Could Uniden Ever Design A Scanner To Properly Decode Trunked Simulcast Systems?
- Thread starter JASII
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If Motorola can design and manufacture a hand-held 2-way that will decode simulcast digital systems then Uniden or Whistler can as well. The question isn't can it be done, the question is are you willing to pay for it? They don't think you are or they'd have done it already.
Yes, this has been discussed elsewhere in the forums, but don't let that deter you from wishing, hoping, dreaming . . .
If I remember correctly, Paul Opitz indicated that Uniden was working on solutions to the problem, but I don't think anything was shared that was more specific than that.
I recently became the victim of a Harris P-25 simulcast system in my listening area. My (perhaps) naïve assumption is that if the Harris radios are "LSM ready," than it should be technically possible to build a scanner that is "LSM ready" as well. I don't know enough about how, exactly, the Harris radios in use up here go about untangling simulcast signals (signal-strength thresholds?, subaudible tones?, alien technology?), but I'm hopeful that something can be done soon about this growing challenge.
FWIW, my best LSM scanner performers are the BCD436HP and BCD396XT (with its latest firmware update) for close-up monitoring and the BCD325P2 and GRECOM PSR-800 for monitoring more distant signals. None of them are entirely acceptable, and there's a lot of "magic" (for lack of a better word) involved in radio placement (a few inches can make a huge difference) and antenna selection.
In the meantime, I've bought my last scanner until Uniden, Whistler, or whomever develops one that can reliably handle LSM systems and/or DMR.
Hang in there!
-Johnnie
If I remember correctly, Paul Opitz indicated that Uniden was working on solutions to the problem, but I don't think anything was shared that was more specific than that.
I recently became the victim of a Harris P-25 simulcast system in my listening area. My (perhaps) naïve assumption is that if the Harris radios are "LSM ready," than it should be technically possible to build a scanner that is "LSM ready" as well. I don't know enough about how, exactly, the Harris radios in use up here go about untangling simulcast signals (signal-strength thresholds?, subaudible tones?, alien technology?), but I'm hopeful that something can be done soon about this growing challenge.
FWIW, my best LSM scanner performers are the BCD436HP and BCD396XT (with its latest firmware update) for close-up monitoring and the BCD325P2 and GRECOM PSR-800 for monitoring more distant signals. None of them are entirely acceptable, and there's a lot of "magic" (for lack of a better word) involved in radio placement (a few inches can make a huge difference) and antenna selection.
In the meantime, I've bought my last scanner until Uniden, Whistler, or whomever develops one that can reliably handle LSM systems and/or DMR.
Hang in there!
-Johnnie
Yep. Of course, the issue isn't all that simple since some LSM systems decode fine.
Could Uniden Ever Design A Scanner To Properly Decode Trunked Simulcast Systems?
Not sure if you have tried the BCD536 or 436HP but I drive to work and listen to a simulcast 800MHz system and they both work great on simulcast compared to my GRE and older Uniden scanners with no issue at all nice a clear.
Mike
Not sure if you have tried the BCD536 or 436HP but I drive to work and listen to a simulcast 800MHz system and they both work great on simulcast compared to my GRE and older Uniden scanners with no issue at all nice a clear.
Mike
My 536HP performs pretty darn good receiving the Camden County, NJ simulcast LSM system.
It also performs pretty good receiving the New Jersey State Police 800 MHz simulcast system with an in the house antenna. I have noticed that the scanner seems to be de-sensed pretty bad by a local cell tower about .2 miles away. I have also confirmed this when I have my iPhone 6S in my radio room. I use a 700/800 MHz antenna sitting on my window sill in the front of the house for NJSP. The house blocks the close cell tower but like I said when I have my iPhone in the room I completely loose the NJSP.
There seems to be no affect on the 700 MHz Camden County system. I use an the same antenna but is on my tower at 35'.
I have a 3rd 536HP that I use to monitor the local air traffic control frequencies with a wide band discone on my roof. It works great. I can hear the controllers at Philly Intl., about 10 miles away.
JACKJ, you can't compare a Motorola handheld to the Uniden 536/436 scanners. The Motorola handheld is designed to work on 1 frequency band only. I consider the 700/800 MHz public safety frequencies 1 band. The 536 is designed to work on multiple frequency band and decode multiple modulation modes. I compare it to trying to put 20 pounds of candy in a 5 pound bag.
The FAA had 2 communications test sets that worked OK. They had about 4 or 5 different functions. Each function worked OK for the most part BUT they didn't work exceptionally well. The modulation meter function read AM modulation about 10 - 15% low. The spectrum analyzer would intermod in a not so high RF environments. The tracking generator worked pretty good though.
So as far as I'm concerned the BCD536HP has had some problems but it does exactly what I want it to do. In October 2013 Camden County Fire/rescue and Police went to the new system. With my BCD996 I couldn't listen to anything except the VHF paging frequency. With the 536 HP I can now listen to the fire/rescue units with very little problems. I still can't listen to the Police since they are encrypted.
It also performs pretty good receiving the New Jersey State Police 800 MHz simulcast system with an in the house antenna. I have noticed that the scanner seems to be de-sensed pretty bad by a local cell tower about .2 miles away. I have also confirmed this when I have my iPhone 6S in my radio room. I use a 700/800 MHz antenna sitting on my window sill in the front of the house for NJSP. The house blocks the close cell tower but like I said when I have my iPhone in the room I completely loose the NJSP.
There seems to be no affect on the 700 MHz Camden County system. I use an the same antenna but is on my tower at 35'.
I have a 3rd 536HP that I use to monitor the local air traffic control frequencies with a wide band discone on my roof. It works great. I can hear the controllers at Philly Intl., about 10 miles away.
JACKJ, you can't compare a Motorola handheld to the Uniden 536/436 scanners. The Motorola handheld is designed to work on 1 frequency band only. I consider the 700/800 MHz public safety frequencies 1 band. The 536 is designed to work on multiple frequency band and decode multiple modulation modes. I compare it to trying to put 20 pounds of candy in a 5 pound bag.
The FAA had 2 communications test sets that worked OK. They had about 4 or 5 different functions. Each function worked OK for the most part BUT they didn't work exceptionally well. The modulation meter function read AM modulation about 10 - 15% low. The spectrum analyzer would intermod in a not so high RF environments. The tracking generator worked pretty good though.
So as far as I'm concerned the BCD536HP has had some problems but it does exactly what I want it to do. In October 2013 Camden County Fire/rescue and Police went to the new system. With my BCD996 I couldn't listen to anything except the VHF paging frequency. With the 536 HP I can now listen to the fire/rescue units with very little problems. I still can't listen to the Police since they are encrypted.
KA1RBI
Member
The LSM simulcast problem was solved long ago in the OP25 project. There are success reports from many users in this thread: http://forums.radioreference.com/so...-virtualbox-project-run-op25-windows-7-a.html
It is interesting to note that the OP25 contributions were made by unpaid volunteers, working in their spare time.
Many of the users who are reporting good success using a PC equipped only with a $20 USB RTL stick. The significant point is NOT that the PC isn't as convenient to carry around as a handheld (indeed it isn't) - the point is that a solution has been demonstrated.
Customers need to demand Uniden (and Whistler) produce designs with IF-DSP. This isn't rocket science, the amateur radio manufacturers have been doing it for a long time now (and they are not shy about advertising it)...
73
Max
I love how some promote the $20 solution, but it's only $20 if the PC was free. Odds are the PC is much more powerful than the x36 processor.
Hi Voyager,
It's the use of the IQ demodulator and not the power of the computer which is needed. From what I understand it's the AM component in the IQ demodulator is what is missing from the FM discriminator which allows LSM to be properly decoded. If the manufacturers use IQ demodulation similar to OP25 them simulcast reception will be much improved. CML micro's CMX981 advanced baseband chip demodulates I&Q for the front end of APCO25 and TETRA all by itself.
The higher power computers are needed for the SDR's high bandwidth (2 - 10 MHz) I believe.
Max please correct me if I am off base here.
thanks!
KA1RBI
Member
<snip>
yes, it is, but the x36hp can only receive one frequency at a time (the PC can eat entire trunked systems - including LSM - for breakfast)
Max
KA1RBI
Member
The presence of the AM component in the LSM waveform causes trouble when the signal is applied to an FM demodulator. LSM switches back and forth (at regular intervals at a frequency of 4,800 Hz for P25P1) from zero-strength to full-strength. Specifically when the received signal is at zero-strength (i.e., I-squared plus Q-squared equals zero at the input of the FM demod), the output of the FM demodulator is undefined and may assume random values.
In DQPSK reception, the signal need only be sampled at the optimum (peak power) points, then sliced...
73
Max
p.s. to answer the original OP question... IMHO... yes of course they could. the cost delta at a hardware level to add IF-DSP would be a few dollars, say $10 or $20. The chip only needs to run a low IF rate, for example a 24 KHz IF. Part of this added cost would be an added oscillator/mixer to downconvert the 455 KHz 3rd IF to 24 KHz... On top of that is a big one-time cost, which may contain legal and/or political components as well as technical/engineering considerations....
Concur
I am in total agreement with you regarding the Uniden 436. My PSR 500 fails miserably in the presence of linear simulcast distortion. This is why I bought this radio. I don't regret my purchase. The Uniden firmware updates are usually spot-on, particularly the PV option.
I am in total agreement with you regarding the Uniden 436. My PSR 500 fails miserably in the presence of linear simulcast distortion. This is why I bought this radio. I don't regret my purchase. The Uniden firmware updates are usually spot-on, particularly the PV option.
Moved to the Uniden Tavern 
Marshall KE4ZNR
Marshall KE4ZNR
KC9WWJ
Technician
just my 2 cents (agree)
Heck, a couple of my ham buddies with the home patrols had the same issue here in Indianapolis. My previous RS pro-106 and 197 were terrible too...
But, sold those off in december, bought the Whistler WS-1088, and i love it. Listening to the IDPS system, doesnt matter if im on the edges of the county (where i would get most simulcast distortion previously), or right downtown; theres almost NEVER any issue with this 1088. (800mhz antenna, not stock duckie) Locks onto voice right at the beginning of transmission, and id say 99.9% follow all the way through. The clairty/fullness/realness of voice is amazing. Now indianapolis is still P25 phase 1, dont have anywhere near me phase 2 to test yet. But, from this last month and a half, 1088 is my recommeded handheld.
And as far as the software radio, i currently run 4 R820T2 sticks on one machine, trunking two different systems with dual instances of unitrunker/dsd/scannercast running. (providing two different feeds) Theyre just on a single mag-mount antenna on the ac unit, and no distortion at all with em. So id say, especially for the $300-400 that can be saved, its a valid alternative if youre cool with less mobility, not too bad to get em up n running either.
Heck, a couple of my ham buddies with the home patrols had the same issue here in Indianapolis. My previous RS pro-106 and 197 were terrible too...
But, sold those off in december, bought the Whistler WS-1088, and i love it. Listening to the IDPS system, doesnt matter if im on the edges of the county (where i would get most simulcast distortion previously), or right downtown; theres almost NEVER any issue with this 1088. (800mhz antenna, not stock duckie) Locks onto voice right at the beginning of transmission, and id say 99.9% follow all the way through. The clairty/fullness/realness of voice is amazing. Now indianapolis is still P25 phase 1, dont have anywhere near me phase 2 to test yet. But, from this last month and a half, 1088 is my recommeded handheld.
And as far as the software radio, i currently run 4 R820T2 sticks on one machine, trunking two different systems with dual instances of unitrunker/dsd/scannercast running. (providing two different feeds) Theyre just on a single mag-mount antenna on the ac unit, and no distortion at all with em. So id say, especially for the $300-400 that can be saved, its a valid alternative if youre cool with less mobility, not too bad to get em up n running either.
The point Voyager was trying to make that seems to be missed is how much did you pay for the computer? Even if it's used for other things, it was still an out of pocket expense that is necessary to make the dongles work. Is a person really saving $300-400 when you factor that in?
I'd be happy to pay several hundred dollars more for a scanner that correctly deals with simulcast issues. That cost would be offset by the savings from not needing to buy yagi antennas, cabling, adapters, etc. Plus, we could go mobile or portable again.
KC9WWJ
Technician
Clarify
Sorry, i did make that statement assuming a computer was already in possession.
Cool cool, 1088 :wink:
Sorry, i did make that statement assuming a computer was already in possession.
Cool cool, 1088 :wink:
KA1RBI
Member
<snip>
As are the points I've been making
* there is a proven solution to the LSM issue
* anyone who wishes to do so can test this assertion for him/herself
* many people who have done so have reported success in the aforementioned thread
* the CQPSK solution was developed by an unpaid volunteer contributor, working in spare time
* the code was contributed as GPL'ed Free Software to the GNU OP25 project
* the combination of the PC and SDR is comparable price-wise to the scanner
* feature-wise there's no comparison whatsoever (x36hp: poor LSM support, no graphical tuning aids, no multi-channel simultaneous operation, prohibition against user-contributed enhancements)...
I hope the above will help to debunk the myth that LSM would require monstrous engineering or hardware costs. However it will require scanner makers to move away from analog FM discriminator-tap based architectures... It will require scanner makers to stop doing things the way things have always been done...
More than that - I hope it will help scanner consumers to start asking for the right things (IF-DSP) and manufacturers to respond... If / when they do, I might become a customer again...
73
Max
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