US 1968106 A
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y 1934- D. THIERBACH 1,968,106
TRANSMISSION SYSTEM Filed Feb. 4, 1932 INVENTOR DIETWALD THIE'RBACH WWW ATTORNEY Patented July 31, 1934 UNITED- sat-Ares I TRANSMISSION SYSTEM Dietwald Thierbach Berlin-Spandau, Germany, assignorto Siemens & Halske, Aktiengesellschaft, Siemensstadt, near Berlin, Germany, a corporation. of Germany Application February 4-, 1932, Serial N0. 590,976
- Germany February 19., I931.
'7. enl sts; (or 25.0 m
The 'invention is concerned-with a. method: to control the: transmission measure by the aid or a control frequency; and the same distinguishes itself from methods known the. prior artin that the control action is enacted by altering thefrequency of thecontrolling current.
In the operation of regeneration looks" or blocks it has been customary in the prior art to block transmission in one directionin the presence of the: control frequency, and to block transmission:
in the other direction upon the failure or absence of this control frequency. According to the meth- 0d of the present invention t'rafiic inone direction is blocked by one control frequency, and traffic in the other direction by another control frequency; Theconnection or switching and rendering operative of. the various control frequenciesisinsured in this scheme by the signal currents by art. 7 I
The inventionwill be found'particularIy ad vantageous if inaddition to the regeneration block also a regulation of the volume level is to be secured. By the use of two comparatively adjacent frequencies it is: possible to effect: both these regulative actions. The volume regulator: and stabilizer means would in this case have to-be so designed that they will respond to both: frequencies' Inasmuchas a control frequency ispresent all the time thismeans'thata continualregulation of volume level is insured. If the two frequencies are located close, enough together, for example, say about. 100 cycles per second apart, then fluctuations in the intensity of the: energy transmission over the distance: covered,- say, by radio will affect both frequencies in likemanner so that'a change of-the frequencyused for volume control and regulation will not-be at-- tended by any inconvenience The regeneration blocks should be so designed that they will be able to distinguish between or respond selectively tothe frequencies so that one or the other or the: two transmission paths will be opened or cleared depending upon the frequency of the control-current, that is, which control current isoperative;
Designing the regeneration blocking means in such a manner that in the presence of' both no: quencies of about like amplitude simultaneously nochange in thesense' of" transmission is'produ'ced, this meansthat a rather thorough insenways and means well-known in Y the sitiv'eness of the arrangement to disturbing o;
methods: known in. the prior art which utilize but one control frequency, do: notv offer this chance of obtaininga compensation of atmospherics: or similar disturbances v The invention shall be explained in. more detail by reference toa. practical; embodiment given. by way of example. The drawing showsa trans.- m-iss'ion: system. wherein. the control frequencies used for the actuation of the regeneration. blocks are used atthe' same time for controlling or. stabilizing the level of the volume, Double conductors arev represented by single line,
The: merit residing. irrthe circuit scheme illustrated'. primarily consists in. that the operation of the blocking meansfor the two directions are perfectly similar inasmuch as. a definite frequency is: provided. for: each direction of transmission. In. the. circuit arrangements heretofore. used; owing to the presence of the control frequency, one direction of traffic was blocked and the other one cleared; in other-words, the two blocks were actuated in contrary directions.
1 The subscribers'T and T are united. by radio; S and E', respectively, denote the radio; transmitters and receivers; The receiving means are connected with the regulating amplifiersRV whose transmission. measure or'amplification characteristic is regulated by the rectifiers G14. The rectifier-s: G14 respond to the: control frequencies.- transmitted'; according to the invention. The-fil ter- K3 is broad: enough to pass both of the con.- trolling frequencies, which, as indicated above, are separated by a relatively small difference frequency; as,. for example, 100*- cycles per second,. whereas the filterKe. also connected with RV does: not. permit these frequencies to: reach the subscribersconnections r1, T. To actuate the. regeneration: blocks two'rectifiers G11 and G12: are connectedfby way of. the. filters K1 and K2 respectively to RV by way 'of'Ks, as shown. The reversing of the subscribers linesgjthat is, the changing from and to the transmitter and; receiver means, respectively, is effected by the agency of a relay R1 which is'provided with twoopposed windings which are associated with the rectifiers. G1 1 and G121 respectively. a
At the transmittingend there are two gener-. ator's GIand'G2 provided to supply the control frequencies; 'The changing-over of the generators is effected by way-of the keeper T2 of relay R32. This latter relay is united with the subscribers' line by way of the rectifier G13.
In the state of inoperation' of the communication equipment in which the relays occupy positions as shown'in the drawing, the subscribers ofiices are connected with the corresponding transmitter means; hence,'regeneration is not possible. The frequency furnished from the generator G2, in a way well-known in the art, serves for fading regulation (compensation). This frequency is fed from the aerial to the receiver E and from E through the regulating amplifier RV, through the filter chain K3 and the rectifier G14 and back to RV to regulate the same against fading.
The filter chains K1 and K2 are so dimensioned that the frequency of the generator G2 will be transmitted only by the filter chains K2. Through the intermediary of the rectifier G12 the action of this wave is so that the relay R1 holds its keeper in the position as illustrated. When the subscriber T is sending out a communication the signal currents will cause the relay R2 to respond by Way of the rectifier G13. The generator G2 is switched off, while the generator G1 is connected with the transmitter. The frequency of the generator G1 is fed by way of the filter K3 for the regulation or compensation of the fading effects to the rectifier G14, and by i way of the filter chain K1 to the rectifier G11 which energizes one of the windings of the relay R1, so that the keeper 1" is thrown over with the result that subscriber T is connected with the receiver E.
Now, if disturbing potentials happen to reach the receiver the risk of faulty operation of the regeneration block is very slight. For if these disturbing potentials happen to fall inside the region of the control frequency they will normally be contained in both frequencies to approximately the same amplitude. The disturbing potentials will thus actuate both rectifiers G11 and G12. Since the currents furnished from the rectifiers are brought to act upon the relay R1 in opposite senses, these troublesome potentials will fail to release an action.
In case of a communication proceeding from the subscriber T to the subscriber T, similar circuit changes will occur in the transmission arrangement of the subscriber T and in the receiver arrangement of the subscriber T.
Instead of using two generators for the production of the two control frequencies, it would be feasible also to employ but one generator to which a condenser is connected in parallel for the object of insuring changes in wave-length. The mechanical relays shown in the exemplified scheme of the drawing, as will be evident to the expert, could be replaced also by thermionic tubes.
The application of the basic idea of this invention of using two frequencies for the control of the transmission measure affords certain advantages for the reasons as above set forth (atmospherics compensation) if distinct level regulation is dispensed with or if this is replaced by another regulation.
1. A duplex signalling system, each end of which includes a transmitting means, receiving means, a subscribers line, a first switch connected thereto, a plurality of control frequency generators at each transmitter, switching means for alternately connecting said control frequency generators to said transmitter, a balanced relay at each receiver, said relay being opcratively related to said first switch, a contact adjacent said first switch connected to said transmitter, said contact being normally closed, a contact adjacent said first switch connected to said receiver, said contact being normally open, and filter means interposed between said receiver and said relay whereby when one control frequency is transmitted said subscribers line is connected by said first switch to said transmitter, and when another control frequency is transmitted said subscribers line is switched to said receiver.
2 An arrangement as claimed in claim 1 in which said control frequency generators operate at different frequencies and in which the position of said switching means for alternately connecting said control frequency generators determines which control frequency generator is connected to said transmitter.
3. A duplexing system comprising, two or more stations, each including a transmitter and a subscribers line, a pair of control frequency generators, switching means normally connecting one of said control frequency generators to said transmitter, a second switching means normally connecting said subscribers line to said transmitter, a relay associated with said first named.
receiver at each of said stations disconnected from said subscribers line, each of said receivingmeans also including a second filter connected with said receiver and with said relay andresponsive to the frequency transmitted when said other control frequency generator is connected with said transmitter of said other station to energize said relays to move said second switch in a position to connect said receiver to said subscribers line when signal frequencies are im- 1 pressed from the subscribers line at the. other station on the transmitter.
4;. A duplexing system as claimed in claim,3 in which each of said receivers includes automatic volume control means actuated by either of said control frequencies. I
5. A duplexing system as recited in claim 3 in which said control frequency generators generate frequencies separated by a narrow band of frequencies, and in which said receivers each in clude a filter tuned broad enough to pass the frequencies of both of said control frequency generators, and automatic volume control means connected with said filter and with said receivers.
6. A duplexing system comprising stations in cluding, a transmitter and a receiver, a sub-- scribers line normally connected with said transmitter, a pair of oscillation generators generating frequencies which differ by approximately- 100 cycles per second, a relay in said receiver responsive to one of said control frequencies for maintaining said transmitter normally connected to said subscribers line, and means in said relay responsive to the other of said control frequenl1 cies for disconnecting said transmitter from said subscribers line and connecting said receiver to said subscribers'line."
7. A duplexing system as recited in claim in which each of said receivers includes an automatic volume control means responsivev to either of said control frequencies.