Pro-668 Poor trunking performance during scan

AerialEars · Feb 5, 2016

I have a new Pro-668 and am disappointed with its performance while SCANNING trunked systems.

I'm listening to my local P25 Phase I system with control channels in the 850 MHz range.

During scanning, the "T" on the display rarely indicates that trunking information is being received. But, if I use the browser and manually tune to a talk group, the trunking data indicator is solid and I hear communications occurring in talk groups loud and clear. The signal strength indicator is full scale.

When I return to scanning, I hear nothing. Occasionally, the display will stop and quickly display the information like it has detected a conversation, but I may hear just a tiny bit.

I appreciate your wisdom into how I may remedy this!

Greg

sallen07 · Feb 5, 2016

More than one site?

Do you have more than one site for that system loaded? If so, you might try locking out (or deleting) all but the closest one and see if that helps.

AerialEars · Feb 9, 2016

Thank you!

buddrousa · Feb 9, 2016

You may be in a RF overload area. I would try to turn on the attenuator and see if that helps as this scanner has a very hot receiver.

bharvey2 · Feb 9, 2016

When I first started using my PRO-668, I had a similar problem. In my case, I was trying to scan so much traffic that I was never hearing anything. Trying turning of all systems but one and see if that improves things.

Acru1012 · Feb 9, 2016

What does a RF overload area mean buddrousa?

bharvey2 · Feb 9, 2016

RF Overload:

Many modern receivers employee circuitry known as AGC or Automatic Gain Control. When the incoming signal is too strong, the circuit adjusts itself so that the incoming signal is within tolerable limits. One thing to keep in mind though is that while listening to one frequency, your receiver isn't completely deaf to adjacent ones as the filtration isn't perfect. The adjacent ones just aren't as strong. Those adjacent frequencies could still be strong enough however to reduce the gain of your receiver to a level that is makes you desired signal too weak to listen to. This isn't a perfect explanation but hopefully you'll get the jist of it.

buddrousa · Feb 9, 2016

It means you are near a HIGH RF TRANSMITTER TV, FM, CELL TOWER close to where you located causing the receiver to be deaf. Sometimes an outside antenna causes more trouble than good.

wbswetnam · Feb 12, 2016

Last summer I was in Minneapolis MN for a few days, and I had brought my Home Patrol 1 with me. I did the zip code location thing and I was disappointed that I was hearing almost nothing. Fortunately I also brought my laptop computer with Sentinal loaded onto it. I created a favorites list of agencies I wanted to listen to, and limited its access to a single tower. Taaaa-daaaa! It worked beautifully then. You might want to try the same thing with your Pro-668 (I also have this unit). Good luck!

NavyBOFH · Feb 12, 2016

I JUST had to chase this issue, and hours of searching as well to get a list of acceptable answers.

If you're in an RF overloaded area, you can try turning on the attenuator. When you seem to be receiving a signal, is it 1-3 bars, or full signal? That will tell you if you need the attenuator on.

Originally I thought I was having the same issue, being in a county with a simulcast system, neighboring the next county's simulcast system. Found it to be the stock antenna. The Radio Shack 800mhz scanner antenna (part number escapes me) is literally a night and day difference. I will from now on suggest to anyone scanning an 800 system to get that antenna. It will still receive quite well on VHF/UHF as well, as we have a state ham system that I still got clear as day as well.

Also, there are your DSP and Data Decode Threshold settings for trunking systems that can be changed. I am in a Frankenstein FM/P25 mix system so I had a very hard time getting all signals to come in right. The conventional/analog signals were helped by the antenna. The P25 signals were helped by going into the scanner settings and changing DSPLevelAdapt from its stock of 64 up to around 92. That allows the DSP to detect and adapt to modulating P25 signals quicker, allowing you to hear them clearly and without much delay. There is also a DAC Level, which I bumped to +1 which seemed to help as well.

The second setting, the Data Decode Threshold, is the levels at which the Control Channel will be detected and decoded to allow the scanner to do its job. IIRC, the stock setting was a min of 88 and a max of 94. I changed that to a min of 15 and a max of 95. No longer having issues with trunked systems missing calls. That setting is changed in the scanner PC software, under the Trunked Radio Systems tab. Click on a site and you'll see it in the bottom left of the window. Change the values and check the box to change across all sites.

These settings were learned from other posts and threads on here. Might not work 100% for you, but I will tell you it went from my scanner being deaf to hearing 90% of whats out there. Only way I was able to confirm it is my wife is a county EMS employee and would text me occasionally and say "did you hear that call". I kept tweaking till I was able to keep saying yes.

I hope this will help you get towards better usage of the scanner. It's sad it takes this much tweaking to get it going, but once it is - the thing is unstoppable. PS - Buy the 800 antenna! I cannot stress that enough.

NavyBOFH · Feb 12, 2016

Also, forgot to add to my last post - do all your scanning either on AC power or with NIMH AA batteries of at least 2500mAh. I bought the Panasonic Enloop Pro batteries and they work wonders. The alkaline AA batteries will cause the scanner to start going deaf and missing transmissions as the batteries get low - and AC power was inconvenient for my testing so I learned the hard way with that. BUT - when you're on AC power, use the stock USB cord - it does make a difference in RFI.

If you haven't read as well, make sure to power off the scanner when switching from AC to battery power. Maybe I am giving into the rumors, but my scanner would corrupt its SD card a couple of times before I learned to do that.

MaximusTheGreat · Feb 12, 2016

What is the maximum number reachable on the DSP Level Adapt on the main menu settings ?

NavyBOFH · Feb 12, 2016

MaximusTheGreat said:
What is the maximum number reachable on the DSP Level Adapt on the main menu settings ?

I saw that somewhere once before but can't remember. I think it was upwards of 120. I know it breaks 100 though.

Sent from my iPhone using Tapatalk

MaximusTheGreat · Feb 13, 2016

Is level adept better lower/higher or is pretty much depending on the system being monitored?

N2SCV · Feb 13, 2016

NavyBOFH said:
I saw that somewhere once before but can't remember. I think it was upwards of 120. I know it breaks 100 though.

Sent from my iPhone using Tapatalk

255.

bama9999 · Dec 30, 2016

NavyBOFH said:
I JUST had to chase this issue, and hours of searching as well to get a list of acceptable answers.

If you're in an RF overloaded area, you can try turning on the attenuator. When you seem to be receiving a signal, is it 1-3 bars, or full signal? That will tell you if you need the attenuator on.

Originally I thought I was having the same issue, being in a county with a simulcast system, neighboring the next county's simulcast system. Found it to be the stock antenna. The Radio Shack 800mhz scanner antenna (part number escapes me) is literally a night and day difference. I will from now on suggest to anyone scanning an 800 system to get that antenna. It will still receive quite well on VHF/UHF as well, as we have a state ham system that I still got clear as day as well.

Also, there are your DSP and Data Decode Threshold settings for trunking systems that can be changed. I am in a Frankenstein FM/P25 mix system so I had a very hard time getting all signals to come in right. The conventional/analog signals were helped by the antenna. The P25 signals were helped by going into the scanner settings and changing DSPLevelAdapt from its stock of 64 up to around 92. That allows the DSP to detect and adapt to modulating P25 signals quicker, allowing you to hear them clearly and without much delay. There is also a DAC Level, which I bumped to +1 which seemed to help as well.

The second setting, the Data Decode Threshold, is the levels at which the Control Channel will be detected and decoded to allow the scanner to do its job. IIRC, the stock setting was a min of 88 and a max of 94. I changed that to a min of 15 and a max of 95. No longer having issues with trunked systems missing calls. That setting is changed in the scanner PC software, under the Trunked Radio Systems tab. Click on a site and you'll see it in the bottom left of the window. Change the values and check the box to change across all sites.

These settings were learned from other posts and threads on here. Might not work 100% for you, but I will tell you it went from my scanner being deaf to hearing 90% of whats out there. Only way I was able to confirm it is my wife is a county EMS employee and would text me occasionally and say "did you hear that call". I kept tweaking till I was able to keep saying yes.

I hope this will help you get towards better usage of the scanner. It's sad it takes this much tweaking to get it going, but once it is - the thing is unstoppable. PS - Buy the 800 antenna! I cannot stress that enough.

I know this post is from nearly a year ago, and I hope I don't get scolded for resurrecting an older thread, but I just wanted to say thank you for the above information. My P25 reception on the MSWIN system on my Pro-668 was a bit sketchy most of the time, and so I changed the settings to what you mentioned in your post, and the difference in reception is dramatic! Much better decoding and audio improvement. Not a single incidence so far of a transmission "going digital", whereas before it was a fairly common occurrence.

Pro-668 Poor trunking performance during scan

AerialEars

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sallen07

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AerialEars

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buddrousa

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bharvey2

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Acru1012

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bharvey2

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buddrousa

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wbswetnam

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NavyBOFH

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MaximusTheGreat

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NavyBOFH

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N2SCV

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bama9999

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