Crossband Repeater

[scc1c01]

The 911 center I’m employed by is starting up a 700MHz P25 phase 1 system and we are looking at cross banding it to our current VHF conventional system.

Is it possible to use 2 XTL2500 mobiles to link these 2 systems together? Or is there a better commercial solution?

Thanks!

 

[wa8pyr]

The 911 center I’m employed by is starting up a 700MHz P25 phase 1 system and we are looking at cross banding it to our current VHF conventional system.

Is it possible to use 2 XTL2500 mobiles to link these 2 systems together? Or is there a better commercial solution?

Thanks!

Using two back-to-back radios isn't a really good way to do what you want; unless you get it just right PTT and audio levels can be very tricky to set up right, even with the various aftermarket gadgets to do that.

Don't know what brand system you're putting in, but if I were putting in another Motorola system I'd put in a conventional channel gateway (CCGW) and connect VHF and UHF interop radios to that. You can then access those from your dispatch consoles, and patch that way. Much more reliable than using two back-to-back radios.

Harris has a similar capability but I don't remember what it's called off the top of my head.

 

[scc1c01]

Using two back-to-back radios isn't a really good way to do what you want; unless you get it just right PTT and audio levels can be very tricky to set up right, even with the various aftermarket gadgets to do that.

Don't know what brand system you're putting in, but if I were putting in another Motorola system I'd put in a conventional channel gateway (CCGW) and connect VHF and UHF interop radios to that. You can then access those from your dispatch consoles, and patch that way. Much more reliable than using two back-to-back radios.

Harris has a similar capability but I don't remember what it's called off the top of my head.

The current 700mhz system is just in the testing phase so only a handful of us have the radios for this. So we were looking at an inexpensive option to link these systems.

Do you happen to have some model numbers I can research for this project? For our VHF system the repeaters are Kenwood, and most of our mobiles are as well.

 

[mmckenna]

If this is a trunked system, the only real consideration would be to do it through the core. Work with the system administrator and/or vendor to do it correctly.

Other way to do it would be through the console.

As said above, back to back mobile radios isn't a great idea. They can quickly overheat, getting the audio to be useable is a challenge, making sure it doesn't hose up one/both systems is a real important step. Running it through the console means a dispatcher can kill if it there's an issue. Two radios in a back room somewhere is a disaster waiting to happen.

 

[johng]

In addition to connecting both to a CCGW and doing a console patch, you have another option. Get V.24 interfaces on your base stations and use this to connect the two stations together. The advantage of this is better audio quality due to no double vocoding. Also IDs, supplementary signaling and crypto will be transparent and will be repeated at both stations.

 

[buddrousa]

The safest option is to patch at the console as it is controllable and can be turned off quick if there is a problem and not render either or both systems useless if the systems lock up.