trunked radio

I am a newbie with the PSR 500. I apologize if this is covered on another thread. I ordered my unit last year with local programming from Scannermaster (Katy/Fort Bend County). The unit works fine on conventional channels, but I am not getting the trunked systems at all. I ordered the...

Can somebody tell me about the preceding tone I hear on the Motorola Radios used by Nashua Fire? I understand that when a user presses the PTT button a 3 beep tone it emitted by THEIR radio as part of the trunked system letting the user know that the system has recognized the radio, processed...