GB2161344A - Transmission of digital data - Google Patents
Transmission of digital data Download PDFInfo
- Publication number
- GB2161344A GB2161344A GB08417283A GB8417283A GB2161344A GB 2161344 A GB2161344 A GB 2161344A GB 08417283 A GB08417283 A GB 08417283A GB 8417283 A GB8417283 A GB 8417283A GB 2161344 A GB2161344 A GB 2161344A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sub
- channel
- digital data
- atransmission
- channels
- Prior art date
- 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.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/12—Frequency diversity
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
- H04L1/04—Arrangements for detecting or preventing errors in the information received by diversity reception using frequency diversity
Abstract
The transmission of digital data over a data link, particularly an H.F. radio link, can be corrupted by narrow-band, high level interference signals randomly distributed in frequency. The uncorrupted transmission of data can be made more possible by a frequency diversity digital data transmission system in which a signal channel is divided into a plurality of lesser bandwidth sub-channels, each of which is modulated across substantially its entire bandwidth by a multi-level, spectrally efficient modulation scheme, for example 8PSK, 16QAM, 64QAM. In a receiver the sub-channels are examined for narrow-band interference and the data signal is demodulated using a decision algorithm based on the sub-channel outputs, and an assessment of sub-channel reliability. <IMAGE>
Description
SPECIFICATION
Transmission of digital data
The present invention relates to the transmission of digital data in the presence of narrow-band interference,
A problem when transmitting digital information over a data link, which may be an H.F. radio link, is that the information becomes corrupted in transmission by narrow-band, high level interference signals randomly distributed in frequency. Known systems for combating such interference involve reducing the data rate in a given bandwidth or, conversely, increasing the bandwidth for the same data rate.
An object of the present invention is to reduce the effects of narrow-band interference when transmitting digital information at a high data rate over a data link of a predetermined bandwidth.
According to the present invention there is provided a digital data transmission system in which a transmission channel of defined bandwidth is divided into a plurality of lesser bandwidth subchannels, digital data informatin to be transmitted is modulated over substantially the entire bandwidth of each of the said sub-channels using a multi-level modulation scheme and at the receiver the digital data is recovered from at least one of the subchannels.
By using a combination of frequency diversity and a spectrally efficient, multi-level modulation sheme, the chance of at least one of the frequency diversity sub-channels being received uncorrupted is much greater than the chance of the complete channel being interference free. A further improvement can e gained by making use of all the received subchannels.
Suitable multi-level modulation schemes may comprise for example, 8PSK (8 phase shift keying), 16QAM (16 quadrature amplitude modulation) or 640AM.
At the receiver, the sub-channels are dmodulated and either steps are taken to select the best subchannel at any instance or the data is recovered by making a decision using all the sub-channel outputs.
The present invention will now be described, by way of example, with reference to the accompanying drawings, wherein:
Figure lisa graph of an example of H.F.
interference, and
Figures 2 and 3 are block schematic circuit diagrams of a transmitter and a receiver, respectively, suitable for use with the data transmission system in accordance with the present invention.
Referring to Figure 1, there is shown a graph of power Pin 10dB per division against frequency F in 1kHz per division and illustrates typical H.F. interference. Part of the interference consists of a background of noise-like signals, but another part, the large amplitude peaks in Figure 1, consists of narrow-band interference. In many cases the narrow-band interference is the dominant cause of errors at the output of the receiver.
Thus, taking as an example a transmission channel of 5.0kHz occupied by a signal with a data rate of 2.4k bits/sec., if the channel is badly corrupted by narrow-band interference then the entire signal is unusable. Since as is shown in Figure 1 the narrowband noise is not distributed uniformly across the frequency band, then adopting frequency diversity using several, for example 5, sub-channels within an overall channel it is likely that at any instant in time at least one of the sub-channels is free from narrow-band interference and the data is received uncorrupted. Because all the message information is transmitted in each sub-channel, then the transmitted data can be recovered even if one or more sub-channels are unusable.This frequency diversity can be achieved without reduction in data rate if a spectrally efficient multi-level modulation scheme is used so that each sub-channel of for example 1 kHz bandwidth is sending data at 2.4k bits/sec. Such multi-level modulation schemes may comprise, for exm ple, 8PSK, 160AM or 640AM. At a receiver all the sub-channels are received and demodulated and either digital data is recovered from one of the sub-channels, that is the one having least interference, or the data value is recovered by making a decision vased on all the sub-channel outputs.
For example, considering single data bits, the following algorithm could be used to obtain the recovered data value (D):
where Di is the output of the 1-th sub-chanel and wi is the a weighting factor applied to the i-th sub-channel output. The decision alogorithm can take various forms. For example, if the weights are all unity then it is equivlent to majority decision decoding. If all the weights are zero except one then this amounts to selection of a single sub-channel. If the weights are chosen according to the estimated reliability of the associated sub-channels then this is a weighted combining scheme. The reliability of each subchannel could be determined, for example, by the signal-to-noise ratio in that sub-channel.The data reliability can be estimated either on a bit by bit basis or using a short term average. A new set of weights could be determined for each received bit, or alternatively, less frequently.
Figure 2 shows a transmitter system which comprises a 2.4k bits/second digital data encoder 10 which is coupled to five multi-level modulators 12, 14, 16, 18 and 20 which may comprise 8PSK, 16QAM or 640AM modulator. The five sub-carriers f1 to (f1 +4kHz) spaced one from another by 1 kHz are are generated by oscillators 22, 24, 26, 28 and 30, respectively and are modulated according to the predetermined multilevel modulation scheme to form a frequency diversity signal. This signal is applied to a transmitter 32 which could be conventional single sideband (SSB) transmitter accepting a 5kHz bandwidth signal. The transmitter output is applied to an antenna 34.
The reciever system shown in Figure 3 comprises a receiver 38 which could be a conventional SSB receiver which is connected to an antenna 36 and has an output bandwidth of 5kHz. Each of the sub-channels of the frequency diversity signal is applied to a respective demodulator 40,42,44,46 and 48 which has its own sub-carrierfrequency generator. The detected signals from the demodulators 40 to 48 are applied to a decision unit 52 which makes a decision based on a decision algorithm as to the correct output data value, based on the sub-channel outputs and the assessment of subchannel reliability made by a reliability measurement unit 50. The decision making process will usually be continuous because the occurrence of narrow-band interference cannot be predicted. The output of the decision unit 52 is supplied to a data decoder 54.
Various ways may be used for determining the degree to which each of the sub-channels is corrupted by H.F. narrow-band interference. For example, a comparison can be made between the amplitude of the signal in each of the respective subchannels and the mean amplitude for all the subchannels. It is then reasonable to assume that any sub-channel with an amplitude much larger than the mean is corrupted by interference. The phase jitter on each of the sub-carriers could also be used as an indication of interference. Another method would be for the encoder 10 to insert error detection or correction coding into the encoded signal and for this coding to be used in the receiver to determine which sub-channels are corrupted by interference.
The digital information bits applied to each of the
modulators 12 to 20 in Figure 2 need not necessarily
be transmitted on all the sub-channels simul
taneously. For example, the sub-channel signals
could each be delayed in time by a different amount
resulting in both time and frequency diversity.
However, the complete message would still be transmitted down each sub-channel. At the receiver
corresponding time delays would be required after
demodulation to enable correct combining of the
sub-channel signals.
Not shown in Figure 3, the sub-channel signal
combination with appropriate weighting factors
could be carried out before demodulation. In this
case the sub-carriers should be phase locked to each
other. This phase locking would also be desirable in
minimising the peak-to-mean power ratio of the
transmitted signal.
Although not shown, instead of using a single
receiver one could use five separate receivers each
one assigned to a different channel.
The modems 12 to 20 and 40 to 48 may be serial
modems with or without adaptive equalisers or
parallel modems, although the latter are more
complicated technically and have a peak power
limitation.
The transmission system in accordance with the
present invention is particularly applicable to
groundwave communication over distances of up to
about 150 km, but could be used over longer ranges
with adaptive equalisation.
Claims (12)
1. A digital data transmission system in which a
transmission channel of defined bandwidth is divided into a plurality of lesser bandwidth subchannels, digital data information to be transmitted is modulated over substantially the entire bandwidth of each of the said sub-channels using a multi-level modulation scheme and at the receiverthe digital data is recovered from at least one of the subchannels.
2. Atransmission system as claimed in Claim 1, wherein the receiver includes means for examining each of the sub-channels and for selecting a subchannel having the minimum of narrow-band noise for further processing.
3. Atransmission system as claimed in Claim 2, wherein in encoding the digital data an error detection code is applied and in the receiver, said means detects the number of errors in each sub-channel signal.
4. Atransmission system as claimed in Claim 2, wherein said means compares the digital data signals in each of said sub-channels and a majority voting system is used to recover the transmitted data.
5. Atransmission system as claimed in Claim 2, wherein said means compares the amplitude of the signal in each sub-channel with an expected amplitude and determines which sub-channel(s) at any one time is (or are) deemed to be interference free.
6. Atransmission system as claimed in claim 1, wherein the receiver includes means for combining the signals on the respective sub-channels and providing an output digital signal for further processing.
7. Atransmission system as claimed in Claim 6, wherein the receiver includes means for estimating the reliability of each of the sub-channel data signals and using this information in an algorithm to combine the sub-channel signals.
8. Atransmission system as claimed in any one of Claims 1 to 7, wherein the multi-level modulation scheme is 16QAM (quadrature amplitude modulation).
9. Atransmission system as claimed in any one of Claims 1 to 7, wherein the multi-level modulation scheme is 640AM
10. Atransmission system as claimed in any one
of Claims 1 to 7, wherein the multi-level modulation
scheme is 8PSK (phase shift keying).
11. Atransmission system as claimed in any one
of Claims 1 to 10, wherein the digital signals used to
modulate each of the sub-carriers are delayed in time by different amounts.
12. A digital data transmission system substantially as hereinbefore described with reference to the
accompanying drawings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08417283A GB2161344A (en) | 1984-07-06 | 1984-07-06 | Transmission of digital data |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08417283A GB2161344A (en) | 1984-07-06 | 1984-07-06 | Transmission of digital data |
Publications (1)
Publication Number | Publication Date |
---|---|
GB2161344A true GB2161344A (en) | 1986-01-08 |
Family
ID=10563514
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB08417283A Withdrawn GB2161344A (en) | 1984-07-06 | 1984-07-06 | Transmission of digital data |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2161344A (en) |
Cited By (38)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0238813A2 (en) * | 1986-02-27 | 1987-09-30 | Datawatt BV | Method for transmitting data over mains lines |
EP0283299A2 (en) * | 1987-03-20 | 1988-09-21 | Nippon Telegraph And Telephone Corporation | Radio receiver |
GB2208985A (en) * | 1987-08-24 | 1989-04-19 | Kokusai Denshin Denwa Co Ltd | A radio communication system |
WO1991018458A1 (en) * | 1990-05-11 | 1991-11-28 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | A high frequency multichannel diversity differential phase shift (dpsk) communications system |
WO1992004783A1 (en) * | 1990-09-07 | 1992-03-19 | Telefunken Systemtechnik Gmbh | Method of determining the frequency deviation in digital communications transmissions |
WO1993009618A1 (en) * | 1991-10-31 | 1993-05-13 | Massachusetts Institute Of Technology | Communication system utilizing self-similar signals |
FR2755460A1 (en) * | 1996-11-07 | 1998-05-07 | Kiekert Ag | MOTOR VEHICLE WITH A CENTRALIZED LOCKING SYSTEM AS WELL AS A REMOTE CONTROL DEVICE |
US6049706A (en) | 1998-10-21 | 2000-04-11 | Parkervision, Inc. | Integrated frequency translation and selectivity |
WO2000020712A1 (en) * | 1998-10-05 | 2000-04-13 | Lear Automotive Dearborn, Inc. | Multiple channel remote keyless entry system |
WO2000024120A1 (en) * | 1998-10-21 | 2000-04-27 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
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 |
GB2349544A (en) * | 1989-05-30 | 2000-11-01 | Secr Defence | Covert communication system |
US6370371B1 (en) | 1998-10-21 | 2002-04-09 | Parkervision, Inc. | Applications of universal frequency translation |
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 |
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 |
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 |
EP1551127A1 (en) * | 2001-12-21 | 2005-07-06 | Mitsubishi Denki Kabushiki Kaisha | Radio communication system and transmitter for implementing frequency diversity |
WO2006120319A1 (en) * | 2005-05-10 | 2006-11-16 | Societe Stantec | Device and method for receiving binary data radio frequency |
US7519400B2 (en) | 2005-05-27 | 2009-04-14 | Dei Headquarters, Inc. | Multi-modulation remote control communication system |
US7653158B2 (en) | 2001-11-09 | 2010-01-26 | Parkervision, Inc. | Gain control in a communication channel |
US7693230B2 (en) | 1999-04-16 | 2010-04-06 | Parkervision, Inc. | Apparatus and method of differential IQ frequency up-conversion |
US7724845B2 (en) | 1999-04-16 | 2010-05-25 | Parkervision, Inc. | Method and system for down-converting and electromagnetic signal, and transforms for same |
US7773688B2 (en) | 1999-04-16 | 2010-08-10 | Parkervision, Inc. | Method, system, and apparatus for balanced frequency up-conversion, including circuitry to directly couple the outputs of multiple transistors |
US7822401B2 (en) | 2000-04-14 | 2010-10-26 | Parkervision, Inc. | Apparatus and method for down-converting electromagnetic signals by controlled charging and discharging of a capacitor |
US7865177B2 (en) | 1998-10-21 | 2011-01-04 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
US7894789B2 (en) | 1999-04-16 | 2011-02-22 | Parkervision, Inc. | Down-conversion of an electromagnetic signal with feedback control |
US7929638B2 (en) | 1999-04-16 | 2011-04-19 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments |
US7991815B2 (en) | 2000-11-14 | 2011-08-02 | Parkervision, Inc. | Methods, systems, and computer program products for parallel correlation and applications thereof |
US8019291B2 (en) | 1998-10-21 | 2011-09-13 | Parkervision, Inc. | Method and system for frequency down-conversion and frequency up-conversion |
US8160196B2 (en) | 2002-07-18 | 2012-04-17 | Parkervision, Inc. | Networking methods and systems |
US8233855B2 (en) | 1998-10-21 | 2012-07-31 | Parkervision, Inc. | Up-conversion based on gated information signal |
US8295406B1 (en) | 1999-08-04 | 2012-10-23 | Parkervision, Inc. | Universal platform module for a plurality of communication protocols |
US8407061B2 (en) | 2002-07-18 | 2013-03-26 | Parkervision, Inc. | Networking methods and systems |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2023971A (en) * | 1978-05-10 | 1980-01-03 | Nippon Telegraph & Telephone | Digital signal transmission system |
GB2092415A (en) * | 1981-01-29 | 1982-08-11 | Secr Defence | Digital communications system |
EP0065764B1 (en) * | 1981-05-27 | 1986-03-26 | Siemens Aktiengesellschaft | Digital radio system |
-
1984
- 1984-07-06 GB GB08417283A patent/GB2161344A/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2023971A (en) * | 1978-05-10 | 1980-01-03 | Nippon Telegraph & Telephone | Digital signal transmission system |
GB2092415A (en) * | 1981-01-29 | 1982-08-11 | Secr Defence | Digital communications system |
EP0065764B1 (en) * | 1981-05-27 | 1986-03-26 | Siemens Aktiengesellschaft | Digital radio system |
Cited By (73)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0238813A3 (en) * | 1986-02-27 | 1989-05-10 | Bbc Brown Boveri Ag | Method for transmitting data over mains lines |
EP0238813A2 (en) * | 1986-02-27 | 1987-09-30 | Datawatt BV | Method for transmitting data over mains lines |
EP0283299A2 (en) * | 1987-03-20 | 1988-09-21 | Nippon Telegraph And Telephone Corporation | Radio receiver |
EP0283299A3 (en) * | 1987-03-20 | 1991-03-13 | Nippon Telegraph And Telephone Corporation | Radio receiver |
GB2208985A (en) * | 1987-08-24 | 1989-04-19 | Kokusai Denshin Denwa Co Ltd | A radio communication system |
GB2208985B (en) * | 1987-08-24 | 1991-07-31 | Kokusai Denshin Denwa Co Ltd | A radio communication system |
GB2349544A (en) * | 1989-05-30 | 2000-11-01 | Secr Defence | Covert communication system |
GB2349544B (en) * | 1989-05-30 | 2001-04-04 | Secr Defence | A wideband high frequency covert communications system |
AU637703B2 (en) * | 1990-05-11 | 1993-06-03 | Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland, The | A high frequency multichannel diversity differential phase shift (dpsk) communications system |
GB2259228B (en) * | 1990-05-11 | 1994-06-01 | Secr Defence | A high frequency multichannel diversity differential phase shift (DPSK) communications system |
GB2259228A (en) * | 1990-05-11 | 1993-03-03 | Secr Defence | A high frequency multichannel diversity differential phase shift (DPSK) communications system |
WO1991018458A1 (en) * | 1990-05-11 | 1991-11-28 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | A high frequency multichannel diversity differential phase shift (dpsk) communications system |
WO1992004783A1 (en) * | 1990-09-07 | 1992-03-19 | Telefunken Systemtechnik Gmbh | Method of determining the frequency deviation in digital communications transmissions |
US5305347A (en) * | 1990-09-07 | 1994-04-19 | Deutsche Aerospace Ag | Method of detecting the frequency deviation in digital communication transmissions |
WO1993009618A1 (en) * | 1991-10-31 | 1993-05-13 | Massachusetts Institute Of Technology | Communication system utilizing self-similar signals |
FR2755460A1 (en) * | 1996-11-07 | 1998-05-07 | Kiekert Ag | MOTOR VEHICLE WITH A CENTRALIZED LOCKING SYSTEM AS WELL AS A REMOTE CONTROL DEVICE |
US6694128B1 (en) | 1998-08-18 | 2004-02-17 | Parkervision, Inc. | Frequency synthesizer using universal frequency translation technology |
WO2000020712A1 (en) * | 1998-10-05 | 2000-04-13 | Lear Automotive Dearborn, Inc. | Multiple channel remote keyless entry system |
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 |
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 |
US6266518B1 (en) | 1998-10-21 | 2001-07-24 | Parkervision, Inc. | Method and system for down-converting electromagnetic signals by sampling and integrating over apertures |
US6353735B1 (en) | 1998-10-21 | 2002-03-05 | Parkervision, Inc. | MDG method for output signal generation |
US6370371B1 (en) | 1998-10-21 | 2002-04-09 | Parkervision, Inc. | Applications of universal frequency translation |
US6421534B1 (en) | 1998-10-21 | 2002-07-16 | Parkervision, Inc. | Integrated frequency translation and selectivity |
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 |
US6580902B1 (en) | 1998-10-21 | 2003-06-17 | Parkervision, Inc. | Frequency translation using optimized switch structures |
US6647250B1 (en) | 1998-10-21 | 2003-11-11 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
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 |
WO2000024120A1 (en) * | 1998-10-21 | 2000-04-27 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
US8340618B2 (en) | 1998-10-21 | 2012-12-25 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
US7826817B2 (en) | 1998-10-21 | 2010-11-02 | Parker Vision, Inc. | Applications of universal frequency translation |
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 |
US6049706A (en) | 1998-10-21 | 2000-04-11 | Parkervision, Inc. | Integrated frequency translation and selectivity |
US8233855B2 (en) | 1998-10-21 | 2012-07-31 | Parkervision, Inc. | Up-conversion based on gated information signal |
US8190108B2 (en) | 1998-10-21 | 2012-05-29 | Parkervision, Inc. | Method and system for frequency up-conversion |
US8190116B2 (en) | 1998-10-21 | 2012-05-29 | Parker Vision, Inc. | Methods and systems for down-converting a signal using a complementary transistor structure |
US8160534B2 (en) | 1998-10-21 | 2012-04-17 | Parkervision, Inc. | Applications of universal frequency translation |
US8019291B2 (en) | 1998-10-21 | 2011-09-13 | Parkervision, Inc. | Method and system for frequency down-conversion and frequency up-conversion |
US7937059B2 (en) | 1998-10-21 | 2011-05-03 | Parkervision, Inc. | Converting an electromagnetic signal via sub-sampling |
US7936022B2 (en) | 1998-10-21 | 2011-05-03 | Parkervision, Inc. | Method and circuit for down-converting a signal |
US7693502B2 (en) | 1998-10-21 | 2010-04-06 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, transforms for same, and aperture relationships |
US7697916B2 (en) | 1998-10-21 | 2010-04-13 | Parkervision, Inc. | Applications of universal frequency translation |
US7865177B2 (en) | 1998-10-21 | 2011-01-04 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
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 |
US8594228B2 (en) | 1999-04-16 | 2013-11-26 | Parkervision, Inc. | Apparatus and method of differential IQ frequency up-conversion |
US7773688B2 (en) | 1999-04-16 | 2010-08-10 | Parkervision, Inc. | Method, system, and apparatus for balanced frequency up-conversion, including circuitry to directly couple the outputs of multiple transistors |
US8036304B2 (en) | 1999-04-16 | 2011-10-11 | Parkervision, Inc. | Apparatus and method of differential IQ frequency up-conversion |
US7929638B2 (en) | 1999-04-16 | 2011-04-19 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments |
US8077797B2 (en) | 1999-04-16 | 2011-12-13 | Parkervision, Inc. | Method, system, and apparatus for balanced frequency up-conversion of a baseband signal |
US8229023B2 (en) | 1999-04-16 | 2012-07-24 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments |
US8223898B2 (en) | 1999-04-16 | 2012-07-17 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same |
US8224281B2 (en) | 1999-04-16 | 2012-07-17 | Parkervision, Inc. | Down-conversion of an electromagnetic signal with feedback control |
US7894789B2 (en) | 1999-04-16 | 2011-02-22 | Parkervision, Inc. | Down-conversion of an electromagnetic signal with feedback control |
US7693230B2 (en) | 1999-04-16 | 2010-04-06 | Parkervision, Inc. | Apparatus and method of differential IQ frequency up-conversion |
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 |
US7822401B2 (en) | 2000-04-14 | 2010-10-26 | Parkervision, Inc. | Apparatus and method for down-converting electromagnetic signals by controlled charging and discharging of a capacitor |
US8295800B2 (en) | 2000-04-14 | 2012-10-23 | Parkervision, Inc. | Apparatus and method for down-converting electromagnetic signals by controlled charging and discharging of a capacitor |
US7991815B2 (en) | 2000-11-14 | 2011-08-02 | Parkervision, Inc. | Methods, systems, and computer program products for parallel correlation and applications thereof |
US8446994B2 (en) | 2001-11-09 | 2013-05-21 | Parkervision, Inc. | Gain control in a communication channel |
US7653158B2 (en) | 2001-11-09 | 2010-01-26 | Parkervision, Inc. | Gain control in a communication channel |
US7502357B2 (en) | 2001-12-21 | 2009-03-10 | Mitsubishi Denki Kabushiki Kaisha | Radio communication system and transmitter |
EP1551127A1 (en) * | 2001-12-21 | 2005-07-06 | Mitsubishi Denki Kabushiki Kaisha | Radio communication system and transmitter for implementing frequency diversity |
US8407061B2 (en) | 2002-07-18 | 2013-03-26 | Parkervision, Inc. | Networking methods and systems |
US8160196B2 (en) | 2002-07-18 | 2012-04-17 | Parkervision, Inc. | Networking methods and systems |
WO2006120319A1 (en) * | 2005-05-10 | 2006-11-16 | Societe Stantec | Device and method for receiving binary data radio frequency |
FR2885751A1 (en) * | 2005-05-10 | 2006-11-17 | Univ Joseph Fourier Etablissem | DEVICE AND METHOD FOR RADIO FREQUENCY RECEPTION OF BINARY DATA |
US7519400B2 (en) | 2005-05-27 | 2009-04-14 | Dei Headquarters, Inc. | Multi-modulation remote control communication system |
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