The official "I want LSM to work properly in my scanner" thread

[troymail]

I think you are going to be hard pressed to find many significant PUBLIC SAFETY P25 system in 800/700 MHz that are not simulcast and fewer phase 2 that are not simulcast. These systems are designed around portable radios, and where you have portables in 800/700 MHz, you require remote receivers, and as a result, you have simulcast almost by default from Motorola and now Harris. It has been a trend since the mid 80's and with P25 it has become universal. Bear in mind, these are metro areas, I am sure there are some systems for highway patrol in Iowa or Wisconsin (VHF anyways) or over in podunk that are multisite, not simulcast.

My comment keeps getting "other conditions" added to it.... All I said was that you can have Phase 2 on non-simulcast sites - that is all. I agree that many/most are simulcast but I direct your attention to the Maryland FiRST system - which has simulcast sites covering most counties. However, you'll also see that there are many non-simulcast sites on the system for various reasons - and all sites, regardless of simulcast - are by default - Phase 2.

I am not saying scanner manufacturers should not fix the simulcast issue - they should (Unication has done it - and yes, I myself repeat again and again that a Gx is not a scanner - that's not the point). I am simply saying that you can and do see Phase 2 non-simulcast so equating Phase 2 with simulcast is not accurate.

 

[jasonhouk]

Geez....that sounds rough. Has anyone tried using a Unication pager there?

Do any scanners work on that system?

Marshall KE4ZNR

I've tried HP1, WS1080, HP2, 996P2, 325P2 and a 436HP(best so far). All with similar results so users can check them off the list.

Houk

 

[Project25_MASTR]

I think you are going to be hard pressed to find many significant PUBLIC SAFETY P25 system in 800/700 MHz that are not simulcast and fewer phase 2 that are not simulcast. These systems are designed around portable radios, and where you have portables in 800/700 MHz, you require remote receivers, and as a result, you have simulcast almost by default from Motorola and now Harris. It has been a trend since the mid 80's and with P25 it has become universal. Bear in mind, these are metro areas, I am sure there are some systems for highway patrol in Iowa or Wisconsin (VHF anyways) or over in podunk that are multisite, not simulcast.

It really just depends. Small, county owned/operated systems are typically simulcast where larger systems require wide-area multi-site systems (though you may see smaller simulcast systems under in a large system). Great example of this would be City of Austin's GATRRS system. Williamson county, Bastrop county, Texarkanna, and Travis county have simulcast. However, Lee county, Caldwell county, Hays county and Travis county (at the time of this posting) have traditional multi-site sites as well in the 7/800 MHz spectrum...not even accounting for the VHF sites that make up Western Counties, Middle Rio Grande Valley, (the merging) Permian Basin system and other systems that are merging. Another example would be that of TxWARN...it's a mix of simulcast and traditional sites. Once the Permian merger is completed, GATRRS will become the largest P25 system in the state in terms of coverage while TxWARN will remain the largest in terms of infrastructure and loading.

 

[radio3353]

I've tried HP1, WS1080, HP2, 996P2, 325P2 and a 436HP(best so far). All with similar results so users can check them off the list.

Houk

You either learn to live with it or buy a radio that handles simulcast. Hint...it will not be a Uniden or Whistler. Stop wasting your time and money.

 

[KA1RBI]

you can and do see Phase 2 non-simulcast so equating Phase 2 with simulcast is not accurate.

The question was NOT about the correlation (or lack thereof) between phase II and simulcast. As has been discussed, you can have phase II without necessarily having simulcast.

The question IS about whether you can have phase II without PSK (i.e., whether you can have a C4FM phase II TDMA channel - something not in the standard specs).....

And the reason for making a distinction between phase I QPSK and phase II QPSK was that the latter is the only method specified in the standards. The loophole in the standards that allowed for C4FM-only receivers to be technically (but not actually) "compatible" was removed in phase II. Only QPSK receivers are compliant with the phase II spec.

Sure I agree you can arrange a C4FM scanner to listen "all day" to a phase II system, just as you can get a scanner to listen to an LSM Phase I system. However the fact that it works (sometimes) doesn't make it standards-compliant. The fact that it's advertised as phase II also doesn't make it standards-compliant.

73

Max

p.s. the references that were made above to the Arizona and Ohio systems are irrelevant - both are phase I only, according to the RR db.

 

[UPMan]

p.s. the references that were made above to the Arizona and Ohio systems are irrelevant - both are phase I only, according to the RR db.

I'm going to take the liberty of clarifying this, as I know that you didn't mean that simulcast is irrelevant on Phase 1 systems, only that the issue of whether it is part of the standard is irrelevant.

 

[KA1RBI]

I'm going to take the liberty of clarifying this, as I know that you didn't mean that simulcast is irrelevant on Phase 1 systems, only that the issue of whether it is part of the standard is irrelevant.

Yes, thanks Paul. Sorry I wasn't fully clear. I meant that the two systems that were mentioned (AZ and OH) are phase I only, and therefore irrelevant to the discussion about what modulation method(s) are standard and proper on phase II systems.

73

Max

 

[UPMan]

Based on a little bit of personal experience <ahem> I know how a sentence can be taken out of context and used to beat you over the head, later.

 

[Nasby]

Geez....that sounds rough. Has anyone tried using a Unication pager there?

Do any scanners work on that system?

Marshall KE4ZNR

Unication works.

 

[Project25_MASTR]

The official &quot;I want LSM to work properly in my scanner&quot; thread

The question IS about whether you can have phase II without PSK (i.e., whether you can have a C4FM phase II TDMA channel - something not in the standard specs).....

Simple answer, no. Phase 2 officially uses 2 different modulation schemes. Harmonized Continuous Phase Modulation (H-CPM) at 6,000 bps for uplink and Harmonized Differential Quadrature Modulation (H-DQPSK) at 12,000 bps for the downlink. In reality, you can’t forget about the fact that the control channel is the same C4FM or CQPSK transmission at 9,600 bps that Phase 1 uses as well bringing the total to 3 modulations schemes on any Phase 2 site at a given time. But unless something like close call is in use by the scanner receiver, the uplink isn’t a factor to those monitoring systems.


Sent from my iPhone using Tapatalk

 

[KA1RBI]

Simple answer, no. Phase 2 officially uses 2 different modulation schemes. Harmonized Continuous Phase Modulation (H-CPM) at 6,000 bps for uplink and Harmonized Differential Quadrature Modulation (H-DQPSK) at 12,000 bps for the downlink. In reality, you can’t forget about the fact that the control channel is the same C4FM or CQPSK transmission at 9,600 bps that Phase 1 uses as well bringing the total to 3 modulations schemes on any Phase 2 site at a given time. But unless something like close call is in use by the scanner receiver, the uplink isn’t a factor to those monitoring systems.


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In phase I FDMA the uplinks are always C4FM and can be received cleanly on a scanner (within range of the mobile station). I'd be surprised if there is any scanner that implements a demodulator for H-CPM. It would be interesting to know if close call would even detect it...

Max

 

[RFI-EMI-GUY]

Simple answer, no. Phase 2 officially uses 2 different modulation schemes. Harmonized Continuous Phase Modulation (H-CPM) at 6,000 bps for uplink and Harmonized Differential Quadrature Modulation (H-DQPSK) at 12,000 bps for the downlink. In reality, you can’t forget about the fact that the control channel is the same C4FM or CQPSK transmission at 9,600 bps that Phase 1 uses as well bringing the total to 3 modulations schemes on any Phase 2 site at a given time. But unless something like close call is in use by the scanner receiver, the uplink isn’t a factor to those monitoring systems.


Sent from my iPhone using Tapatalk

Is anyone anywhere sucessfully demodulating 12 kbps H-DQPSK with a Uniden BCD536HP? Simulcast or not?

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[Ubbe]

It would be interesting to know if close call would even detect it...

Close Call uses a small frequency counter chip and needs an uninterupted signal for about 1 second and small variations for a normal frequency modulation level or AM signal strenght level doesn't interfere it.

/Ubbe

 

[KA1RBI]

Is anyone anywhere sucessfully demodulating 12 kbps H-DQPSK with a Uniden BCD536HP? Simulcast or not?

Sure, any Phase II-capable scanner can attempt to demodulate it - with all the same hit or miss results as on LSM. H-DQPSK is (basically) LSM.

I suspect the situation with the 6K baud rate with its shortened symbol intervals and corresponding tightened time constraints would make things somewhat worse than 4.8K though...

Max

 

[KA1RBI]

Close Call uses a small frequency counter chip and needs an uninterupted signal for about 1 second and small variations for a normal frequency modulation level or AM signal strenght level doesn't interfere it.

/Ubbe

Well, the uplinks in phase II (TDMA) are going to consist of TDMA bursts - the format is certainly not "uninterrupted". During any appreciable interval of time (assuming you're hearing only one of the two slots of course) the signal you hear will have a duty cycle (on-time) of less than 50%. Each individual burst is very much shorter than one second... This is why I was questioning whether close call would work on TDMA uplink frequencies...

73

Max

 

[UPMan]

If it is not a continuous signal, it likely would not be detected (DMR simplex cannot be detected for this same reason...it is only transmitting during one slot interval).

 

[Skypilot007]

If it is not a continuous signal, it likely would not be detected (DMR simplex cannot be detected for this same reason...it is only transmitting during one slot interval).

19 pages of how bad scanners perform with LSM. Will they ever work correctly as advertised ?

 

[UPMan]

19 pages of how bad scanners perform with LSM. Will they ever work correctly as advertised ?

We have never advertised nor have I ever claimed that any of our scanners could get a Close Call hit on the input side of a DMR or P25 transmission, where the transmit is discontinuous (referencing the text you quoted).

 

[MTS2000des]

19 pages of how bad scanners perform with LSM. Will they ever work correctly as advertised ?

No.

Consumer scanners lack the proper HARDWARE to properly receive and demodulate useful data to feed the vocoder to produce consistently good audio.

No amount of firmware/software can address what is a hardware problem.

 

[Skypilot007]

We have never advertised nor have I ever claimed that any of our scanners could get a Close Call hit on the input side of a DMR or P25 transmission, where the transmit is discontinuous (referencing the text you quoted).

I meant Phase II LSM, not a close call hit. I could care less about that. MTS2000des pretty much expalins the situation anyone with a clue about these scanners including the manufactures know. So I ask you again. Will they ever work as advertised. Currently they do not.