‘June 13, 1933,.
‘
“mm
1,914,219.
SIGNALING SYSTEM
‘
Filed Jan. 3, 1927
?lVeiovg/numfa‘el PHtaheontds
lnteqsz'ty of Impressed High Frequency [mpu/ses
'
Inventor‘:
Dewey TS Lmonds.
M142
Hus Attop ney.
1,914,219
Patented June 13, 1933
‘ pullrsn» STATES
PATENT OFFICE
NEW YORK, ASSIGNOR '1‘0 GENERAL ELECTRIC_
-=.: paw-n! r-s-mouns, orscnnnnorany,
- comrarw,_a oom'ona'rxon or NEW YORK
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sresmmno sYs'r-EM- v
Application ?led Ianuary a, 1927. Serial in. 158,454.
"My invention: relates to signaling systems
and-particularly to systems for the reception
of high frequency signaling currents, and
h'a's'for ‘its purpose to provide a signaling sys
mentalities having moving ‘parts introduce
disturbances and time delay in the operation
of the system which in turn result in unde
sirable elfects upon the receiver.
purpose of my invention is to provide
‘ tern such-that the intensity of the received anThe
apparatus
of the type mentioned, which
signal‘ will be automatically maintained at or
will be entirely automatic in its operation;
bel'ol'wa predetermined, level.
_
i It is ‘well i-known'that when the receiving and which will be simple in its circuit con
and entirely electrical‘ in its opera-v
circuits of a high frequency signaling system struction
tion.
By
the provision of such‘an apparatus 6'05
it have heen'adjusted to produce great enough I have found that the disadvantage of pre4
ampli?cation for reception of signals ‘from a viousiapparatus referred to above may be
.
distant station the signals from a near by
station will be received in much greater vol—
largely eliminated.
ume than is desired. Likewise, it may re
pli?cation of the signaling circuit in direct ct";
it? sult-that-during‘ reception from a single sta
tion'the transmission characteristics of the
media over'which the signals are being trans
mitted may vary'causing the intensity of the
received signals to ?uctuate thereby necessi
tating frequent readjustment of the receiv
ing ‘circuit to compensate for the variations
v
v
"
By my invention I vary the degree of am
electrical response to the intensity of the high
frequency impulses which are impressed upon
the system. .
The novel features which I believe to he
characteristic of my invention are set forth
with particularity in the appended claims.
both as to its
in the transmission media and to maintain My invention itself, however, operation
will.
organization and method of
the1 desired‘ volume level of the received sig best
be understood by reference to the follow
description taken in connection with‘the
Means have heretofore been provided for ing
accompanying
drawing, in which Fig. 1 illus
automatically controlling the‘ transmission
level in high frequency systems. These means trates diagrammatically one form of my in
Fig. 2 presents curves illustrating
have usually involved relays which operate vention;
responsively to the intensity of the received its operation; and in which Fig. 3 illustrates
a modi?cation of the circuit shown in ‘Figt 1.
‘to high frequency impulses to control the power
With reference to Fig. 1, 1 illustrates a
na
‘
'
circuit to a motor which affects appropriate
.35
leading to the usual antenna or wire
adj ustinents'in the transmission circuit. Oth circuit
line
depending
upon the particular applica
ers have involved relays which operate re
for which the system is employed.
sponsively to the intensity of pilot frequen tion
cies transmitted over the same transmission and 3 represent the usual radio frequency am
pli?ers of the receiving circuit, ampli?er 2
being
supplied ‘with energy from the input
volved relays which operate responsively to
media as the signal, while still others have in
’ - changes in current passed through pilot wires transformer 4 and input circuit 5 which is’
which are subjected to the same transmission connected to the control electrode 01' grid 6
conditions as the media. over which the de ofthe ampli?er 2. Likewise, energy is sup
from the output circuit 7 of the electron
sired signal is bein gtransmitted. Still other plied
discharge
device 2 through the transformer
means have been provided for manually con
8, and tuned circuit 9 to the control electrode
trolling the'transmission level.
or grid 10 of the ampli?er 3., 11 represents
All of‘ these systems have inherent disad
‘i vantages in that they either require the pres
the detector of the usual receiving circuit.
ence of a skilled operatoror are complicated This detector receives its energy from the outin their 'circult construction - necessitating put circuit 12 of the amplifier‘ 3 through the '
the use ofv auxillary carr1er current genera transformer 13 and input circuit 14. Audio
tors, pilot wires and the like. Furthermore, - frequency currents from the detector are sup 100
the use ofrelays, motors and other instru plied from the output circuit 15 through
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1,914,219
transformer 16 to the audio ampli?er 17 current which flows in the output circuit of
where they are ampli?ed and impressed upon the detector 11 flows through the resistance
the head phones 18. While the ampli?ers 2 28. Since this current varies in response to
and 3. and the detector 11 are shown as of
'5 the electron discharge type, it will be appar
cut that any type of ampli?er or detector may
be used. Since the circuit connections of the
ampli?ers and detector, as thus far described
the intensity of the high frequency impulses
which are impressed upon the detector 11, the 70
potential upon the resistance 28 will corre
spondingly vary. I utilize this potential
upon the resistance 28 as a means for con
are merely those of a common receiving cir trolling the ampli?cation of the radio am
cuit,-only so much detail is given as is neces— pli?ers 2 and 3. To this end the ampli?er 75
sary to an understanding of my invention. 43 having an anode 44, a cathode 45 and a
15
Thevcathodes 19, 20, 21 and 22 of the radio control electrode or grid 46 is employed. A
ampli?ers 2 and 3, detector 11 and audio am— suitable source of potential is impressed upon
pli?er 17 are shown connected to a circuit 23 the control electrode 46 with respect to the
which is energized through resistance 25 cathode 45 through an input circuit including
from a suitable source ofpotential 26. Suit
80
the cathode 45, cathode conductors 23, con
able high potential is supplied to the output ductor 24, source of potential 27, resistance
circuit of the detector 11 from the high po
28 which constitutes a variable source of o
tential source 27 through a circuit as fol
tential, conductor 29, adjustable tap 47, t at '
portion of the resistance 48 which is between 85
ac lows: cathode 21, cathode conductors 23, con
ductor 24, source of potential 27, resistance the adjustable tap 47 and adjustable tap 49,
28, conductor 29, primary winding 30 of the adjustable tap 49, that portion of the source
. transformer 16 to the anode of the detector of potential 50 which is»,between the contact
11. The source ‘of potential 27 which com
49 and conductor 51, conductor 51 to the con
prises the usual B battery of a receiving cir trol electrode 46. A portion of the source of
cuit is provided with an adjustable tap 31 potential 50 is closed circuited through the
90
from which a suitable potential may be sup-v adjustable tap 49, resistance 48‘ and conductor
plied through conductor 32 and conductor 52. The purpose of this arrangement will
80
85
33' to the anode of the ampli?er 2 through
the primary winding 33 of the transformer
8, to the anode of the ampli?er 3 through
the primary winding 34 of the transformer
be seen later. A suitable potential is im
pressed upon the anode 44 of the ampli?er 43
with respect to the cathode 45 through an
95
output circuit including the cathode 45,
13- and to the anode of the ampli?er 17 cathode conductors 23, conductor 24, that por
through the head phones 18. Likewise, a tion of the source of potential 27 which is be-4
suitable source of potential is impressed upon tween the conductor 24 and the adjustable tap
the control circuits of the ampli?ers 2 and 3 24’, adjustable tap 24’, resistance 35, conduc
with respect to their cathodes 19 and 20 tor 53 to the anode 44.
For the purpose of preventing alternating
ductors 23, conductor 24, that portion of the ' current from being supplied from the output
100
through a circuit as follows: cathode con
source of potential 27 which is between the of detector 11 to the input of the ampli?ers
105
‘conductor 24 and the adjustable tap 24’, ad 2 and 3 through the volume control circuits
justable tap 24', resistance 35, conductor 36, the condenser 55 is inserted between the con
source of potential 37, conductor 38, thence ductor 29 and the cathode conductors 23 and
throu h conductor 39, and a portion 40 of the condenser 56 between the conductor 41 and
w 'secon ary winding of the transformer 8 to cathode conductor 23.
The operation of the circuit is as follows:
thecontrol electrode 10 of the ampli?er 3,
and through the conductor 41 and a portion During normal operation when the volume of
42 of the secondary winding of the trans the received signal is at or below a predeter
110
former 4 to the control element 6 of the am mined level, current will be ?owing in the
w pli?er 2. It will be seen that the source of anode circuit of the detector 11 and through 115
potential 37 is in series with that portion of the resistance 28. The sum of the potentials
\ the source of potential 27 which is between in the control circuit of the ampli?er 43 which
55
50
the conductor 24 and the adjustable tap 24'. includes the source of potential 27, resistance
Hence the e?ective potential on the control 28, a portion of resistance 48, and that por
elements 6 and 10 of the ampli?ers 2 and 3 tion of the source of potential 50 which is
with respect to their respective cathodes will ‘between the adjustable contact 49 and the
be determined by the sum of these two sources conductor 51 will be such that a strong nega
of potential and by the potential'on resist tive potential will ‘be impressed upon the
ance 35. This biasing potential is normally electrode 46: This being the case, no current
such that these devices operate principally will ?ow in the anode circuit of the ampli?er
as ampli?ers, and with substantially a mini
mum of detecting e?ect.
- As already explained the resistance 28 is
connected .in a circuit including the output
120
125 '
43 and asa result no voltage will appear upon
the resistance 35. The sum of the potential
37 and that portion of the source of potential
27 , which is between the adjustable contact
'65 circuit of the detector 11. Hence the direct 24' and the conductor 24, is such that the am
130
3
1,914,219 I
(.1
pli?cation of the ampli?ers 2 and 3 will be ume level will be unaffected. If it be desired
increase the volume level of the received,
a maximum and reception will take place in to
signal, then the contacts 47 and 49 maybe
theNow
usual
assume
way. that
' - a signal of 'higher inten so adjusted that a stronger negative potential
sity is impressed upon the receiving system.’ will be ‘impressed upon the grid 46. With
Then the voltage on the resistance 28 will di
such an "adjustment a greater‘ volume must be
28 before the
minish. and the source of potential 27 will impressed upon theonresistance
the electrode 46 will be
‘negative
potential
become effective upon the electrode 46 cans
ing it to assume a less negative or even posi su?ieiently diminished to permitthe ?ow of
current through the anode circuit of the am
tive potential depending upon the intensity pli?er
43.’ Hence, only intensities above those
of the received high frequency impulses. represented
by the curve 3 will be diminished
Hence, current will ?ow in the anode circuit and reception will take place on‘ the curve 3.
of the ampli?er 43 and through the resist
ance 35 causing a voltage to appear upon By adjusting either of the contacts 47 or 49 80
in the opposite direction reception can be
this resistance having the polarity indicated made
to take place upon the cirve 4.
in the drawing. ‘Since- thisvoltage is in se
lVith
the potentiometer contact 47 adjusted
ries with the. source of potential 37 in the
impress any desired bias on the grid of the .
circuit of the control elements of the ampli? to
direct current ampli?er,v current starts to
ers 2 and 3, the potential upon the control build
up in the anode circit of the ampli?er
elements will be increased in a negative direc- 7
a corresponding critical value of input ra
tion, thereby correspondingly diminishing at
the ampli?cation of the circuit and thereby dio frequency voltage to the detector.
the radio frequency input voltage to the de
diminishing the intensity of the signals at tector
increases beyond this critical value the
the , receiver.
'
current
in the direct current ampli?er in 90
This operation may best be understood by creases extremely
rapidly, and in a substan
reference to Fig. 2 in which I have plotted tially linear relation
to the radio frequency‘
the intensity of the high frequency impulses
voltage. In this way su?icient control
which are impressed upon the receiving cir input
of
the
is had to maintain the
cuit as abscissae and the intensity of the sig— volume ampli?cation
of
signal
at
the
head hones within
nal at the head phones for any given percent
age modulation-as ordinates- The curve 1
represents the operation of the circuit when
(.0
95
a satisfactorily small range 0 variations in
intensity.
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In Fig. 3 of the drawing 1 have shown a
the potential upon the electrode 46 of the am modification of my invention in which the
pli?er 43 is so strongly negative that no cur- '
ampli?er 46 hasbeen omitted. It will. be 100
rent flows through the anode circuit of this seen
that in this case conductors 39 and 41
ampli?er or through the resistance 35. As are connected
through the source of potential
sume that it be desired to maintain the vol 37 and the resistance
48’, which have been
ume of the received ‘signals at the head phones connected in parallel relation
for purposes of
at a level indicated by the curve 2. The con
adjustable contact 54 and con 105
tacts 47 and 49 will be adjusted to impress ‘adjustment,
a negative potential on the control electrode ductor 55 to the point on the resistance 28, >
43 such that no current will flow through the which is connected tothe output circuit of the
detector 11. Hence, it will be seen that any
resistance 35 until the high. frequency im ?uctuations
in the potential of the resistance
pulses impressed upon the detector are of 28 will be impressed
directly upon the control 110
such volume as to produce a signal at the
circuits
of
the
amplifiers
2 and 3. An ar
head phones corresponding to the level rep
resented by the curve¢~2 at the given percent
age modulation. Then for all high frequency
intensities which produce'si-gnals below this
level the amplification of the circuit will be
rangement of this type may be preferable in
on the curve 1. If the volume of the high fre
pli?ers are- used, such that the adjustment is
av circuit where only small adjustments are
required as where the changes in the char
acteristics of the transmission media are
115
at a maximum and reception will take place small, or in a circuit where a number of am
quency impulses which are impressed upon effective upon a number of ampli?ers. This
the detector 11 become so great as'to cause the arrangement effects a substantial economy in
‘120
volume of the received signal at the head the apparatus required.
_While I have describedmy invention with
phones toexceed the level represented by the particular
reference to a common receiving
curve 2 vthen the negative potential on the
circuit
employing
a particular type of detec
electrode 46 will be so diminished thatcur- '
rent will flow through the anode circuit of tor it will be apparent that it is not so limited 125
the ‘ampli?er 43, causing a diminution in the but rather that it may be employed in almost
ampli?caiton of the ampli?ers 2 and 3. any. type of high frequency receiving system
a contact volume of output is desired.
Hence, all high frequency impulses which where
in the embodiment shown I have
produce signal intensities above the level 2 at Likewise,
the given modulation will be diminished to employed a detector as the controlling tube .130
this level, whereas, intensities below this vol purely from considerations of economy in the
1,914,219
.
apparatus since, obviously, any type of recti
fying device may be em loyed as well. -
in the output circuit of said detector, an elec—
tron discharge device having an anode, a
Furthermore, it will be apparent that the cathode and a grid, said resistance being con
control device may be made to operate upon nected between said cathode and said grid, a ‘
“5 ampli?ers subsequent in the circuit to the con-7 second resistance connected between the an- 70
trolling tube 11 rather than prior to it as in ode and cathode whereby the potential on
the embodiment shown and that such an ar said second resistance is dependent upon the
rangement will have certain advantages such output current of said detector and means
as results from the fact that it entirely elimi for varying the potential on said control ele~
10 nates regeneration or any tendency to oscil ment in response to the potential on said sec 75
late. This also enables me to make condensers ond resistance thereby to control the ampli?
55 and 56 of very small capacity, thereby cation of said ampli?er.
eliminating any time delay in the operation
‘
2. The combination, in a receiving circuit '
of the device which may be produced by embodying an electron discharge ampli?er
1.5 the char ing of these condensers. However, having a control element, connections where—
I have ound that with this arrangement by current having amplitude dependent upon
greater difficulty is encountered in obtaining the characteristics of the transmission medi
substantially horizontal characteristics as
shown in Fig. 2 over a large range of in
v 20. tensities of impressed high frequency im
’pulses,than is the case in the embodiment
shown.
It may thus be seen that I have provided a
80
um over which currents are received are sup
plied to said ampli?er, means ,for rectifying
a portion of said current thereby to produce a
source of direct current potential which is
85
variable in response to the intensity of the '
received current, means for amplifying said
volume control device which is simple in its direct current potential and for supplying the
25. circuit structure and its operation and which ampli?ed potential to the control element of
does not require the attention of a skilled said ampli?er thereby to control the ampli?
operator, which operates directly in response cation in response to the intensity of the re
90
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"
to the high frequency impulses which are im ceived current.
pressed upon the circuit rather than in re
3. The combination in a signaling system,
30 sponse to changes in a pilot frequency which employing an electron discharge device hav- 95
is transmitted over the same media as the ing a grid, means for impressing a biasing
received signal, or in response to current potential on said grid such that said device
?owing in pilot wires, which are subjected to operates principally as an ampli?er and with
the same conditions as the media over which a minimum of detecting effect, means for sup
plying current to be ampli?e to said grid,
done heretofore. My invention has the fur a. second electron discharge de ice having an
ther advantage that it is completely electrical anode circuit, a cathode and .a grid, means
35- the received signal is transmitted, as has been .
100'
in its operation and does not. involve any for impressing a uni-directional biasing po
mechanical moving parts, such as motors, re tentialon the grid of said second device such
40. lays and the like, which introduce undesir , that substantially no current ‘normally flows
‘ v
able elfects in the operation of the system. in the anode circuit thereof, means for vary- -'
Hence my device is practically instantaneous ing said uni-directional biasing potential on
in its operation. My invention has a further the grid of said second device in response to
advantage in that it involves but a small the intensity of the received current and to
‘45 amount of apparatus and that it may .be ap
cause current to flow in the anode circuit
110
plied with facility and without great expense thereof when the intensity of received cur
rent exceeds a predetermined value and means
to any of the usual signaling circuits.
While I have shown and described a speci?c
embodiment of my invention, it will be ap
50. parent that it—is not limited to the particular
embodiment shown but that many modi?ca
tions in the circuit arrangements and instru
mentalities employed \in carrying out my in
vention may be made without departing from
for controlling the potential on the grid of
said ?rst device in response to the current in
this anode circuit of said second device th'ere 115
by to regulate the simplification of said ?rst
device.
.
l
4. In a high frequency receiving system,
sound reproducing means, an electron dis
55.. the scope thereof as set forth in the appended charge device having a grid, means for im
claims.
-
.
120
pressing high frequency potential on said
What T'claim as new and desire, to-secure grid, means for impressing a biasing poten
by Letters Patgit of the Unted States is :— tial on said grid such that said device oper
1. The combmation in a receiving circuit ates principally as an ampli?er of said high
60' employing an electron discharge ampli?er frequency current andwith a minimum of de 125
having a control element, a detector and con tecting effect, additional means comprising
nections whereby current having amplitude an electron discharge detector for deriving
dependent upon the characteristics of the audio frequency current from the ampli?ed
transmission medium are supplied to said high frequency current and for supplying
65. ampli?er and detector, a resistance connected said current from said detector to the sound 130
1,914,219
reproducing means, and means including said‘
detector for varying the direct current poten
tial upon the grid of said ?rst mentioned
electron discharge device only when the high
frequency input to said detector exceeds a
predetermined value and then to vary said
5
' 11. The combination with an audion, of
means for biasing said audion by a direct
current voltage, means for automatically va
rying said bias voltage in accordance with the
strength of an incoming signal, at least one 70
of said means comprising a rectifying system
including an element having. a“ critical work
direct current potential substantiallyl linearly ing voltage, and means where y/said critical
with respect to variation in said igh fre
quency input to said detector thereby to con
v10 trol the ampli?cation of said electron dis
charge device.
-
voltage may be adjusted.
12. In combination, an audion, an out ut 75
circuit therefor, means for suppressing ?YlC
tuations in said output circuit due to varia
ceiver of the type including a carrier wave tions in the strength of an incoming signal,
said means comprising a rectifying system
ampli?er, a detector and an audio frequency having
a certain input voltage below‘ which 80
output circuit fed from said detector, the substantially
no direct current output is ob
method of automaticallyv reducing the effects tained and above
which said direct current
of varying signal strength which comprises
5. In the operation of a carrier wave re
-15
20
amplifying the direct current potential devel
oped in the plate circuit of the detector, and
impressing the ampli?ed direct current po
output rapidly rises and attains an approxi
control the ampli?cation thereof.
certain input voltage.
mately linear relation with respect to the in-,
tensity of the signal applied to the input of
85
tential upon said carrier wave ampli?er to ‘said detector, and means for adjusting said
In witness whereof, I have hereto set my
6. In a carrier wave receiver, the combina
hand
this 31st day of December, 1926.
tion with a carrier wave ampli?er, a detector
.
DEWEY T. 'SIMONDS.
and an audio frequency output circuitfed from
said detector, of an impedance in the plate
25
circuit of said detector, a direct current am
pli?er connected ‘across said impedance, and
circuit connections for impressing the ampli
?ed output of said direct current ampli?er
30
95
upon the carrier wave ampli?er to control the
ampli?cation thereof.
7 . A carrier wave ampli?er of the vacuum
tube type and including circuit elements for
automatically impressing upon said ampli?er .
. an ampli?cation-control voltage proportional
35
100V
to received signal strength, characterized by
the fact that said circuit elements include a
direct current ampli?er.
‘
8. In combination, an audion, an out ut
circuit therefor, means for suppressing uc
tuations in said out ut circiut due to varia
45
tions in the strengt of an incoming signal,
said means comprising a rectifying system
having a critical input voltage below which
105
110
substantially no direct-current out ut is ob
tained, and means for adjusting said critical
vo ta
9.
50
e.
"
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11 an electrical system, the combination '
with an audion .having input and output cir
c-uits, of means for suppressing ?uctuations
in said out at circuit due to variations in the
115
strength 0 an incoming signal in said input
circuit, said means comprising a rectifying
55
system of the type having an approximately
120
' linear relation between direct-current output
and radio frequency input above a critical in
put voltage, and means for varying the crit
ical voltage of said rectifying system.
60
v10. In an electrical system, the combina
125
tion with an audion, of means energized by
said audion for impressing va variable bias
on said audion, said means having'a critical
working voltage, and means for adjusting
85
said critical voltage‘.
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130