Batboard

Our area has a new 700/800MHz trunked system they are trying to get all county departments on, only downfall is they will not pay for the radios for us to get on it. My knowledge on radios is pretty basic so bare with me...

We have a VHF repeater system already setup for our area. we have 3 Voters and 1 MTR Transmitter. Is there a way we can integrate a 700/800MHz mobile radio to work with our current system? My idea would be to hook up the 700/800 radio to the MTR so when we key up on a portable it will still work the same way on our vhf end, but it will also key up on the 700/800 system as well and vise versa, when we are called on the 700/800mhz system it is sent over our vhf mtr. Is this something that is even possible? Our current VHF system has great coverage and works flawlessly I am trying to figure out the most cost effective way to get onto the new system without buying all new portables and mobiles.

Thank you.

- Ben

It's called a cross band repeater, and it's totally possible, but prone to disappointment. Be prepared to fiddle with it. If you are tying into a 700/800 trunking system, it's not going to be as snappy as the VHF repeater because of the timing issues of waiting for the channel allocation before speech will pass. You might miss only a syllable, or maybe a whole word, going from VHF to 800. Then, there are the levels issues. It can be made to sound horrible very easily. And finally, there is the P25 versus analog audio quality issue. Normal noise on the VHF will turn into terrible distortions on the P25 side, and P25 mushiness will sound even more muffled on analog.

There a number of ways to do it. You should probably have your radio shop walk you through it, and get you pricing. It's not going to be super cheap. And in fact, it's something dispatch should work on to build it into their console. I'm sure some of the guys will offer more specific recommendations. I tend to stay away from them because they are a PITA when it's between a trunking and an analog system. But, Lord knows there are hundreds of Interoperability folks out there that will tell you it works perfect when done correctly - for the right amount of money.

thank you for the response Bill. I have to set up a meeting with our radio shop to talk about this for sure, just trying to get a little background so I am not going into the meeting with nothing.

I believe Harris has a bit of kit that does this. I saw a demo at APCO a couple of years back. It stores up the analog audio until it gets the channel grant, aka go ahead tones, on the trunking system. Complex, expensive, but it works.