Hello! This is my first time posting, so please bear with me. I'm still learning the jist of the "Radio" in "Radio over IP."
I'm in a bit of a pickle regarding an MTR2000 and remote keying via Raytheon NXU-2A. When I send audio from my software dispatch console, I can hear the tones and see that it's keying the MTR2000 just fine, but the MTR2000 "reflects" my audio back at me almost immediately after keying it up.
I don't have this problem when using HT stations, and in fact my software dispatch console can receive audio coming back from the MTR2000 quite well. The trouble is keying and maintaining latch. I almost feel like the MTR2000 is pre-empting my dispatch console.
The MTR2000 is configured in Base Operation, Conventional, Analog Only, using a 4 wire TTN5067 wireline board. The wireline interface is where I'm connected to the NXU-2A. I'm also in full duplex mode.
Is there something I'm missing? What should I be checking?
I've been lurking the forums for a while looking for an answer, but I haven't found one yet. Any help you folks are able to offer would be immensely appreciated!
MTR2000 Remote Keying via RoIP
Moderator: Queue Moderator
Re: MTR2000 Remote Keying via RoIP
So, you're saying the MTR keys up, then immediately dekeys?
Tell us a bit more about your set up - is it deployed, or on the bench for test? What tone standard is your soft console using? What soft console are you using?
Tell us a bit more about your set up - is it deployed, or on the bench for test? What tone standard is your soft console using? What soft console are you using?
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Astro Spectra
- Posts: 668
- Joined: Sat Sep 22, 2001 4:00 pm
Re: MTR2000 Remote Keying via RoIP
You say base, is it single frequency? If yes then the MTR's receiver is listening to its own transmitter as you would expect unless you take steps to mute it.
Alternative if it is a two frequency set up then is the interface two or four wire?
Alternative if it is a two frequency set up then is the interface two or four wire?
Re: MTR2000 Remote Keying via RoIP
Oh yeah. Thanks for the memory jog. Totally true. The MTR2000 always receives. So, in a simplex base with a four wire full duplex interface, you will always hear yourself coming back down the line. The fix is to set the NXU and/or the console for half duplex to mute the receive side during xmit.Astro Spectra wrote:You say base, is it single frequency? If yes then the MTR's receiver is listening to its own transmitter as you would expect unless you take steps to mute it.
Alternative if it is a two frequency set up then is the interface two or four wire?
But, I suspect what is happening is he's losing low level guard tone through the NXU link causing the station to dekey. He may have the levels set too low, or he's having high frame loss causing the LLGT to warble making the station dekey. He can increase his delays to collect more packets, but if it's real bad, that won't help. He'll have to switch to hardware control (PTT and COR).
I have notes from 2009 on this very problem - NXU's through a dsl to a simplex MTR2000 base station.
Re: MTR2000 Remote Keying via RoIP
Sorry I didn't reply to this sooner. Been banging my head against this one for a while.
Bill_G was right. It was a tone issue; the low level guard was set to the right frequency but the amplitude wasn't enough to keep the radio system keyed up. I was trying to do too much with too many different moving pieces, there are some desk sets in play from a different radio manufacturer that the MTR2000 was set to compensate for (this rabbit hole goes way too deep, honestly), but I was using the factory default settings from Motorola.
To be sure, I broke out the oscilloscope and tested the receive audio coming out of the NXU-2A over the wireline interface. Bupkuss. Increasing the amplitude on the low level guard tone fixed me right up.
Thanks for the nudges in the right direction!
Bill_G was right. It was a tone issue; the low level guard was set to the right frequency but the amplitude wasn't enough to keep the radio system keyed up. I was trying to do too much with too many different moving pieces, there are some desk sets in play from a different radio manufacturer that the MTR2000 was set to compensate for (this rabbit hole goes way too deep, honestly), but I was using the factory default settings from Motorola.
To be sure, I broke out the oscilloscope and tested the receive audio coming out of the NXU-2A over the wireline interface. Bupkuss. Increasing the amplitude on the low level guard tone fixed me right up.
Thanks for the nudges in the right direction!
Re: MTR2000 Remote Keying via RoIP
Well, that's good news. Glad it was so simple.
The NXU has a LED to show relative audio levels. ie: dark = too low to detect, super bright = clipping. You want it to blink with normal conversation. There are pots on the back to set the in and out levels preset at the factory to -10db. It's best to get the input level in the -10db range (if possible), and leave the pots alone (if possible). That way you know that a steady LED is neg ten. But, it means you can't see if LLGT is present. And, of course, with it's DB15 connector, it's difficult to breakout the pins so you can measure gozzinta and gozzoutta. I made an intercept block out of old cables and a barrier strip that I labeled so I could easily measure levels at the back of the box. Real time saver.
The NXU has a LED to show relative audio levels. ie: dark = too low to detect, super bright = clipping. You want it to blink with normal conversation. There are pots on the back to set the in and out levels preset at the factory to -10db. It's best to get the input level in the -10db range (if possible), and leave the pots alone (if possible). That way you know that a steady LED is neg ten. But, it means you can't see if LLGT is present. And, of course, with it's DB15 connector, it's difficult to breakout the pins so you can measure gozzinta and gozzoutta. I made an intercept block out of old cables and a barrier strip that I labeled so I could easily measure levels at the back of the box. Real time saver.