This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/op25-dev@lists.osmocom.org/.
'Ralph A. Schmid, dk5ras' ralph@schmid.xxx [op25-dev] op25-dev at yahoogroups.comHi, Usually the uplink frequency is quite a bit away, and very often this is a fixed spacing. In Germany for example the uplink is, depending on the frequency band, 4.6, 5 or 10 MHz below the downlink. Ralph. From: op25-dev at yahoogroups.com [mailto:op25-dev at yahoogroups.com] Sent: Monday, May 8, 2017 5:44 AM To: op25-dev at yahoogroups.com Subject: [op25-dev] Control channel questions Hello, 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/20170508/ccd4280f/attachment.htm>