Interference listening to 700MHZ Public safety.

[Ronnierozier2]

Good Morning,

I live in a small town in Mississippi and I think im having some major interference from an ATT tower about a mile away. From my home thats in the middle of town I can barley get a signal from the three sites close to me. they are around 15-18 miles away. By the way this is the MSWIN system in Mississippi. back to the ATT tower..... I just looked it up but it seems like ATT FirstNET uses 758-768MHz and the system im listening to uses 769-775MHz.

If this is the source of my interference how can I improve my signal or block out the ATT FirstNET? If i drive right outside of town away from the ATT tower I'm able to pickup 7-8 MSWIN towers with a strong signal.

 

[IAmSixNine]

I have had interference from cell towers but i have to be pretty darn close to them for the interference to happen. 1/4 mile or less away from them.
We aslo need to know more about your setup.
What scanner? external antenna? both internal and external?

 

[kc8gjh]

I had the same problem with a cell tower less than a mile from my house and my TRX-1 went silent when I moved to that area. I tried all sorts of filters and even went the SDR route with no luck. I decided to buy a Uniden SDS-100 to see if a different type and model of scanner would work and buying the SDS-100 solved the problem and I get zero interference now. Not sure why the Uniden worked when no others did but now I have no more intereference.

 

[sonm10]

I wonder how this might work on your 700... Worth a try

BPF-800-EN | Scanner Master

BPF-800-EN

www.scannermaster.com

I know is says 800, but it says it goes down to 765

 

[kmartin]

I wonder how this might work on your 700... Worth a try

BPF-800-EN | Scanner Master

BPF-800-EN

www.scannermaster.com

I know is says 800, but it says it goes down to 765

It shows out of stock

 

[majoco]

ATT FirstNET uses 758-768MHz and the system im listening to uses 769-775MHz.

Be a bit of a stretch to filter out the 758-768MHz and keep the 769-775MHz,

 

[Ubbe]

If this is the source of my interference how can I improve my signal or block out the ATT FirstNET? If i drive right outside of town away from the ATT tower I'm able to pickup 7-8 MSWIN towers with a strong signal.

I see from your other messages that you use a SDS100 scanner and you have probably already tried the different filter settings for the sites and also tested to enable IFX on the control channels. When you point your scanners antenna to a transmitter source it will attenuate the most in that direction, the FirstNET, but will still receive from other directions, your MSWIN towers. You should probably test that outside with less indoor reflections.

It could be that you are in a bad spot with low coverage as 15 miles isn't nearby and there could be some terrain or buildings blocking the signals. You don't have another scanner, even analog, that can be tuned to the control channels and listen if the signal sounds as clean data or if it's a lot of noise indicating bad coverage or even some interfering signals?

Program the control channels from some towers, perhaps it is the same frequency if it is a simulcast system, in the SDS100 scanner and set the mode to only do analog so that you can listen to the audio. Set squelch to 0 and listen to the data signal and move around in the house or outdoors, try different heights if possible, and see if you can improve the signal quality. Also try that when pointing the antenna in different directions to try and minimize any interfering strong signals.

When trying to receive the MSWIN system you can enter the control channel by Channel+frequency+Channel and edit the display to show digital error and set squelch to 0 and try to get as low error value as possible, 5 or lower are good but could work up to 10. Test different filters and IFX and if you manage to get a bit error below 10 you can use that filter setting for the sites and start scanning to see if it starts to monitor the system.

SDS scanners will reduce its sensitivity if it senses any strong nearby transmitter within a 10MHz window that are not affected by filter settings. If that is the case then an external filter are needed but can be a bit difficult if the signal are too close in frequency. It could help if you have a SDR dongle to look at the frequency spectrum using SDR# to see where any offending strong signals are located. But perhaps it's just a bad coverage problem needing an external antenna positioned higher up above ground. You testing will probably prove what solutions you'll need to use.

/Ubbe

 

[reconrider8]

Not trying to hijack the thread but what kind of interference are you seeing? I ask because I bought me an 800 mhz antenna and I went to set it up and it didn't recieve squat long story short I tried another antenna and it would recieve a little on the ground but nothing in the air until I cut the attenuator on on the scanner then it would barely recieve. I did some looking around and I have a cellular water tower about 2 blocks from my house. So I'm thinking the 800 cellular is overloading the scanner on the front end