SDS200 Filter setting Question ?

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BOBRR

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Hi,

Have a SDS 200.

Tried experimenting, but results inconclusive, and hard
to reach a conclusion.

Which Filter do you folks (usually) use ? Auto, Wide Normal, or...?

Different for different freq. ranges ?

I do a lot of monitoring in Aero. freq's around 118 MHz.

What do you think would work best ? Why ?

Thanks,
Bob
 

nessnet

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No one here can answer that question - because it all depends on YOUR RF interference situation where YOU are.
I can have a certain filter setting, get in my car and drive 2-3 blocks and the (filter) situation can completely change.

Experiment - it is the only way YOU can tell what is best for your location.
 

Ubbe

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The one setting that I think would work best in VHF airband are Invert, as Normal will open for all the FM broadcast stations when monitoring the lower end of the band. Frequencies 100KHz and maybe 150 and 300Khz from the monitored frequency create intermod with almost as good sensitivity as the monitored frequency. If you are unlucky the intermod frequencies are in use at your location. Then try IFX as it will probably move the intermod to other intervals, where it hopefully will be free of other transmissions.

/Ubbe
 

letarotor

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I'm glad this question was asked because I seem to have lost the location of a post that came out around the time that the first filters were included in a firmware update. Somebody had broken down what each filter's details were as best as they could. I have since looked for that thread, and I am pretty sure it was here on RR, but I have not been able to find it.

It can sometimes be difficult to see which filter works best on a frequency just by trying them especially if the frequency is not a busy one. I've been thinking about taking my SDS100 and SDS200 and hooking them both up to the multi coupler so they have the same exact antenna feed. I'm not sure if that would really work well or not with the two radios not being exactly the same but I thought it might help as a comparison? But I know a lot of people don't have both of the radios and can't do that either. So one other thought I had was just setting the radio of choice on a frequency of interest and letting the audio record to the SD card. Just change the filter maybe once a day or twice a day. At least then you could go back and listen to the audio of interest and see if one filter works a lot better than the others. But from seeing the reply above, I'm now wondering if the filter might even need to be changed on different days due to different RF propagation or electronics in the room?

The different filters definitely affect the different speeds the radio can scan it appears. And even though we all want the fastest scanning possible, I'd be willing to slow it down a little bit just to be able to get the best signal possible if that was needed.

Does anyone know of a thread here on RR that details the filters? If there is one and you have the link to it, I sure would appreciate it.

Brian (COMMSCAN)
KI5FLE
 

BOBRR

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Hi All,

Thanks for the information, and thoughts on.
Sure is a lot to know. (particularly re Filters).

Might someone, if they get a spare minute, explain the "AUTO" filter characteristics for me ?
e.g., what does it do, and not do ?

And, is it, usually, a fairly good "compromise" setting ?

etc. ?

Thanks, stay safe,
Bob
 

Ubbe

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The different filters definitely affect the different speeds the radio can scan it appears.
It is interferencies that makes the scan hesitate and slow down. When you have no interferencies, pretty much impossible with a SDS scanner, it will always scan at full speed, 45ch/s. Even if you remove the antenna it will have hickups in the scanning from the internal interferencies in the scanner, even the display in SDS100 emits interferencies when the backlight are on.


Might someone, if they get a spare minute, explain the "AUTO" filter characteristics for me ?
e.g., what does it do, and not do ?

And, is it, usually, a fairly good "compromise" setting ?
The only parameters the scanners logic can look at are Noise level for analog channels and also D-error for digital systems. It has to test each filter and use the one that gave the best result. It has to sample the signal a fairly long time to be able to make a good choise.

If you use Auto filter it will slow down scanning and you might not catch conversations happening in other systems as it will take a long time to do a full scan cycle. If you do not use Auto you could experiance total blackout of some frequencies so that you miss conversations where those frequencies are used. Neither option are really any good. If you only scan very few systems would Auto be prefered.

/Ubbe
 

letarotor

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It is interferencies that makes the scan hesitate and slow down. When you have no interferencies, pretty much impossible with a SDS scanner, it will always scan at full speed, 45ch/s. Even if you remove the antenna it will have hickups in the scanning from the internal interferencies in the scanner, even the display in SDS100 emits interferencies when the backlight are on.


The only parameters the scanners logic can look at are Noise level for analog channels and also D-error for digital systems. It has to test each filter and use the one that gave the best result. It has to sample the signal a fairly long time to be able to make a good choise.

If you use Auto filter it will slow down scanning and you might not catch conversations happening in other systems as it will take a long time to do a full scan cycle. If you do not use Auto you could experiance total blackout of some frequencies so that you miss conversations where those frequencies are used. Neither option are really any good. If you only scan very few systems would Auto be prefered.

/Ubbe
Thank you Ubbe. I will take a look at the link also and see what it says but your description was also helpful and I think I can relate to a lot of what you were describing as I changed different filters checking them out. I'm usually not scanning more than two or three Favorites Lists at a time but then sometimes a Favorites List I have may have 15 or 20 Departments. Thank you for your reply and this will give me something to work with and do some checking on.

Brian (COMMSCAN)
 
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