US1479516A

US1479516A - Signaling by high-frequency waves

Info

Publication number: US1479516A
Authority: US
Publication date: 1924-01-01
Anticipated expiration: 1941-01-01

Description

Jan. 1, 1924 7 1,479,516 I E. 0. SCRIVEN SIGNALING BY HIGH FREQUENCY WAVES Filed Sept. 29, 1919 3 Sheets-Sheet 1 F/gi.

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Patented Jan. 1, 1 324.

lglldlt UNETED STAT ES PATENT Ol FlfiE.

EDVARD O. SCRIVEN, OF NEW YORK, N. Y., ASSIGNOR TO 'WE STERN ELECTRIC COLL PANY, INCORPORATED, OF NEW YORK, N. 'Y., ACGRPORATION OF NEW YORK.

SIGNALING BY HIGH-FREQUENCY waves.

Application filed September 29, 1919. Serial No. 327,038.

To (ZZZ whom it may concern:

Be it known that I, EDWARD O. SCRIVEN, a citizen of the United States,residing at New York, in the county of New York, State of 6 New York, have invented certain new and useful Improvements in Signaling by High- Frequency Waves, of which the following is a full, clear, concise, and exact description.

The present invention relates to the transmission and control of current waves for signaling or other purposes. The invention relates also to multiplex transmission of the type employing current waves of different frequencies each of which waves is controlled in accordance with signals or other impulses to be transmitted.

A feature of the invention lies in an improved modulating arrangement. Another feature lies in providing a centralized source of high frequency waves and method and means whereby waves from said source are controlled to effect multiplex transmission in both directions over a line or similar system.

In systems heretofore used it has been customary to impress a high frequency wave and low frequency signaling currents separately upon a control device or modulator,

and in another circuit suitably associated with the modulator to derive the combina- 39 tion frequencies. The only high frequency waves impressed on the line or-transmission circuit in the process of transmission were those transmitted through the modulator itself. I

In the present invention the same circuit which impresses the high frequency currents upon the modulator may serve to convey the modulated currents to the line or common transmission circuit, and it is not necessary, therefore, to provide a source of high frequency Waves from a separate high frequency circuit for each modulator dis tinct from the circuit for carrying the 1110Cl1llated waves. The high frequencies are impressed froin the generatingsources upon the line or common transmission circuit, and each modulator derives its supply of high frequency from the line or common trans mission circuit and feeds back through the same circuit the modulated current when the signaling currents are also impressed upon the modulator. By associating the high frequency sources with the line or common transmission circuit instead of with the separate modulators the present invention makespossible the use of centralized sources of high frequency waves for supplying a number of modulators. These wave sources may be located at some convenient point on the line and at a distance, if desired, from the transmitting sets to which they supply energy.

Other features and objects of the invention will appear from the following description together with the accompanying drawings, of which Figs. 1 and 2, when placed side by side, illustrate diagrammatically a complete two-channel high frequency telephone system, and Fig. 3 shows modified arrangement.

Referring first to Figs. 1 and 2, the main line 1 is shown as terminating at two stations, one of which has transmittingsets T and T and receiving sets R and 3,, and the other of'which has sets R and R and T and T cooperating respectively with the transmitting and receiving sets of the first station. For enabling simultaneous twoway communication, the line 1 is provided with the usual conjugate coils i and 5 and harmonics from the base frequency wave from source 6. The distorted and amplified wave from the relay 9 is transmi ted through the coupling 10 and impressed upon the amplifier 11, the output circuit of which includesthe resonant circuits 12 and 13. In the case of a system employing more than two communication channels, additional circuits similar to 12 and 13 would be provided forderiving still other harmonics from the base frequency wave. Individual amplifiers 14: and 15 are provided for the harmonic waves which are selected by the circuits 12 and 13 respectively. I

Coupled to the amplifiers 1d and 15 are the coils l6 and 17 which are included serially with a coil 1.8 coupled to the coil 7in the circuit of source 6 and the circuit including coils 16, 17 and 18 is finally connected across he terminals of the output lin winding Between the coil 18 and tne remainder of the circuit there is inserted a filter 19 so proportioned as to transmit only the base frequency current from the source 6, and to prevent frequencies impressed upon coils 16 and 17 from reacting on the circuit of source 6. There are, therefore, waves of three different frequencies simultaneously impressed upon the main line 1, one of which waves is the wave directly transmitted from the source 6 and the other two of which have frequencies which are harmonics of the base frequency. Also connected across the terminals of the input coil of the line coupling 1, are

filters

20 and 21. The filter 20 is designed to admit to the coil 22 a band of frequencies sufiicient in breadth to include one of the high frequency waves iii-pressed on the input coil 1, together with the side bands of frequencies which result from inodulating said wave in accordance with speech. For the particulars relating to the design and construction of'such a filter reference may be had to the patent to G. A. Campbell No. 1,227,113, issued May 22, 191?. This ilter prevents currents of all other frequencies from reaching the coil 22 on account of the hi 'hly attenuating which it possesses for foreign freouencies. @ne of the high frequency waves w impressed on the main line 1 fro fiers 1 1 or 15 is therefore transm c t coil 22 by the filter 20, and virtue 0 coupling with the coil 23 sets up corr spo ing voltages across the terminals of coil The latter coil is included in the outp L plate circuit of the modulator M, which also 2 1 and the plate or anode 25. Due to the potential variations induced in the coil23, th re will be a circuit of the modulator M the magnitude of which current will depend upon the im pedance of this circuit. Practically the whole of this impedance lies in the modulator tube itself, and this ii pedance, in turn, depends upon the potential. of the grid 26 which is determined by voice currents in the circuit 27 due to speech waves directed against the microphone 28. By speaking into the microphone 28, which forms a part of the transmitting set T varia l of the frequency of the wave admitted by the filter 20 from the main line 1 will be setup in the 'output coil 23 and will be impressed through the filter 20 upon the line 1. The action of the modulator M, is apparently the same as though the high frequency waves were impressed upon the plate circuit through a separate coupling, but by virtue of the present arrangen'ient no such s parate coupling is needed, and, sta ed, the high and 1), respectively.

current flow in the output frequency may be derived from the transmission line itself.

The transmitting set T differs from that just described only in the frequency ofthe wave whichis employed for transmission; that is, the Illtfil' 21 is so proportioned as to transmit a different high frequency voice modulated wave. The modulated high frequency waves from the modulators M and M are, therefore, impressed through the ling 4 upon the main line 1 and are transmitted to the distant station indicated in Fig. 2. Bridged across the line at this station is the coil 30 to which are coupler filters 31, 32 and which are or may be identical respectively with the

filters

19, 20 and 21, shown at the transmitting station. Frequencies from the transmitting sets impressed upon the coil 30 are, therefore, selectively transmitted by the filters 32 and 33, associated with which are the detectors D, These serve to detect the speech component of the modulated waves and render the waves receivable respectively in the telephone receivers 3 1- and The

lil sis

20, 21, 31, 32, 33, F and F, are each composed of a plurality of sections. The end s ctions of

filters

20 and 21, which are adjacent to the common line 1, are con nected together in series with respectto line. These end sections form paths of low inipedance to currents of all frequencies except those which the filter is designed to pass. Similarly the end sections of filters 31, 32 and 33 as a group and those of filters 1 ant T as a group are connected together in As already stated, the source 6 supplies energy for all of the high frequency waves used to transmit in both directions through the system being described. For transmitting in the direction opposite to that above described, two waves, which may or may not have the same frequencies as those employed by the transmitters T and T are derived from the same source 6. The wave of base frequency transmitted over the line is selectively transmitted through the filter 31, as described, and is impressed upon the distorting relay 36 for the purpose of producing harmonics. Coupled to the distorting relay 36 is an amplifier 37 containing in its output circuit the resonant circuits 12' and 13 respectively. and these are coupled to the separate amplifiers 38 and 39, which supply the amplified currents of harmonic frequencies through the coils e0 and all to the output line coil 5. The transmitting sets T and T, are associated through the respective modulators M and M and the band filters F, and F, with the main line in asimilar manner to that described in connection with the transmitting sets T and T6, the same harmonics are employed (ill for transmission in both directions, the lilters F and F, may be identical with the filters and 21. from the transmittingsets T and T, are impressed upon the main line 1, and are re ceived at the station, shown in Fig; 1, where they-are separated by the filters F and IQ to be separately received. The detectors D and D render the wave receivable in the receivers shown for the receiving sets R and R respectively. i I

By virtue of the conjugate arrangements of the coils 4 and 5 and corresponding nets 2 and 3, the modulated waves produced in each station are prevented from affecting the receiving sets located in the same station, according to standard practice. Referring now to Fig. 3, there is shown a main line 42 which may be provided with

branches

48 and 49, as may be desired. The main line is shown as provided with con jugate coils 4-3 and'net-work 44c and the branches may be similarly provided. At some convenient point on the main line 42, for instance in a central station, maybe located the wave sources 45, i6 and 4: having frequencies f, f and j, which sources may be separated or may, be related in some such way, as described in connection with the other figures. These sources supply waves of their respective frequenc'es to the main line 42, which waves are made available for all of the transmitting sets located upon the line. A part of the energy of each wave will find its way into the transmitting and receiving side of the station shown at the left of the line. matically indicated as F, F and F serve to convey to the respective modulators the waves that are to be utilized by the trans mitting sets, three of which are indicated. Modulated high frequency currents from these modulators M, M and M are in turn impressed through the coils upon themain line 42, and may be received at such of the distant stations indicated on the respective branches l8 and 49 as are adapted. to receive and detect it. The balanced relation between the transmitting and receiving sides of each station, however, will prevent the,

modulation component, resulting from the interaction of each high frequency ,wave with the signaling currents, from reaching the receiving side of the same station. Modulated waves impressed upon the line at another station, however, will, in the usual manner, be impressed through. the filters 1*, F and F upon the detectors ;D, D and D and will be received in the respective receivers.

While the invention has been illustrated and described with reference to a particular The modulated waves The band filters diagrannimoressin on said line a luralitv of hi h- J. 2: t b

frequency waves of different frequencies,

and means for modulating each of said waves in accordance with signals to be transmitted over said line, the modulating means for each of said waves comprising a modulator, a band filter for diverting one of said waves from the line to said modulator, a coupling for impressing said wave upon said modulator, a circuit for also impressing signaling current on said modulator to modulate said high-frequency wave, said coupling and selective circuit serving also to impress the modulated wave upon said line.

2. In a signaling system, a line, a source of high-frequency waves supplying waves to said line, and means for impressing signal-modulated high-frequency waves upon said line, said means comprising a modulator having an input circuit for signaling current and an output circuit both for the high-frequency waves to be modulated and for'the high-frequency waves modulated in accordance with said signaling current, a band filter connected between said output circuit and said line, whereby said high frequency waves are applied to said output circuit from said line through the medium of said band filter.

3. Ina signaling system, a line, a source of high-frequency waves for supplying current thereto, a modulator for controlling said waves in accordance with signals, means to connect said source of waves to said line, and a band filter connected between said means and said modulator for transmitting selectively said waves to said modulater and the signal-modulated wave from said modulator to said line.

4c- In a telephone system, a line, a source of sustained high-frequency waves for supplying current to said line, a modulator having meanswhereby speech variations may be impressed thereon for modulating said high-frequency waves, means to connect said at a station, and conjugate connections for making the receiving branch neutral as to current impressed from the transmitting branch, sources of high frequency waves for supplying current to said line, modulators associated with said transmittting branch accordance with signals, and plurality of sectional band-pass filters connected between said modulators and said line, the end sections of said band-pass filters being connected in series with each other.

7. in a telephone system, a line, aplurality of sources of sustained high-frequency waves for supplying current to said line, a plurality of modulators having means whereby speech variations ma be impressed thereon for modulating a high-rreqency wave, and a plurality of sectional band-pass filters between said modulators and said line, the end sections of said'band-pass filters being connected in series with each other.

8. In asignaling system, a line, a plurality of sources of high-frequency waves ior suppl ing current to said line, a plurality of modulators "for controlling said waves in accordance with signals, and a plurality of sectional band-pass filters, one of said filters being connected between said line and each modulator for transmitting selectively a high-frequency wave to said modulator and nal modulated wave from said modulator to said line, the end sections adjacent to said line or all of said filters being connected in series with each other.

9. In a telephone system, a line, a source of sustained high-frequency waves for supplying current to said line, a modulator having means whereby speech variations may be impressed thereon for modulating a high frequency rave, and a plurality of sectional band-pass filters, one filter being connected between each modulator and said line for impressing a high-frequency wave upon said modulator to be modulated in accordance with, speech and for transmitting the speech modulated wave from said modulator to said line, the end sections of said filters adjacent id line being connected in series with l0 SZlrxL each other.

10. A high frequency wave signaling system comprising a line having stations, a plurality of transmitting and a plurality of receiving branches for said line at said station and conjugate connections for making the receiving branches neutral as to current impressed from the transmitting branches, a plurality of sources of high-frequency wayes for supplying current to said line, a modulator associated with each of said transmitting branches and controlled by signals, a sectionalband-pass filter between each modulator and said line adapted both for impressing said waves upon the respective modulators and for transmitting the resultant modulate-d waves from said modulator to said line, the end sections of said filters adjacent to said line being connected in se ries with each other, and receivers at another station for the waves so modulated.

11. A high-frequency wave signaling system comprising a line having stations, a plurality of transmitting and a plurality of receiving branches for said line at a station and means to connect said transmitting and receiving branches to said line, a plurality of sources of high-frequency waves for supplying current to said line, a modulator associated with each transmitting branch and controlled by signals, a sectional bandpass filter connected between said modulator and said line adapted both for impressing said waves upon the connected modulator and for transmitting the resultant modulated waves from the connected modulator to the line, means to connect the end sections of said filters adjacent to said line in series with each other, and receivers at another station for the waves so modulated 12. In a multiplex signaling system, a

plurality of sources of high-frequency waves, a plurality of means to modulate said high-frequency waves in accordance with signals, a common transmission circuit, and a band-pass filter connected between each modulating means and said transmission circuit comprising a plurality of sections, the end sections being connected in series with each other.

13.111 a multiplex signahig system, a plurality of sources of high-frequency Waves, plurality of means to modulate said high-frequency waves in accordance with signals, a common transmission circuit, a sectional band-pass filter connected between each modulating means and said transmission circuit, and means to connect the end sections adjacent to said transmission circuit in series with each other.

14-. In a multiplex signaling system, a. plurality of sources 0t high-frequency waves, a plurality of thermionic vacuum tubes each having an. anode, a cathode and an impedance controlling element or grid, a source of signaling current, means to sup ply said high-frequency current and said signaling current simultaneously to said vacuum tubes to produce high-frequency current modulated in accordance with signaling current, a common transmission circuit, a sectional band-pass filter connected between each vacuum tube modulator and said transmission circuit, and means to conmet the end sections nearest said transmis sion circuit together in series.

15. A common transmission circuit, a plurality of channels associated therewith, means for transferring currents of a given range of frequencies between one of said channels and said circuit and currents of a different range of frequencies between each of the other channels and said circuit comprising a band filter connecting each channel to said circuit and having a transmission range such that itfreely passes currents of the range of frequencies supplied from the associated channel, said band filters having ter inations connected in series in said circuit, the termination of each filter ofi'ering low impedance to currents Within the frequency transmission range of the other filters.

16. A common transmission path, a plurality of channels each adapted to transmit currents of differ nt frequency from those transmitted by the other channels, and a separate band filter connecting each channel to said path, the terminations of said filters electrically adjacent said path being connected in series.

17. In a modulating circuit, an electric discharge modulator tube having an anode, a cathode and a grid or impedance control element, a circuit for impressing signal variations across the grid and cathode of said tube, a source of waves to be modulated, a circuit for impressing Waves from said source across the anode and cathode of said tube, a band filter included in said latter circuit having a selective transmission range such as to include the frequencies of the Waves to be modulated and at least a portion of the resulting signal-modulated components, and an outgoing circuit for the modulated Wave connected to said modulator tube through said filter.

18. In a modulating circuit, an electric dischargetube modulator having an anode, a cathode and a grid or impedance control element, means to impress speech variations across the cathode and grid, a source of Waves to be modulated, a band filter having a selective frequency transmission range such as to include the frequency of the Wave from said source and at least a portion of the frequency components of the resultantmodulated Wave, but excluding speech frequencies, a circuit including said band fil e: for impressing Waves from said source across the anode and cathode of said tube, and an outgoing circuit for the modulated Wave connected to said modulator through said filter.

In Witness whereof, I hereunto subscribe my name this 26th day of September EDWARD o. SCRIVEN.