Astro uhf

AngelFire_91 · Post by **AngelFire_91** » Thu Jul 31, 2003 6:56 pm

I guess I thought I knew what I was doing but I'm still having a problem.

On a UHF Type II system I programmed my XTS 3000. It keeps giving me an "Out of Range" error. Now I figured it was the Channel Assignments so I took a look, now here is my question that I thought I knew the answer to but I guess I don't since I'm asking it.

What exactly are the Channel Assignments (F4, F4, F3, F6) used for. Why isn't a UHF system just like an 800 where all you need is a Control Channel Assignment. It's because there is different Base frequencies and seperation right??

I was trying to program them in and I can only select 406-410 12.5khz spacing. anything else gives me an out of range warning. on another system I can't even seem to get it to work at all, I just get the warning.

Thanks,

Post by **batdude** » Fri Aug 01, 2003 9:52 pm

the radio needs the base freq, offset and freq range to enable it to work properly... here's why.

in 800 Mhz systems, all channels are assigned an FCC ID #, UHF channels are not (at least to my knowledge)

so...

in an 800 system, the outbound control channel data, when communicating with a radio to tell it what channel to go to ... just sends the FCC channel #, not the freq... and since ALL 800 repeaters are separated at 45Mhz, it's easy for the radio to compute everything.

in OBT (other band trunking) - VHF and UHF, the radio base frequency must match the central controller programming info - most UHF systems use 406.000. the freq range for TX and RX, as I recall, is kinda backwards - the TX data is the CENTRAL CONTROLLER TX info (radio receive freq), and the RX info is also the CENTRAL CONTROLLER RX info (radio transmit freq)

once your radio is programmed with the correct freq ranges for TX and RX, and you have the proper base freq *AND* offset, your Out of Range will go away.

hopefully, you've realized by now that since the central controller in OBT systems can't just send a channel # for the radio to go to, THE RADIO uses the base freq as a reference, and the offset, to determine what exact frequency to tune to for incoming audio.

be advised - this info is NOT easy to come by without either some serious data snooping (trunker) and some guesswork.... of course, easy way #2 is to just read one of the radios on the system for this info.

hope this helps a bit

doug

RocketNJ · Post by **RocketNJ** » Sat Aug 02, 2003 5:05 am

you can also check http://www.trunkedradio.net and look in the trs database. Maybe the info is there.

George

AngelFire_91 · Post by **AngelFire_91** » Sat Aug 02, 2003 9:38 am

Hey thanks for the info, That's what I thought it was. I just wanted to double check myself to make sure. Also as far as trunkedradio.net goes, I'm vary aware of it. I'm an administrator over there and have put in many many hours helping keep all the info in order. Thanks for mentioning it

Thanks,
Kevin

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