Roanoke County p 25

[kju1]

I just moved back to the area I have a pro96 and I live near cave spring corners and on the Roanoke system I just get lots of digital modulation (broken audio)or no reception at all and can not seem to get it to go away I have ventured around and it seems to be pretty consistent. I pick up Va Stars system just fine with no problems I believe it is a reception issue any ideas ?

 

[John]

Roanoke City/County P25

You are using a PRO-96? It will pickup the City/County P25 system but since the system is Simulcast from 4 mountain tops it is difficult to receive well. The problem is getting strong signals from more than one site slightly out of sync with each other. The Motorola radios handle this OK but scanners don't. If you are located in an area where one signal is much stronger than the others then the scanners work fine. I have one in my office downtown and since that is right underneath Mill Mountain it picks up great but at home near the airport it doesn't. At home I pick up signals from 3 or more sites.

The solution is trying to get one site and not the others. On a fixed radio such as at home you may be able to do this by adjusting the length of the antenna or using the builtin attenuator. Or you may be more successful with a directional antenna. Mobile is more of a problem since a directional antenna is not practical. All you can do is try different antennas to find one that matches the areas you travel. I have heard of people having some success with a UHF rubber duck antenna on the handheld.

Sorry but it isn't easy.

John

 

[kju1]

Thanks

Thanks John,
I think that makes sense I am used to living in areas with more than 1 site and a control channel for each site not simulcast like you are speaking of so it sounds that each site is interfering with the other sites.

 

[kju1]

No luck

I am still having no luck with this system. Does anyone know of any fleet mapping/ frequency tables that may be needed to use with this system I cannot grasp the concept that its a weak signal or interference. I was setting beside a officer yesterday and he was using his radio and on my scanner all I heard when he keyed up was digital noise if I am having a reception issue they should too. I am not on the edge of the coverage area so reception should not be a problem. I also ventured out and everywhere I went I had the same issue I believe it is a settings issue and I do believe that all the info posted here on RR is incomplete or inaccurate in some way .

 

[richrowl]

PRO-96 tables

I am still having no luck with this system. Does anyone know of any fleet mapping/ frequency tables that may be needed to use with this system .

You may want to look at the frequencies and then select one of these two tables

REBANDING TABLES using WIN96 software programming

TABLE - 1
Pro-96 and 2096

If there are no frequencies above 862 MHz program the two ranges below.
CH Lo CH Hi Base Freq Offset Step
440 559 851.0250 440 25.0
000 719 851.0125 0 25.0

TABLE - 2
Pro-96 and 2096

If the frequencies are above and below 862 MHz program the six ranges below
CH Lo CH Hi Base Freq Offset Step
440 559 851.0250 440 25.0
000 719 851.0125 0 25.0
720 759 848.0000 0 25.0
815 831 846.6250 0 25.0
958 958 868.9750 958 25.0
961 1022 843.4000 0 25.0

 

[John]

Rebanding doesn't apply to a P25 system like Roanoke. The freq tables should be set as

0 4095 851.00625 0 6.250
4096 8191 762.00625 0 5.000
65535 65535 0.00000 0 5.000
65535 65535 0.00000 0 5.000
65535 65535 0.00000 0 5.000
65535 65535 0.00000 0 5.000

And yes, their radios will work a lot of places yours don't. For one thing theirs have a dedicated P25 decoder while the scanner has a software DSP function trying to do the same thing.

Have you tried driving into downtown Roanoke and checking? By downtown and mean the actual downtown and not just nearby. That would give you a good idea of whether it is a signal reception (too much signal from multi-sites) or not.

John

 

[John]

BTW, the 853 CC channel listed in RR is probably not correct. The others are OK.

John

 

[beastieboy101]

Alexandria City and Fairfax County are on new P25 Simulcast systems and I sometimes have trouble getting Alexandria City to come in clearly. I have a pro-96 also and have found that removing the stock antenna yields better results for Alexandria. I can see the nearest antenna from my apt.

 

[fredva]

I've not tried this myself, but I found an interesting article on how to use a Yagi antenna to alleviate simulcast reception issues. Of course, this would only work on stationary scanners. http://forums.radioreference.com/sc...ated-guide-yagi-solving-simulcast-issues.html

 

[kju1]

Stk antenna

Alexandria City and Fairfax County are on new P25 Simulcast systems and I sometimes have trouble getting Alexandria City to come in clearly. I have a pro-96 also and have found that removing the stock antenna yields better results for Alexandria. I can see the nearest antenna from my apt.

I threw the stock antenna away about 2 wks after buying the scanner years ago the stock antenna sucked. I have the radio shack 800mhz rubber duck I have also tried other antennas. Still working on it though.

 

[kju1]

Maybe some success???

I have tried all the options that all of you guys have provided me and none of them solved the issue. However I did take some of that info and some info i got from running Pro96com and I set the custom Motorola custom Trunking table using win96 to

Base Frequency 851.00625
Offset 0
Step Size kHz 6.25

and so far it seems that it has helped maybe not solved the issue totally. But I think I may have gained some ground with it.

Thanks to all for the help or any help you all have/may continue to provide.