SDS200 "filter" settings

[sibbley]

Just my 2 cents. I believe the SDS scanners would benefit greatly from a variable attenuator. Maybe like 5,10,15,20. Sometimes you need just a little, and 20db is just too much. Actually, I think all scanner would benefit greatly from this!

IFX = Func+7 while holding on the frequency you want to use IFX on.

• Intermediate Frequency Exchange - changes the IF used for a selected frequency to help avoid image and other mixer-product interference on a frequency.

 

[skidplate]

If there are some people on here that have access to some test equipment, maybe they could actually run some tests and try adjusting the
filter settings and see if they do anything at all. Trying to monkey around with those settings just by using off the air signals sucks.

 

[mule1075]

I could only find it on Sentinel, not on the scanner itself.

Hold on the channel you want press function and then the 7 key.

 

[Ubbe]

I should have been more clear. I wasn't implying fixed, but software defined.

I should also have been more clear. All filters are based from the frequency you are currently monitoring and not other frequencies, like filtering FM broadcast and pagers when monitoring VHF frequencies. It's filtering frequencies lower or higher from the one you are monitoring so if you monitor 118-137MHz air the high pass will filter FM broadcast better and low pass will filter 155MHz pager transmitters better.

/Ubbe

 

[Ubbe]

If there are some people on here that have access to some test equipment, maybe they could actually run some tests and try adjusting the
filter settings and see if they do anything at all. Trying to monkey around with those settings just by using off the air signals sucks.

Yes, someone here in the forum did that a while ago when there where only normal and invert filters available and they did work.

How the filters should be set are only based on your own unique listening positions. It depends of what frequencies do interfere with your monitoring and needs to be reduced to hopefully lessen the interference. It will not always work, as other scanners also could fail, and other options like external filters or band specific antennas or plainly a better scanner or a radio are needed to cope with strong interference situations.
Even in professional installations of radiosystems you sometimes need extraordinary solutions to make a radiosystem work satisfactory. But sometimes the hardware are impossible to work with and even big statewide systems are thrown out in favour for another suppliers hardware or system solution.

/Ubbe

 

[mortoma61]

In my #1 case of problematic receiving, which were several 800 MHz conventional police frequencies that were close in frequency to a strong control channel for the local smartzone of our state police TRS, I found that using the IFX with the invert filter worked superbly. The filters alone did not make an overwhelming difference for me by themselves. I too would like to see a detailed description of what the actual intention of these filters are. There is some description of a few of them at this link:

http://info.uniden.com/twiki/bin/view/UnidenMan4/SDS200FirmwareUpdate

Helped me a little but then they talk about something called 'HPF" and apparently assume you know what that is all about. That was Greek to me so I have to find out what HPF is in order to understand this better.

 

[mortoma61]

Hey everyone can someone fill me in on this ifx setting and where to find this?

Plus what does IFX even mean! What do the letters stand for?? Maybe it's 'Internal-Flux-X-radiation?? That old dude from Back to the Future would know?? LOL....

 

[kruser]

Plus what does IFX even mean! What do the letters stand for?? Maybe it's 'Internal-Flux-X-radiation?? That old dude from Back to the Future would know?? LOL....

IFX stands for Intermediate Frequency Exchange. It alters the IF frequency in the radio in an attempt to try and shift interference from an interfering frequency away from the frequency you are monitoring. Read Post 41 above.

HPF stands for High Pass Filter. It's a filter that attempts to stop interference from frequencies below the one you are monitoring and only allow those from your frequency and higher to pass through the radio to your speaker. If it works, it should attenuate signals lower than the one you are monitoring to reduce overload from strong signals that may desense the front end.

They can both help but you must play with them to find the best setting for your area.

 

[ansky]

I should also have been more clear. All filters are based from the frequency you are currently monitoring and not other frequencies, like filtering FM broadcast and pagers when monitoring VHF frequencies. It's filtering frequencies lower or higher from the one you are monitoring so if you monitor 118-137MHz air the high pass will filter FM broadcast better and low pass will filter 155MHz pager transmitters better.

/Ubbe

I think I'm starting to understand. Let me give you an example. When I listen to 460.150 I can hear interference from 477.2375. So should I be using the Wide Normal filter because I'm trying to filter out a higher frequency?

 

[iMONITOR]

I should also have been more clear. All filters are based from the frequency you are currently monitoring and not other frequencies, like filtering FM broadcast and pagers when monitoring VHF frequencies. It's filtering frequencies lower or higher from the one you are monitoring so if you monitor 118-137MHz air the high pass will filter FM broadcast better and low pass will filter 155MHz pager transmitters better.

/Ubbe

I understand what low pass and high pass filters do. What about notch filters? They are the total opposite of what you're describing.

 

[buddrousa]

I think I'm starting to understand. Let me give you an example. When I listen to 460.150 I can hear interference from 477.2375. So should I be using the Wide Normal filter because I'm trying to filter out a higher frequency?

1st I would try IFX and then work with filters.

 

[mule1075]

1st I would try IFX and then work with filters.

That's what I did some needed just the IFX set and filters set to off and some needed trial and error. It might seem to be a pain but well worth it in the long run. With the new technology there will be growing pains no doubt.

 

[KevinC]

I think I'm starting to understand. Let me give you an example. When I listen to 460.150 I can hear interference from 477.2375. So should I be using the Wide Normal filter because I'm trying to filter out a higher frequency?

In theory "Invert" would be want you'd want. This is supposedly low pass, but we don't know what the cutoff frequency is unfortunately.

 

[Hit_Factor]

I understand what low pass and high pass filters do. What about notch filters? They are the total opposite of what you're describing.

If looking at audio signal display, and adjusting the notch filter, you can see an area of silence cut (notched) out of the signal. The width of the notch is usually adjustable, and so is the position.

If there is interference (whistling, squeal) from another freq close to the one you are monitoring, sometimes the notch filter helps. Often at the expense of some portion of the Audio signal being lost. Such as low, mid, or high freq portions of speech (broadcast).

73, K8HIT
Icom: IC-7300, IC-PW1, ID-5100A, ID-51A Plus 2, IC-R30, Hytera PD782G, Kenwood TH-D74, Uniden SDS100, DVMega, SDRplay RSPduo

 

[garys]

This isn't the first Uniden scanner to have IFX. The 996XT had is do the x36HP scanners. The information is out there for those ambitious enough to do just about 5 seconds worth of research.

Plus what does IFX even mean! What do the letters stand for?? Maybe it's 'Internal-Flux-X-radiation?? That old dude from Back to the Future would know?? LOL....

 

[Hit_Factor]

Here are two examples of the notch filter. Top example using a medium width and is notching (blanking) the audio signal at approx 2.5 kHz, bottom pic is using a narrow notch at .4 kHz.

The red arrow points to the notch in each pic. As you can see, it complete blocks out that portion of the audio signal. Generally you want to start with the narrow notch, increase the width as needed.

 

[iMONITOR]

Here are two examples of the notch filter. Top example using a medium width and is notching (blanking) the audio signal at approx 2.5 kHz, bottom pic is using a narrow notch at .4 kHz.

The red arrow points to the notch in each pic. As you can see, it complete blocks out that portion of the audio signal. Generally you want to start with the narrow notch, increase the width as needed.

I'm talking about RF notch filters, not AF. See the chart below taken from PAR Electronics by Dale Parfitt. This an FM notch filter used to help reduce or eliminate interference from the standard FM broadcast band. Typically used when monitoring VHF aircraft. I'm not implying the SDS-200 has filters like that buy rather software defined filters that provide similar results.



(source)
VHF-FM Broadcast Filters | PAR Electronics | Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave listening enthusiasts

 

[N8TXX]

I Thought I recognized those screen shots, I have an IC-7300 and the filters are awesome!

 

[Hit_Factor]

I didn't understand your question, I thought it was a general question about what is a notch filter. I did think to my self, that's odd, I though he (iMONITOR) was pretty knowledgeable and would know about these.

Hopefully anybody with notch filter questions, now has an understanding.

 

[Hit_Factor]

The IC-7300 is awesome, I have a PW-1 to go with it and can really get out.