I have the Uniden BCD436HP and attempting to monitor Philadelphia p25 from about 15 miles out. I have had some success in the past, with CC decode and broken up transmissions. Lately I haven't heard anything. I have a yagi 800 antenna pointed west towards Philly airport and am using firmware version 1.05.01. I am mainly looking for an optimal p25 threshold level in Manual mode (Or should I be in auto?) or any other tips to help with audio quality?
Getting the Most Out of Philly on your 436
- Thread starter policefreak
- Start date
- Status
Pointed west from where?
Berlin, NJ.
What's your signal level look like?? You may want to look at your coax.....how long the run is...what quality it is...especially look at your PL-259 or other connectors and how good the solders are etc. There's no replacement for lots of RF signal..
My two cents anyway...I have little luck out here near Valley Forge, PA with PHL.
My two cents anyway...I have little luck out here near Valley Forge, PA with PHL.
phillydjdan
Member
- Joined
- Jan 27, 2011
- Messages
- 2,075
I haven't noted any significant changes with the Philly system on their end, so I would mirror pwscott's suggestions and look into a feedline issue. I know from personal experience, good quality cable makes a BIG difference. I have a few BNC 3 foot patch cables that literally cut a given signal in HALF. Needless to say they are in a box in the basement lol. I would also investigate possible corrosion on or near the antenna. It can make for problems if the joints are not sealed properly.
I found the best set up was a 13 element 700-800 mhz yagi pointed west towards Philly (that's about 20 miles!) attached to a GRE Superamp (yea I still have one of those) attached to the 436with the squelch all the way down and the p25 threshold number set to 6 for both police and fire. Its not a constant copy but I am receiving about 70% of traffic so I have a pretty good idea of what is going on.
Policefreak, you may want to try using some mapping software and get an exact heading for the closest site to you. That yagi you have has a narrow beamwidth. If you are off just a couple degrees from the target site the attenuation could be significant.
I use a 5 element yagi at 40ft feed with 9913 coax with N connectors feeding a 4 port active stridsburg multicoupler. This antenna has less gain but is more forgiving when pointing it. My receive results are about the same as yours.
I use a 5 element yagi at 40ft feed with 9913 coax with N connectors feeding a 4 port active stridsburg multicoupler. This antenna has less gain but is more forgiving when pointing it. My receive results are about the same as yours.
It's more effective to point a Yagi in a direction that NULLS every site but one rather than pointing it toward a site hoping to get the signal strength substantially higher than the other sites. The best direction usually is not directly at a site.
This is only in the case where you are receiving multiple sites on a simulcast system.
For non-simulcast systems, or locations where only one site is receivable, the best route would be to point to that one site.
This is only in the case where you are receiving multiple sites on a simulcast system.
For non-simulcast systems, or locations where only one site is receivable, the best route would be to point to that one site.
Philadelphia uses 10 simulcast sites in relatively close proximity in the city. It would be virtually impossible to null out 9 out of 10 sites from 15 miles away in Berlin. Police freak would have an easier time if he were located in the city close to a site. Until a scanner manufacturer changes their hardware to properly handle LSM without the scanner distortion, there will always be problems in reception using consumer scanners.
The only alternative other than using a real Motorola radio, is to use the OP25 software, which handles LSM when using an SDR such as Airspy. However it takes a lot of technical expertise to set up and install the program and it's many dependencies on a dedicated fast Linux machine.
The only alternative other than using a real Motorola radio, is to use the OP25 software, which handles LSM when using an SDR such as Airspy. However it takes a lot of technical expertise to set up and install the program and it's many dependencies on a dedicated fast Linux machine.
I hate trying to monitor Philly on the 436. I was based on the grounds of Lankenau for the Montco Pope detail and I had a helluva time monitoring the city. I ended up using a uhf portable monitoring SEPTA for J Band comms to keep an ear on what was happening downtown. The 436 would be dead for 20-30 minutes at a time...maybe longer. I brought the 436 along to see how it would do on the city system from right next door. Epic fail.
phillydjdan
Member
- Joined
- Jan 27, 2011
- Messages
- 2,075
Joe, you'll have to excuse my pal Voyager, he's a Uniden fanboy that doesn't live in LSM alley... lol
For the record, I'm in the middle of LSM alley and have been for over 10 years. That's where my comments and experience originate. I've solved many issues through the techniques I've passed on. I have a system that I monitor that is 60 miles away. Yet I have difficulty monitoring a system that is only 2 miles away. That is due to intentional coverage nulling on the part of the system designer. Philly's system is similar - designed to only cover the city and little else. There have been reports (I cannot affirm or deny them) that Philly's system has been intentionally mis-tuned to not work well on lower end equipment such as scanners (lower end being those costing less than $2K). Again, I cannot say they have or have not, but it is a plausible theory and would explain much.
Septa3371CSX1
Member
I don't have too many issues monitoring Philly with my Pro 651 (and before that my Pro 106 before the antenna connector became too loose to reliably monitor). I do get transmissions dropping out or not fully coming over and some LSM issues but not as bad as my Pro 668 which gets LSM issues pretty bad. I've had similar issues trying to monitor Camden County on my 668 but last month when I went down to MD I had no LSM issues with monitoring First Net down there. I've also been able to monitor Berks County on it with decent decode. All seems to be dependent on the set up of the system.
Voyager is absolutely correct about the nulling. Again sometimes it just can't be accomplished.
Again until Uniden or Whistler solve the LSM problem - and that means a complete redo of the receiver front end - consumer scanner owners will keep having problems. Unless
- You live next to a site
- You can effectively null out all other "offending" sites
- You use a real Motorola radio to monitor
- You use OP25 to monitor
Also I believe Denny was modifying his SDRTrunk program to handle LSM. Not sure if it's working yet but here is the link to the thread:
http://forums.radioreference.com/vo...308299-sdrtrunk-p25-decoder-test-release.html
Again until Uniden or Whistler solve the LSM problem - and that means a complete redo of the receiver front end - consumer scanner owners will keep having problems. Unless
- You live next to a site
- You can effectively null out all other "offending" sites
- You use a real Motorola radio to monitor
- You use OP25 to monitor
Also I believe Denny was modifying his SDRTrunk program to handle LSM. Not sure if it's working yet but here is the link to the thread:
http://forums.radioreference.com/vo...308299-sdrtrunk-p25-decoder-test-release.html
- Status
Similar threads
- Locked
