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Old 11-10-2017, 10:07 PM
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Default Pro 106 threshold levels on simulcast systems

I can't believe I haven't thought of this before; has anyone fiddled with the low threshold setting when attempting to compensate for simulcast distortion on P25 systems?

I have adjusted the low threshold from 75 (default) to 85 on the Virginia Beach system. Seems to have an immediate improvement on reception; will have to pay attention over the weekend. I've also adjusted the low threshold for Norfolk & Chesapeake systems. No noticeable improvement yet.

If you have tweaked the low and high threshold settings, what has been your experience?


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Old 11-12-2017, 12:54 AM
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I assume you are referring to the Roam "Threshold Lo" setting?

This setting determines when the scanner should look for a better control channel.

If you have only one frequency as a control channel this setting will not make a difference. If you have more than one control channel then setting the "Threshold Lo" to a higher setting will help the scanner lock onto a better control channel (assuming they are all simulcast control channels).

At my location, I have a number of simulcast control channels for the same system. I have found that a "Threshold Lo" setting of around 92-94 works best. Lower than 92 allows a weak and unstable control channel to be maintained at times while a setting of 96 causes the scanner to move on unnecessarily from a fairly stable control channel. I always use a Threshold Hi setting of 99.

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Old 11-12-2017, 8:06 PM
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Yes I am.

If I'm understanding you correctly, with a simulcast system with a single control freq increasing the low threshold will NOT help in "nulling out" towers further away from my current location?
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Old 11-13-2017, 10:35 AM
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Quote:
Originally Posted by kc4jgc View Post
If I'm understanding you correctly, with a simulcast system with a single control freq increasing the low threshold will NOT help in "nulling out" towers further away from my current location?
That's correct. That setting simply adjusts how the scanner handles control channels (specifically when to move on to a better control channel). If only one control channel is entered in the system changing this setting will not have any real affect.

Some have mentioned turning the squelch down helps on simulcast systems. If the scanner is stationary you can try to block some of the simulcast towers with a metal object (such as a computer tower off to the side of the scanner) or the use a directional or Yagi antenna pointed in a specific direction helps. On my county system, some of the frequencies are assigned to simulcast towers and some are assigned to non-simulcast towers. Possibly there is a non-simulcast tower you can receive which will help as well. The signal strength on simulcast towers will be erratic and jump up and down considerably while the signal strength on non-simulcast towers will remain fairly consistent.

Overall, I'm just glad we still have scanners capable of receiving these systems although not perfectly.

Shawn
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