Pulse or digital communications – Repeaters – Testing
Patent
1993-10-19
1994-12-27
Cangialosi, Salvatore
Pulse or digital communications
Repeaters
Testing
H04L 2730
Patent
active
053772261
ABSTRACT:
An adaptively-tuned filter (80) for use within the receiver (14) of a multiple-access code division (CDMA) communication system permits spectrally-inefficient transmissions to be made from each transmitter (12) used with such system, thereby simplifying the transmitter circuits, yet still achieves a signal-to-noise ratio (SNR) that approaches the SNR achieved when spectrally-efficient transmissions are made. The adaptive filter (80) also compensates for signal distortions resulting from multiple signal paths. The receiver (14) includes RF receiving circuits (60, 62), a matched filter (64), downconversion circuits (66, 68, 92), sampling circuits (70, 71, 72), a time acquisition circuit (76), an adaptive filter (80), a decimator circuit (75), a despreader circuit (77), and an accumulator circuit (78). The adaptive filter (80) includes, e.g., two LMS gradient filters (96a, 96b), or equivalent, that operate independently in parallel, with an accurate bit decision being used to select the tap signals to be used as the starting point for the next bit. The filters (80, 96) function as a fractionally-spaced chip-MSE equalizer that improves the bit-SNR in the presence of sufficient multi-access noise, and also provides narrowband noise rejection.
REFERENCES:
patent: 5161168 (1992-11-01), Schilling
patent: 5208829 (1993-05-01), Soleimani et al.
patent: 5276705 (1994-01-01), Higgins
patent: 5280472 (1994-01-01), Gilhousen et al.
Cangialosi Salvatore
Denson-Low Wanda K.
Gudmestad Terje
Hughes Aircraft Company
Lindeen III Gordon R.
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