SDS-100 problem with Fairfax VA P25 system

My SDS-100 is not picking up anything on the Fairfax County VA P25 system (link below), while it has performed beautifully on other Northern VA and Maryland trunked systems. I have a 436 and an HP-2 right beside it that are having no trouble with Fairfax P25. I am using Identical favorites list and the same database in the 436 and the SDS-100.

While scanning that system on the SDS-100 using the detailed display, the frequencies are displaying as well as "P25 NAC:3C2h" but SysID, RFSS ID, WACN, and Site ID are not populating.

I have tried to ensure everything within my control (service types, etc) are the same.

Any clues what the problem might be? Thanks in advance,

David
KU8V



https://www.radioreference.com/apps/db/?sid=6957

Make sure you have the correct Target Model selected when you Write To Scanner. I've seen several reports where having the wrong Target Model selected when writing to scanner caused scanning problems with some or all trunked systems.

Jon, I was hopeful but did the above and still same result. I changed the target model, and even after that created a new profile, reconstructed the database in Sentinel, made a new FL from the newly reconstructed database, erased the user data on the SDS-100.

Using the Analyze feature, all the local systems except for Fairfax County P25 are testing fine - quickly populating with system data.

Any other ideas you may have, I will try them! (reinstalling Sentinel?)

I have no problems on that system with my sds100.
I only listen to the police piece of it in this particular fav list.

https://youtu.be/WLT0b93dHJ0

If you like I can share the Sentinel file with you.

Please, both of you post the favorite lists you are using to monitor Fairfax. Don't change your current setups. If rdb3141's SDS100 is monitoring other similar systems successfully, then it is unlikely to be a defective unit. And if ecarvalho is successfully monitoring Fairfax, then there must be some difference between rdb3141's favorite list and his favorite list causing the problem. Comparing the lists may provide a clue as to why this is happening.

I’ll post mine tonight. (at work now)

rdb3141 said:

Jon, I was hopeful but did the above and still same result. I changed the target model, and even after that created a new profile, reconstructed the database in Sentinel, made a new FL from the newly reconstructed database, erased the user data on the SDS-100.

Using the Analyze feature, all the local systems except for Fairfax County P25 are testing fine - quickly populating with system data.

Any other ideas you may have, I will try them! (reinstalling Sentinel?)

Click to expand...

This indicates you have zero or erratic reception. Either weak signal, or possibly something changed on that site. Do you have a 2nd radio of any type to try?

Does it show anything in RSSI field? What about noise?

phask said:

This indicates you have zero or erratic reception. Either weak signal, or possibly something changed on that site. Do you have a 2nd radio of any type to try?

Click to expand...

Per post #1, a HP-2 and a 436, which are both receiving the system without issues.

Try moving closer to Fairfax and try listening and running the Analyze feature again.

Also what antenna are you using? Stock antenna or an aftermarket antenna?

When I first received my SDS100 I used the stock antenna and thought the scanner had a problem as it was not receiving Fairfax in my house, then changed over the one of my Radio Shack 800 MHz antenna and performance was night and day difference.

While I have not done any exhaustive testing, I pretty much put the stock antenna back in the box.

I am in Fairfax and can easily pick up Fairfax, Arlington, Montgomery County with my SDS100 and the Radio Shack 800 MHz antenna.

The user is in Alexandria and not close enough to receive Fairfax? That doesn't make much sense....

Not able to hear Fairfax from McLean VA with a non-stock antenna? Isn't McLean IN Fairfax County?

I’m in Aldie by South Riding and Fairfax comes through fine as seen in my post above.
Let’s see if with comparing my fav list and settings the OP is able to determine what is wrong.

The DC/Metro Area is tricky due to a lot of hills, valleys and dense vegetation along with MANY, MANY radio systems, both public safety and cellular.

In my house, I am in a lower hole and my house has the foil covered Styrofoam insulation under brick and in some places aluminum siding. So in the house,I have some challenges.

While I can pick up Fairfax P25 in the house, I am also probably in a Simulcast location and I have a bunch of cell phone towers within about 1/2-3/4 mile if my house along with KILLER FM Broadcast and TV transmitters. So along with reduced signal levels in the house, I have to contend with a lot of other signals.

While my SDS100 can pick up Fairfax in the house with the stock antenna, I just put both my BCD436HP and the SDS100 side by side using the exact same scan list and locked on the same System. The 436HP is running the Radio Shack 800 MHz antenna and it is CLEARLY out performing the SDS100 with the stock antenna. While the SDS100 can and does pick up some of the traffic, it is probably around 15%-20% of what the 435HP is receiving as a guess at this moment when comparing the 2 radios.

On a side note NONE of my scanners can pick up the VHF VA STARS system in the house, but can outside or if I am using my attic mounted antenna with a VERY good LNA mounted right after the 90 dB FM Broadcast filter that is mounted right at the base of the antenna.

While I can sometimes pick up Arlington in the house, I have never been able to pick up Alexandria in my house. Matter of fact I am not even sure I have bothered to program any of the Alexandria systems to attempt to listen from my attic mounted antenna.

I have few other Radio Shack 800 MHz antennas, so I will install one on the SDS100 so I can run a side by side comparison with the 436HP and using the same antenna and same Fairfax Favorite that are the same between the radios.

I would highly suggest a different antenna for the SDS100 as a start. Not sure what is going on, I may have more information once I run both radios with the same antenna side by side. If needed I have 8 ports off my attic antenna feed so I can also connect both scanners to the same antenna and see how things perform.

Would be very interested in how a Unication performs in these same areas.... Having lived in Maryland (south of BWI) until just over a year ago, I will agree that simulcast was a problem and cell towers many times crushed older analog systems. However, last spring, I was receiving numerous northern VA systems (including Fairfax, Arlington, and Alexandria) on my G4/G5 from my inside my house near BWI with just a RS 800 antenna (while my scanners couldn't receive even the neighboring counties simulcast P25 systems). I've also never had any trouble receiving NoVA systems on many drives through the area. I just cannot understand how with these brand new radios, you can't receive the local system without alot of effort....

Scratching my head....

Try you have to be very careful about things in this area and what to expect.

My aunt lives in Howard County and I would travel from Fairfax to Howard County and I could often hear Fairfax and Arlington VERY good up near Silver Spring and other areas of the County that were up rather high. I was surprised I was hearing Fairfax and Arlington so well and this was typiclly on my HP1 using the Radio Shack 800 MHz antenna. I would typically travel on Route 29 and occasionally I would have the same situation when traveling on Route 50 from Annapolis. Could hear very well on parts of Route 50 into Fairfax and Arlington.

Now back to the SDS100 and the stock antenna. Shooting from the hip, I am starting to think the stock SDS100 antenna SUX!!! I tried 2 different antenna on the SDS100 side by side with both my 436HP and a 396XT. The 396XT is not the exact same scan list but very close.

After putting the same Radio Shack 800 MHz antenna on the SDS100 it is seems to be performing as well as the 436HP, not sure if it is better, but FAR better than the SDS100 with the stock antenna. I also had a cheap Comet type 8" SMA clone dual band antenna like the one linked below that blew away the stock SDS100 antenna when installed on the SDS100 radio.

https://www.ebay.com/itm/Comet-HT-5...704874?hash=item56ab189eaa:g:Ex8AAOSwCj5amcxP

I then installed the stock SDS100 antenna on my 396XT and for 10 minutes it only stopped on 2 transmissions. While I have not spent much time with the stock SDS100 antenna on the 436HP, it seems to be working far better on the 436HP than the SDS100.

I put the Radio Shack 800 MHz antenna back on the 396HT and it was like a new radio when compared to when the stock SDS100 antenna was installed. I am also hearing Arlington in the house easily with the 396XT with the Radio Shack 800 MHz antenna. I think I have a very different scan list on the 396XT that probably included both Arlington and Fairfax.

Again, I am was not and am not a fan of the stock SDS100 antenna. Seems that anything other than than the stock antenna is a great improvement for 700-800 MHz.

Further detective work on Fairfax P25 system - persistent avoids

First, this community is absolutely remarkable for the outpouring of advice in such a short amount of time. If this site was just a database and did not have so many helpful experts, I don't think I would be into scanning. A few notes in response:

Persistent avoids; One big clue and what I now think is the likely culprit I discovered was looking at 'review avoids' revealed that multiple things were being avoided, including Fairfax P25. None of the avoid tags were in my favorites file for the system (see attached file). Here's the weird part - these avoids are very persistent. I have stopped all avoiding via the scanner settings for both the favorites list and the full database. It shows when I review avoids immediately after I do that, that it took, indicating nothing is avoided. Yet after I back out of the menus, all of those avoids re-appear. This happens even after I wipe data from the scanner using restore and re-populate the scanner with sentinel (set to SDS-100 target). Any suggestions on doing some kind of fuller wipe/restore (reformatting SD card?)

Antenna - I am using the Radio Shack 800 Mhz antenna and that pulls in Fairfax P25 fine on both the HP-2 and the 436.

Location - I am in a bad place radio-wise, in a low part of Alexandria (Del Ray) just behind some hilly terrain to my west. In a while I will try with better elevation, but everything else indicates that is not the culprit. The persistent avoid probably is.

Thanks again for all the detective work!

I would say try a different card. If you can't change settings in the scanner, that is usually a card problem. If that doesn't clear the problem, then it's likely a firmware bug activating unwanted avoids.

rdb3141
You are on the latest firmware as well, correct?

Imported and using your Fairfax .HPE file, it is working pretty good for me using the Radio Shack 800 MHz antenna inside the house.

Interesting I added Alexandria to my SDS100 and was unable to hear anything with my attic mounted antenna, went out a few blocks from my house to a higher elevation and only heard 1 Police Dispatch while stationary for about 15 minutes.

I know that Alexandria is a difficult system for me to hear from my home location and I am not that far up the river.

Best to take the scanner in the car and work your way over to Springfield area and see what happens.

I feel kind of silly now but moving away from home slightly west (I’m talking maybe a quarter mile but out from behind some hills), the radio now IS picking up Fairfax P25. Of course I should have done this first, but I refused to believe that my new $650 can’t read a major system that is close by that my 436 and HP-2 can copy with no sweat. I may fool around with some outdoor antennas, but I expect they will not overcome geography.

I have seen some sensitivity plots posted and will take a look at those. I bough knowing going in that the SDS-100 was not advertised for superior sensitivity, but I am wondering if this is below spec. But for SDR, I imagine there are fewer hardware variables. Thanks all for jumping in.

Ok so I won’t post my fav file anymore. Looks like is a location issue and perhaps the antenna... good luck