XTS/XTL narrowband audio

[ski7669]

Several of my local counties are migrating their VHF conventional simulcast systems to narrowband. Since the switch the audio is very chopped and mutes the receiver very often on our fleet of XTS (1500, 2500, 5000) and XTL2500 mobiles. They are all programmed to transmit and receive narrow (2.5kc). Analog radios (ht1250, MT2000) radios programmed the same don't experience the same issues. Is there any way to "widen" the tolerance of the receivers of the XTS/XTL radios to stop them from clipping and muting the audio?

[Bill_G]

I've had that happen on narrow banded radios listening to wide band audio from radios we hadn't gotten to yet. Depending on the model of receiver, it can sound merely rough, or raspy, or crispy. But, in really bad cases it mutes the audio poking holes in the conversation. I suggest you have your techs PM the radios. I'm betting the mobile transmitter deviation is set too high, or the repeater deviation is too high, or both.

[alf2109]

Seeing where you're at, I'd make sure the "counties" are Txing the proper narrow band PL/DPL. A certain PSAP in NEPA is Txing wide band PL/DPL to compensate for radios that have not been converted. A quick check for you would be to disable the Rx PL/DPL to see if the "clipping and/or muting" disappears.

[Bill_G]

I'd love to know what modern radio cannot work with 500hz of PL. If it can't, it's broken. Almost two years ago I had an agency all worried about narrowbanding. They were at the point of indecision. Set all the repeaters down to 2.5kc and nobody noticed. Not one complaint. Let them run for about a month. Then I told them.

What does mess you up is hitting a narrow banded receiver with good, loud wide band. If the techs do their job right, there aren't any problems. if they just reprogram without checking alignment, they didn't do their job.

[ski7669]

It is that county you speak of in NEPA that was another frequency they did that on though. I really wish they had a way to widen the rx bandwidth a littl more on the xts xtl line

[KE7JFF]

I was going to say check the tuning for the narrow band side of things; I'm running across "new but used" radios here in SAR bought by members of groups that the narrowband specific tuning values have never been touched and wonder why everything sounds awful in and out.

[Bill_G]

I was going to say check the tuning for the narrow band side of things; I'm running across "new but used" radios here in SAR bought by members of groups that the narrowband specific tuning values have never been touched and wonder why everything sounds awful in and out.

Bingo. I've found the same thing. A lot.

[escomm]

What narrowband specific tuning values are we referring to in the Astro25 tuner?

[Bill_G]

Just deviation.

[escomm]

There's nothing narrowband specific about the deviation in tuner..... 2.83KHz does it all, wideband, narrow, P25, so on and so forth....

[Bill_G]

Ah, I see what you're asking me. You're right. There are no NB specific alignment settings in the XTS series, but there are in a lot of other models. There's nothing NB specific in MTR or Quantar alignment either. One procedure, and then we have to have faith it comes out right on each mode which it generally doesn't. Moto products tend to come out on the quiet side (+/-1.5khz), but I have seen them too high. Icom comes out hot (+/-3khz). Kenwood lands in between tending slightly high. There is a freq dependent curve. The techs have got to check the radios especially when they hear about performance issues like holes in the rx audio.

[escomm]

That's the kicker with Astro25... even the digital tuning isn't there, everything is based on the analog values. Sure you can test the BER but no adjustments to be made. MRs from the big service monitor companies get a little mad when people point this out to them

[com501]

I have been running into radios with VERY old firmware, and with tuning partitions in the R01. range. Some radios completely failed to function even line of sight a 10th of a mile until the firmware was upgraded. On wideband they were fine.