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Thread: Theoretical question on XTL2500 cross-band repeater.

  1. #1
    duberr No Longer Registered

    Default Theoretical question on XTL2500 cross-band repeater.

    Theoretical question before I start diving into a project, not looking for information on how to do it, I'd like to work on figuring that out on my own, just if you think it's plausible. It's been years since I've done any serious radio tinkering, and this is really the first time I've started diving into Astro25 radios other than simple programming changes or firmware updates here and there, so I want to make sure I'm not trying something that's been tried and didn't work, or that isn't possible due to some technical limitation I'm not aware of. I've got two XTL2500 remote mounts installed in my truck, one 700/800 primarily for use on an analog type II TRS and a P25 TRS, the other XTL is a VHF for use on repeaterized and simplex VHF frequencies. I've got an 800 XTS5000 portable. Is it possible (ignoring potential desense issues, duty cycle limitations, licensing etc.) to link the two XTLs via the accessory ports "rick style" and use them as a full duplex cross band repeater so I could carry my 800 radio and communicate via this repeater with users operating on VHF side (assuming I'm in range of my vehicle of course)? Assuming it's possible, would there be any benefit or detriment to using digital between the portable and the 800 XTL, while remaining analog on the vhf radio?


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    I've done exactly this with VHF MCS2000 going to 800MHz XTL1500 & also XTL2500. In my case, the XTL units were in analog mode on a SmartZone system, so I can't say 100% that it'll work in digital mode, but I don't believe you'll have an issue with it.

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    would expect digital signal would be double vocoding and sound quality would be a little degraded.

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    Quote Originally Posted by b16a2 View Post
    would expect digital signal would be double vocoding and sound quality would be a little degraded.
    OP specified the VHF side would be analog, so no double vocoding would be happening.

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    A friend has done this with one of the simple interop gateways and a pair of APX7500s. The audio was double-vocoded but we successfully patched two TGs on two wide-area systems.

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    I do something simular but different per se. I link a 800 MHz type 2 analog system to a Astro25 digital system on 2 talkgroups. I do this via a radio patch setup in a Gold Elite console which is parked on the digital system. I bring the analog talkgroups in via a Consolette. When I first set this system up, both systems were analog and everything worked fine. When the local system went digital, this patch arrangement gave some issues. Noise on the analog side creates crap on the digital side. All sorts of burps and farts. Granted, this is pretty extreme on my part as the analog system is 20 miles + from my op center and I have to point a yagi through a bunch of high level RF signals to link this. On your issue, I don't think there would be any problem on your uplink being digital since you would be in close proximity to your repeat setup in the mobile. You might find issues if the analog system on the downlink side had noise either transmitted along with audio or just a weak signal that had hiss or simulcast "crackle" if it is simulcast. In that case, it would be better if the link existed in analog on both sides. Your ears can decode voice with noise on it a heck of a lot better than a digital radio with the same noisy input can transmit it and it come out right on another digital radio.

    Dave