Charleston SC and SC systems

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thrownout27

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Please let me know what your thoughts are. I have a BCD996XT. I have used FreeScan and RR to program everything that I think will be relevant in monitoring the Charleston area. My questions are these. Am I correct in assuming that Palmetto 800 is digital and analog while Palmetto P25 is all digital? Are there any tips or tricks to monitoring the area? I am used to monitoring Viper in Western NC along with a host of analog community repeater systems. Thanks for the help.
 

brian

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You are correct in your understanding of the local trunking systems in Charleston. Palmetto P25 is a simulcast P25 system (all digital) and is what most Charleston City, County and municipal public safety agencies can be heard on. Because it's simulcast you may have trouble successfully decoding the digital voice.

Palmetto 800 is like VIPER in that it is a state-wide Smartzone mixed mode (analog and digital) system. Most talkgroups active on Palmetto 800 in the Charleston area will be analog, like SCHP, MUSC and SCE&G. Site 9 is the site to use for the Charleston area, with site 26 to the far North of Charleston Co and Site 27 to the South. Use sites 12 and 62 for the Dorchester area.

There aren't many conventional public safety systems to monitor in the area. Consider programming the Joint Base Charleston system (SysID 14C) if you're interested in that. The Port Authority runs an EDACS trunked system for port operations, but some operations can also be heard on the 2 Public Safety trunked systems listed below.

There is also some MilAir activity in the area from MCAS Beaufort and Charleston AFB, Federal activity and activity on the Marine channels.

Hope that helps. Have a nice visit.
 

thrownout27

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Further

That was probably the best response I've ever seen to my questions..appreciated. We'll be down this weekend, I may shoot you something if we have trouble. Can I change settings to decode Pal. P25 eaiser? Why does a simulcast create decoding issues?
 

milf

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The original Statewide TRS, the Palmetto 800, is an "Legacy" Motorola Type II system using both analog and digital talkgroups. The new Palmetto P25 is the pure digital upgrade/overlay of the old system, using several new sites, as well as the eventual upgrading of the current Palmetto 800 sites. Almost everyone in Charleston County is primarily using the P25 system. Berkely, Dorchester are still on the old system, with a few agencies in BC on still using VHF for primary comms. Beaufort County is, or has also moved to the P25 system. I am not sure what , if any comms are still on the old City of Charleston TRS.

Simulcast causes problems due to every repeater broadcasting the exact same thing at the exact same time. Scanners, at least up to the newest ones can not adequately cope with the overlapping signals, and this causes distortions. Sometimes so bad that intelligble comms are impossible to hear. This can be eased through careful antenna selection/placement, having roam on on the scanners via software... Or just being lucky enough to be close enough to one site that it overpowers the others.
 
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brian

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As Milf said, up until now (and maybe ongoing) scanners really struggle with the type of modulation (LSM) used in these P25 simulcast systems, and with the signals from multiple towers arriving at slightly different times to your radio. It seems to be an inherent design limitation of the scanners.

On the PSR-800 there is a setting (DSPLevelAdapt) that can be adjusted that seems to help with this problem to some degree. But it's never perfect. I'm not sure if there is anything equivalent on the 996.

Antenna placement seems to be the key factor, as Milf pointed out. Sometimes less antenna is better, particularly if you're in the downtown Charleston area in the "center" of the system coverage area.

Beyond that, there's not a lot you can do. I hope you have a nice trip and visit. I don't live in or near Charleston, but I visit or pass through that area a few times a year. Feel free to post anytime and we'll do our best to help.

Brian
 

thrownout27

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We'll get down this evening and we'll stay at Isle of the Palms so hopefully I'll have limited simulcast issues out there. I'll let you know how we do and again, I am very appreciative of you helping me.
 

caldwest

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Brian and Milf . . . thank you for your comments about the two Charleston systems. I have just recently gotten back into scanning and your comments confirmed some things that I learned on my own.

I live in the West Ashley area and receive the P25 and Palmetto 800systems very well with the standard telescoping antenna that came with my BCD996XT. I have a P25 tower less than two miles from my house. The only problem I have is with the P25 system when it rains. I lose all communications. Rain has no effect on the Palmetto 800 system. In fact, I can receive the Palmetto 800 system quite well on the 996XT as well as my 396T without antennas being hooked up.

I have been exploring 800 MHz antennas as a solution to the rain problem and after much reading I came to the conclusion to leave well enough alone. I was afraid that I would pull in more P25 towers in addition to the one that is close to me.

Maybe there is a solution to the P25 problem with the new BCD436HP and BCD536HP scanners. I have been reading that upgraded chips in these new units address the issue.

Thanks again, Sam
 

milf

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With the 2 new Unidens, we should know pretty conclusively by Christmas at the latest. That should be enough time for some pretty extensive field testing under multiple varying conditions. Just to test one particular system would take at least a month to do properly. Testing the reception in the middle of an area, then between multiple sites, then close range inside area, then outside the area. then testing on "normal" weather days, and inclement conditions. Not to mention multipl antennas on them. So yeah, by Christmas we should know the "real deal" on how they do on P25 LSM Systems. As well as how they react to P25 X-2 TDMA, and Phase II TDMA systems. All the other bells and whistles for GPS, and recording etc... Not concerned with really. The "line out" usability for Pro96Com, DSD, DSD+, DMR Decode, Unitrunker, T-88, and the LTR software operations interests me far more. Anyway, let us know how it goes, and if you find new TG's and can ID them etc... And have fun!
 

caldwest

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With the 2 new Unidens, we should know pretty conclusively by Christmas at the latest. That should be enough time for some pretty extensive field testing under multiple varying conditions. Just to test one particular system would take at least a month to do properly. Testing the reception in the middle of an area, then between multiple sites, then close range inside area, then outside the area. then testing on "normal" weather days, and inclement conditions. Not to mention multipl antennas on them. So yeah, by Christmas we should know the "real deal" on how they do on P25 LSM Systems. As well as how they react to P25 X-2 TDMA, and Phase II TDMA systems. All the other bells and whistles for GPS, and recording etc... Not concerned with really. The "line out" usability for Pro96Com, DSD, DSD+, DMR Decode, Unitrunker, T-88, and the LTR software operations interests me far more. Anyway, let us know how it goes, and if you find new TG's and can ID them etc... And have fun!
Thanks Milf. A couple of days ago I downloaded the Pro96Com and I am in the process of learning how to use it and understand what it tells me.

Sam
 

brian

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There are all sorts of posts on this forum about the P25 LSM/CPSQK issue with current scanners. It's a well documented limitation that we just have to live with as best we can and go to all sorts of trouble with antennas to minimize.

I recently read a post on the SDR forum about the benefits of SDR and some of the decoding software that's now available, specifically OP25. This is the thread, specifically post #37 that was most interesting to me:
http://forums.radioreference.com/software-defined-radio/282056-sdrs-vs-hardware-scanners-receivers-2.html

I only comprehend about half to 2/3s of what's written here because I don't have the knowledge of all the technical details that are referenced, but this would seem to indicate that a significant change to typical scanner hardware is necessary to enable successful decoding of some modulation schemes, including LSM.

So, read up on some of these other threads if you're interested. I do hold out hope that both scanner hardware and SDR software will eventually solve these problems for us hobbyists.
 

caldwest

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There are all sorts of posts on this forum about the P25 LSM/CPSQK issue with current scanners. It's a well documented limitation that we just have to live with as best we can and go to all sorts of trouble with antennas to minimize.

I recently read a post on the SDR forum about the benefits of SDR and some of the decoding software that's now available, specifically OP25. This is the thread, specifically post #37 that was most interesting to me:
http://forums.radioreference.com/software-defined-radio/282056-sdrs-vs-hardware-scanners-receivers-2.html

I only comprehend about half to 2/3s of what's written here because I don't have the knowledge of all the technical details that are referenced, but this would seem to indicate that a significant change to typical scanner hardware is necessary to enable successful decoding of some modulation schemes, including LSM.

So, read up on some of these other threads if you're interested. I do hold out hope that both scanner hardware and SDR software will eventually solve these problems for us hobbyists.

Thanks, Brian. I read the messages in the above link. I have a long way to go before I'll understand what they are talking about.

Sam
 

thrownout27

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It would seem you were all correct. I could see the scanner stop on the specific group (p25) and had full signal strength but no audio, or little audio, could be heard on P25. I did get good traffic on the SCHP group on the old 800 network and some traffic from the port and airport. I have to say though I was disappointed after knowing there was a lot going on around me but I couldn't get to it. I was in the Isle of Palms area btw.
 

milf

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If you get lucky, and get just far enough from the overlap, and closer to one specific site, its not as bad. Or run only a rubber ducky, or even NO antenna on handhelds you can get good results sometimes. For base use.. You really have to use an directional type antenna such as an Yagi style, or "shielded dish" type...
 

caldwest

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It would seem you were all correct. I could see the scanner stop on the specific group (p25) and had full signal strength but no audio, or little audio, could be heard on P25. I did get good traffic on the SCHP group on the old 800 network and some traffic from the port and airport. I have to say though I was disappointed after knowing there was a lot going on around me but I couldn't get to it. I was in the Isle of Palms area btw.


Yes, the P25 system is really crazy. This past week I was hospitalized downtown for four days for adjustments to my heart medications. I took my 396T with me looking forward to some quality scanning time while being held captive. Much to my disappointment, I could receive nothing on the P25 (I got three to five bars but no audio) while the Palmetto 800 system came through loud and clear. Go figure?

Sam
 
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