Patent ID: 9578469
Date: 2017-02-21
CPC Classifications: H04L,H04W

Claim:
1. A method for receiving at a radio receiver a direct mode operation (DMO) transmission to a talkgroup, the method comprising: scanning at the radio receiver a defined radio frequency spectrum; receiving at the radio receiver in the defined radio frequency spectrum a wake-up signal; identifying a talkgroup identifier in the wake-up signal, wherein the talkgroup identifier corresponds to a talkgroup being monitored by the radio receiver; in response to identifying the talkgroup identifier, decoding code sequences received at the radio receiver and associated with the talkgroup identifier; identifying in at least one of the code sequences both a center frequency and a transmission bandwidth of the DMO transmission; tuning the radio receiver to receive the DMO transmission at the center frequency and transmission bandwidth; and wherein the code sequences are Walsh code sequences and wherein decoding the code sequences comprises digital signal parallel processing of matched filters for Walsh sequence cross-correlation.