Reports are beginning to surface of strange digital signals starting to appear on federal VHF frequencies in the Phoenix / Tucson areas of Arizona. The signals resemble Motorola trunking control channel data, but no one was able to decode or read these data channels.
The frequencies that were active with these signals were 167.6500 MHz, 167.7375 MHz, 170.7625 MHz, 173.0500 MHz, 173.2375 MHz and 173.7625 MHz. 163.8375 MHz was also heard, but very weak. It could have been an image or perhaps a mobile that was broadcasting the signal in to the repeaters.
Most likely these are digital "test patterns" used to check system coverage and signal propagation on digital radio systems. This V.52 test signal is used to check Bit Error Rate (BER) which is an important consideration in digital radio coverage. This may indicate that new trunked sites on the Justice Department's Integrated Wireless Network (IWN) P25 radio system are about to start appearing the Southwest US.
The prime contractor for the IWN is General Dynamics. Their web site, and the DoJ web site for the IWN reveal no new updates on the status of the IWN, so no idea when these new sites will be up and running, but keep searching the federal VHF band for new P-25 activity!
