US2270385A - Multicarrier transmission system - Google Patents
Multicarrier transmission system Download PDFInfo
- 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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- United States
- Prior art keywords
- modulators
- band
- frequency
- frequencies
- transmission system
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J1/00—Frequency-division multiplex systems
- H04J1/02—Details
- H04J1/12—Arrangements for reducing cross-talk between channels
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J1/00—Frequency-division multiplex systems
- H04J1/02—Details
- H04J1/04—Frequency-transposition arrangements
- H04J1/045—Filters 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.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Transmitters (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
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.
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.
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 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2270385A true US2270385A (en) | 1942-01-20 |
Family
ID=10158969
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US298331A Expired - Lifetime US2270385A (en) | 1938-10-10 | 1939-10-06 | Multicarrier transmission system |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US2270385A (en) |
| BE (1) | BE436617A (en) |
| CH (1) | CH212071A (en) |
| FR (1) | FR860788A (en) |
| GB (1) | GB519264A (en) |
Cited By (55)
| 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 |
| US6061555A (en) * | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
| US6061551A (en) * | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for down-converting electromagnetic signals |
| 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 |
| US20040013177A1 (en) * | 2002-07-18 | 2004-01-22 | Parker Vision, Inc. | Networking methods and systems |
| US20040015420A1 (en) * | 2002-07-18 | 2004-01-22 | Sorrells David F. | Networking methods and systems |
| US6694128B1 (en) | 1998-08-18 | 2004-02-17 | Parkervision, Inc. | Frequency synthesizer using universal frequency translation technology |
| US6704549B1 (en) | 1999-03-03 | 2004-03-09 | Parkvision, Inc. | Multi-mode, multi-band communication system |
| US6704558B1 (en) | 1999-01-22 | 2004-03-09 | Parkervision, Inc. | Image-reject down-converter and embodiments thereof, such as the family radio service |
| 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 |
| US7072390B1 (en) | 1999-08-04 | 2006-07-04 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments |
| US7085335B2 (en) | 2001-11-09 | 2006-08-01 | Parkervision, Inc. | Method and apparatus for reducing DC offsets in a communication system |
| US7110435B1 (en) | 1999-03-15 | 2006-09-19 | Parkervision, Inc. | Spread spectrum applications of universal frequency translation |
| US20070230611A1 (en) * | 1999-04-16 | 2007-10-04 | Parkervision, Inc. | Apparatus and method of differential IQ frequency up-conversion |
| US7295826B1 (en) | 1998-10-21 | 2007-11-13 | Parkervision, Inc. | Integrated frequency translation and selectivity with gain control functionality, and applications thereof |
| US7321640B2 (en) | 2002-06-07 | 2008-01-22 | Parkervision, Inc. | Active polyphase inverter filter for quadrature signal generation |
| US7515896B1 (en) | 1998-10-21 | 2009-04-07 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
| US7554508B2 (en) | 2000-06-09 | 2009-06-30 | Parker Vision, Inc. | Phased array antenna applications on universal frequency translation |
| US7724845B2 (en) | 1999-04-16 | 2010-05-25 | Parkervision, Inc. | Method and system for down-converting and electromagnetic signal, and transforms for same |
| US8295406B1 (en) | 1999-08-04 | 2012-10-23 | Parkervision, Inc. | Universal platform module for a plurality of communication protocols |
-
1938
- 1938-10-10 GB GB29358/38A patent/GB519264A/en not_active Expired
-
1939
- 1939-10-06 US US298331A patent/US2270385A/en not_active Expired - Lifetime
- 1939-10-07 BE BE436617D patent/BE436617A/xx unknown
- 1939-10-09 CH CH212071D patent/CH212071A/en unknown
- 1939-10-10 FR FR860788D patent/FR860788A/en not_active Expired
Cited By (160)
| 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 |
| US6694128B1 (en) | 1998-08-18 | 2004-02-17 | Parkervision, Inc. | Frequency synthesizer using universal frequency translation technology |
| US8190116B2 (en) | 1998-10-21 | 2012-05-29 | Parker Vision, Inc. | Methods and systems for down-converting a signal using a complementary transistor structure |
| US6836650B2 (en) | 1998-10-21 | 2004-12-28 | Parkervision, Inc. | Methods and systems for down-converting electromagnetic signals, and applications thereof |
| US6091940A (en) * | 1998-10-21 | 2000-07-18 | Parkervision, Inc. | Method and system for frequency up-conversion |
| US6266518B1 (en) | 1998-10-21 | 2001-07-24 | Parkervision, Inc. | Method and system for down-converting electromagnetic signals by sampling and integrating over apertures |
| US7218907B2 (en) | 1998-10-21 | 2007-05-15 | Parkervision, Inc. | Method and circuit for down-converting a signal |
| US7515896B1 (en) | 1998-10-21 | 2009-04-07 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
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| US6542722B1 (en) | 1998-10-21 | 2003-04-01 | Parkervision, Inc. | Method and system for frequency up-conversion with variety of transmitter configurations |
| US20030068990A1 (en) * | 1998-10-21 | 2003-04-10 | Parkervision, Inc. | Method and system for frequency up-conversion with a 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 |
| US6580902B1 (en) | 1998-10-21 | 2003-06-17 | Parkervision, Inc. | Frequency translation using optimized switch structures |
| US20030112895A1 (en) * | 1998-10-21 | 2003-06-19 | Parkervision, Inc. | Intergrated frequency translation and selectivity |
| US7389100B2 (en) | 1998-10-21 | 2008-06-17 | Parkervision, Inc. | Method and circuit for down-converting a signal |
| US20030186670A1 (en) * | 1998-10-21 | 2003-10-02 | Sorrells David F. | Method and circuit or down-converting a signal |
| US6647250B1 (en) | 1998-10-21 | 2003-11-11 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
| US20090181627A1 (en) * | 1998-10-21 | 2009-07-16 | Parkervision, Inc. | Applications of Universal Frequency Translation |
| US20090221257A1 (en) * | 1998-10-21 | 2009-09-03 | Parkervision, Inc. | Method and System For Down-Converting An Electromagnetic Signal, And Transforms For Same, And Aperture Relationships |
| US7194246B2 (en) | 1998-10-21 | 2007-03-20 | Parkervision, Inc. | Methods and systems for down-converting a signal using a complementary transistor structure |
| US6687493B1 (en) | 1998-10-21 | 2004-02-03 | Parkervision, Inc. | Method and circuit for down-converting a signal using a complementary FET structure for improved dynamic range |
| US6061555A (en) * | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
| US7697916B2 (en) | 1998-10-21 | 2010-04-13 | Parkervision, Inc. | Applications of universal frequency translation |
| US7245886B2 (en) | 1998-10-21 | 2007-07-17 | Parkervision, Inc. | Method and system for frequency up-conversion with modulation embodiments |
| US8190108B2 (en) | 1998-10-21 | 2012-05-29 | Parkervision, Inc. | Method and system for frequency up-conversion |
| US6798351B1 (en) | 1998-10-21 | 2004-09-28 | Parkervision, Inc. | Automated meter reader applications of universal frequency translation |
| 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 |
| US8160534B2 (en) | 1998-10-21 | 2012-04-17 | Parkervision, Inc. | Applications of universal frequency translation |
| US6061551A (en) * | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for down-converting electromagnetic signals |
| US20050009494A1 (en) * | 1998-10-21 | 2005-01-13 | Parkervision, Inc. | Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same |
| US7826817B2 (en) | 1998-10-21 | 2010-11-02 | Parker Vision, Inc. | Applications of universal frequency translation |
| US7076011B2 (en) | 1998-10-21 | 2006-07-11 | Parkervision, Inc. | Integrated frequency translation and selectivity |
| US7376410B2 (en) | 1998-10-21 | 2008-05-20 | Parkervision, Inc. | Methods and systems for down-converting a signal using a complementary transistor structure |
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| US7620378B2 (en) | 1998-10-21 | 2009-11-17 | Parkervision, Inc. | Method and system for frequency up-conversion with modulation embodiments |
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Also Published As
| Publication number | Publication date |
|---|---|
| FR860788A (en) | 1941-01-31 |
| BE436617A (en) | 1939-11-30 |
| GB519264A (en) | 1940-03-20 |
| CH212071A (en) | 1940-10-31 |
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