Loose (Open) Squelch Improves LSM (Simulcast) Reception

[nr2d]

Diversity antenna systems have been used in the aviation industry for over 2 decades primarily on the TCAS systems on aircraft. When I worked avionics we had to test the system and it was required to have a 20 dB switchover between the top vs. bottom. When tested the system we would install a RF "muff" on the bottom that theoretically added -20 dB attenuation.

I do have a question. I see that you can change the P25 Wait Time and P25 Threshold. What dies adjusting them do?

 

[KA1RBI]

I found the biggest problem was from the control channel of the system signal strength would vary up to 30 dBm on my spectrum analyzer

30 dBm = 1 Watt. Suspect that you meant "30 dB" not "30 dBm"

Diversity antenna systems have been used in the aviation industry for over 20 decades

20 decades = 200 years. Suspect that you meant "20 years" not "20 decades"

Respectfully

Max

 

[nr2d]

Post deleted.

 

[policefreak]

Wirelessly posted (Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; LG-LS720 Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30)

Just fyi, I have noticed improved p25 decoding by lowering the squelch on the BCD436HP for distant/weak signal only.

 

[Ishmole]

Thanks! I am located outside the user area for the Rockland County System in NY. Opening up the squelch makes the difference in receiving the system or not receiving the system. I also changed the antenna to the RS 800 Mhz rubber duck and have found a few "sweet spots" in my house where I can get reception. One problem. By opening the squelch, scanning other systems, especially conventional frequencies, becomes impossible. Is there a way (Firmware) that the squelch can be set for each individual system?

Mike

 

[productionguy85]

Just an FYI, not debating anything just stating that on my simulcast system, leaving the squelch open actually does more bad then good. It constantly is held up on scanning for current CCs and I find that at the end of the convo, rarely it won't return to scan. But it has happened. As far as reception between open and closed, no difference. Just my observations from an 8 site simulcast.

 

[mtindor]

The whole "loose squelch helps multipath distortion" argument is total BS. It doesn't help that out any more than it helps out any other weak signal detection. I am really surprised that Paul, of all people, would post such nonsense.

productionguy85 is right when he says it does more harm than good. Leaving the squelch open causes difficulties with the system not reverting back to the control channel after a voice call is finished.

I should have posted as soon as this thread was started, but I waited a long time because I'm lazy. Loosening up the squelch isn't a solution or a fix for anything really, except for weak signal decode. And in the case of weak signal decoding of digital signals, if it's so weak that the squelch must be kept loose or open, then it's more than likely going to be too weak to decode anyway.

There is only one true way to combat the multipath distortion issue when it comes to scanners, and KA1RBI has already documented it well. Scanner manufacturers simply need to get on board.

Mike

 

[whsbuss]

There is only one true way to combat the multipath distortion issue when it comes to scanners, and KA1RBI has already documented it well. Scanner manufacturers simply need to get on board.

Mike

Please post the link

 

[mtindor]

Please post the link

Search for posts from KA1RBI. I'd venture to say every post Max makes is a worthy read. He has posted about it in various threads, so one link isn't going to do the trick.

Mike

 

[AndrewGS]

I cranked my squelch up all the way and I think it helped quite a bit by dropping the weaker towers off on the LSM site I'm listening to.

 

[AK9R]

Search for posts from KA1RBI. I'd venture to say every post Max makes is a worthy read. He has posted about it in various threads, so one link isn't going to do the trick.

One can start with this thread:

http://forums.radioreference.com/di.../283705-lsm-why-scanners-suck-real-story.html

And then go searching for Max's other posts on the subject.

 

[jdobbs2001]

I bet the next generation of scanners will use the actual I/Q baseband to demodulate digital vs the old school method of using the audio discriminator tap method.

 

[RF23]

I bet the next generation of scanners will use the actual I/Q baseband to demodulate digital vs the old school method of using the audio discriminator tap method.

Where did you find the info showing that the new x36HP radios are using the old school audio discriminator tap method?

I was under the impression that we have not figured out yet just how the new x36HP radios are demodulating digital signals.

 

[LiquidPandora]

Careful to many Ears tie Lips shut

 

[stgilmer]

Last post was at the beginning of 2014. Is there or has there not been a scanner developed that will scan LSM yet?

 

[phillydjdan]

Nope. Just tested a bunch of the newer models last weekend and they all failed miserably. There's a Youtube video if you'd like to see.

https://www.youtube.com/watch?v=QfqP8VYw-M0

 

[stgilmer]

Nope. Just tested a bunch of the newer models last weekend and they all failed miserably. There's a Youtube video if you'd like to see.

https://www.youtube.com/watch?v=QfqP8VYw-M0

They all seem to sound better than what i have and keep in mind 2 weeks ago it was crystal clear.

http://youtu.be/VuF9k5DdbaY

 

[JASII]

Nope. Just tested a bunch of the newer models last weekend and they all failed miserably. There's a Youtube video if you'd like to see.

https://www.youtube.com/watch?v=QfqP8VYw-M0

Thank you for posting that.

 

[mjs438]

Loose squelch does help a little.

 

[ansky]

Adjusting the squelch has not made any difference on my LSM issues. I also tried adjusting the attenuator settings but that hasn't helped much either. The only thing that works for me is very careful adjustments to my antenna position. I have to point the antenna at an odd angle and that seems to resolve most of my LSM issues.