Do I need a FM filter

[mikec10]

My scanner antenna is in my attic which is the 3rd floor. I have quad shield r-6 100 feet of coax. I only need about 75 feet. When I had my sds100 and now that I have the sds200 I notice that it receives a signal of some sort and stops the scanning until the signal stops. There is no noise or audible transmission. I thought this was what used to be called a "Birdy". Not sure if it is or not. I was wondering if a FM filter would help stop that. If so it would make the scanning go faster. Thank you for any thoughts on this.

 

[belvdr]

What frequency does it stop on? To see if it is a birdie, disconnect the antenna. Typically, a birdie can still be heard if the antenna is disconnected. You might also find the SDS filters to be of use.

 

[Whiskey3JMC]

More info is needed. Is it the same frequency every time or different frequencies at random? If the scanners don't exhibit the same behavior when a different antenna is connected & due to the fact that although the antenna is in the attic, it's still indoors. There could be one or more sources of electrical interference which an FM filter may not stop. Does enabling IFX (Press Function key and 7) get it to stop?

 

[mikec10]

Not the same frequency but it involves simulcasting frequencies 850mhz-865mhz. I take the attic antenna off or the rubber duckie antenna off and it will stop. Again no audible transmission or static. the rssi meter will vary in strength. Signal strength varies depending on frequency from3 to 4 bars.

 

[Whiskey3JMC]

If it stops when you move the SDS100 outside with the rubber duckie then chances are something inside your house is generating the noise

 

[mikec10]

My Global Auto Filter is set for Wide Invert. Seems to be the best.......

 

[Ubbe]

More info are needed. Is th

it involves simulcasting frequencies 850mhz-865mhz.

I assume this is a digital system and depending of how you have it programmed it could stop on a data channel. I don't know if Uniden have solved the issue where scanners stop on data channels that are used by the systems users to send messages or GPS positions.

Do you have those frequencies programmed as digital only?

Do the display indicate anything else besides the 3-4 bars of signal strength? You might need to use the detailed display mode.

As it happens to different frequencies it will probably not help to change filter settings or IFX.
When using a bigger antenna there will always be a risk of getting FM broadcast interference so a $25-$50 filter are always a good addition, even if it doesn't solve your current problem. Look in the thread about the analyze of different FM broadcast filters here at RR.

/Ubbe

 

[dave3825]

Post a video if you can with the scanner in full detail mode as it may help troubleshooting.

 

[iMONITOR]

My scanner antenna is in my attic which is the 3rd floor. I have quad shield r-6 100 feet of coax. I only need about 75 feet. When I had my sds100 and now that I have the sds200 I notice that it receives a signal of some sort and stops the scanning until the signal stops. There is no noise or audible transmission. I thought this was what used to be called a "Birdy". Not sure if it is or not. I was wondering if a FM filter would help stop that. If so it would make the scanning go faster. Thank you for any thoughts on this.

Sometimes I'll run into what sounds like a dead carrier or just some kind of undetermined unidentifiable noise that will cause the scan to stop and sit on it almost indefinitely. I run into this when scanning military aircraft frequencies. Possibly data or encryption. I just hit the temporary L/O (lock out) button and keep scanning.

If you have excess length of coax and you don't anticipate needing it in the future you could benefit from shortening it regardless.

 

[mikec10]

Thanks for all the info. It is all digital as one asked. I have changed the filter to wide auto which is actually better. On one favorites list which is 90 percent encrypted it does look like a dead carrier or possibly a encryption transmission since it is strong. Either way it did clear up some questions. I may just try a FM filter just to see if there is a difference. Also I am tempted to shorten my coax by 20 or 25 feet. I just don't like to reattach the connection. I never feel I do it correctly.

 

[krokus]

If there is a signal coming in via the antenna, that is causing the issue,, shortening the cable could make the problem a bit worse.

 

[Ubbe]

... It is all digital as one asked. .... it does look like a dead carrier or possibly a encryption transmission since it is strong.

Neither of those two. If it's a dead carrier or some kind of interference of a sort it isn't picked up in digital mode, it has to be scanning in analog mode to have any impact. Encryption are immediately skipped in scan mode and just hesitate for a half second or so until it continuous to scan.

Can you state the system(s) it happens on and the frequencies it stops on and are those all control channels or voice channels?

/Ubbe

 

[dlwtrunked]

My scanner antenna is in my attic which is the 3rd floor. I have quad shield r-6 100 feet of coax. I only need about 75 feet. When I had my sds100 and now that I have the sds200 I notice that it receives a signal of some sort and stops the scanning until the signal stops. There is no noise or audible transmission. I thought this was what used to be called a "Birdy". Not sure if it is or not. I was wondering if a FM filter would help stop that. If so it would make the scanning go faster. Thank you for any thoughts on this.

FM broadcast filters do not stop biries or interference form other stations. They will help in eliminating some intermod and in other cases, they will improve receiver sensitivity due to countering de-sense that caused by nearby FM broadcast stations. Note that de-sense is a devious thing, it just causes your receiver to be less sensitive and you do NOT hear the audio of the station causing it. Generally all should use an FM notch filter unless they desire to receive the FM broadcast band or desire to monitor the lower end of the VHF aero band (in the latter case, they need to pay more attention to the specifications of the the filter and buy a good (like the ZBSF-95)) more expensive one. Youor signal being intermittent indicates it is not a problem with the FM broadcast band. You really need to use a spectrum analyzer or cheap SDR to find out what (the frequency coming up) that is causing it .