CSP On 436HP

[dispatcher812]

Ok, I am beyond frustrated. I just got back from a trip to PA. I went 84 from Route 74, North of Hartford to the NY border. I have the CLMRN loaded directly from the database. only changes made were deleting some TG I did not want. All sites scanning. All necessary service types active. Location control NOT engaged but GPS is connected. Attenuator is off, Threshold at 8. I am using a Comtelco All-Band Low-Profile Mobile Antenna from scanner master fender mounted to a Prius. I had just this system on hold. My ride home was almost 2 hours and this is all I heard:
LCD twice and service patrol twice just over NY/CT Border
Troop H twice, Troop A once, Norwich police once, Troop K Twice: while actually driving through Hartford, and I mean IN Hartford, not on the outskirts.
Troop K twice in Killingly CT (Where I live)

I do notice that I do not see the DAT under the GPS very often. Does this mean I am not getting the control channel therefore no voice? The antenna is new but I also had this issue with the old one which was mounted the same way. I know it works because I do occasionally hear traffic.

 

[GTR8000]

I do notice that I do not see the DAT under the GPS very often. Does this mean I am not getting the control channel therefore no voice?

That's exactly what it means. No steady DAT = no steady decoding. This is classic behavior when scanning simulcast cells with scanners that were not designed to properly decode the particular type of modulation used in P25 trunking simulcast.

Despite what a few others may claim regarding "no issues" with models like the x36HP or 996P2 handling simulcast, the issues are in fact real. This is especially evident when mobile scanning and you're driving in areas of overlapping coverage by multiple subsites (aka physical transmitter sites that make up the simulcast cell).

The only real solution is to use an SDS series, or some alternate hardware/software that is optimized to handle P25 simulcast.

 

[dispatcher812]

That's exactly what it means. No steady DAT = no steady decoding. This is classic behavior when scanning simulcast cells with scanners that were not designed to properly decode the particular type of modulation used in P25 trunking simulcast.

Despite what a few others may claim regarding "no issues" with models like the x36HP or 996P2 handling simulcast, the issues are in fact real. This is especially evident when mobile scanning and you're driving in areas of overlapping coverage by multiple subsites (aka physical transmitter sites that make up the simulcast cell).

The only real solution is to use an SDS series, or some alternate hardware/software that is optimized to handle P25 simulcast.

I have no issue with simulcast sites in Mass though. I work in Boston, and commute daily from CT and have no issues with either MSP system.

 

[Cheeseburgers]

Yeah but CLMRN has been constantly been evolving since its deployment. The ONLY scanner I've been able to use reliably is the P25rx. Todd has gotten the firmware refined it works fantastically. Where mh SDS100 and even my G4 would miss traffic from my office, on the fringe between H and L... the P25rx sits on H all day, no problems.

 

[pboissy]

I have no issue with simulcast sites in Mass though. I work in Boston, and commute daily from CT and have no issues with either MSP system.

The reason u have no issues in Mass is because their system in central and east parts of the state are analog.

 

[pboissy]

The reason u have no issues in Mass is because their system in central and east parts of the state are analog.

Their digital system is phase l. CLMRN IS PHASE ll.

 

[W1KNE]

Their digital system is phase l. CLMRN IS PHASE ll.

CoMIRS is actually Phase II, but 90% of the TGs are operating in FDMA/Phase I.
The Worcester and Cambridge sites have some TDMA TGs active.

 

[darkness975]

Ok, I am beyond frustrated. I just got back from a trip to PA. I went 84 from Route 74, North of Hartford to the NY border. I have the CLMRN loaded directly from the database. only changes made were deleting some TG I did not want. All sites scanning. All necessary service types active. Location control NOT engaged but GPS is connected. Attenuator is off, Threshold at 8. I am using a Comtelco All-Band Low-Profile Mobile Antenna from scanner master fender mounted to a Prius. I had just this system on hold. My ride home was almost 2 hours and this is all I heard:
LCD twice and service patrol twice just over NY/CT Border
Troop H twice, Troop A once, Norwich police once, Troop K Twice: while actually driving through Hartford, and I mean IN Hartford, not on the outskirts.
Troop K twice in Killingly CT (Where I live)

I do notice that I do not see the DAT under the GPS very often. Does this mean I am not getting the control channel therefore no voice? The antenna is new but I also had this issue with the old one which was mounted the same way. I know it works because I do occasionally hear traffic.

My BCD325P2 picks up CLMRN decently when driving around mobile. But the best reception is still with my SDS100/SDS200.

 

[ecps92]

Simulcast P25 is entirely different from Simulcast Analog
Central/Eastern Mass MSP is the Analog Simulcasting [for now]

I have no issue with simulcast sites in Mass though. I work in Boston, and commute daily from CT and have no issues with either MSP system.

 

[dispatcher812]

I know it been a couple months since this post came out but I thought I would update what i have done. In another thread in the Antennas forum, I mention removing a BNC extension cable and that really helped with reception. So today from Killingly Ct to the MASS border I had the scanner hold on the CLMRN system in the scanner. For that time I had an almost steady DAT indication. However the only Troops I picked up was C and one transmission from E. Nothing from D. And that seems to be the case 95 % of the time. I hear C more then another other troop. If I understand correctly, the problem has to do with overlapping sites. Would getting rid of one, say the C site help?

 

[cg]

Are you monitoring 3 troop talkgroups or 3 different sites? Two different things. When you are trying to monitor a P25 Phase 2 Simulcast system like CLMRN with less than optimal equipment, a number of things all have to work to hear it. If you are receiving two towers from the same Troop Site, if you have cellular tower interference, if you have less than a strong signal you will likely not hear the traffic.
Some people are fortunate and it works with the conditions near them. Many others hear nothing or poor quality reception.
Keep experimenting but you may be fighting a losing battle.

chris

 

[n1chu]

You mention a “BNC extension cable”… how long is it? I run a short cable due to the stiffness of my LMR400 antenna cable and have no issues. A short run should not cause the kind of loss you experienced but only if you use the right cable. Suggest a low loss cable at the higher frequencies, a more flexible cable, if that’s the issue. As CG noted, having more than one site programmed could cause losses also. You didn’t mention if this is a mobile or base setup. When mobile, you may need more than one site for good coverage due to your location changing all the time but if it’s a base, find the one strongest site and ignore all others listed for the same troop. (I defer to CG if anyone takes issue with this suggestion, because I’m still learning why CLMRN does what it does, I’m no expert, but so far I experience no simulcast issues with previous x36HP scanners I have owned. (I sold my two 536HP’s and currently run one 436HP, which I kept because it’s got the added DMR, one SDS100 and two SDS200’s. (I also run an older 996 and the newer BCD325P2.)

 

[cg]

I did not say that having multiple sites programmed would cause losses, I am trying to determine if he is trying to monitor 3 sites or just hearing 3 different troops on 1 site.
There is all sorts of information about how simulcast systems work online but very simply, (as I understand it) they rely on the capture effect of stronger FM signals to minimize the influence of weaker signals. Where sites are close to the same distance from the receiver, reception issues are the greatest. That is why using a yagi antenna can help as it increases the signal strength from a certain direction.
You can have some success with the non-SDS radios, but location is very important. Keep experimenting, every person will have a different experience with what is needed to hear a P25 P2 simulcast system with a scanner. Even the system subscribers can have issues but it is more being out of range than interference.

 

[n1chu]

I thought it was the very slight difference in time when the same transmission arrives at a receiving station, coming from two or more sites that differ in distance to the receiving station. It’s been my understanding the simulcast issue goes away when all but one site is eliminated. But I also recall being corrected on this point… that’s why I defer to others more knowledgeable. In defense of myself, I still offer what I have experienced when listening to CLMRN… not as an expert, but instead, to draw out from those knowledgeable whatever I can, an opportunity to gain more understanding on how the system works or is supposed to work.

So, what is he saying? You write “Is he is trying to monitor 3 sites or just hearing 3 different troops on 1 site?” I would think hearing 3 different troops on a single site would eliminate any evidence of simulcasting being the cause of poor reception, instead blame his poor reception is caused by weak signals or no signal at all because the troops he’s interested in are not attempting to broadcast thru multiple sites at the time. The site or sites he is listening to are simply not being accessed at the time?

 

[dispatcher812]

I was using the 436 as a mobile device in my car. I do not quite understand how the system all work. The extension cable was 3 feet long. I had everything for the CSP programmed as it is on the database and I was using Location control. I would see all my transmissions on the Troop D site but ironically very rarely hear D. Mostly C, K, E and Plainfield police. It would be the only site I see when scanning. During my travels recently in CT I would see other site but still not hear very much. I want to thank you all for your help. I went and purchased an SDS 100 and I am hearing much more then I ever had.

 

[cg]

Since your issue is more or less fixed with the purchase of the SDS100, I won't spend too much time on it but it is likely you were missing a lot from the other troops too. Since D is fairly quiet, the busier troops would take up more radio time but you would be thinking it was simply not hearing Troop D.

chris

 

[dispatcher812]

I just opened Sentinel and saw that the sites have a NAC Code. They are not all the same for each troop. Could that have something to do with it? Never saw that when I had the 436 as the target model. The Database does not even show them.

 

[doctordialtone]

If you have the wrong NAC entered, you won't hear anything from that site.

I would remove the NAC and select "search"

 

[n1chu]

I did not say that having multiple sites programmed would cause losses, I am trying to determine if he is trying to monitor 3 sites or just hearing 3 different troops on 1 site.
There is all sorts of information about how simulcast systems work online but very simply, (as I understand it) they rely on the capture effect of stronger FM signals to minimize the influence of weaker signals. Where sites are close to the same distance from the receiver, reception issues are the greatest. That is why using a yagi antenna can help as it increases the signal strength from a certain direction.
You can have some success with the non-SDS radios, but location is very important. Keep experimenting, every person will have a different experience with what is needed to hear a P25 P2 simulcast system with a scanner. Even the system subscribers can have issues but it is more being out of range than interference.

I’ve heard the term “comparator” used with trunked systems. But don’t know if it applies to simulcast. It’s my understanding a comparator simply compares the strength of signals from multiple sites and passes along the strongest to be repeated… all well and good until we consider that single, strongest signal is pushed out to more than one site, the various sites for rebroadcast… and simulcast raises its ugly head, the micro second differences coming from sites with differing distances to the listening station causing the transmissions to be out of sync. Having said all this, I still can’t wrap my head around how the commercial gear is not bothered by simulcast… do each of those commercial radios have comparators built in? Where the radio chooses which site to listen to?