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Alex alex323@gmail.com [op25-dev] op25-dev at yahoogroups.comHello, Let's say you're scanning the airwaves in the frequency range of a known P25 system and come across a spike in power at one particular band that never shuts off. * You should think that you've located a control channel, correct? * If so, is it safe to say that the upstream and downstream channels are side-by-side (one contiguous frequency band)? * What is the most accurate way of determining whether what you've discovered is a Phase I or Phase II system? * When someone keys up a radio, is the following sequence of events accurate?: 1. The radio sends a packet via the upstream control channel indicating that it wishes to speak. 2. The fixed site sends a packet via the downstream control channel indicating a frequency X on which it wants the speaker to transmit. 3. The fixed site sends a packet via the downstream control channel instructing all radios in the talk group to tune in to a frequency Y. 4. The speaker transmits on frequency X, and the fixed site acts as a repeater, re-broadcasting the audio to frequency Y. -- Alex -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/op25-dev/attachments/20170507/7dc38c08/attachment.htm>