newtoscanning
Member
- Joined
- Jan 28, 2007
- Messages
- 154
A question as to how they work. I understand in principal (referring to BMR) that the ambulance/cruiser/etc. will have a smartzone radio (VHF) in it, connected to a simplex radio (UHF). When an officer/medic keys up their portable the radio transmits on a simplex frequency into the radio into the car, then it in turn keys up the trunked radio, and repeats it into the system; hence the vast spread of transmitting sites. I also understand that the actual repeaters are probably not two radios linked more so just one with dual function.
The part that I don't understand is if two (or more) units (regardless if EMS/Police/Fire) attend a call, how do they keep all of the repeaters from all trying to key up and repeat the voice into the trunk system; obvious answer, all the portable's have different frequencies. However there are how many OPP units, how many different ambulances/response cars, how many fire trucks, it would be a logistical nightmare trying to co-ordinate that (from a programming/frequency allocation perspective).
The only conclusion I can come to is that the radio has a frequency bank, and it will auto-negotiate with radios in the area (only a 1/2-1 mile range) to ensure everyone is on a different simplex frequency.
Any ideas?
Thanks
The part that I don't understand is if two (or more) units (regardless if EMS/Police/Fire) attend a call, how do they keep all of the repeaters from all trying to key up and repeat the voice into the trunk system; obvious answer, all the portable's have different frequencies. However there are how many OPP units, how many different ambulances/response cars, how many fire trucks, it would be a logistical nightmare trying to co-ordinate that (from a programming/frequency allocation perspective).
The only conclusion I can come to is that the radio has a frequency bank, and it will auto-negotiate with radios in the area (only a 1/2-1 mile range) to ensure everyone is on a different simplex frequency.
Any ideas?
Thanks