I live in Marin County and public safety here uses a fairly new Motorola Type II Smartzone TRS with IMBE digital voice. On one of their new radio sites, I was hearing two control channels at once - One normal Smartzone CC, and another one that sounded very similar to that (kind of like a Type I CC but with even more time between peaks). I was told that it was some kind of datastream generated by the motorola site trunking equipment as a test signal for radios.sounds like a datastream not a control channel. but i could be wrong. i haven't heard anything like that before.