Abstract: An apparatus for acquiring a pseudo-random (PN) sequence timing for a code division multiple access (CDMA) radiotelephone. A buffer stores samples of representations of at least one pilot signal. A correlator coupled to the buffer is operable to correlate at least a portion of the samples with a PN sequence at each of a plurality of different PN offsets to produce corresponding correlation energies. A controller coupled to the correlator interrupts the correlator as soon as the PN sequence at a particular PN offset produces a correlation energy at least equal to an energy threshold.

Abstract: A method of activating a radiotelephone operable in a spread-spectrum multiple access radiotelephone system. A searcher receiver (114) is activated, and the searcher receiver (114) acquires a PN sequence timing of a pilot signal. At least one demodulation branch (122) is activated after activation of the searcher receiver (114), and the demodulation branch synchronizes to the PN sequence timing of the selected pilot signal after the searcher receiver (114) has acquired the PN sequence timing.

Abstract: By time-sharing demodulator hardware between a primary data path (165), a power control data path (161), and a received signal strength indicator (RSSI) path (163), an entire power control data path (161) can be implemented in a demodulator (140) of a spread spectrum subscriber unit receiver with a low increase in gate count. The primary data path (165) and the power control data path (161) time-share a complex conjugate generator (270), a complex multiplier (280), and a real component extractor (290). Due to timing requirements, though, the channel estimation filter (240) of the primary data path cannot be time-shared with the power control data path. Instead, dynamic coefficient scaling is added to an infinite-duration impulse response (IIR) filter in the RSSI path (163) so that the IIR filter (250) with dynamic coefficient scaling can be time-shared between the RSSI path (163) and the power control data path (161).

Abstract: By time-sharing demodulator hardware between a primary data path (165), a power control data path (161), and a received signal strength indicator (RSSI) path (163), an entire power control data path (161) can be implemented in a demodulator (140) of a spread spectrum subscriber unit receiver with a low increase in gate count. The primary data path (165) and the power control data path (161) time-share a complex conjugate generator (270), a complex multiplier (280), and a real component extractor (290). Due to timing requirements, though, the channel estimation filter (240) of the primary data path cannot be time-shared with the power control data path. Instead, dynamic coefficient scaling is added to an infinite-duration impulse response (IIR) filter in the RSSI path (163) so that the IIR filter (250) with dynamic coefficient scaling can be time-shared between the RSSI path (163) and the power control data path (161).

Abstract: In the digital FM demodulator (330), a hard limiter (333) receives a modulated analog IF signal and limits the voltage of the IF signal to two levels. Next, a direct phase digitizer (336) uses zero-crossings of the limited IF signal to generate N-bit digital words. A phase differential circuit (340) computes the phase shift of the signal from the direct phase digitizer over a predetermined time interval. The dynamic range of the phase differential signal can be increased by replacing the phase differential circuit (340) with a high-resolution phase differential circuit (700). After digital demodulation and filtering and gain control by audio processor (360), the recovered signal is forwarded to a speaker (390) to produce an audio output. Thus, the digital FM demodulator both avoids problems common to analog discriminator circuitry and offers a reduced complexity, size, and power consumption alternative to conventional digital FM demodulators.