Tweaking Motorola PII performance in the TRX-2

[fluke281]

The performance of the TRX-2 on my local PII trunked system is much better than that of my Uniden BCD 996XT which has been tweaked every way possible. The performance of the TRX-2 on our Ohio MARCS system is also
superb with very little jitter and its clarity surpasses the local PII system. Although I have five bars of signal and I can choose between three antennas, the control channel (T indicator) is not always solid and there is some signal dropout and jitter from a fixed location with no wind. I am located only two miles from a transmit tower.
Under the Advanced features tab, I do see settings for DSP adjustment. Does anyone have any ideas about how this or any other setting can be used to overcome this issue?

 

[darunimal]

So Ohio Marc's ip superb,
When you say 3 antennas to pick from are you talking about 3 Digital "Sites"? And is this the site? http://www.radioreference.com/apps/db/?sid=4239

If you meant 3 Digital Sites then here is some info: 1 of a Site's Transmit/Receive Towers is close by: turn Attenuation On for that Site, in that System, so you block out the other 5 or 6 Transmit/Receive Towers, from that Site. You should be able to more cleaning decode the signal w ATT ON; that's because 1-4 Bars is better than 5 with a Digital System's Site. 5 bars could be a clear indication of receiving multiple Towers at once inside the scanner (aka simulcast signal distortion) which causes decode errors.

"Multi-Site Setting" will help while roaming get the scanner to move onto the next Site as the width is narrowed or with the number wider it will not move on so quickly.

DSP is the Digital Signal Processor 64, is the standard number for most Systems, after everything is dialed in, with both AGC 0, and both ADC & DAC at 0, with bad decode still occurring you could try -8 or +8 (to/from 64), to see if there is decode improvement (integers of 8 is just easiest). But if everything's fine and your just going off the T and 5 bars ATT ON will help the most.

 

[Nasby]

You are discovering what many of us have learned the hard way.

The GRE / Whistler scanners completely outperform the over priced, over hyped, "feature rich" Unidens (which I happen to own).

Don't even mess with the DSP. Simply program your Whistler scanner with the local towers and you are off and running. Tweaking is not needed.

 

[AggieCon]

Your biggest improvement will come from:

• Wide open squelch
• Program only one site
• Program only the active control channel
• Play around with antenna placement and orientation
• ADC not too hot
• Play with DSP if you want. Many report improvement. I've found it to be pretty mundane.

I'd keep working on it until the T is pretty much solid.

I have a 1080. Perhaps it is local conditions, but over the past 1-2 weeks (i.e. since I've done two different firmware upgrades), my P25 performance has degraded substantially. I can maintain the "T" perhaps half of the time I used to (which was almost continuously) and I have a lot of late entries to calls or complete misses. Voice decode quality is sometimes degraded too, sometimes fine.

Has anyone else noticed anything like this with the new firmware or a TRXx compared to a non-upgraded WS10xx?

 

[fluke281]

Thanks for the help. I was referring to the MARCS site in NW Ohio, not the one mentioned by darunimal. The latter one is always a problem in terms of signal dropout. I was told by a major seller of Unidens in downtown Toledo that five bars was needed for a solid signal. In the car, I only use a 3 inch antenna to avoid multipath from the 13 towers in the county but I will try the attenuator as well.
I have an antenna switch with which I choose from two outdoor antennas and an indoor. The problem with opening the squelch is that some of the channels are conventional. A digital only scanlist may be the way to go.

 

[AggieCon]

If you can afford the TRX-2, perhaps you can also get a sub-$100 scanner for the analog channels?

 

[SOFA_KING]

Can someone tell me what the latest factory settings are for the TRX-2 on ADC and DAC gain?

Mine showed ADC -2 and DAC -6, but those could have been loaded from my imported WS1080 config. I need the stock factory settings, or the settings from the last firmware update.

My digital setting of 64 is Donald-ducking a bit even on 2 bar signals, so I'm looking to optimize all these settings. 62 used to work better on the PSR-800 and WS1080. Any recommended ADC and DAC settings would be appreciated.

Thanks,

Phil

So Ohio Marc's ip superb,
When you say 3 antennas to pick from are you talking about 3 Digital "Sites"? And is this the site? Northwest Ohio Regional Public Safety System Trunking System, Toledo, Ohio - Scanner Frequencies

If you meant 3 Digital Sites then here is some info: 1 of a Site's Transmit/Receive Towers is close by: turn Attenuation On for that Site, in that System, so you block out the other 5 or 6 Transmit/Receive Towers, from that Site. You should be able to more cleaning decode the signal w ATT ON; that's because 1-4 Bars is better than 5 with a Digital System's Site. 5 bars could be a clear indication of receiving multiple Towers at once inside the scanner (aka simulcast signal distortion) which causes decode errors.

"Multi-Site Setting" will help while roaming get the scanner to move onto the next Site as the width is narrowed or with the number wider it will not move on so quickly.

DSP is the Digital Signal Processor 64, is the standard number for most Systems, after everything is dialed in, with both AGC 0, and both ADC & DAC at 0, with bad decode still occurring you could try -8 or +8 (to/from 64), to see if there is decode improvement (integers of 8 is just easiest). But if everything's fine and your just going off the T and 5 bars ATT ON will help the most.

 

[fluke281]

Yep, I have an old BCD796 for analog. My P25 quality issues are now 95% solved! I was reading about some people using 800 Mhz beam antennas to overcome the simulcast (multipath) troubles. So I converted a corner reflector UHF TV antenna by drilling the boom to allow vertical polarization, trimming the driven element to 3.5 inches on either side , and aiming it at the nearest tower. Mounted at ten feet above ground, it works great! I also saw 800 MHz Yagi's online for as little as $20. Too bad I can't use one in the mobile! Thanks for all of the help.

 

[AggieCon]

Excellent. Yes, I have to use a Yagi to receive some systems, and it helps on all of the others. I have one of the less than $20 ones. It would be funny to make a rotating directional antenna mount for the truck.

By the way, it's my guess that multipath isn't the whole problem. I think the biggest problem is the dynamic amplitude of simulcast modulation, and the discriminator constantly thinks it is losing the signal. It would also explain why leaving the squelch open helps so much.

 

[SCPD]

I wish I could hear the NJPSIC 700MHZ system good,it has LSM issues.........I was hoping the TRX-1 would be better,it is,just still have to turn the squelch down to monitor this system,im in nj.