Could someone please tell me WHY do they say that the Pro-94 will work after rebanding but yet it will work perfect for all the sites that i have in the scanner?????? I am out in left field on this one and don't know what they mean
Scanners track trunking systems by monitoring the control channel. When the scanner detects a talkgroup ID that the user has programmed in, it picks up the channel assignment for that talkgroup from the control channel, then performs a calculation to determine the actual frequency to be tuned. The calculation uses the assigned channel number, a predetermined "base" frequency, and the step or distance between channels (12.5 or 25 KHz).
Today if a non-rebanded scanner is told to go to channel 448 in a rebanded Motorola system, it calculates the frequency as (862.0125 + (8 x 25 kHz)) and jumps to 862.2125 MHz. The problem is that channel numbers 440-559 have been "borrowed" to cover the new channels at 851-854 MHz. The correct frequency for channel 448 in a public safety system is 851.2250 MHz, but the scanner doesn't know this. Even if all of the new frequencies for the system are programmed in, the scanner still relies on the above calculation during trunking and will always tune to the wrong frequency.
If a public safety site or system uses ONLY the general category or 1-120 channels described above and/or channels between 854-862 MHz, a non-rebanded scanner should still track that system correctly, because it knows how to find those channels. However, most Public Safety systems are using a mix of existing (1-120) and "new" channels (440-559), and they will miss any communications which are assigned to the new channels. Of course, any 800 MHz scanner will still monitor the new channels in conventional mode, but talkgroups cannot be followed when scanning conventionally.
It would be helpful to know what system is being discussed, but if that system only has 1 or 2 freqs that have a 0 in the 4th decimal, it's quite possible that you might not notice the lost conversation hardly at all. If your set of users never hits those freqs, then everything would appear to be fine even with a non-rebanding supported scanner