US2270385A - Multicarrier transmission system - Google Patents

Multicarrier transmission system Download PDF

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Publication number
US2270385A
US2270385A US298331A US29833139A US2270385A US 2270385 A US2270385 A US 2270385A US 298331 A US298331 A US 298331A US 29833139 A US29833139 A US 29833139A US 2270385 A US2270385 A US 2270385A
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modulators
band
frequency
frequencies
transmission system
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US298331A
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Skillman Thomas Samuel
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Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J1/00Frequency-division multiplex systems
    • H04J1/02Details
    • H04J1/12Arrangements for reducing cross-talk between channels
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J1/00Frequency-division multiplex systems
    • H04J1/02Details
    • H04J1/04Frequency-transposition arrangements
    • H04J1/045Filters applied to frequency transposition

Definitions

  • the frequency S of the auxiliary carrier and the frequencies of the main carriers T1, TzTn are so selected that they are multiples of the same fundamental frequency a, which is determined by and is slightly wider than the width of the speech frequency band to be transmitted, and are in such relation to each other that the sumand difference-frequencies arising in the second modulation fall in two different frequency ranges.
  • the two frequency ranges are separated by means of a filter connected between the output circuit of the second modulators of all the channels and the common transmission line so that either the sum frequencies T1+(S+a), Tz+(S+a) Tn+ (8+0) or the difference frequencies T1(S+a), Tz-(S-I-a) Tn(S+a) are transmitted to the receiver.
  • Theobject of my invention is to overcome the above difiiculty and to increase the eiliciency of such systems and for this purpose I provide a simple band-pass filter in the output circuit of each of the second modulators.
  • the speech currents received from the three subscribers I, 2 and 3 are fed through three low-pass filters 4, 5 and 6 respectively to three first modulators I, 8 and 9 respectively.
  • the auxiliary carrier S which is derived from a generator I0 if necessary through a frequency multiplier II, is modulated in modulators l, 8 and 9 by the speech currents.
  • a side band S+a is separated by means of band-pass filters I2.
  • I3 and I4 is supplied to three second modulators I5, I6 and II, wherein main carrier waves T1, T2 and T3 are modulated successively by these side bands.
  • the main carrier waves are also derived from the generator I0 and fed to the second modulators I5, I6 and through frequency-multipliers I8, I9 and 20.
  • the output circuits of modulators I5, I6 and II are connected in parallel and are connected through a filter 2
  • shown as a high-pass filter but which may be a low-pass filter, serves to eliminate the frequency range in which extend either the sum frequencies T1+(S+a), Tz+(S+a) and Tz+(S+a) o r t h e difference frequencies T1(S+a), Tz-(S+a).
  • the band-pass filter provided in the output circuit of one of the second modulators must produce only a comparatively low damping in the frequency range in which extend the side bands arising from the other two modulators. Thus substantially the entire output energy of each of the second modulators I5, I6 and I! will be fed to the transmission line 22.
  • the band-pass filter 23, 24 and 25 may be of very simple construction and need contain only a few elements so that they do not appreciably increase the costof the system.
  • the cost of the system according to the invention is even maintained considerably lower than that of the other known system, wherein the afore-mentioned relation between the frequencies of the auxiliary and main carriers does not exist and In a multichannel carrier wave system, a plu- 10 rality of channels each transmitting a conversation.
  • a first modulator in each channel means for supplying to each of said first modulators an auxiliary carrier having the same frequency in each of the channels, a first band-pass filter in each channel and separating one of the side bands produced in the first modulator of the channel by the modulation of the auxiliary carrier by the conversation, a second modulator in each channel, means for supplying to said second modulators the side band separated by said first band-pass filter, means for supplying to said second modulators main carriers having frequencies which are different for each of the channels and which are so selected that all the lower side bands and all the upper side bands produced in the second modulators lie in two separate frequency ranges, a common transmission line, and a second band-pass filter in each channel and connected between the second modulator of the channel and said transmission line, all oi. said second band-pass filters transmitting side bands produced in the corresponding second modulators and lying in the same one oi said separate frequency ranges.

Description

Jan; 20, 1942. T. s, SKILLMAN 2,270,385
MULTICARRIER TRANSMISSI ON SYSTEM Filed Oct. '6, 1959,
Patented Jan. 20, 1942 MULTICARRIE-R TRANSMISSION SYSTEM Thomas Samuel Skillman, Eindhoven, Nether lands, assignor, by mesne assignments, to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application October 6, 1939, Serial No. 298,331 In Great Britain October 10, 1938 1 Claim. 101. 179-15) bands isseparated by a filter'and modulated on a main carrier-wave in a second modulator. The frequency T of the main carrier wave for each speech to be transmitted is difierent and the main carriers T1, Tz-Tn are so selected that the frequency ranges occupied by the side bands to be transmitted are as close together as possible in the total frequency band to be transmitted.
According to the above patent the frequency S of the auxiliary carrier and the frequencies of the main carriers T1, TzTn are so selected that they are multiples of the same fundamental frequency a, which is determined by and is slightly wider than the width of the speech frequency band to be transmitted, and are in such relation to each other that the sumand difference-frequencies arising in the second modulation fall in two different frequency ranges. Thus, the sum frequencies T1+(S+a), T2+(S+a), Tn+(S+a), fall in a frequency range other than the difference frequencies T1(S+a) T2(S+a) ...Tn=(S+a), whereby it is supposed that after the first modulation in each channel the upper side band S+a is separated and applied to the second modulator. In this patent the two frequency ranges are separated by means of a filter connected between the output circuit of the second modulators of all the channels and the common transmission line so that either the sum frequencies T1+(S+a), Tz+(S+a) Tn+ (8+0) or the difference frequencies T1(S+a), Tz-(S-I-a) Tn(S+a) are transmitted to the receiver.
In such systems the output circuits of the second modulators are connected in parallel and this has the disadvantage that a large portion of the output of each of the modulators is lost in the other modulators and as a result only a small portion of the output energy reaches the transmission lines. Consequently, the efiiciency of the system is reduced.
Theobject of my invention is to overcome the above difiiculty and to increase the eiliciency of such systems and for this purpose I provide a simple band-pass filter in the output circuit of each of the second modulators.
In order that my invention may be clearly understood and readily carried into effect I shall describe the same in more detail with reference to the accompanying drawing in which the single figure is a schematic diagram of a multi-carrier transmission system embodying the invention.
In the drawing the speech currents received from the three subscribers I, 2 and 3 are fed through three low-pass filters 4, 5 and 6 respectively to three first modulators I, 8 and 9 respectively. The auxiliary carrier S, which is derived from a generator I0 if necessary through a frequency multiplier II, is modulated in modulators l, 8 and 9 by the speech currents. A side band S+a is separated by means of band-pass filters I2. I3 and I4 and is supplied to three second modulators I5, I6 and II, wherein main carrier waves T1, T2 and T3 are modulated successively by these side bands. The main carrier waves are also derived from the generator I0 and fed to the second modulators I5, I6 and through frequency-multipliers I8, I9 and 20. The output circuits of modulators I5, I6 and II are connected in parallel and are connected through a filter 2| to a transmission line 22.
Filter 2|, shown as a high-pass filter but which may be a low-pass filter, serves to eliminate the frequency range in which extend either the sum frequencies T1+(S+a), Tz+(S+a) and Tz+(S+a) o r t h e difference frequencies T1(S+a), Tz-(S+a).
In accordance with the invention I provide in the output circuits of the second modulators I5,
I6 and I1, band- pass filters 23, 24 and 25mspectively, which transmit one of the side bands arising in the corresponding modulators. The band-pass filter provided in the output circuit of one of the second modulators must produce only a comparatively low damping in the frequency range in which extend the side bands arising from the other two modulators. Thus substantially the entire output energy of each of the second modulators I5, I6 and I! will be fed to the transmission line 22.
The band- pass filter 23, 24 and 25 may be of very simple construction and need contain only a few elements so that they do not appreciably increase the costof the system. Thus the cost of the system according to the invention is even maintained considerably lower than that of the other known system, wherein the afore-mentioned relation between the frequencies of the auxiliary and main carriers does not exist and In a multichannel carrier wave system, a plu- 10 rality of channels each transmitting a conversation. a first modulator in each channel, means for supplying to each of said first modulators an auxiliary carrier having the same frequency in each of the channels, a first band-pass filter in each channel and separating one of the side bands produced in the first modulator of the channel by the modulation of the auxiliary carrier by the conversation, a second modulator in each channel, means for supplying to said second modulators the side band separated by said first band-pass filter, means for supplying to said second modulators main carriers having frequencies which are different for each of the channels and which are so selected that all the lower side bands and all the upper side bands produced in the second modulators lie in two separate frequency ranges, a common transmission line, and a second band-pass filter in each channel and connected between the second modulator of the channel and said transmission line, all oi. said second band-pass filters transmitting side bands produced in the corresponding second modulators and lying in the same one oi said separate frequency ranges.
THOMAS SAMUEL SKILLMAN.
US298331A 1938-10-10 1939-10-06 Multicarrier transmission system Expired - Lifetime US2270385A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB29358/38A GB519264A (en) 1938-10-10 1938-10-10 Improvements in or relating to multi-carrier transmission systems

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CH (1) CH212071A (en)
FR (1) FR860788A (en)
GB (1) GB519264A (en)

Cited By (55)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2444534A (en) * 1946-02-01 1948-07-06 Farnsworth Res Corp Single side-band modulation system
US2474249A (en) * 1946-04-08 1949-06-28 Int Standard Electric Corp Multichannel carrier communication system
US2489361A (en) * 1945-05-02 1949-11-29 Hartford Nat Bank & Trust Co Multichannel carrier wave system employing multiple modulation
US2522846A (en) * 1943-08-02 1950-09-19 Comm Engineering Pty Ltd Multichannel carrier telephone system providing for music transmission at carrier frequencies
US2546994A (en) * 1945-05-15 1951-04-03 Int Standard Electric Corp Multiplex carrier current telephony
US2607853A (en) * 1947-01-27 1952-08-19 British Telecomm Res Ltd Telecommunication system
US2775646A (en) * 1950-11-30 1956-12-25 Hartford Nat Bank & Trust Co Single-sideband apparatus
US2883464A (en) * 1953-02-18 1959-04-21 Ericsson Telefon Ab L M Device for signal receivers
US3068454A (en) * 1959-01-30 1962-12-11 Zack D Reynolds Method of recording a multiple of electrical signals
US3495188A (en) * 1965-05-24 1970-02-10 Siemens Ag Single-sideband carrier frequency system utilizing a premodulation stage for providing the base primary group
USB504899I5 (en) * 1943-10-04 1976-03-09
WO1985000944A1 (en) * 1983-08-16 1985-02-28 The Variable Speech Control Company ("Vsc") Audio channel stacking with speech compression for narrow band transmission with provision for dialed calls
US4586174A (en) * 1983-08-16 1986-04-29 The Variable Speech Control Company ("Vsc") Audio channel stacking with speech compression for narrow band transmission with provision for dialed calls
US6049706A (en) * 1998-10-21 2000-04-11 Parkervision, Inc. Integrated frequency translation and selectivity
US6061551A (en) * 1998-10-21 2000-05-09 Parkervision, Inc. Method and system for down-converting electromagnetic signals
US6061555A (en) * 1998-10-21 2000-05-09 Parkervision, Inc. Method and system for ensuring reception of a communications signal
US6091940A (en) * 1998-10-21 2000-07-18 Parkervision, Inc. Method and system for frequency up-conversion
US20010027561A1 (en) * 1998-11-30 2001-10-04 Microsoft Corporation Video on demand methods and systems
US20010038318A1 (en) * 1999-11-24 2001-11-08 Parker Vision, Inc. Phased array antenna applications for universal frequency translation
US6370371B1 (en) 1998-10-21 2002-04-09 Parkervision, Inc. Applications of universal frequency translation
US20020042257A1 (en) * 2000-04-14 2002-04-11 Sorrells David F. Apparatus, system, and method for down-converting and up-converting electromagnetic signals
US20020049038A1 (en) * 2000-01-28 2002-04-25 Sorrells David F. Wireless and wired cable modem applications of universal frequency translation technology
US20020124036A1 (en) * 2000-11-14 2002-09-05 Parkervision, Inc. Method and apparatus for a parallel correlator and applications thereof
US20030022640A1 (en) * 1999-08-23 2003-01-30 Parker Vision, Inc. Method and system for frequency up-conversion
US6542722B1 (en) 1998-10-21 2003-04-01 Parkervision, Inc. Method and system for frequency up-conversion with variety of transmitter configurations
US6560301B1 (en) 1998-10-21 2003-05-06 Parkervision, Inc. Integrated frequency translation and selectivity with a variety of filter embodiments
US20030181189A1 (en) * 1999-04-16 2003-09-25 Sorrells David F. Method and apparatus for reducing DC offsets in communication systems using universal frequency translation technology
US20040015420A1 (en) * 2002-07-18 2004-01-22 Sorrells David F. Networking methods and systems
US20040013177A1 (en) * 2002-07-18 2004-01-22 Parker Vision, Inc. Networking methods and systems
US6694128B1 (en) 1998-08-18 2004-02-17 Parkervision, Inc. Frequency synthesizer using universal frequency translation technology
US6704558B1 (en) 1999-01-22 2004-03-09 Parkervision, Inc. Image-reject down-converter and embodiments thereof, such as the family radio service
US6704549B1 (en) 1999-03-03 2004-03-09 Parkvision, Inc. Multi-mode, multi-band communication system
US20040185901A1 (en) * 2003-03-18 2004-09-23 Tdk Corporation Electronic device for wireless communications and reflector device for wireless communication cards
US6813485B2 (en) 1998-10-21 2004-11-02 Parkervision, Inc. Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same
US20040230628A1 (en) * 2000-11-14 2004-11-18 Rawlins Gregory S. Methods, systems, and computer program products for parallel correlation and applications thereof
US6873836B1 (en) 1999-03-03 2005-03-29 Parkervision, Inc. Universal platform module and methods and apparatuses relating thereto enabled by universal frequency translation technology
US20050100115A1 (en) * 1999-04-16 2005-05-12 Sorrells David F. Method, system, and apparatus for balanced frequency Up-conversion of a baseband signal
US20050123025A1 (en) * 1999-08-04 2005-06-09 Sorrells David F. Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments and circuit implementations
US20050136861A1 (en) * 1998-10-21 2005-06-23 Parkervision, Inc. Method and system for frequency up-conversion with modulation embodiments
US6963734B2 (en) 1999-12-22 2005-11-08 Parkervision, Inc. Differential frequency down-conversion using techniques of universal frequency translation technology
US6975848B2 (en) 2002-06-04 2005-12-13 Parkervision, Inc. Method and apparatus for DC offset removal in a radio frequency communication channel
US7006805B1 (en) 1999-01-22 2006-02-28 Parker Vision, Inc. Aliasing communication system with multi-mode and multi-band functionality and embodiments thereof, such as the family radio service
US7027786B1 (en) 1998-10-21 2006-04-11 Parkervision, Inc. Carrier and clock recovery using universal frequency translation
US7054296B1 (en) 1999-08-04 2006-05-30 Parkervision, Inc. Wireless local area network (WLAN) technology and applications including techniques of universal frequency translation
US7072427B2 (en) 2001-11-09 2006-07-04 Parkervision, Inc. Method and apparatus for reducing DC offsets in a communication system
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Cited By (160)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2522846A (en) * 1943-08-02 1950-09-19 Comm Engineering Pty Ltd Multichannel carrier telephone system providing for music transmission at carrier frequencies
USB504899I5 (en) * 1943-10-04 1976-03-09
US3991273A (en) * 1943-10-04 1976-11-09 Bell Telephone Laboratories, Incorporated Speech component coded multiplex carrier wave transmission
US2489361A (en) * 1945-05-02 1949-11-29 Hartford Nat Bank & Trust Co Multichannel carrier wave system employing multiple modulation
US2546994A (en) * 1945-05-15 1951-04-03 Int Standard Electric Corp Multiplex carrier current telephony
US2444534A (en) * 1946-02-01 1948-07-06 Farnsworth Res Corp Single side-band modulation system
US2474249A (en) * 1946-04-08 1949-06-28 Int Standard Electric Corp Multichannel carrier communication system
US2607853A (en) * 1947-01-27 1952-08-19 British Telecomm Res Ltd Telecommunication system
US2775646A (en) * 1950-11-30 1956-12-25 Hartford Nat Bank & Trust Co Single-sideband apparatus
US2883464A (en) * 1953-02-18 1959-04-21 Ericsson Telefon Ab L M Device for signal receivers
US3068454A (en) * 1959-01-30 1962-12-11 Zack D Reynolds Method of recording a multiple of electrical signals
US3495188A (en) * 1965-05-24 1970-02-10 Siemens Ag Single-sideband carrier frequency system utilizing a premodulation stage for providing the base primary group
WO1985000944A1 (en) * 1983-08-16 1985-02-28 The Variable Speech Control Company ("Vsc") Audio channel stacking with speech compression for narrow band transmission with provision for dialed calls
US4586174A (en) * 1983-08-16 1986-04-29 The Variable Speech Control Company ("Vsc") Audio channel stacking with speech compression for narrow band transmission with provision for dialed calls
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US6091940A (en) * 1998-10-21 2000-07-18 Parkervision, Inc. Method and system for frequency up-conversion
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CH212071A (en) 1940-10-31
FR860788A (en) 1941-01-31

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