Loose (Open) Squelch Improves LSM (Simulcast) Reception

[jcardani]

Hi Max,

Where can I find the code that you wrote for the Gardner DQPSK demod block and C4FM modulator block?
I did not notice it in the OP25 site unless I was looking in the wrong folder.

Would also like to bring this to PM (off list) because it is not on topic for the "open squelch" fix.

thanks,
Joe

 

[bhall7]

FYI, I downgraded the firmware in my BCD396XT to 1.10.00 (from 1.11.01) and I have noticed a major improvement in reception of LSM P25 systems.

 

[KA1RBI]

Hi Max,

Where can I find the code that you wrote for the Gardner DQPSK demod block and C4FM modulator block?

Pull the OP25 repo and then do

find | grep -e gardner -e op25_c4fm_mod.py  | grep -v svn

Max

 

[SCPD]

From what I understand is that it's not the antenna side.... it's the scanner. You can have a ton of antennas and it's not going to change anything with decoding. The problem lies with the decoding not the signal....however this is my personal thoughts.... I could be wrong.

The problem resides with the scanner jumping from SITE to SITE instead of locking on to the strongest site.... this has been a known uniden issue since the bcdx96t models and with almost full certainty will continue until UNIDEN fixes their control channel decoder and adds a little less sensitivity to their scanners. and the ability to block out sites by site ID..... every site has an ID... if uniden could let the SITE ID "***" be set to a SINGULAR site it would work just fine... but uniden allows their scanners to SITE HOP and accept interference from stronger neighboring sites which locks onto a new site with because of adjacent intermod frequencies for same system ... and the uniden antenuation is too much... make it for selectable between 1 3 and 6.. and so on... that would solve the intermod interference that causes sites to be dropped......

 

[KC8ESL]

The simulcast is multiple sites transmitting exactly in phase with each other on the same frequency. The problem is that all of those sites aren't delivered to your antenna at precisely the same moment in time.

Your radio cant decypher which site it is listening to because the way it sees it, it is all the same.

Again, I say: the poor mans fix is to use the worst antenna you can get your hands on and hope it doesn't pick up more than one simulcast site.

 

[tsalmrsystemtech]

That's SAD that you have to dumb down your scanner to a bad antenna and use yagi antenna's and bury your scanner in a ditch and put dirt on top of it to hopefully make it stop picking up strong signals.

Its pretty SAD. Get a real radio which will cost you about the same amount of money for a new phase II scanner and set it to CQPSK and problem is fixed for once and for good.

Trust I love scanners too because of the all bands all in one. Having a variety of commercial grade radios and Uniden BCT15X and a 996XT and a GRE PSR 600 in your stable will make you a real happy listerner.

 

[KC8ESL]

Its a hobby, not a profession. I don't want to endlessly search for codeplugs for moto gear etc etc etc. I want to easily program my scanner and listen.

What's sad is investing $100 into a yagi and getting the same results, at higher gain.

Not to turn this into a ham radio mentality type thread but if it's in your junkbox, use it.

 

[AZScanner]

Sounds to me that you've found a niche in the market that needs filling. If you can build such a mod, I say do it. Suppose the board and installation instructions could be provided to buyers for $100 or so... If that were the case and the product existed, I would buy one right now. Today.

Something to consider.
-AZ

Sent from my HTC Desire C using Tapatalk

 

[kaiserfan]

That's SAD that you have to dumb down your scanner to a bad antenna and use yagi antenna's and bury your scanner in a ditch and put dirt on top of it to hopefully make it stop picking up strong signals.

Its pretty SAD. Get a real radio which will cost you about the same amount of money for a new phase II scanner and set it to CQPSK and problem is fixed for once and for good.

Trust I love scanners too because of the all bands all in one. Having a variety of commercial grade radios and Uniden BCT15X and a 996XT and a GRE PSR 600 in your stable will make you a real happy listerner.

If I'am reading your post right there isn't a fix for the HP1 or any Uniden scanner but at the end you recommend a Uniden BCT15X dose this scanner work on simulcast systems?

 

[AZScanner]

If I'am reading your post right there isn't a fix for the HP1 or any Uniden scanner but at the end you recommend a Uniden BCT15X dose this scanner work on simulcast systems?

I would say out of the box, no. With a lot of work (such as tapping the discriminator, feeding that to Unitrunker and DSD, etc), yes, with the caveat that you'll still struggle with simulcast distortion after all that work.

-AZ

Sent from my HTC Desire C using Tapatalk

 

[kaiserfan]

I would say out of the box, no. With a lot of work (such as tapping the discriminator, feeding that to Unitrunker and DSD, etc), yes, with the caveat that you'll still struggle with simulcast distortion after all that work.

-AZ

Sent from my HTC Desire C using Tapatalk

Why should anyone buy a Uniden product if this true

 

[AZScanner]

Why should anyone buy a Uniden product if this true

What I stated would be the case with ANY analog scanner, not just the Uniden models like the BC15. None of them will work on a LSM digital radio system out of the box. They are analog scanners!

I'm hopeful that the new Unidens hitting the streets next month will be a big improvement on LSM. I will be posting a video comparison between my BC796D and my new BC436HP when it arrives. I would suggest waiting for that video before making any overall judgement on Uniden scanners.

-AZ

 

[kaiserfan]

What I stated would be the case with ANY analog scanner, not just the Uniden models like the BC15. None of them will work on a LSM digital radio system out of the box. They are analog scanners!

I'm hopeful that the new Unidens hitting the streets next month will be a big improvement on LSM. I will be posting a video comparison between my BC796D and my new BC436HP when it arrives. I would suggest waiting for that video before making any overall judgement on Uniden scanners.

-AZ

Sorry but that statement isn't accurate i have an HP1 it gets progressively worse at decoding signal of simulcast signal i also listen to a live broadcast of the same channels on broadcastfy and they are clear as a bell they were garbled at one time but no longer so there is a scanner that will work however i have no way to find out what it is

 

[RF23]

See if the Broadcasity site you listen to lists the radio being used, many do this may help.

I know of several people in the same city with the same radio model that have very different success rates with multiple towers transmitting the same info. It appears that location and kind of antennae used are critical for success in this area. Therefore, the people who are asking “how well will the new radios work where they live” are critical questions but with simulcast problems they may have to actually use one of the new radios at their home with their antenna setup to see how it will work.

 

[kayi4cle]

Sorry but that statement isn't accurate i have an HP1 it gets progressively worse at decoding signal of simulcast signal i also listen to a live broadcast of the same channels on broadcastfy and they are clear as a bell they were garbled at one time but no longer so there is a scanner that will work however i have no way to find out what it is

I’m not an expert, but I think the problem is that there are many factors entering into simulcast reception. For example, at my home I struggle to receive a certain simulcast system with my Pro-106 and other digital radios. But, if I get in my car and take my Pro-106 five miles in a certain direction, reception drastically improves. At home on an upper floor I can get the same system pretty well only with a yagi antenna using a Uniden 996T, but not as well with a Pro-197. Certainly my urban location factors into that equation. And whoever is providing the live Broadcastify stream you are listening to would surely not be providing it if reception weren’t clear where their particular setup was located. So my point is, any newer digital scanner will work if placed at such point in the simulcast system area where reception is clear, but if you are right between several towers, you can expect a garbled mess. Of course, YMMV!

I am hoping that some of the newest radios that are expected out next year will show some improvement on simulcast. If not, yagi antennas that are constructed with flexible coax and BNC connection attached would be very helpful to me. And, I also want a desktop version!

 

[AZScanner]

Sorry but that statement isn't accurate i have an HP1 it gets progressively worse at decoding signal of simulcast signal i also listen to a live broadcast of the same channels on broadcastfy and they are clear as a bell they were garbled at one time but no longer so there is a scanner that will work however i have no way to find out what it is

No. It very much IS accurate. The scanner being used to provide that feed could be identical to yours. The difference is probably where its located and what type of antenna is in use. I've studied this issue backward and forward and tried numerous solutions. The only way to truly resolve this issue is to isolate the signal to one tower via a directional antenna or just not use a scanner at all - use a Motorola radio instead. That is the plain and honest truth.

-AZ

Sent from my HTC Desire C using Tapatalk

 

[kaiserfan]

See if the Broadcasity site you listen to lists the radio being used, many do this may help.

I know of several people in the same city with the same radio model that have very different success rates with multiple towers transmitting the same info. It appears that location and kind of antennae used are critical for success in this area. Therefore, the people who are asking “how well will the new radios work where they live” are critical questions but with simulcast problems they may have to actually use one of the new radios at their home with their antenna setup to see how it will work.

This particular Broadcastfy feed dosn't list scanner being used or a way to contact the provider

 

[nr2d]

post deleted. discussed early on in this thread. Sorry.

 

[DaveIN]

Lets get back to signal reports for Simulcast P25 systems guys.

 

[nr2d]

That's the difference between a $6000 radio and a $400 scanner.

Not necessarily true. I was asked to help a local PD who was having coverage problems on their analogue trunk system it shared with the adjoining town. The site was 3 miles away. Everyone blamed it on the aircraft on approach to the airport where I work at.

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. And this didn't happen when aircraft were flying over either. They happened at all times. I gave my findings to the PD and their system engineers and of course the engineers said I didn't know what I was talking about.

As UPMan said many factors can cause the problem of signal drop out, rain fade, vegetation i.e. leaves on the trees, loose transmit antennas, multi-path cause by structures, antenna attenuation i.e. using a handheld radio with the antenna close to the users body.

The way I look at digital communication vs analogue communications is that in digital it is either there or it isn't vs analogue at least if the signal faded you might still be able to hear it.

Just my $0.02.