SIGNALLING SYSTEM

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-00120R000100010007-9
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 8
• Document Creation Date: December 22, 2016
• Document Release Date: December 8, 2003
• Sequence Number: 7
• Content Type: CONT

Approved For Release 2009/04/10 :CIA-RDP81-001208000100010007-9
June 16, 1964
Filed Nov. 4, 1959
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Approved For Release 2009/04/10 :CIA-RDP81-001208000100010007-9
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Approved For Release 2009/04/10 :CIA-RDP81-001208000100010007-9
 Approved For Release 2009/04/10 :CIA-RDP81-001208000100010007-9
R. A. KLEIST
.SIGNALLING SYSTEM
3,137,847
Filed Nova-4,.1959 .. 3 Sheets-Sheet 3
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June 16, 1964
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Approved For Release 2009/04/10 :CIA-RDP81-001208000100010007-9
 Approved For Release 2009/04/10 :CIA-RDP81-001208000100010007-9
SIGNALLING SYSTEM ~ eAUCiuc~y auvtui~rbcvua uvut ~tauupwuts ur rena~ru[y
Robert A. Kleist, Sunnyvale, Calif., assignor to Link Avla- and noise-rejection, partly because they utilize response
Hon, Ina, 13ingirarntoo, N.Y., n corporation of New carriers which differ in frequency from the interrogator
_York 6 carriers needed to produce ilrem. It should be noted,
tion. Although the transmission of the sub-carvers on .
This invention relates to signalling systems and is a the interrogator carrier (f:om the interrogator to a re- -
continuation of and improvement to inventions shown in IO spender) and back oa the response carrier (from the
earlier coper:ding applications of Clarence S. Jones, Serial responder to the interrogator) may result in all of the
No. 7IS,S99, filed February 18, 1958, and Serial No. subcarricrs being changccl in amplitude, and further result
739,909, filed June 4, 1958, now U.S. Patent No. 3,054,- in one or more of the sulz-carriers being completcly elimi.
100
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ssue
eptember 11, 1962, both of which are as- noted from the response carrier, the ghase of each of the
signed to the same assignee as the present invention. I5 sub-carriers is controlled at the interrogator, where each
These prior applications disclose signalling systems ca- sub-carrier is .generated. Since the phase of the sub-
paLle of electronically transmitting data between an inter- carriers en the response carrier is controlled. at the inter-
rogator device and one. ar more passive responder devices, rogator, a phase comparison may be made between the
where the two devices are capable of relative motion with phases of response sub-carriers and interrogator sub-
- respect to each other,- so that signals may be provided 20 carriers, and any resporse sub-carrier modulation deter-
from the responder which uniquely rdentify the responder, mined not to have originated at the interrogator may be
and, or instead, if desired, indicate one or more condi- rejected as noise, thereby enhancing the sensitivity, accu-
tions associated with the responder. One exemplary dis- racy and reliability of the system.
closed application of the above-mentioned previous inven- Thus it is a primary abject of the present invention to
tions is the use of responder devices on vehicles, such as 25 provide an improved signalling system of the character
railroad box cars, for the purpose of identifying each vehi- described which is Iess susceptible to noise.
cle as it passes 2long a track beside which an interrogator It is another abject of tl;e invention to provide an im-
unit is located. The responder devices shown in those proved signalling system of the character described which
previous systems arc small and inexpensive, and being may utilize an inexpensive and simple low-pass filter in
passive, no wired power sources or batteries are needed. 30 lieu of band-pass filters heretofore used.
Due to a number of reasons considered in detail in the It is a further object of the invention to provide an
previous applications, those systems era more accurate improved low-noise signalling system of the character de-
and reliable and. less susceptible to noise than prier art scribed wherein aeupliEcation may be effected principally
systems. The present invention is an improvement over et lower subcarrier frequencies, so that transistorization
those prior inventions in that it provides systems of even 35 may be more readily effected.
greater accuracy and reliability which are even further less It is yet another abject of the invention to provide an
susceptible to noise. Any system which is more immm~e improved responder devise for use in signalling systems
?rom noise than another system may be designed to use of the character described, in which clipping and cross-
less power ar bandwidth while still providing equal ac- modulation of subcarrier modulation frequencies does not
curacy. 40 occur.
1n my prior s;+stems the interrogator units supply one Other objects of the invention will in part be obvious
or more electromagnetic signals .having one or more fre- and will in part appear hereinafter.
quencies to power-inducing coils, which may be mounted The invention accordi rgly comprises the features of
below or alongside the track, for example, in the case of construction, combinations of elements, and arrangement
a railroad idcntificatian application, so that power is in- 45 of parts, which will Lc, e;semplified in the constructions
duced info tuned circuits of various responder units as hereinafter set faith, and the scope of the invention will
box cars carrying the responder units pass along the track. be indicated in the claims.
The .power induced into the responders is u:x,d to develop For a fuller understanding of the nature and objects-
and provide response signals, which may ba received by of t^.a invention reference should be had to the following
a receiver and de-coded to provide data identifying the 50 detailed description taken in connection with the accom-
respander uni?s. Each responder unit may be arra;iged ponying drawings, in whiclt?
to provide response sio als of a different orunique-nature. FIG. 1 is an electrical schematic block diagram of an
In application Ser. No. 739,909, now Patent 1\To. 3,054,? exemplary embodiment of the invention, wherein acon-
100, there is shown a system of the above-described gen- trot sub-carrier received in the response signal is compared
eral type in which an interrogator unit supplies to its 55 with a reference sub-carrier supplied from the transmitter
power-inducing coil apparatus, a high frequency carrier unit to derive a central signal which phase-locks the re-
paving a phrrality of sub-carriers modulated. on it. A ceiver to tl'ae response carrier;
responder, when it is located within the effective field of FIG. 2 is an. electrical seliematic diagram of an exem-.
the. carrier, such as when a boxcar carrying a responder glary responder unit utilized in the prior art and zlso with
passes near a stationary interrogator, operates to demod- 60 some embodiments of the present invention?
Mate the l;igta-frequency interrogator carrier to provide FIG. 3 is an electrical schematic block diagram of an
power to operat;; an oscillator in the responder, thereby alternative embodiment of the invention, wherein sub-
to provide a response carrier. Each responder also op- carrier modulation in the side-bands of the re;iaonse car-
? e* s upon tine subcarricrs received, and selectively fitters riar sio*?:al provides a control signal which phase-lacks the
out or selectively preserves certain of the subcarricrs to 65 receiver to the response carrier;
provide a different group of sub-carriers, which are used FIG. 4 is an eiectric:il schematic block dia;rsm of a
to modulate the response carrier, thereby providing sub-~ further alternative embodiment of the invzrrtion wherein
carrier modulation on tl;e response carrier from each the response carrier oscillator in each responder is caused
responder which is unique to the particular responder.- to lock in phasa?with a master carrier frequency from the
By demodulating the response carrier and determining 70 transmitter, and tho response carrier signal receivel at
which sup-carriers are present or which ure absent, the the receiver is prase-dFtected by a synchronous detector
identity of the responder may be detcrmiried. ' responsive as well to the master frequency;
Approved For Release 2009/04/10 :CIA-RDP81-001208000100010007-9
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