So what is the technical issue with decoding simulcast?

Status
Not open for further replies.

scanmanmi

Member
Joined
Sep 25, 2011
Messages
828
Location
Central Michigan
Since simulcast has been an issue for so long why aren't many, or all, scanners proficient in decoding it? I can't believe scanner manufaturers are allowed to sell them knowing they will not work correctly in many areas of the country. It isn't an elusive secret of the universe since Unication and professinal radios have dealt with it. Is it a difficult technological issue or a patent issue? What is the additional cost?
 

kayn1n32008

ØÆSØ
Joined
Sep 20, 2008
Messages
6,636
Location
Sector 001
The various waveforms used for P25 (WCQPSK/CQPSK ect era) simulcast can not be reliably/properly decoded using a discriminator tap that is used in majority of consumer scanners. The Unication, actual subscribers and the SDS series do not use this method to receive signals.
 

W8RMH

Feed Provider Since 2012
Joined
Jan 4, 2009
Messages
8,110
Location
Grove City, OH (A Bearcat not a Buckeye)
Few systems are actually simulcast. Manufacturers have built 100s of thousands of scanners before anyone was aware of the simulcast issues, they are not going to just destroy them, when they work fine on other P25 systems, Air, VHF, UHF, DMR, etc. Models built after the simulcast issues were recognized (SDS models) have overcome the issues. Many, like myself, have switched to Unication pagers which work very well.
 
Last edited:

GTR8000

NY/NJ Database Guy
Database Admin
Joined
Oct 4, 2007
Messages
15,482
Location
BEE00
Few systems are simulcast.
Maybe not in your neck of the woods, however P25 simulcast cells are quite prolific around the country. A number of systems feature both non-simulcast sites (single physical location), as well as having one or more simulcast cells in the mix. To state that "few systems" are simulcast is a gross underestimation of just how many are out there.
 

MTS2000des

5B2_BEE00 Czar
Joined
Jul 12, 2008
Messages
5,226
Location
Cobb County, GA Stadium Crime Zone
To state that "few systems" are simulcast is a gross underestimation of just how many are out there.
Just about every 7/800 system in my area (including one I care and feed) are all LSM. Simulcast makes sense for many metro areas.

The fact that consumer scanner manufacturers neglected this in their design is on them.
 

W8RMH

Feed Provider Since 2012
Joined
Jan 4, 2009
Messages
8,110
Location
Grove City, OH (A Bearcat not a Buckeye)
My point is if you look at every single agency nationwide, simulcast systems are a small percentage. I don't think all previously made scanners should be outlawed and Whistler and Uniden should go bankrupt because the technology changed after they manufactured scanners prior to the simulcast issue coming to light.

For example when the HomePatrol 2 was released no one knew what simulcast was, how is this negligence.
 

MTS2000des

5B2_BEE00 Czar
Joined
Jul 12, 2008
Messages
5,226
Location
Cobb County, GA Stadium Crime Zone
My point is if you look at every single agency nationwide, simulcast systems are a small percentage. I don't think all previously made scanners should be outlawed and Whistler and Uniden should go bankrupt because the technology changed after they manufactured scanners prior to the simulcast issue coming to light.

For example when the HomePatrol 2 was released no one knew what simulcast was, how is this negligence.
The HP2 was released, and the county where I live was on Astro 25 LSM release 7.8 for over three years. LSM has been a part of the P25 standard for years. The fact that scanner manufacturers chose to use tired old discriminator tap is their oversight. Once the cries began, they continued (only until the SDR based models in the last TWO YEARS appeared) to IGNORE their customers. As more and more MAJOR METRO areas transition to large trunking systems, most of which are using LSM- they're forced to sell actual NEW hardware not based on their ancient 20 year old designs with a vocoder stuck on the end.

That's negligence to their customers. But should they be banned? Nope.
 

Citywide173

Member
Premium Subscriber
Joined
Feb 18, 2005
Messages
2,151
Location
Attleboro, MA
Just about the entire state of Michigan is.
For public safety....I believe the reference was when compared to ALL systems nationwide. There's plenty of analog and non-LSM digital in Michigan, there's just no interest in monitoring much of it.
 

zz0468

QRT
Banned
Joined
Feb 6, 2007
Messages
6,034
Another aspect of the simulcast problem as it relates to scanners is, hobbyists frequently want to monitor simulcast systems from outside their intended coverage area. Many systems are designed to specifically NOT cover much outside the political boundaries that define the user agencies.
 

ofd8001

Member
Premium Subscriber
Joined
Feb 6, 2004
Messages
7,915
Location
Louisville, KY
I agree with relatively speaking, simulcast systems are in the minority with a "but". Simulcast systems tend to be used in metropolitan areas so as to achieve coverage in large buildings, since the FCC doesn't like big blow torch transmitters these days.

It's the metro areas where the populations centers are and probably where a bigger percentage of scanner listeners are. Thus the issue is prevalent.
 

WX4JCW

Member
Premium Subscriber
Joined
Jun 26, 2006
Messages
3,403
Location
Stow, Ohio
I think the scanner manufacturers got complacent in addressing it, plus the rollout for P25 only really started becoming mainstream over the last 10 years
 

scanmanmi

Member
Joined
Sep 25, 2011
Messages
828
Location
Central Michigan
The various waveforms used for P25 (WCQPSK/CQPSK ect era) simulcast can not be reliably/properly decoded using a discriminator tap that is used in majority of consumer scanners. The Unication, actual subscribers and the SDS series do not use this method to receive signals.

I am not familiar with the electrical terms you use. Why have they still been using that technology? Is it manufacturing cost, patent, or just R&D? If the Unciation and SDS do not use discriminator then what are they doing that works; and why does the SDS not work as well as the Unication?
 

iMONITOR

Silent Key
Premium Subscriber
Joined
Sep 20, 2006
Messages
11,156
Location
S.E. Michigan
Since simulcast has been an issue for so long why aren't many, or all, scanners proficient in decoding it? I can't believe scanner manufaturers are allowed to sell them knowing they will not work correctly in many areas of the country. It isn't an elusive secret of the universe since Unication and professinal radios have dealt with it. Is it a difficult technological issue or a patent issue? What is the additional cost?

You seem to like beating this subject to death in multiple threads and have yet to find a satisfactory answer. Have you considered asking Uniden directly? Maybe try post in the Uniden Technical Support section, or writing Uniden directly.


Have you considered selling what you have and buying something else that works better?
 
Status
Not open for further replies.
Top