Sample timing and carrier frequency estimation circuit for sine-

Details Sample timing and carrier frequency estimation circuit for sine- Sample timing and carrier frequency estimation circuit for sine-

1991-05-21

1992-09-29

Chin, Stephen

Pulse or digital communications

Repeaters

Testing

329304, H04L 2722

Patent

active

051519267

ABSTRACT:
A digital radio receiver for synchronization of radiowave transmissions for digital and analog FM signals in TDMA systems such as cellular telephones uses a Sine/Cosine detector that minimizes the bit error rate. The detector employs an A/D converter, a sorter circuit that produces a predetermined number of samples to be used in the decoding based upon a sample timing adjustment, and a sample and phase adjustment circuit that selects samples based on a sample timing adjustment and adds a carrier phase adjustment to the samples. A cosine detector and a sine detector each decode samples into signals that are measured by a cosine level check circuit and a sine level check circit respectively. A decision logic circuit produces a pair of bits from the levels detected by the cosine level check circuit and the sine level check circuit as the decoded transmitted information. Adjustments to the sample timing and carrier phase are performed by an adjustment circuit that monitors the phase error between the decoded information and a predetermined information set in the preamble of each TDMA slot. The adjustment circuit sends the sample timing and carrier phase adjustments to the SPA circuit which selects different samples to be decoded and uses the carrier phase adjustment to recalculate different coefficients from these samples and pass the signal through the remainder of the circuit and eventually to the adjustment circuit. The signal is iteratively cycled through this loop until the best sample timing and carrier phase adjustments are reached.

REFERENCES:
patent: 3993956 (1976-11-01), Gilmore et al.
patent: 4608540 (1986-08-01), Tsuchiya et al.
patent: 5029186 (1991-07-01), Maseng et al.
T. S. Rappaport, S. Y. Seidel and R. Singh, "900 MHZ Multipath Propagation Measurements for U.S. Digital Cellular Radiotelephone," IEEE Globecom Conference Record, Nov. 1989, Dallas, TX vol. 1, pp. 3.2.1-3.2.6.
Motorola, Inc., Arlington Heights, Ill. "Discussion of Pi/4 Shift DQPSK," Submitted to the TIA Technical Subcommittee, TR-45.3 WG III Modulation Task Force, Washington, DC pp. 1-13.
G. J. Saulnier; C. McD. Puckette, IV;R. C. Gaus, Jr.; R. J. Dunki-Jacobs and T. E. Thiel, "A VLSI Demodulator for Digital RF Network Applications: Theory and Results," IEEE Journal on selected Areas in Communications, Oct. 1990, vol. 8, No. 8, pp. 1500-1511.

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