Pulse or digital communications – Receivers – Angle modulation
Patent
1994-03-28
1998-11-24
Chin, Stephen
Pulse or digital communications
Receivers
Angle modulation
375332, 375347, 375366, 455134, 455137, 4552772, H04L 2722, H04L 106, H04L 704, H04B 708
Patent
active
058418164
ABSTRACT:
A method and system for demodulating received signals in radio communication systems. Pi/4-DQPSK modulated signals can be demodulated to provide additional quality measurements and to facilitate diversity combination or selection. For example, a carrier is modulated with digital data using Pi/4-DQPSK to convey two bits of data by changing the radio carrier phase from the value at the end of the last symbol through an angle of either .+-.45 degrees or .+-.135 degrees, these four possibilities representing the bit pairs 00, 01, 11 or 10. The transitions of the radio signal are filtered in the complex (I,Q) plane to limit the spectrum. At the receiver, the received signal is downconverted, filtered and amplified using a hard-limiting intermediate frequency (IF) amplifier. The IF amplifier also produces an approximately logarithmic indication of the signal strength before limiting. The hard-limited IF signal containing phase information is fed to a direct phase digitizer. A numerical value representing instantaneous phase is produced and processed to demodulate data symbols. The demodulated data symbols can be combined with the logarithmic signal strength information to produce quality-annotated data bits to an error-correction decoder.
REFERENCES:
patent: 3783385 (1974-01-01), Dunn et al.
patent: 3987422 (1976-10-01), Yanagidaira et al.
patent: 4099121 (1978-07-01), Fang
patent: 4531235 (1985-07-01), Brusen
patent: 4871974 (1989-10-01), Davis et al.
patent: 4879728 (1989-11-01), Tarallo
patent: 5016206 (1991-05-01), Shinonaga
patent: 5017883 (1991-05-01), Divsalar et al.
patent: 5020076 (1991-05-01), Cahill et al.
patent: 5031193 (1991-07-01), Atkinson et al.
patent: 5048059 (1991-09-01), Dent
patent: 5065411 (1991-11-01), Muto
patent: 5084669 (1992-01-01), Dent
patent: 5095392 (1992-03-01), Shimazaki et al.
patent: 5109392 (1992-04-01), McDonald
patent: 5122758 (1992-06-01), Tomita
patent: 5140613 (1992-08-01), Birgenheier et al.
patent: 5151926 (1992-09-01), Chennakeshu et al.
patent: 5157693 (1992-10-01), Lemersal, Jr. et al.
patent: 5165057 (1992-11-01), Sharples
patent: 5182749 (1993-01-01), Kazecki et al.
patent: 5187719 (1993-02-01), Birgenheier et al.
patent: 5202643 (1993-04-01), Sato
patent: 5202901 (1993-04-01), Chennakeshu et al.
patent: 5203027 (1993-04-01), Nounin et al.
patent: 5208836 (1993-05-01), Edbauer
patent: 5214687 (1993-05-01), Kansakoski et al.
patent: 5220275 (1993-06-01), Holmqvist
patent: 5241545 (1993-08-01), Kazecki et al.
patent: 5260673 (1993-11-01), Pham
patent: 5280637 (1994-01-01), Larosa et al.
patent: 5289504 (1994-02-01), Wilson et al.
patent: 5291519 (1994-03-01), Tsurumaru
patent: 5295162 (1994-03-01), Zarembowitch
patent: 5299235 (1994-03-01), Larsson et al.
patent: 5325403 (1994-06-01), Siwiak et al.
patent: 5335250 (1994-08-01), Dent et al.
patent: 5347535 (1994-09-01), Karasawa et al.
patent: 5363412 (1994-11-01), Love et al.
patent: 5369378 (1994-11-01), Kosaka et al.
patent: 5428647 (1995-06-01), Rasky et al.
patent: 5436942 (1995-07-01), Cheng et al.
patent: 5465271 (1995-11-01), Hladik et al.
patent: 5488638 (1996-01-01), Kazecki et al.
"Bird Watching", Dan Sweeney, Cellular Business, pp. 23-46, Jul., 1993.
Croft Thomas M.
Dent Paul W.
Chin Stephen
Ericsson Inc.
Gluck Jeffrey W.
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