Signal Help

[kb9hgi]

I'm not sure where to post this so I will try here and sorry if it does not blong in this topic.
I live in Illinois where we have IL State Police on Starcom which is a P25 800mhz system. Where I live there is 2 large towers and I think one of them is registered to Nextel. Anyway my problem is what ever signal is come off one of those towers which I think is for cell phone is knocking out my receive on this P25 800mhz system. First thought is was my 996 and my friend came over with his GRE and same thing and was watching the signal on his GRE. So we know something is blocking my receive.

Now my question is there anything out there to block or filter this signal that is comeing off that tower? I think its cell phone signals off that tower doing it.

 

[rvictor]

Looks like you are probably listening to the Fowler Starcom tower. You might want to try the Kingston, Mendon, or New Canton towers which are on different frequencies and see if you can hear Starcom on those towers. Perhaps the different frequencies would avoid the interference from the cell tower. Could be, of course, that you're too far from those other towers for decent reception, but it's worth a try.

73
Dick

 

[fineshot1]

I'm not sure where to post this so I will try here and sorry if it does not blong in this topic.
I live in Illinois where we have IL State Police on Starcom which is a P25 800mhz system. Where I live there is 2 large towers and I think one of them is registered to Nextel. Anyway my problem is what ever signal is come off one of those towers which I think is for cell phone is knocking out my receive on this P25 800mhz system. First thought is was my 996 and my friend came over with his GRE and same thing and was watching the signal on his GRE. So we know something is blocking my receive.

Now my question is there anything out there to block or filter this signal that is comeing off that tower? I think its cell phone signals off that tower doing it.

The answer is yes - there are filters that can possibly help BUT first you must identify exactly what
is causing this interference. The cellphone and nextel bands are adjacent to each other and it could
be one or the other(or both) or even perhaps something else coming off those towers. Once you do
identify the source contact the folks in the link below. Par Electronics makes filters for just this sort
of interference problem. Good luck.....

PAR Electronics Inc. Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave

 

[kb9hgi]

Yes you are correct about Fowler Tower but there is no fowler tower the system is south of Quincy at Marbelhead, IL and I can not receive it but do pick up control channel on it and warsaw but that signal kncoks it out. I can hear Mendon which is about 10 miles from me with 2 bars which that signal robs it and that why I only get 2 bars. Hmmm this is going to be hard to tell what is doing it to get a filter too much stuff on those towers near me.

 

[rvictor]

Yes you are correct about Fowler Tower but there is no fowler tower the system is south of Quincy at Marbelhead, IL and I can not receive it but do pick up control channel on it and warsaw but that signal kncoks it out. I can hear Mendon which is about 10 miles from me with 2 bars which that signal robs it and that why I only get 2 bars. Hmmm this is going to be hard to tell what is doing it to get a filter too much stuff on those towers near me.

I'm sure that you are more knowledgeable than I as to the actual tower locations in your area. I was working off the system information and maps provided by the Starcom link on this page which shows all the towers, frequencies, locations, etc. and may be helpful in your effort to get the problem resolved.

CARMA Profiles

Looks like it's going to be a bit of a challenge, but one would hate to not receive that system given all the agencies that are on board.

Good luck!

73
Dick

 

[jim202]

This is not much of an answer, but it might help if you can make friends with someone on the police
force in your area. Ask them if they know if the trunking system will be rebanded in the near
future. What this will do is relocate the radio control and voice channels 45 Mhz lower than where
they are at present. Reason is to resolve just the problem that your having. Only it is also
causing problems for the public safety people also.

Jim

I'm not sure where to post this so I will try here and sorry if it does not blong in this topic.
I live in Illinois where we have IL State Police on Starcom which is a P25 800mhz system. Where I live there is 2 large towers and I think one of them is registered to Nextel. Anyway my problem is what ever signal is come off one of those towers which I think is for cell phone is knocking out my receive on this P25 800mhz system. First thought is was my 996 and my friend came over with his GRE and same thing and was watching the signal on his GRE. So we know something is blocking my receive.

Now my question is there anything out there to block or filter this signal that is comeing off that tower? I think its cell phone signals off that tower doing it.

 

[rfradioconsult]

First, Nextel is not a cellular carrier provider; it is an ESMR and shares the same 800 MHz band with public safety users, most likely a notch filter will not be beneficial in eliminating the interference. Depending on how re-banding will impact your particular site you should see an improvement. Trying to receive other sites may not be a solution as all their sites will be in the same 800 MHz band.

Rebanding does NOT move the channels down 45 MHz but move those PS frequencies between 866-869 MHz down approxmately 15 MHz; however, the benefit comes in moving the Nextel channels up in frequency and creates a guard band between them and PS and other trunked users.

 

[N0KMA]

One down and dirty way to get rid of an offending signal de-sensitizing the font end of the receiver is to first know what frequency is causing the problem. Then grab a T connector. Hook the T to your receiver then on one input of the T connect your antenna, on the other input of the T trim a length of coax to a quarter wavelength of the offending signal, short the center and braid and the offending signal will be gone. May take a bit of trimming to find the sweet spot but once on target will work like a charm.

Todd
NØKMA