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Патент USA US2111647

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March 22, 1938.
A. J. SORENSEN
2,111,647
APPARATUS FOR RAILWAY TRAIN COMMUNICATION SYSTEMS
Filed Oc‘t. 22, 1936
2 Sheets-Sheet 2
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Andrew
BY
INVENTOR
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HIS ATTORNEY
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Patented Mar. 22, 1938
2,111,647
UNETED STATES PATENT OFFICE
2,111,647
APPARATUS FOR RAILWAY TRAIN COM
IVIUNICATIGN SYSTEMS
Andrew .F. Sorensen, Edgewood,‘ Pa., assignor to
The Union Switch & Signal Company, Swiss
vale, Pa, a corporation of Pennsylvania
Application ()ctober 22, 1936, Serial No. 106,969
12 Claims.
My invention relates to apparatus for rail
way train communication systems, and particu
larly to apparatus for combined code signaling
and telephone systems for railway trains.
I will describe one form of apparatus embody
ing my invention, and will then point out the
novel features thereof in claims.
In railway train communication systems of the
type here contemplated, a carrier frequency cur
10 rent modulated with voice frequencies is used for
telephone communication. For code signaling, a
carrier modulated by a single predetermined voice
frequency or its equivalent is used. In either
case, the same carrier frequency is used for trans
15 mission in both directions. The communication
channel preferably includes the track rails in the
manner described and claimed in the United
States application for Letters Patent, Serial No.
450,135, filed May 1, 1930 by L. O. Grondahl for
Electric train signaling systems. Communica
tion current is supplied to and received from the
communication channel through the medium of
circuit elements electrically coupled with the
track rails. Switching apparatus .is provided at
each station for selectively coupling either the
transmitting apparatus or the receiving appa~
ratus to the track rails. In systems heretofore
proposed, the operator manually actuates such
switching apparatus, especially during telephone
30 communication, and there is no limit imposed on
the length of time the equipment of a station
can be left in the position for transmitting a
telephone current.
Hence,v the operator at one
station is unable to break in to either speak or
signal to an operator at the other station when
he is transmitting a telephone conversation. It
is desirable that either operator may interrupt
the conversation of the other operator in order
vided so that each train of a railroad can have a
distinctive channel frequency of its own and in
terference between different trains is avoided.
Other features and advantages of my invention
will appear as the speci?cation progresses.
In the accompanying drawings, Figs. 1 and 2,
when taken together, constitute a diagrammatic
view of one form of apparatus embodying my
invention when applied to a railway train for
telephone and code signaling, the code signaling 10'
being utilized for governing the operation of the
train brakes. The apparatus of Fig. 1 is that to
be installed on the train at the location of the
supervising operator, which location may be, for
example, the locomotive of a freight train, the 15
engineman being the supervising operator.
The
apparatus of Fig. 2 is that installed at another
location on the train, which location may be the
caboose of a freight train, the train brakes being
manually controlled at the caboose by a trainman 20
in accordance with code signals received from
the locomotive.
In the following description, like reference
characters refer to similar parts in each of the
two views.
25
In certain instances, circuit. controlling con»
tact ?ngers are shown remote from the relay
windings or other devices which operate them.
The relationship between these elements is indi
cated by the fact that each such circuit contact 30
?nger bears a reference character corresponding
to the reference character of the associated relay
or device plus a distinctive numeral, and each
such contact finger is illustrated in the position
corresponding to the position of the relay or 35
device.
Referring to Fig. l, the reference character
EV designates the usual engineer’s brake valve
that a message may be delivered relating to the
capable of establishing the release, running, lap,
control of the train without delay. For example,
where the train brakes are to be governed at two
service and emergency conditions of the brake 40
pipe pressure. As shown schematically, a cir
cuit contact assembly is associated with the brake
valve EV, the contact members [2 and I23 of
which assembly are connected to and actuated
by handle I3 of the brake valve. The contact 45
different locations on‘ a train through the medium
of the communication system, it is desirable that
the operator at either station may order a change
” in the'brake condition without delay,
Accordingly, a feature of my invention is the
provision of novel and improved apparatus for
systems of the type here under consideration
wherewith an operator at the station-receiving a
telephone message may breakin upon the con
versation of the operator talking. Another fea
ture of my invention is the provision of novel and
_ 55.
(Cl. 246-8)
member [2 is adapted to engage an arcuate con
tact M in all positions of handle I3, to engage
an arcuate contact H3 in release, running and
lap positions of the brake valve; and to engage
an arcuate contact l6 in the service and emer
50
gency positions. The contact member I23 is
adapted to engage the arcuate contacts l2l and
I22 in the release, running and lap positions.
improved apparatus for systems of the type here
The reference character MS designates a three
involved by means of which'apparatus a num- _
position circuit controlling master switch. The 55
ber of different channel frequencies can be pro
2
.
‘2,111,647
three positions of the switch are indicated by the
numerals i, 2, and 3. The numerals l, 2, and 3
are placed on the drawings only in connection
with the contact 32 of the switch for the sake of
clearness, and it will be understood that the other
contacts 35, 35, 3?, 38, 39, and 53 of the switch
drections from the locomotive in the well
known manner.
A manually operated dial selector switch DS
by which different channel frequencies for code
signaling are obtained for different trains is pro
vided. In this instance, this selector switch DS
MS are each adaptable of movement to three cor
comprises ?ve contact members, 23, 24, 25, 26,
responding positions.
and 2'! which are operatively connected together
The position No. l of the
switch MS, that is, the position illustrated in
10 Fig. 1, is the normal position of the switch to.
which
spring
either
switch
it returns under the action of a biasing
not shown when not manually held at
its No. 2 or No. 3 position. When the
MS is in the No. 1 position the locomotive
equipment is capable of being actuated either
automatically or manually between the transmit
ting and receiving conditions to send and receive
code signaling impulses in a manner to appear
hereinafter. The No. 2 position of the switch is
selected when it is desired to send a telephone
current, and the No. 3 position of the switch sets
the equipment in a condition for receiving a tele
as indicated by a dotted line, the several contact
members being insulated from each other in any 10
convenient manner. The selector switch DS has
four distinctive positions to which the ?ve con
tact members may be set by rotation in a clock
wise direction, as viewed in Fig. 1, the contacts
being illustrated as set at the ?rst one of the four
positions. Each of the ?ve dial contact members
controls four condensers so that any one of the
four associated condensers may be included in a
circuit with which the contact member is asso
ciated. For example, the contact member 23 in
the first position of switch DS, that is, in the
position illustrated, connects a condenser 40 be
phone current.
tween the wires 4i and 42 of an associated cir
The locomotive equipment includes a mechani
cally tuned oscillator or coder N. The type of
coder is immaterial and it may be that dis
closed in the United States Letters Patent No.
cuit, and rotation of the contact member 23 in
the clockwise direction includes condensers 43,
B4, and 45 in the same circuit for the second,
third and fourth positions of the selector switch,
respectively. In a similar manner, rotation of
the contact members 24, 25, 26, and 2'! to the
diiferent positions connects different condensers 30
in the associated circuits, as will be ‘understood
by an inspection of Fig. 1. The manner where
with the different positions of the selector switch
DS are effective to adjust the associated equip
ment for different channel frequencies will ap
1,858,876, granted May 17, 1932 to P. N. Bossart
for Coding apparatus. It will su?ice for this de
scription to say that the operating winding 4
of the coder N is continuously supplied with
current from a battery 5 over its own contact
member 6, with the result that the contact mem
bers ‘I and 8 of the coder are continuously oscil~
' lated between a left-hand position illustrated by
solid lines and a right-hand position illustrated
pear as the system is described.
by dotted lines at a predetermined rate, say, for
example, 120 times per minute. The contact
includes a code frequency generator or oscillator
member ‘I engages a contact 9 when swung to its
40 left-hand position and the contact member 8 en~
gages a contact ill when swung to its right-hand
position. As will shortly appear, time is divided
into sending and receiving periods by the contact
members 'i and 8 under the normal position of
the master switch MS and with the brake valve
EV set at the release, running or lap position.
Under the No. 2 and No. 3 positions of the master
switch MS, and also when the brake valve is
operated to the service and emergency posi—
tions, the coder N is ineifective.
Two independent inductor coils CC and V0 are
mounted on the locomotive in inductive relation
with the track rails. These coils are preferably
of the air core type and may be mounted on the
top of the locomotive tender. It follows that
communication current ?owing in the track rails
induces electroniotive forces in the inductor coils
CC and V0. As will later appear, the coil CC is
utilized for reception of code signaling current
60 and the coil V0 is utilized for reception of tele
phone current.
Both code signaling and telephone currents are
supplied to the track rails through the medium
of a sending circuit directly coupled with the
'H‘ rails, and which circuit may be traced from the
secondary winding ll of an output transformer
T5 over wire l1, rear tender truck wheels !8, track
rails l9, forward truck wheels 20, and wire 2| to
the opposite terminal of the secondary winding
"ll.
It is clear that in response to an electromo
tive force induced in the secondary winding II,
in a manner to be described, current is supplied
to the track rails with the result that such cur~
rent is transmitted along the track rails in both
The transmitting apparatus on the locomotive
OSI, a power ampli?er PA, a voice converter CO,
and a microphone M.
40
The oscillator OSI is preferably an electron
tube oscillator of the well-known Hartley type.
The oscillating circuit comprises a reactor 22 and
any one of the four condensers 40, 43, 44 or 45
in accordance with the position of the selector
switch DS, as well as condenser I09, which con
denser |09 is interposed in the circuit over a back
contact H0 of a relay Ill to be referred to later.
That the invention may be better understood, I
shall assume by Way of illustration that the re
50
actor 22 and the condensers 40, 43, 44, and 45,
as well as the condenser I09, are so proportioned
that the carrier frequencies generated by the
oscillator OSI are rI000, 6000, 5000, and 4000
cycles per second for the ?rst, second, third and ..
fourth positions of the selector switch DS, respec
tively, these respective carrier frequencies serving
as channel frequencies for the four respective
positions of the switch DS.
‘ Furthermore, I shall asume that when relay
H I is operated to open back contact H0 and re
move condenser l09 from the oscillating circuit
of oscillator OSI, the channel frequency supplied
by the oscillator OSI is varied a few cycles, say,
50 cycles. By way of illustration, when the selec 65
tor switch DS is set at its ?rst position and the
channel frequency is r7000 cycles, operation of re
lay III to remove condenser I09 from the oscil
lating circuit raises the channel frequency to
7050 cycles. Consequently, periodic operation of
relay I l l to periodically disconnect the condenser
I09 causes the channel frequency to be varied
or “Wobbled”.
The power ampli?er PA may be any one of
several types, for example, it may be two power
3
2,111,647
electrontub'es connected in the usual push-pull
arrangement. The power ampli?er PA is shown
conventionally for the sake of simplicity since its
speci?c structure forms no part of my present in
vention. When the master switch MS is set at its
No. 1 position and the brake valve EV is operated,
to either the release, running or lap position, the
input terminals of the power ampli?er PA are
connected with the code oscillator 7 OS!
over
10 the code contact member ‘I; and the output ter
minals of the power ampli?er are connected with
the primary winding 28 of the output transformer
Tl through a ?lter selectively tuned to. e?iciently
pass the channel frequency. Under these con
15 ditions, theinput circuit for the power ampli?er
PA may be traced from the right-hand terminal
of the oscillating circuit of oscillator OS! over
wires 29 and 52, code contact L0, wire 30, con
tacts I5, I2, and M of the contact assembly, wire
20 3|, contact 32 of the master switch MS in its
No. 1 position, wire 33, input side of» the power
ampli?er PA, and wire 3!; to the left-hand ter
minal of the oscillating circuit. ‘The output cir
cuit of the power ampli?er PA extends from its
25 lower right-hand terminal over wire 46, primary
winding 2870f transformer Tl, contact 35 of the
master switch, wire M, contact member 24 of the
selector switch DS in its ?rst position, con
?er PA, virrespective of the operation of the coder
and position of the brake valve. As set' forth
previously, removal of the condenser Hi9 from
the oscillating circuit causes‘ the carrier fre
quency supplied by the oscillator OS! to be varied
50 cycles. Thus, operation of the push button,
when the selector switch DS is set at its ?rst
position and the master switch is in its No. 1
position, is effective to supply to the track rails
code signaling current having a frequency varied 10
between ‘7000 and rZ050 cycles.
When the master switch MS is operated to
its No. 2 position the input of the power ampli
?er PA is shifted to include the voice converter
CO and its output is shifted to exclude the ?lter 15
ll8—49. The output circuit now consists of lower
right-hand terminal of ampli?er‘ PA, wire 46,
primary winding 28, contact 35 of master switch
MS in'its No. 2 position, back contact ERS of
a relay RS to be referred to later, and thence 20
to the lower left-hand terminal of the ampli?er.
The input circuit maynow be traced from the
lower right-hand terminal of the voice converter
(30 over wire 54, contact 32 of the switch MS in
its No. 2 position, back contact iRS, wire 33,
input side of power ampli?er PA, and wires 34
and 42 to ‘the lower left-hand terminal of the
voice converter. The input terminals of the voice
denser 48, reactor 49, and to the lower left-hand - converter C0‘ are connected with the microphone
M over a simple circuit easily traced. The voice -30
30 terminal of the power ampli?er. The condenser
converter CO may be any one of several types,
48 and reactor 49 are so proportioned that the
above traced output circuit is tuned to e?iciently
pass-‘the generated frequencies of the oscillator
OSI, which, as here assumed, are 7000 cycles
35 with selector switch DS at the ?rst position. and
relay lll released, and 7050 when relay iii is
operated. _It follows that as long as the brake
valve EV is set at a running position and the
master switch MS is at its No. 1 position and
40 relay Ill is released, an impulse of current of
l7000 cycles is supplied to the primary winding
28 of transformer Ti during each period the
code contact 1-9 is closed. Each such impulse
such as, for example, a balanced electron tube
modulator wherewith a carrier frequency gen
erated therein is modulated by the voice fre
quencies and the carrier and one side band are 35
suppressed, leaving the remaining side band to be
supplied to its output circuit. The voice con
verter CO is shown conventionally only since its
speci?c structure forms no part of my present
40
invention.
To‘ ?x the ideas, I shall assume the carrier fre
quency generated within the voice converter CO
of code signaling current supplied to the primary
is 7000 cycles per second, the voice frequencies
utilized extend from 500 to 2500 cycles, and that
45 winding 28 of transformer Ti induces electromo~
the upper side band is transmitted. In this case,
tive forces in the secondary windings H and 50
of that transformer, the secondary winding ll
being interposed in the sending circuit for sup
plying current to the rails as pointed out here
50 inbefore. The secondary winding 50 is connected
with the input terminals of a recti?er 5!, the
output terminals of which are connected with
an operating winding of a relay VR, with the re
sult that the relay VB. is energized during each
outgoing impulse. The function of the relay VR
will be referred to hereinafter.
With the brake valve EV operated to either
its service or emergency position when the switch
MS is in its No. 1 position, the connection ex
60
tending from wire 52 and. including contacts l6,
the transmitted carrier telephone current has
the frequency range of 7500 to 9500 cycles. It
follows that by shifting the master switch MS to
its N0. 2 position and speaking into the micro
phone causes a side band carrier telephone cur 50
rent of the frequency range of ‘7500 to 9500 to be
supplied to the track rails, a portion of the out
going energy being recti?ed and utilized for ener
gizing the relay VR.
‘
It is well known that even apparently sus
tained speech contains short intervals when the
energy of the speech is only a small fraction of
the average volume. This being so, the relay VB.
is deenergized or is energized at so low a value
that it is released during each pause in the con
I2 and M of the contact assembly provides a
versation.
shunt path around the, code contact 1-9, with
the result that code signaling current from the
code oscillator CS1 is continuously supplied to
the track rails and to the relay VR.
For example, a pause of the order of 0.1 second
frequently occurs in a conversation and relay VB
The relay III is controlled over its own ‘back
contact H3 and a contact H4 of a common
spring return push button PB. Depressing push
button PB causes relay Ill to be operated and
contact H0 is periodically opened and closed to
periodically disconnect the condenser E00 from
its associated oscillating circuit. Depressing
push button PB also closes contact H5 and com—
pletes, when the master switch MS is in its No.
1 position, the input circuit of the power ampli
The relay VB is proportioned and ad
justed for relatively quick acting characteristics.
is adjusted to release at something less than 0.1
second. The pickup period of the relay would
be of the order of 0.02 second. Hence, during
the sending of a telephone current the relay VB
is picked up during speaking periods, is released
during normal pauses that occur at the end of a 70
phrase, and is again picked up on the ?rst syl
lable of the next group of words. The relay VB
is also released, of course, during sustained
pauses in the conversation. The function of such
operation of the relay VR will appear hereinafter. 75
aiiresv
The receiving apparatus of Fig. 1, which in
cludes a loud. speaker LS, an ampli?er demodu
lator DM, an oscillator CS2 and several ?lters,
will now be described.
. The ampli?er demodulator DM may be any one
of several types, among them being a balanced
electron tube demodulator with one or more
stages of ampli?cation, and it is shown conven
tionally only for the sake: of simplicity. With the
10 master switch MS in its No. 1 position and the
brake valve EV set at a running position, the in
ductor coil CC is interposed in an input circuit
network of the demodulator DM over the code
contact 8-H]. Starting from the inductor coil
CC a circuit may be traced over wire 55, code
contact 8-!0, contacts l2l-l23—l22, Wire 50,
condenser 51, contact member 25 of switch DS,
lower portion of reactor 58, condenser 59, contact
member 28‘ of switch DS, upper portion of reactor
20 60, wire 6|, a normally closed contact PBI of
the push button PB, and back to the coil CC.
The input terminals of demodulator DM are con
nected across the reactor 60 over a circuit in
cluding wire 62, contact 3'! of switch MS, wire
63, reactor 60, and wire 54. The reactors 58 and
60, together with the condensers 57 and 59, con
stitute a ?lter for tuning the input circuit net
work to pass the channel frequency of the code
signaling current. With the selector switch DS
30 set at its ?rst position as illustrated in Fig. 1,
this ?lter would be proportioned to pass a code
signaling current of 7000 to 7050 cycles, which are
the same as the frequencies delivered by the os
cillator OSI, it being recalled that the same chan
nel frequency is used for transmission in both di
rections.
When the master switch MS is shifted to its
No. 2 position to bring contacts 36 and 3'! to their
respective No. 2 positions, this input circuit net
40 work for the demodulator DM is completed at
the front contact 3R8 of relay RS and a back
contact IVR of relay VR. Consequently, the
locomotive equipment is also conditioned to re
ceive code signaling current during pauses in the
45 transmission of a telephone current from the
locomotive, since the relay VB is released during
each pause as explained hereinbefore and relay
RS is picked up during each pause in a manner
shortly to appear.
The oscillator 082 is preferably similar to
50
the oscillator OS! and the carrier current gen
erated thereby is applied to the demodulator DM
for demodulation purposes. The frequency de~
livered by the oscillator CS2 is governed by the
55 position of the selector switch DS and the posi
tion of the master switch MS and relay RS. A
condenser 65 is permanently connected across a
reactor 61 to form an oscillating circuit for oscil
lator OS2, and one of four additional condensers
60 is interposed in this oscillating circuit in accord
ance with the position of contact 21 of the se
lector switch DS to adjust the oscillator CS2 to
the channel frequency. With switch DS set at
its ?rst position, a condenser 68 is connected in
parallel with condenser 65, the connection for
condenser 68 being completed either by contact
39 of switch MS in its No. 1 position or by the
front contact 4R8 of relay BS. The current
generated by oscillator CS2 is delivered to the
70 ' demodulator DM through the medium of a wind
ing 66 coupled with reactor 61 of the oscillating
circuit. The parts are so proportioned that the
carrier frequency generated by the oscillator 082
during code signaling is of a frequency which is
,,different from the channel frequency, say, 1000
cycles less. Thus, when the selector switch DS
is set at its ?rst position to select a channel fre
quency of 7000 cycles, the frequency generated by
oscillator 082, when the master switch is set at
its No. 1 position or when the front contact 4R8
is closed, is 6000 cycles per second. On the as
sumption that the second, third and fourth posi
tions of the selector switch DS are effective to se
lect channel frequencies of 6000, 5000, and 4000
cycles per second, respectively, the current gen 10
erated by the oscillator CS2 is of 5000, 4000, and
3000 cycles per second for the second, third and
fourth positions of the selector switch, respec
tively.
The condenser 65 is so proportioned that
when it alone is interposed in the oscillating cir
cuit the carrier frequency generated by the os
cillator CS2 is the same as the carrier frequency
of the telephone current and in this instance is of
7000 cycles per second. Consequently, when the
selector switch is set at its ?rst position and the 20
master switch MS is set either at its No. 1 posi
tion or at its No. 2 position, and the relay RS is
picked up, that is, the positions in which the in
put circuit for the demodulator DM is conditioned
to receive the code signaling current of 7000
cycles, the oscillator 0S2 supplies to the de
modulator a current of 6000 cycles, with the re
sult that the output of the demodulator is a cur
rent of 1000 cycles. When the code signaling
current is varied between 7000 and 7050 cycles 30
in the manner explained hereinbefore, the out
put of the demodulator is a current which varies
between 1000 and. 1050 cycles. When the input
circuit for the demodulator DM is conditioned,
in a manner shortly to appear, to receive a car
rier telephone current of the range of 7500 to
9500 cycles, the oscillator 0S2 delivers a current
of 7000 cycles to the demodulator and the voice
frequencies appear in the output of the demodu
lator.
'
The loud speaker LS is normally connected
with the output terminals of the demodulator
DM through a ?lter 59, which ?lter is propor
tioned to pass a current of 1000 to 1050 cycles.
It is clear, therefore, that a note is sounded at
the loud speaker during such periods as a code
signaling current is picked up from the track
rails, the note being of a steady pitch when the
frequency of the code signaling current is uni
form and being varied in pitch when the fre
quency of the code signaling current is varied.
In the No. 3 position of the master switch M8
the inductor coil V0 in connected to the input
terminals of the demodulator DM through a band
pass ?lter BPF having a pass band of 7500 to 55
9500 cycles, the connection between the ?lter
BPF and the demodulator DM being completed
by the contact 3'! of the switch MS in the No. 3
position. With the master switch MS moved to
its No. 3 position, the contact 38 thereof com
pletes a connection by which the loud speaker LS
is connected directly with the output terminals
of the demodulator. As set forth hereinbefore,
operation of the switch MS away from its No. 1
position to open contact 39 increases the carrier
current generated by oscillator CS2 to the fre
quency of 7000 cycles. Consequently, an upper
side band telephone current of 7500 to 9500 cycles
picked up by the coil VC is demodulated and the
resultant audio frequencies are reproduced by
the loud speaker LS.
With the master switch MS in its No. 2 po
sition, the contact 30 completes a circuit by
which a reactor 10 and a. condenser ‘H are con
nected with the output terminals of the demodu~
M
‘2,111,647
U
pass frequencies of the order of_10'00 to 1050
cuit for relay
but the relay it remains picked
up for aw‘period since it is slow releasing in char
acter. This cycle of operation of relays RS and
cycles. A portion of the reactor 70‘ is connected
with the input terminals of a ‘recti?er T2, the
mission “of telephone conversation continues.
lator DM in parallel with the loud speaker. The
reactor 70 and condenser 7| are proportioned to
output terminals of which are connected with
the winding of a relay 13'. Hence, when the
master ‘switch MS is at its No. 2 position and a
current of 1000 to 1050 cycles appears in the
M) output of the demodulator DM, the relay i3 is
energized, as well ‘as a note being sounded by the
loud speaker.
‘
p
i For controlling the relay RS, the contacts 5R5,
ZRS, 3RS and GRS of which are utilized at times
15 for switching the locomotive equipment as point~
ed out hereinbefore, a motion responsive means
is ‘provided. This motion responsive means com;
prisesa motion actuated device 77 and relays ‘l5
and 75.
The motion actuated device Tl may take
20 different forms and is effectively operated in re
sponse to motion of the locomotive due vto the
vibration created by the locomotive in motion,
‘I0 is repeated as long as the pause in the trans
Relays RS and 76 are proportioned to allow relay
RS to remain energized for a suitable length of
time, for eka‘mple, 0.1 second, and to allow a
suitable period between successive operations of
rela}r "£6, for example, 1 second. , _
During the "period the relay RS is picked up .10
the receiving apparatus on the locomotive is con
ditioned for the reception of the code signaling
current as described‘hereinbefore. In the event
code signaling current appears at ‘the locomotive 15
and is picked up by the inductor coil CC‘, the
relay 73 is energized and the_loud speaker
sounds a corresponding note. With relay ‘l3
picked up the relay’ RS is retained energized to
retain the apparatus in the receiving condition
as long 'as the code signaling current continues
to be received. Furthermore, further trans
or due to a connection with a ‘moving part of the
mission of telephone current is prevented since
locomotive As here shown, ‘the motion actuated
25 device i7 is a microphone of ‘the type disclosed
in my ‘United States Letters Patent No. 1,834,077,
the transmitting apparatus is disconnected at
granted December 3, 1931, and which micro
phone is mounted in ‘any convenient manner so
as to be vibrated in response to an appreciable
30 speed of the locomotive.
The essential parts of
the microphone ‘I? are two ‘metal electrodes E and
El spaced apart in an insulation housing 78, the
space between the ‘electrodes being partly ?lled 'at
least with carbon granules. When the micro;
35 phone TI is ‘not vibrated the resistance between
the electrodes E and El through the: carbon
granules is relatively low, but when the micro
phone is vibrated the resistance between the
i (it)
the back contacts IRS and 2R8. If no 'code sig- ;
ii'aling current appears, relay RS drops, followed
by relay 76‘ at the end of its release period and
the transmission of the telephone current is re
newed. To prevent loss ‘of essential parts in
the speech, the relays RS and it are propor
tioned so as'to repeat their cycle of operation at
least once‘ every second, as explained above.
Referring to Fig. 2, the caboose is provided
with equipment similar to the equipment on the
locomotive except that the coder is replaced
by three relays, 83, 84, and 85; and the brake
valve EV is, not interlocked with the circuits.
The relays 83, 84, and 85 are effective to syn
electrodes is increased many times its normal
chroni‘ze the caboose equipment with the 1000
value. The relay 75 is provided with a circuit
extending from the B terminal of any convenient
source of current such as a battery not shown,
motive equipment during the normal operation of
the system. That is, the caboose, equipment is,
through the action of the relays 83, 84, and 85,
over winding of relay l5, electrodes and carbon
granules of microphone Ti and to the C terminal
alternately shifted between its transmitting and
receiving positions instep with the locomotive
of the same source of current.
The parts are so
proportioned that relay 75 is energized and
picked up when the microphone Tl is not vibrated
but when the microphone ‘H is vibrated in re
sponse to motion of the locomotive, the energiza
tion of the relay is so reduced that the relay is
released to close its back contact 19.
The relay RS is provided with a control circuit
extending from the B battery terminal over back
contact ‘E9 of relay l5, winding of relay RS, back
55 contact 80 of relay 76, back contact 8! of relay
VR, contact 53 of switch MS in its No. 2 position,
and thence to the C battery terminal. This con
trol circuit for relay RS may also be completed
over the front contact 14 of relay 73, as will be
60 readily understood‘ by an inspection of Fig. 1.
Relay 16 is controlled over a circuit including
equipment, the caboose equipment being condi 45
tioned for receiving during the sending periods
of the locomotive equipment and being condi-,
tioned for transmitting during the receiving pe
riods of the locomotive‘ equipment. It is believed
unnecessary to describe the apparatus of Fig. 2 50
in detail since it would be a repetition of that
of Fig, 1, and it is thought that the caboose ap
paratus can best be understood by a description,
of the operation of the system.
,
-
In describing the operation of the system, I
shall ?rst consider the normalv condition, that is,
the condition where both master switches MS
are set at their respective No. 1 positions, the
selector switches DS being both set at the first
position as illustrated in the drawings so that 60
the channel frequency selected is, as here as
back contact 18 of relay 15, winding of relay’ 76,
sumed, 7000 cycles per second.
front contact 82 of relay RS, back contact 8i of
relay VR and‘ contact 53 of switch MS.
During transmission of a telephone current
with the locomotive in motion, the switch MS is
set at its No. 2 position and the relay VB is
picked up, with the result that the relays RS
and “.16 are deenergized since the relay ‘E3 is
shall assume that the brake valves EV are both
70 now also released.
During a pause in the tele~
Furthermore, I
positioned at the running position for the train
and that the train is in motion so that the relay 65
75 of each motion actuated means. is released.
When the coder Nvis operated to its left-hand
position as illustrated, the closing of code con
tact l-9 completes the input circuit between the
oscillator OSl and the power ampli?er PA and 70
phone conversation the relay VB. is deenergized
an impulse of code signaling current is supplied
and releases to close its back contact 8!. Under
this condition the relays RS and 16 are picked
to the track rails.
upv in turn. With relay 70 picked up the relay
75 R8 is deenergized and releases. to open the cir
20
Relay VR on the locomotive
is also energized and picked up byv a portion of
the outgoing energy, but operation of relay VR.
at this time performs no useful function and need 75
6
2,111,647
not be further considered. When this code sig
naling impulse appears at the caboose an electro
motive force is induced in its inductor coil CC and
is applied to the input of the caboose ampli?er
demodulator DM, the input circuit for the de
modulator DM being ?rst completed at back con
tact 86 of relay 85 and then at front contact 81
of relay 83 after the relays 83, 84, and 85 have
been operated. At the start of the impulse the
relays 83, 84, and 85 are all down and the input
10
circuit network includes coil CC, back contact
86, wire 88; ?lter consisting of condenser 89, con
tact member 90, lower portion of reactor 9|, con
denser 92, contact member 93 and upper portion
of reactor 94; and thence back to the coil CC over
wire Ill. The input terminals of the demodu
lator DM are connected across the reactor 94
over contact 95 of the master switch MS in its
No. 1 position.
20
Since the caboose oscillator CS2
is now supplying a current of 6000 cycles per sec
ond to the demodulator DM for mixing with the
incoming code signaling impulse of 7000 cycles
per second, a current of 1000 cycles is supplied
to the loud speaker and a corresponding note is
sounded.
A circuit including a reactor 96 and a
condenser 91 is also connected across the output
terminals of the caboose demodulator DM in
parallel with the loud speaker, this circuit being
completed by the contact 98 of the master switch
MS in its No. 1 position. The reactor 96 and
condenser 9'! are proportioned to pass current of
1000 to 1050 cycles and hence current is supplied
to the winding of relay 83 through recti?er 99
and that relay is energized by a portion of the
output of the demodulator DM resulting from
the code signaling impulse picked up from the
track rails. Relay 83 on picking up causes the
two relays 84 and 85 to be energized and picked
up in turn, the circuit for relay 84 being com
pleted at front contact I00 of relay 83 and the
circuit for relay 85 being completed at the front
contact I8I of relay 84. Relays 83, 84, and 85
the locomotive inductor CC, which inductor is
now connected with the input circuit network
of the locomotive ampli?er demodulator DM over
the contact 8-“) of the coder, with the result
that a note is sounded at the loud speaker. The
parts are so proportioned and adjusted that the
relay 85 is released and the impulse sent from
the caboose is discontinued, and the caboose ap
paratus is switched back to its receiving condi
tion prior to the time the coder N operates back
to its left-hand position. Consequently, impulses 10
of the code signaling current are alternately ex
changed automatically between the locomotive
and the caboose as long as the normal condition
of the equipments is maintained. This exchange .
of impulses indicates to the trainman in the
caboose that a running position of his brake valve
EV is to be effected. Such exchange of code
impulses also indicates that the system is in
proper operating condition.
20
Movement of the locomotive brake valve EV to
either the service or emergency position causes
the locomotive equipment to continuously send
the code signaling current with the result that
the caboose equipment is continuously held at
the receiving condition and a corresponding note
is sounded without interruption at the loud
speaker. An uninterrupted audible signal of this
pitch is an indication to the trainman in the
caboose that the brake applying position of his
brake valve EV is required.
The selector switches DS being both set at
their ?rst position, the several devices of the
equipment of the locomotive and of the caboose
are adjusted to operate on a channel frequency
of 7000 cycles.
In the event these two selector
switches are each set to the second position the
condensers interposed in the several associated
circuits are such that the equipment at the two
ends of the train are operated on a different
channel frequency such as, for example, 6000
cycles per second. The third position of the
now all remain energized as long as the code im
switches adjusts the equipment to the channel
pulse continues, since the input circuit network ' frequency of, say, 5000 cycles; and the fourth
is held closed at front contact 8‘! of relay 83.
When the coder N swings to its right-hand
position the sending of the code signaling impulse
is discontinued and the locomotive equipment is
switched to its receiving condition. The caboose
relay 83 is deenergized and immediately releases
at the expiration of the code signaling impulse.
Relay 84 releases shortly after relay 83 but relay
85 does not release until the expiration of its slow
release period, this latter relay being slow releas
ing in character. During the period that relay
84 is down and relay 85 is up, the caboose oscil~
lator OSI is connected with the input of the
power ampli?er PA over front contact I02 of
relay 85 and back contact I03 of relay 84, the
60 contact I84 of the master switch in its No. 1
position being also interposed in the circuit.
Since the output circuit of the power ampli?er
PA on the caboose is now completed through
primary winding I05 of the caboose transformer
TI by contact I06 of the master switch, an elec~
tromotive force is induced in each of the sec
ondary windings I01 and I 08 of the output trans
former TI, and a corresponding impulse of code
signaling current is supplied to the track rails
and to the winding of the caboose relay VR.
Operation of the caboose relay VR at this time
accomplishes no useful function and need not
be further considered. The code signaling im
pulse supplied to the track rails at the caboose
75 is effective to induce an electromotive force in
position of the switches adjusts the equipment to
the channel frequency of, say, 4000 cycles per
second. Hence, four different trains, all similarly
equipped, may each be provided with a distinc
tive channel frequency for its code signal system
by the proper setting of the selector switches, .
any caboose equipment being operative with any
one of the different locomotive equipments. If
more than four different channel frequencies are
desired, the selector switches can be readily pro
vided with additional positions and condensers
provided for these additional positions that will
adjust the equipment to still different channel
frequencies.
I shall next consider the case where the engine
man desires to telephone to the trainman in the 60
caboose. The procedure would preferably be as
follows. The engineman ?rst shifts his master
switch MS to the No. 3 position and places his
equipment in speech receiving condition.
This
operation on the locomotive causes the sending
of the normal code impulses to cease. On the
caboose no note will be sounded at the loud
speaker, the absence of which will indicate to
the trainman that telephone communication with
him is desired. The trainman will ?rst shift his
master switch to its No. 2 position, which places
the caboose equipment in the speech sending con
dition. The trainman now verbally informs the
engineman that he is ready to telephone by
speaking the usual “hello” signal. After sending
7
2,111,647
such signal the trainman immediately shifts his
master switch to its No. 3 position. The engine
man, upon receipt of such signal from the train
man that an application of the train brakes is
man, will shift his master switch to its N0. 2
position and initiate the conversation. From this
point on telephone communication between the
two ends of the train will be accomplished by
In the event the trainman in the caboose de
sires to break in upon the engineman during their
the operators actuating their master switches be—
tween the No. 2 and No. 3 positions. At the ter
10 mination of the telephone conversation the mas
ter switches at both locations will be released
and returned to their No. 1 positions and code
signaling will be reestablished. If the trainman
in the caboose desires to initiate telephone com
15 munication, the procedure would be similar to
that described above and need not be repeated.
If, during an interval the trainman is talking,
the engineman desires‘to break in on his con
versation and verbally deliver an order to the
trainman, the procedure is as follows, it being
recalled that it has been assumed that the
train is in motion. The engineman restores his
master switch to its No. 1 position and depresses
the push button PB. Operation of the push but—
5 ton PB causes the locomotive equipment to con
tinuously supply to the track rails the code sig_
naling current, but with “wobbled” frequency.
required and he would operate his brake Valve
accordingly.
telephone conversation, he would ’ release his
master switch MS and depress the push button
PB to close contact H3 and operate relay HI,
the operation of which relay causes the caboose
equipment to supply to the rails code signaling 10
current periodically varied in frequency from
the channel frequency, the connection of oscil
later 08! to the ampli?er PA being completed
at contact 525 of push button PB. During the
?rst pause in the engineman’s conversation the 15
locomotive relay VB, is released and the asso
ciated relay RS is picked up, with the result
that the locomotive receiving apparatus is made
effective through the medium of the front con
tacts 3R8 and @RS of relay RS and back contact 20
WE of relay VB, since switch MS is now at its
No. 2 position. The electromotive force in
duced in the locomotive coil'CC in response to
this code signaling current supplied to the rails
at the caboose is now applied to the locomotive 25
demodulator and demodulated and a note varied
30 relay RS is picked up over back contact l is of the
in pitch is sounded by the loud speaker. A por
tion of the received energy is supplied to the relay
l3 and the relay 73 is picked up to complete at its
front contact ‘M the circuit for the relay RS.
associated relay 16, back contact I20 of relay VR
and contact I24 of switch MS. Thus, the ca
boose equipment is, during the pause, momene
informs the engineman that the caboose train
man'desires to break in upon the conversation
On the ?rst pause in the trainman’s conversa
tion the caboose relay VB is released and the
Such an audible signal received on a locomotive
tarily switched to its code receiving condition by
virtue of the front contacts ‘IRS, BRS, and 9R8
of relay RS since the caboose master switch MS
to deliver a message and the engineman would
shift his master switch to its No. 3 position to re~
is now set at its No. 2 position.
to send.
This code sig
naling current of “wobbled” frequency induces
an electromotive force in the caboose coil CC, and
4.0 is applied to the demodulator DM since the relays
83, 84, and 85 are now all deenergized. The out
put of the caboose demodulator is now a current
of 1000 cycles periodically varied a few cycles
with the result that the note sounded by the loud
speaker is varied in pitch. Furthermore, the
relay 83 is picked up by a .portion of the output
of the demodulator and the caboose relay RS is
retained energized over the front contact Hi3
of relay 83 so that the caboose apparatus is
held at'its receiving condition as long; as this
current continues to appear in the track rails.
The trainman, upon receiving an audible signal,
varied in pitch, would shift his master switch to
its No. 3 position ready to receive any message
i . from the engineman. The engineman, after hav
ceive whatever message the trainman may wish
-
In the event the train is standing still and
telephone communication is effected, the motion
actuated devices render the relays RS ine?ective. 40
Although in the foregoing description I have
assumed definite channel frequencies and also
de?nite carrier frequencies for the telephone cur
rent, it will be understood that my invention is
not limited to these speci?c frequencies and they 45
may be selected as desired.
Although I have herein shown and described
only one form of apparatus embodying my inven
tion, it is understood that various changes and
modi?cations may be made therein within the
scope of the appended claims without depart
ing from the spirit and scope of my invention.
Having thus described my invention, what I
claim is:
1. In communication systems for railway 55.
ing depressed his push button PB for a reasonable
interval, would release the push button and oper
ate his master switch to its No. 2 position and
convey the message he desires to send.
In the event, during an interval when the train
including transmitting apparatus capable of sup
man is talking, an emergency should arise on
tion current as well as manually operable means
the locomotive that required an application of
the train brakes the engineman would operate
his brake valve to a brake applying position and
‘7 at the same time release the master switch MS.
Code signaling current of the channel frequency
is now continuously supplied to the track rails,
which current is picked up at the caboose on the
effective to render either the transmitting ap
paratus or the receiving apparatus active, motion
?rst pause in the trainman’s conversation in
' , the manner explained above, and a corresponding
note is sounded at the loud speaker and the relay
83 is retained energized. This note continues as
trains the combination comprising, a train-can -
ried equipment mounted on a vehicle of a train
plying a periodic communication current and re
ceiving apparatus responsive to such communica
responsive means mounted on the train and ef
fectively operated when the train is in motion, 65
and circuit means controlled by said motion re;
sponsive means to place at times the receiving ap
paratus in an active condition irrespective of said
manually operated means.
2. In communication systems for railway trains 70
the
combination
comprising,
a
train-carried
equipment mounted on a vehicle of a train in
cluding transmitting apparatus capable of sup
long as the brake valve on the locomotive is
retained at a brake applying position. An au
plying a periodic communication current and re
dible signal, steady in pitch, informs the train
ceiving apparatus responsive to such communica
8
2,111,647
tion current as well as manually operable means
effective to render either the transmitting appa
ratus or the receiving apparatus active, motion
responsive means mounted on the train and effec
tively operated when the train is in motion, and
circuit means controlled in part by said motion
responsive means to place the receiving means in
an active condition for an interval when said
manually operated means is set to render the
10 transmitting apparatus active.
3. In communication systems for railway trains
the
combination
comprising,
a
train-carried
receiving apparatus responsive to such communi
cation current as well as manually operable
means effective to render either the transmitting
apparatus or the receiving apparatus active, a re
lay, circuit means to connect a winding of the re
lay with the transmitting apparatus to energize
the relay with a portion of the outgoing com
munication current, motion responsive means
mounted on the train and effectively operated
when the train is in motion, means controlled 10
jointly by said relay and said motion responsive
means to periodically place the receiving appara
equipment mounted on a vehicle of a train in
tus in an active condition during an interruption
cluding transmitting apparatus capable of sup
in the outgoing communication current, and
means controlled by the receiving apparatus to 15
retain itself in the active condition and to estab
lish a signal when current is received during an
interruption of the outgoing communication cur
rentv
7. In communication systems for railway trains 20
the combination comprising, a train-carried
15 plying a periodic communication current and re
ceiving apparatus responsive to such communica—
tion current as well as manually operable means
effective to render either the transmitting appa
ratus or the receiving apparatus active, a relay,
20 circuit means to connect a winding of the relay
with the transmitting apparatus to energize the
relay with a portion of the outgoing communica
tion current, motion responsive means mounted
on the train and eiiectively operated when the
25 train is in motion, and means controlled jointly
by said relay and said motion responsive means to
place the receiving apparatus in an active condi
tion for an interval.
4. In communication systems for railway trains
30 the combination comprising, a train-carried
equipment mounted on a vehicle of a train in
cluding transmitting apparatus capable of sup
plying a periodic communication current and re
equipment mounted on a vehicle of a train in
cluding transmitting apparatus capable of sup
plying a code signaling current or a telephone
current and receiving apparatus responsive to 25
such code signaling and telephone currents as
well as manually operable means effective to place
the equipment in condition to send the telephone
current, a relay, circuit means to connect a wind
ing of the relay with the transmitting apparatus 30
to energize the relay with a portion of the outgo
ing telephone current, motion responsive means
ceiving apparatus responsive to such communica
mounted on the train and effectively operated
when the train is in motion, and means controlled
tion current as well as manually operable means
jointly by said relay and said motion responsive 35
effective to render either the transmitting appa
ratus or the receiving apparatus active, a relay,
circuit means to connect a winding of the relay
with the transmitting apparatus to energize the
40 relay with a portion of the outgoing communica
tion current, motion responsive means mounted
on the train and effectively operated when the
train is in motion, and means controlled jointly by
said relay and said motion responsive means to
45 periodically place the receiving apparatus in an
active condition during an interruption in the
outgoing communication current.
5. In communication systems for railway
trains the combination comprising, a train-car
50 ried equipment mounted on a vehicle of a train
including transmitting apparatus capable of sup
plying a periodic communication current and
receiving apparatus responsive to such commu
nication current as well as manually operable
55 means effective to render either the transmitting
apparatus or the receiving apparatus active, a
relay, circuit means to connect a winding of the
relay with the transmitting apparatus to energize
the relay with a portion of the outgoing com
60 munication current, motion responsive means
mounted on the train and effectively operated
when the train is in motion, means controlled
jointly by said relay and said motion responsive
means to periodically place the receiving ap
65 paratus in an active condition during an inter
ruption in the outgoing communication current,
and means controlled by the receiving apparatus
to retain itself in the active condition when cm‘
rent is received during an interruption of the out
'
70 going communication current.
6. In communication systems for railway
trains the combination comprising, a train-car
ried equipment mounted on a vehicle of a train in
cluding transmitting apparatus capable of sup
75 plying a periodic communication current and
means to place the receiving apparatus in a con~
dition to receive code signaling current during a
pause in the telephone conversation.
8. In communication systems for railway trains
the combination comprising, a train-carried 40
equipment mounted on a vehicle of a train in
cluding transmitting apparatus capable of sup
plying a code signaling current or a telephone cur
rent and receiving apparatus responsive to such
code signaling and telephone currents as well as 45
manually operable means e?ective to place the
equipment in condition to send the telephone cur
rent, means mounted on the train and including
an element which increases its electrical resist
ance when vibrated in response to the train in 50
motion, a relay having a control circuit includ
ing said element to deenergize the relay when the
train is in motion, and means controlled in part
by said relay to at times place the receiving ap
paratus in the condition to receive code signaling 55
current when the manually operated means is set
to place the equipment in a condition to transmit
telephone current.
9. In communication systems for railway trains
the combination comprising,
a
train-carried 60
equipment mounted on a vehicle of a train includ
ing transmitting apparatus capable of supplying
a code signaling current or a telephone current
and receiving apparatus responsive to such code
signaling and telephone currents as well as man
65
ually operable means effective to place the equip
ment in condition to send the telephone current,
means mounted on the train and including an ele
ment which increases its electrical resistance
when vibrated in response to the train in motion,
a relay having a control circuit including said
element to deenergize the relay when the train is
in motion, another relay, circuit means to connect
a winding of said other relay with the transmit~
75
9
2,111,647
ting apparatus to energize the relay during a
telephone conversation but which relay is deen
ergized during normal pauses in the telephone
conversation, and means controlled jointly by said
two relays when both relays are deenergized to
render the receiving apparatus e?ective to receive
code signaling current.
10. In communication systems for railway
trains utilizing the same carrier frequency for
10 transmission in both directions the combination
comprising, two train-carried equipments one at
each of two spaced locations on a train and each
equipment including transmitting apparatus
and receiving apparatus, each transmitting ap
lo paratus including an oscillator to generate cur
rent of said carrier frequency and a power am
pli?er having a ?lter adjusted to- pass said car
rier frequency interposed in its output circuit,
each receiving apparatus including a demodula
tor having a ?lter adjusted to pass the carrier
each receiving apparatus including a demodu
lator having a ?lter adjusted to pass the carrier
frequency interposed in its input circuit and a
signaling device responsive to a given audio fre
quency interposed in its output circuit as well as
an oscillator to generate a carrier frequency
which di?ers from the transmitted carrier fre
quency by said audio frequency for mixing with
the transmitted carrier, means partly at each
location to cause said equipments to exchange 10
impulses of current for signaling between the
two locations; a first set of condensers at each lo
cation associated with the transmitting oscilla
tor, a second set of condensers at each location
associated with the power ampli?er ?lter, a third
set of condensers at each location associated with
the demodulator ?lter, a fourth set of condensers
at each location associated with the receiving os
cillator; and a selector switch at each location to
selectively control the ?rst, second, third and 20
frequency interposed in its input circuit and a
signaling device responsive to a given audio fre
fourth sets of condensers to‘select any one of
everal different carrier frequencies for the com
quency interposed in its output circuit as well
as an oscillator to generate a carrier frequency
which differs from the transmitted carrier fre
quency by said audio frequency for mixing with
the transmitted carrier, means partly at each
location to cause said equipments ‘to exchange
impulses of current for signaling between the
two locations; and a selector switch at each lo
cation having a ?rst circuit member associated
with the transmitting‘ oscillator, a second cir
cuit member associated with the power ampli?er
munication system of the train.
12. In communication systems for railway
trains the combination comprising, two train 25
?lter, a third and a fourth circuit member asso
35 ciated with the demodulator ?lter'and a ?fth,
circuit member associated with the receiving os
cillator, and said switches each capable of being
, set at any one of several different positions to
adjust the two equipments of a train to operate
40 on any one of several different carrier frequen
cies.
11. In communication systems" for railway
trains utilizing the same carrier frequency for
transmission in both directions the combination
45 comprising, two train-carried equipments one at
each of two spaced locations on a train and each
carried equipments one at each of two spaced lo
cations on a train, each equipment including
transmitting apparatus and receiving apparatus,
each transmitting apparatus capable of supply—
ing a code signaling current of a ?rst or a second
frequency as well as a telephone current, each
receiving apparatus selectively responsive to code
signaling current of said ?rst and second fre—
quencies as well as to the telephone current to
produce a ?rst or a second signal as well as the
telephonemessage, a relay at each of said loca
tions, circuit means for each relay to connect a
winding of the relay with the associated trans
mitting apparatus to energize the relay with a
portion of the outgoing telephone current, means 40
controlled by each relay to place at times the as
sociated receiving apparatus in a condition to re
ceive code signaling'current, and manually oper
able means at each location and each e?ective to
cause the associated transmitting apparatus to 45
equipment including transmitting apparatus
and receiving apparatus, each transmitting ap
supply code signaling current of either said ?rst
frequency or said second frequency whereby the
receiving apparatus at either location is ren
paratus including an oscillator to generate cur
dered active to establish either said first or said
rent of said carrier frequency and a power am- ' second signal during a pause in the sending ‘of
plifler having a ?lter adjusted to pass said car
rier frequency interposed in its output circuit,
30V
a telephone current from the same location.
'
ANDREW J. SORENSEN.
50
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