La Porte declared ''dead zone'' for scanners

losttapes219 said:

laporte declared ''dead zone'' for scanners

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That is certainly interesting.

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Oh please.

This is absurd. The garbage pail consumer scanners cannot properly receive LSM and deliver usable audio. Instead of pointing the finger at the system owners, who's priority is delivering a functional, robust radio system for their USERS and not entertainment for scanner owners who's substandard equipment cannot comply with established TIA/EIA P-25 standards, this article blasts the police chief and everyone involved with some voodoo conspiracy theory Alex Jones crap.

How about sticking the microphones in the face of representatives from the consumer scanner radio manufacturers who REFUSE to put out a quality product capable of producing usable sound from the established and industry standard modulation known as linear simulcast? There is the answer as to why digital scanners don't work in LaPorte and thousands of other places where P-25 CQPSK LSM is deployed (and works perfect for those of us who maintain such systems).

How about a real story on the well documented problems that consumer scanners are inferior products hawked by companies who don't care about their customer being able to use the product as advertised?

Oh that would mean real actual reporting and not "fake news".

SMH. The article is a complete puff piece full of stale air.

What a joke. Do the system subscribers work as intended? Then the system is performing correctly.

Gone
Are the days of using cheaply made or low cost scanners to listen to your local police.
The above scanners are not designed for listening to simulcast communications.

LSM=
L=Lousy S=Stifiling M=Motorboating
As opposed to:
Linear simulcast modulation

I am picking up Laporte Co loud and clear, I get the Laporte Co Sheriff, FD and Michigan City PD no problem, strange though it is coming across Lake County SAFE-T. For some reason also I get Jasper and Newton Co also off Lake.

'''I feel very strongly people have a right to hear what their law enforcement is doing. We have a partnership with our public and we're asking them to be our eyes and ears and they've been really good in supporting us and helping us,'' said Boyd.'

That's refreshing to read.

vocoder said:

LSM=
L=Lousy S=Stifiling M=Motorboating
As opposed to:
Linear simulcast modulation

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Back in the day there used to be various modifications for scanners such as Bill Cheeks 4 level discriminator which got him in so much trouble.

Now by design, we have a factory installed 4 level discriminator that is lousy at decoding LSM . So we need an I/Q demodulator for that.

I propose a LSM to C4FM translator circuit.

We need a genius (anyone but me) to design a little board that taps into the IF signal just before the discriminator and does the I/Q demodulator function of LSM and then squirts the data as C4FM IF modulation back into the 4 level demodulator. It could be done in DSP a FPLA or a microchip. Some sort of magic on a board.

You could open up your Uniden or Whistler scanner, cut a trace in the IF, tack in two small coax cables , ground and power and off you go.

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RFI-EMI-GUY said:

Back in the day there used to be various modifications for scanners such as Bill Cheeks 4 level discriminator which got him in so much trouble.

Now by design, we have a factory installed 4 level discriminator that is lousy at decoding LSM . So we need an I/Q demodulator for that.

I propose a LSM to C4FM translator circuit.

Click to expand...

Maybe the scanner manufacturers should just design a modern product that has an I/Q demodulator for LSM? Unication did it. Our agency has 2 demo G5's. Guess what: they pass PERFECT audio as good as our APX radios and cost not too much more what these garbage pail crap scanners do.

MTS2000des said:

Maybe the scanner manufacturers should just design a modern product that has an I/Q demodulator for LSM? Unication did it. Our agency has 2 demo G5's. Guess what: they pass PERFECT audio as good as our APX radios and cost not too much more what these garbage pail crap scanners do.

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Uniden and Whistler probably won't spend the R&D to upgrade to their product line. But a third party could engineer a fix. Think of Sherwood and their filter and synchronous AM upgrades for shortwave radios.

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They make it sound like something terrible but if this is just simulcast distortion a tight beam yagi should take care of it. Unless I'm not seeing more of this picture.

losttapes219 said:

laporte declared ''dead zone'' for scanners

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You might be jumping to unwarranted conclusions of gloom & doom.

RFI-EMI-GUY said:

Uniden and Whistler probably won't spend the R&D to upgrade to their product line.

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All the more reason not to buy their products. If they won't put out a decent product that can properly deal with modern digital voice including LSM, which has been part of the P-25 working group standard for 15+ years, than they won't get my money.

I am for sure going to pick up a Unication G5. The demo I am playing with works flawlessly on our Astro 25 7.14 LSM 800 system. It's also built like a professional piece of equipment and not some cheap flimsy plastic crap.

Here is a small video of my PSR 500 receiving LaPorte County Sheriff coming across Lake Co simulcast CC.

https://youtu.be/A82vrqse20w

Laporte co is probably on lake simulcast cuz it is a peer for now
Porter co simulcast shows as an offline peer until it is brought online.
Lake co might be in (peer) place of porter co until it is online.

OKAY, gonna say this ONE MORE TIME....
For EVERY COUNTY ON SAFE-T, there is an "roaming"' buffer consisting of 2 counties in all directions. That means that unless an TG is SITE LOCKED, you can hear it on ANY SITE that an unit using it affiliates with in an up to 8 -10 county circle of the TG home county! Hmmmm Lake County within that buffer zone of La Porte County? Sure looks like it on the maps. This is for interop locally actually, as well as giving a good area of operations for each county in case of an event like say an fire in next county over, or car chase etc... The next level is Regional MA TG's, then Zone Event TG's, and SWMA TG's.

Could someone in English (plain) explain the difference in a regular site and a simulcast site.
I do know what 'simulcast' means but how does it apply here? Thanks much....

La Porte uses an multi tower simulcast cell of the SAFE-T system as does Lake and other counties as opposed to stand alone single tower sites .

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Craigmoe said:

Could someone in English (plain) explain the difference in a regular site and a simulcast site.
I do know what 'simulcast' means but how does it apply here? Thanks much....

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When two or more sites are simulcasted, there are areas between sites and also behind them where signals from two or more sites arrive at a subscriber receiver with a significant delay to cause distortion of the composite signal. This distortion is called Time Differential Interference or specifically Inter Symbol Interference in the case of digital signals.

If you have ever been to a large venue like a race track or stadium, when an announcement is made you can hear audio from distant loudspeakers having a noticeable delay compared to nearby loud speakers. This is noticeable because the speed of sound is relatively slow.

Because of the relatively high data rate of the P25 signal, a 4 level modulation scheme (C4FM) is normally used in order to convey data using symbols that convey twice the data (bits) in a given time period. C4FM is used in single site systems. But, for simulcast systems, a Linear Simulcast scheme is used, CQPSK provides a cleaner definition of the decision points (phase transitions) in the modulation.

C4FM vs CQPSK | Difference between C4FM and CQPSK modulation

Unfortunately the two largest manufacturers of scanners don't use a demodulator that effectively decodes CQPSK used in simulcast systems.