Fauquier/ Culpeper/ rappahannock

[kc4jgc]

Yes I know it doesn't do phase 2. Previously I asked if the groups were phase 2 and was told no, at least not all. While my first '106 doesn't do simulcast well at all, I picked up another '106 a few years ago that does quite well with such systems. Why I don't know but that's what I take with me.

 

[maus92]

In Moto systems, you buy licenses for each channel you want to have dynamic dual mode (TDMA and FDMA.) Channels are TDMA unless a FDMA sub joins a particular tg, which forces the channel carrying the traffic to fall back to FDMA. Not sure how the licensing works out for Harris, or how this system is configured. I do know that I had no issues monitoring the system driving along I-66; I heard traffic using both the SDS and on a PC running UT2 (UT2 is limited to FDMA voice only,) and logged both FDMA and TDMA traffic.

 

[maus92]

I did a roadtrip today down US301, crossed the Nice bridge to Fredericksburg for BBQ, then NW along VA 3 towards Culpepper. I started to receive the Culpepper site between Chancellorsville and Wilderness, receiving both TDMA and FDMA traffic on the SDS. The PC software / SDR uses a crap on-glass antenna on the back window, so that setup didn't start getting a good decode until about the Walmart just east of Culpepper County. I had usable reception of the system into Fairfax County along I-66. Culpepper was very pretty with the town lit up for Christmas.

 

[ervfc288]

I programmed a new to me bcd996p2 today with the new harris p25 system and the reception is terrible. I live about 3 miles from the dump tower. When it gets audio, it is hardly recognizable. Is there anything I can do to improve this? Or am I SOL with this scanner?

I have also noticed I am not hearing anything on the law enforcement channels, have they gone all encrypted with unpublished talkgroups?

 

[maus92]

I was hearing Fauquier and Culpepper Sheriff tgs yesterday, so they are not encrypted - at least not full time. This is a Harris system, and they are notorious for poor reception using older scanners not specifically designed to receive digital simulcast. Some people are lucky in their specific location, while others are not so lucky. If you are mobile, sell it and get a SDS series or Unication. If you use it at home, there are various tricks people have reported that help (detuning antennas, removing antennas, yagi antennas, etc.) I never had much luck with these kludges. Also note that this system was constructed using directional antennas at the border sites. A good example is the border site at Lignum: it's antenna is oriented NNW, which explains why reception of the system towards Fredericksburg is marginal. The landfill site antenna is oriented NW.

 

[ervfc288]

I was hearing Fauquier and Culpepper Sheriff tgs yesterday, so they are not encrypted - at least not full time. This is a Harris system, and they are notorious for poor reception using older scanners not specifically designed to receive digital simulcast. Some people are lucky in their specific location, while others are not so lucky. If you are mobile, sell it and get a SDS series or Unication. If you use it at home, there are various tricks people have reported that help (detuning antennas, removing antennas, yagi antennas, etc.) I never had much luck with these kludges. Also note that this system was constructed using directional antennas at the border sites. A good example is the border site at Lignum: it's antenna is oriented NNW, which explains why reception of the system towards Fredericksburg is marginal. The landfill site antenna is oriented NW.

Thanks, this scanner is in my home and provides the feed Culpeper County Public Safety on broadcastify. I will have to try a directional yagi pointed towards the landfill. And sds200 is out of my price range right now.

 

[maus92]

Thanks, this scanner is in my home and provided the feed Culpeper County Public Safety on broadcastify. I will have to try a directional yagi pointed towards the landfill. And sds200 is out of my price range right now.

Whatever site you choose as a donor site, try to find a direction that only "sees" one tower; the idea is to limit reception from multiple sites. You can even offset the direction slightly to suppress signals from a more distant tower. Or you might try aiming at a more distant site that will not have any other sites in the yagi's beam width and direction.

 

[ervfc288]

Whatever site you choose as a donor site, try to find a direction that only "sees" one tower; the idea is to limit reception from multiple sites. You can even offset the direction slightly to suppress signals from a more distant tower. Or you might try aiming at a more distant site that will not have any other sites in the yagi's beam width and direction.

I just measured and the landfill tower is 1.19 miles NW as the crow flies from my house. Basically flat terrain.

 

[maus92]

I just measured and the landfill tower is 1.19 miles NW as the crow flies from my house. Basically flat terrain.

It looks like that would be a good direction to point a yagi, as no other member sites are behind / inline to the NW. You might bump it a little south of NW to avoid Rixeyville you still have issues. Good luck.

 

[KC4ASF]

I was hearing Fauquier and Culpepper Sheriff tgs yesterday, so they are not encrypted - at least not full time. This is a Harris system, and they are notorious for poor reception using older scanners not specifically designed to receive digital simulcast. Some people are lucky in their specific location, while others are not so lucky. If you are mobile, sell it and get a SDS series or Unication. If you use it at home, there are various tricks people have reported that help (detuning antennas, removing antennas, yagi antennas, etc.) I never had much luck with these kludges. Also note that this system was constructed using directional antennas at the border sites. A good example is the border site at Lignum: it's antenna is oriented NNW, which explains why reception of the system towards Fredericksburg is marginal. The landfill site antenna is oriented NW.

I may be having a "senior" moment but does all of all the simulcast systems use directional antennas? If so I can understand why several 7 element 850+mhz beams with a 25db inline amplifier and aimed at the towers only gets me minimal signal. I am 5 miles south of Fredericksburg close to route 1. If the answer is yes, then I can stop buying antennas and preamps.

 

[maus92]

I may be having a "senior" moment but does all of all the simulcast systems use directional antennas? If so I can understand why several 7 element 850+mhz beams with a 25db inline amplifier and aimed at the towers only gets me minimal signal. I am 5 miles south of Fredericksburg close to route 1. If the answer is yes, then I can stop buying antennas and preamps.

Not all do, but more recent system design for county systems is to limit signalling to within a jurisdiction / service area.

 

[ervfc288]

I installed my a yagi in the attic and pointed it towards the landfilll... nothing on the scanner, just a constant NFM no matter which way I adjusted it. I pointed it toward Elkwood and now i'm picking up TG's that I expected.

I had one of the Harris subscriber portable radios in the house the other day and zero signal.... zero signal until I stepped outside. My BCD996XT picked up the old motorola system with a stubby 800mhz antenna with crystal clear audio all day long from any room, including the basement.

Live and learn!

Thanks for the help, my Culpeper feed is back up and running. Will check back in periodically for new TG's. I am looking into getting an sds200 for personal use to search for TG's.

 

[maus92]

I installed my a yagi in the attic and pointed it towards the landfilll... nothing on the scanner, just a constant NFM no matter which way I adjusted it. I pointed it toward Elkwood and now i'm picking up TG's that I expected.

I had one of the Harris subscriber portable radios in the house the other day and zero signal.... zero signal until I stepped outside. My BCD996XT picked up the old motorola system with a stubby 800mhz antenna with crystal clear audio all day long from any room, including the basement.

Live and learn!

Thanks for the help, my Culpeper feed is back up and running. Will check back in periodically for new TG's. I am looking into getting an sds200 for personal use to search for TG's.

My guess is that the landfill site is designed to provide coverage into Rappahannock, and not so much in Culpepper. Still, I would have expected you should have heard something from it. Glad you found a donor site that works for you.

Harris seems to favor using directional antennas in its systems to shape coverage - particularly at border sites - to satisfy RPC coordination requirements to minimize interference and promote frequency reuse. Older system designs tended to throw up a few high sites and pump out a lot of power, lol. Our county constructed the first SmartZone system in Maryland using 5 sites; it suffered from dead spots and Nextel interference (interleaved channels,) so when rebanding rolled out, they added 5 fill in sites, relocated a site from a water tower to a monster antenna, and swapped / added some frequencies. The new P25 system that is being build will have 22 sites (I'm assuming to support better portable coverage indoors,) so generally lower and likely a number of directional antennas.

 

[DogT]

Does anyone know that a 996P2 will work with this Fauquier system? I have a 996XT that worked fine with the Moto system, but of course now I hear nothing but with the old RR program. I can see full bars and if I turn off scan and step through, I hear dig noise. The STARS still works. I can't see spending the loot on the Uniden.

 

[maus92]

See post 125 above, and linked below. While the 996P2 is technically capable of decoding P25P2 audio, it seems to only work well in specific locations with certain antennas. I guess you will have to decide whether being able to receive the system flawlessly is worth the money it will cost to upgrade to equipment specifically designed to receive P25P2 simulcast systems like Fauquier.

Fauquier/ Culpeper/ rappahannock

Yes I know it doesn't do phase 2. Previously I asked if the groups were phase 2 and was told no, at least not all. While my first '106 doesn't do simulcast well at all, I picked up another '106 a few years ago that does quite well with such systems. Why I don't know but that's what I take with me.

forums.radioreference.com

 

[DogT]

Yeah, I saw that post, I actually read through the whole thread, not that I understood a lot of it. I'm not willing to spend much money to try to find out, I was sort of hoping that maybe there was another opinion or someone that actually got the BC to work with the P2 version. I suppose I could program in the new stuff in my XT but I don't find much interest in listening to school busses or landfill. Certainly not willing to buy the Uniden.

Also I'm not clear on what a directional antenna does for the system. Keeps the radio 'locked' to one control channel? I don't even know what signal I'm getting, but it's pretty strong, not that anything decodes. The system was always pretty strong here for some reason and I'm right between Warrenton and Front Royal, in the foothills of the Blue Ridge, couple miles from Rapahannoc in very western Fauquier.

 

[fredva]

If you are in Fauquier County, Fauquier Sheriff and Fire/Rescue are listed as Phase 1 (D). The XT is a Phase 1 scanner, so you have a chance of receiving those talkgroups. Warrenton PD is Phase 2 (T), so you won't receive that talkgroup.

There is lots of info on Radio Reference about simulcast. But in a nutshell, a simulcast system transmits simultaneously from multiple towers on the same frequency. These signals coming from different towers can interfere with each other on legacy scanners, and is noticeable on digital because it throws off the digital decoding. The idea of a directional antenna is to point it in a direction so that you only get a signal from one of the transmitters, eliminating interference from other transmitters. Simulcast effects are location specific - some people will have problems with garbled transmissions and missed transmissions while others live in a "sweet spot" where the problems are minimal. The only way to know if an older scanner will work or not is to try it.

 

[maus92]

The issue that you are likely experiencing is "simulcast distortion" - a colloquial term for what is a form of multipath interference, or receiving the same signal from multiple directions at almost the same time. The 996P2 is essentially an analog receiver with a P25 vocoder added to process digital audio, and does an OK job receiving P25 multicast (single tower) sites. A radio specifically designed to receive P25 simulcast has the ability to "throw out" interfering / duplicate signalling data from multiple tower sites to assemble a clear audio stream; an older receiver design like the 996P2 is not capable of performing this function.

The idea behind a directional antenna is to limit your reception to one tower site, which suppresses interfering signalling from all other simulcast tower sites. It makes the radio behave like it is receiving a multicast (single tower) site. The trick is to pick the correct donor site to aim the directional antenna (usually a yagi) - one that is isolated from all others, and one that has no other member sites along the same azimuth. This would depend on where your receiver is located, and where you could mount the antenna. Not always ideal.

The are tons of threads in radioreference about this issue, and they come up every time a jurisdiction changes to a digital simulcast system. A lot of bad advice is often repeated - a lot of it is well intentioned - but only applies to their unique circumstances. The use of a directional antenna seems to be the best solution for those who cannot obtain updated receivers.

Another route you can take is to buy a cheap SDR dongle, and use free software like SDRTrunk to control the SDR. The downside is that requires a computer to run. But if you already own a modern computer, it is a cheaper option than buying a $600 Uniden or Unication.

 

[DogT]

Interesting. I used to work for the Postal Inspectors when they were switching from analog to Moto P25 using Astro Spectra portables and mobiles. I always thought that the towers were all transmitting at the same time/frequency and there was a big woopdedo about locking the frequencies to gps so the transmissions would be in 'sync' where ever you went. I never heard about the older P25 receivers or scanners that couldn't decode because of the 'interference'. But what do I know? I never went to school on the subject. The Astro Spectras didn't have any problems unless the signal was just too weak, but the digital didn't work as far as the analog FM. But this is back in 04-05 so there you go.

I suppose for $15 I could reload my F/C/R system from RR and see what it does. I doubt I could program it myself. Plus I have no clue where the transmission is coming from. I'm certainly capable of building a high gain 800MHz yagi however. I've got the antenna analyzer. Might be a good project. I already have a design for a 700MHz antenna I was trying out for TMobile on B71 for cell internet, but I was looking for the wrong tower, now that I know where it is, I may try it again. It would be no problem to re-scale the 700 to 800, it's a 10MHz wide band yagi.

I've thought about the SDR dongle too, I certainly have a computer that will do it. I didn't know there was any software that would decode P25, I thought it was pretty much proprietary but maybe that's changed. Moto used to have their own encrypted systems that certainly were proprietary however.

All good info. Thanks. The Warrenton PD is boring anyhow. Sherrifs office is interesting sometimes, one of my neighbors gets in trouble regularly and the PD comes out. He's a real d**k, actually a wannabe bully. He rides around on my acreage pretending he's a cowboy.

 

[maus92]

I do recommend SDRTrunk for beginners: it's multiplatform (Windows/MacOS/Linux) and fairly easy to set up if one is good at following instructions / tutorials.

The RRDB entry for Fauquier does show tower site locations for the system, but be aware that some of the towers do incorporate directional antennas. You could do some heavy-duty FCC database research to figure that out.

Most simulcast systems use GPS for timing, including old tech like SmartZone and I assume EDACS. But timing is an art as much as a science, and it's rarely perfect for every receiver. As for the Postal Service's P25 system, it was probably a multicast system as most federal wide area systems are - but I could be wrong about that. Simulcast would be a very expensive solution to support the relatively few postal inspectors in a geographic area. Another factor is the site density of the system - few tower sites are required for mobile coverage vs. portable, thus if it was simulcast, fewer sites (maybe only one) would be "in range" at any one time. Everything is a balance.