenser 2' by lead wires 2”, which
on account of their proximity to ground potential
in the balanced condenser system, may be of rela
tively great length without affecting the tuning
range.
The remote control condenser 3 is pref
20 erably rotated through the- medium of friction
discs 4 by a tuning motor 5.
'I'he tuning motor
is preferably a synchronous motor with a built-in
reduction gear, not shown, but obviously may be
» any suitable type of motor which can be reversed.
26 'I'he motor 5 is controlled by a contactor assembly
which comprises a forward contacter 6, a back
ward contactor 1, and a running contactor 8, all
supplied from A. C. mains Il through contactor
leads III and receiving station leads Il. .The for
v30 ward contactor 6 and backward contactor 1 `are
controlled by coils I2 and I4 through contacts I5
and movable arms I6, of a diñerential polar relay
having coils I1 and I6. Arm I6 is attached to one
of the contactor leads I0 through wire It and the
35 return side of contact coils I2 and I4 connected
by wire 26 to the other of the A. C. leads I0. 'I‘he
common point of relay coils I1 and I6 is con
nected to the midpoint of an A. C. transformer 2I
by a/ relay lead 22, and the ends of relay coils I1
40 and I6 lead to cathodes 26 and 24 of a pair of
double thermionic tubes 21 and 26. While it will
be obvious to those skilled in the art that the
double cathode tubes herein to be described are
the full equivalent of four separate tubes,- sim
45 piicityfof wiring makes the double tube more ad
vantageous.
.
.
,
Considering the tube assembly for operating the
differential relay, the primary 26 of the trans
former 2| is attached to station A. C. leads II , and
50 one end of the secondary is connected directly to
anode26 of the tube 21 and to anode 20 of tube
26. The other end of the secondary of trans
_former 2I goes to another anode II in the tube 21
placed on the opposite side of cathode 2l, and
55 similarly to a second anode 32 in tube 26. Thus>
the anodes similarly positioned in both tubes are
in parallel, and opposite anodes are connected to`
opposite ends of the secondary of transformer 2I
primary.
Simplex channel 48 is not available for
When the telephone pair 44 reaches the tran
scribing station it enters a hybrid coil and bal
ancing impedance network 46’ similar in all re«
spects to the one at the receiving station. Sec
ondary 41 of assembly 46’ leads to a pair of receiv
ing telephones 48 or a loud speaker, as _the case
may be. Alternating current is supplied to the
hybrid coil of assembly 46’ through control leads
49 attached to the primary of the hybrid coil and
directly to the line, and leads 49 emerge from a
reversing switch 50 which is supplied by the sec
ondary 5I of a control power transformer 52, the
primary 53 of which is attached to the A. C. power
lines 9, these being supplied by the same power
system that supplies the. receiver.
Having described the circuital arrangement of
our invention in its lowest terms, we will now de
scribe the operation:
,
The receiver I is tuned roughly by hand, b
the operator in charge of the receiving station, to
the center of the general frequency band from
which signals are to be transcribed, and the re
mote control tuning condenser 3 is rotated so that
it is in the midpoint of the tuning range desired. 30
If coarse tuning with a large range is desired, the
band 4spread condenser 2’ is set to a high ca
pacitance, while if fine tuning with a smaller
range is desired, it is set to a low capacitance.
Signals thereupon emerge from the receiver I,
pass along line 46 to hybrid coil 43, and thence
over the telephone pair 44, through the. hybrid
coil of assembly 46', and are heard at the tran
scrlbing station through receiver 46. The oper
ator listens to the signals, and if he finds that he 40
wishes to change the tuning of the receiver he
operates reversing switch 60. The circuit dia
gram gives, by means of'plus and minus signs, the
phase conditions that> will exist at one particular
point in the A. C. cycle, when the arm of the re 45
versing switch is h_eld to the left.
Y
For example, let us suppose that reversing
switch 66 is in the midpoint so that no A. C. en
ergy is passing into the telephone pair. Under
these conditions all grids of the two tubes are
maintained at a uniform bias by means of bias
batteries 6I and 62, and the anode current through
both tubes is equal and oppositely directed with
respect to the magnetic field in coils I1 and Il,
thus balancing the arm I6 of the diiferentiai 55
polar relay midway between contacts Iland the
motor does not turn. When, however, it is de
sired to run the tuning motor. reversing switch 60
and will thus be always out of phase in the same , may be operated either to the left or right, and
a small amount of A. C. power passes into the
Two grids are provided for each tube between
the cathode and each anode. In tube 21 grids I3
and 34 are connected to the ends of secondary 25
of grid transformer 3l. Similarly, in tube 26.
65 grids 21 and Il are placed between cathode 24 and
local hybrid network. Due to the balance of the
local hybrid network this power does not reach
the local receivers, but a portion of its goes out
over the telephone pair to the hybrid network at
the receiving station, where balancing network
anodes 20 and 22, and are connected to the ends
"of a second grid transformer 4I. 'I‘he primaries
4I andk 42 of transformers I6 and 4l are connected
together in parallel. but in reverse phase. and are
supplied with energy from secondary 42' of hybrid
coil 43, which is connected to standard telephone
4l is preventing-the receiver signals from oper
-ating the motor.' The A. C. power, however, will
pass through hybrid coil 42 directly to grid trans
formers I6 and 40 and all four grids will be ener
gized. However, as the primaries 4I and 42 of
line 44 leading to the transcri ing station through
the medium of the hybrid coil 43 and balancing
nected in parallel in opposite phases, not only will
impedance 4I, asy iseustomary in the art when
76 energy flowing in opposite directions 1S handle@
grid transformers 36 and 40 respectively are con
the potential on each grid of the same tube be
opposite, but the phase of each grid will be re
versed in ac. )rdance with thc phase of the in 75
aliases
3
Seen that if the reversing switch be held to the
multiplication of frequencies, such as are well
known to the art.
It will also be apparent that the tuning motor
left, then tracing through the polarities, the upper
CFI right grid is also positive, permitting current flow
to the upper filament, while in each of the three
remaining combinations of anodes and grids
either plate or grid is negative, preventing in
system, which need not be in synchronism with
coming alternating current, whereas the phase on
the anodes will not be changed. Thus it will be
crease of current flow.
One half-cycle later the
left upper grid and left upper plate will be posi
tive, so that current will still ñow to the upper
filament. Thus, as long as the reversing switch is
held to the left a pulsating double frequency cur
rent is passed through the upper filaments to
15 the upper coil I8 of the differential polar relay,
deflecting the arm I6 of the relay upward, thus
energizing forward contactor 6 and running con
tactor 8. If the reversing switch be held to the
right the two sides of the lower tube become alter
20 nately active, de?lecting the arm I6 of the relay
downward and energizing the backward contactor
1, which supplies current to the motor in reverse
phase, and the motor reverses. When the revers
ing switch is again left open and no A. C. power
25 passed into theA line the tube system immediately
balances again, the relay de-energizes, and the
motor stops. Inasmuch as the running contactor
8 is energized by the closing of either the forward
or backward contactor of the tuning motor, the
motor will always run, irrespective of whether a
forward or backward connection is used. Thus
the operator is able to listen to the signals, and
with one hand manipulate reversing switch 50 to
change the tuning of the receiver slightly, as he
35 desires. When using heterodyne equipment, the
operator will be able to tell by the tone heard in
his receiver whether he is approaching the signal
need. not be driven, as we have shown from the
common A. C. power system. The motor arrange Gl
ment shown is desirable, but we deem as full
equivalents thereof the use of a separate power
the common system, or a direct current motor,
or the use of mechanical reversing means actuable 10
by the polar relay system shown.
We claim:
l. Apparatus for remote control comprising a
two-wire line to apparatus to be controlled,
comprising four cathode-anode current paths in
each of which is disposed a control electrode,
means for so energizing said anodes from an al
ternating current supply system that two of said
anodes shall be in phase opposition to the re
maining two of said anodes, means for passing 20
current from said A. C. supply system over said
two-wire line, means for impressing said A. C.
supply system current upon two of said control
electrodes in similar phase relationship, and upon
the remaining two of said control electrodes in
phase opposition thereto.
2. Apparatus for remote control comprising a
two-wire line to apparatus to be controlled, two
full-wave grid-controlled rectifying units, hav
ing four cathode-anode current paths, with a 30
grid disposed in each of said paths, having two
anodes of said rectifying units energized in paral
lel from a commercial alternating current power
source, and the remaining two anodes thereof
energized in parallel from said source in phase 35
opposition to said first mentioned anodes; means
for directing current from said commercial A. C.
power source onto said two-wire line at a control
or receding from it, since the pitch of the beat
station, means associated with said rectiñer units
note heard will vary in accord with the relation -for applying current from said control station
40 of the signal frequency to the local oscillator fre
over said two-wire line to two of said grids in
quency. If the direction‘of tuning is incorrect,
the operator may reverse it by throwing the
switch 50 to the other side. To maintain the
proper phasal relations at the double anode tubes,
45 it is obvious that suitable phase shifting equip
ment may be used, such phase shifting means
being well known in the art.
g
The amount of A. C. power passed through the
telephone pair need only be small because of the
amplification of the tube system utilized at the
receiving station, and as it is straight alternating
current no interference with standard telephone
equipment is encountered, and both signals and
tuning power can thus be passed over telephone
pairs where only audio frequency rights are avail
able.
'
With some telephone lines the repeating equip
ment available does not have a low frequency
range adequate to care for the transmission of
60-cycle signals; with others, there may be in
terference between the ringing currents and the
tuning equipment.' In such cases it is obvious
that we may use frequencies higher than 60 cycles,
which would, however, be tied together as between
the transcribing station and the receiving station
through the medium of the common alternating
power system as described. For this purpose, it
is obvious that frequency multipliers may be used
at both ends of the two-wire line, involving syn
chronous motors and generators, saturated-core
transformers which generate harmonics of the
power supply frequency, the use of a series of
passive full-wave rectiñers serving as frequency
doublers, or any other Similar equipment for the
phase similarity, and to the remaining two grids
in phase opposition thereto, and means for
changing the phasal relation of the current ap
plied to said grids relative to that on said anodes;
a motor actuated by said A. C. power source, and
means for controlling the direction of actuation
of said motor responsive to the output of said
rectiíier unit.
3. Apparatus for remote control, including a
two-wire line over which audio-frequency rights
only are available, which comprises a motor oper
able by direct current in direction responsive to
the direction of flow of said current, means for
producing a pulsating direct current from a com
mercial A. C. source, means for controlling the
direction of said current in accord with the phase
relations between said A. C. supply and an alter
nating current received over said two-wire lines,
and means at a control station for directing an
alternating current over said line and changing
the phase relation thereof to said A. C. supply.
4. Apparatus for remote control from a sta
tion connected to controllable apparatus by a two
wire line over which audio-frequency rights only
are available, comprising means for impressing
current uponY said line at said station from a
commercial ALC. power supply system, means at
said receiving station energized lfrom said com
mercial A. C. power supply system for produc 70
ing a pulsating direct current at said apparatus
to be controlled, means actuated by current re
ceived over said two-wire line for controlling the
direction of flow of said pulsating direct current,
and means responsive to the direction of flow of 75
4
2,112,446
said pulsating direct current for directly con
trolling said apparatus.
5. Apparatus for remote control from a control
station connected by a two-wire line over which
audio-frequency rights only are available to
rotationally controllable apparatus, comprising
means for impressing current from an A. C. power
supply system upon said two-wire line at said
control station, means energized from said A. C.
10 power supply for producing a pulsating direct
current at said controllable apparatus, means for
controlling the direction of Ilow of said direct
current in accord with the phasal relations be
tween the current from said A, C. power supply
applied to said D. C. producing means and that
received from said two-wire line, and directly
controlling means energized by said pulsating
direct current and responsive to the direction of
said current ilow.
6. A device for remote control of rotationally
controllable apparatus from a station connected
by a two-wire line over which audio-frequency
rights only are available to said apparatus which
comprises a reversible tuning motor, a diiïerential
25 polar relay through operation of which the direc
tion of rotation of said motor may be changed,
two full-wave rectifier units having anodes, grids,
and cathodes, two of said anodes being energized
in phase, and two in phase opposition from a com
mercial A. C. power supply, means for connecting
said differential relay to said rectiñer units where
by the direction of actuation o1' said relay is
dependent; upon the grid energization of said
rectifier unit, and means for directing a current
5
from said A. C. source at said control station to
said rectiiier unit and for controlling the phase
relation of said current to said anode energization.
7. Means for remotely controlling the rota
tional position of apparatus connected to a control
station by two wires on which only audio-fre
quency rights are available, comprising a rever
sible motor, a polar relay arranged to control the
direction of rotation of said motor, two full-Wave
rectifier units having anodes, cathodes, and con
trol grids disposed within an evacuated envelope.
two of said anodes being energized in phase and
two in phase opposition from a commercial A. C.
power supply, said relay being so connected and
arranged with said rectifier units that the direc
»tion of relay actuation is dependent upon the
grid energization of said units, means for direct~
ing a current from said A. C. source at said control
station to said rectiñer unit, and means for con
trolling the phase relation of said current to said
anode energization.
~ CHESTER PELMULDER.
HANS O. STORM.
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