SDS Filter Settings

[xusmarine1979]

Hi all, I hope everyone is healthy and well. I have a question that has probably been covered but I can't quite find what I'm looking for.

As for the filter settings, which filter (wide or not) actually creates a tighter or smaller window to the frequency being monitored. Or if someone knows how many MHz it allows for the radio to hear. I know I've seen someone talk about it before, but can't seem to find the thread.

Thanks in advance!

 

[RandyKuff]

Description of what exactly the filters do is been kind of vague...
It's kind of a trial and error method to see what works best...

There is some info here...

SDS100/SDS200: - So what exactly are the filters, anyway?

Before I start, I'd like to say the manual that comes with the SDS100/200 is the weakest POS I've ever seen. In a radio with so many advanced settings, one would think the manufacturer would at least put together a PDF manual that explains the basics of what they do and examples of when to use...

forums.radioreference.com

 

[xusmarine1979]

Description of what exactly the filters do is been kind of vague...
It's kind of a trial and error method to see what works best...

There is some info here...

SDS100/SDS200: - So what exactly are the filters, anyway?

Before I start, I'd like to say the manual that comes with the SDS100/200 is the weakest POS I've ever seen. In a radio with so many advanced settings, one would think the manufacturer would at least put together a PDF manual that explains the basics of what they do and examples of when to use...

forums.radioreference.com

That's it, thank you kindly.


I always seem to be playing with the filters and IFX but if I understand it correctly the interference tends to come from all different directions. I'm wondering if they could ever have an option to just make a filter setting to narrow or something of that nature. I know the filter won't be perfect but my 100 does seem to perform a bit better than my GRE in noisy environments. But by what Ubbe says that if it's in the off position it's 5MHz both ways, so if I'm monitoring a 700/800MHz system I think off may help with bleedover from other channels from that same system and maybe help a little from cell towers. Hmmm... I see where Ubbe said it's 10MHz wide, but just wondering if there's any way to maybe tweak that.

 

[trentbob]

I'd be glad to give you a quick tutorial on the filters.

Look at filters as a troubleshooting aid and not something that has to be applied to every object.

Keep in mind what works for me won't work for you so when you hear these blanket statements that "no filter" is best or this one is best over another, that's for where they sit and depends on their RF environment. Not yours.

People will say to use Sentinel to apply filters and I disagree, do it on the radio because you're looking for results from real-time reception looking at RSSI and noise levels.

Also avoid using Auto filters, they sample every filter and slows scanning way down and you never know what filter did the trick anyway.

Global filter is set to normal for a reason it's a good starting point. Global filter affects every object in the radio unless you go into the sites of a system and change them or the department settings of a conventional object and change them. Global is not where you want to set your filters and leave it or you will find that other objects will suffer.

You want to set filters on individual sites of a system or on conventional frequencies... you want to use Department options for the Department that the channel you want to apply the Filter to is controlled. No you can't just apply a filter to a channel it has to be to the department options that channel is under which means it affects all of the channels that are under that department... so you can get around that by the way you program your grouping of channels. Aviation frequencies are going to respond to the same filter, so Will Railroad so group them accordingly.

So any object you don't individually change to another filter will remain on normal filter if you leave Global on normal.

Global filter can be used to give you a good idea on how a filter will affect a system or conventional Channel. On the radio while listening to the system or Channel you're having problems with apply the different Global filters or no filter at all and look for the best RSSI and noise level. When you find the most optimal results put Global filter back on normal then...

... go into the system options and go to the sites that you have activated, the less sites the better of course and apply that filter that you found most optimal RSSI and noise levels to that site or sites. Now you're left with just that system having that filter and Global being normal for all the other objects that you have not changed.

Same goes for conventional. Sit on the channel, this could be tedious because sometimes they're not busy but try different Global filters other than Auto and see what gives you the best RSSI and noise level. Repeat steps above. Put Global filter back on normal and apply the appropriate filter to Department options that channel is under.

You can also toggle function 7 on conventional channels to see if that helps also but remember that is a universal application and will change that frequency everywhere in the radio it exists to also have ifx applied. For example in my location all Aviation frequencies have to have ifx applied or they will be deaf.

When you're done make sure to hook up to Sentinel and transfer all the information from your card into Sentinel so as to save your filter changes.

Hope that helps, any questions, just let me know... Bob.

PS... I forgot to mention to make sure to put the filter indicator on your display so as to be able to keep track of every filter that's on every object.

 

[xusmarine1979]

I'd be glad to give you a quick tutorial on the filters.

Look at filters as a troubleshooting aid and not something that has to be applied to every object.

Keep in mind what works for me won't work for you so when you hear these blanket statements that "no filter" is best or this one is best over another, that's for where they sit and depends on their RF environment. Not yours.

People will say to use Sentinel to apply filters and I disagree, do it on the radio because you're looking for results from real-time reception looking at RSSI and noise levels.

Also avoid using Auto filters, they sample every filter and slows scanning way down and you never know what filter did the trick anyway.

Global filter is set to normal for a reason it's a good starting point. Global filter affects every object in the radio unless you go into the sites of a system and change them or the department settings of a conventional object and change them. Global is not where you want to set your filters and leave it or you will find that other objects will suffer.

You want to set filters on individual sites of a system or on conventional frequencies... you want to use Department options for the Department that the channel you want to apply the Filter to is controlled. No you can't just apply a filter to a channel it has to be to the department options that channel is under which means it affects all of the channels that are under that department... so you can get around that by the way you program your grouping of channels. Aviation frequencies are going to respond to the same filter, so Will Railroad so group them accordingly.

So any object you don't individually change to another filter will remain on normal filter if you leave Global on normal.

Global filter can be used to give you a good idea on how a filter will affect a system or conventional Channel. On the radio while listening to the system or Channel you're having problems with apply the different Global filters or no filter at all and look for the best RSSI and noise level. When you find the most optimal results put Global filter back on normal then...

... go into the system options and go to the sites that you have activated, the less sites the better of course and apply that filter that you found most optimal RSSI and noise levels to that site or sites. Now you're left with just that system having that filter and Global being normal for all the other objects that you have not changed.

Same goes for conventional. Sit on the channel, this could be tedious because sometimes they're not busy but try different Global filters other than Auto and see what gives you the best RSSI and noise level. Repeat steps above. Put Global filter back on normal and apply the appropriate filter to Department options that channel is under.

You can also toggle function 7 on conventional channels to see if that helps also but remember that is a universal application and will change that frequency everywhere in the radio it exists to also have ifx applied. For example in my location all Aviation frequencies have to have ifx applied or they will be deaf.

When you're done make sure to hook up to Sentinel and transfer all the information from your card into Sentinel so as to save your filter changes.

Hope that helps, any questions, just let me know... Bob.

PS... I forgot to mention to make sure to put the filter indicator on your display so as to be able to keep track of every filter that's on every object.

Absolutely, thank you Bob. I know it would be easier if we knew what direction the unwanted noise was coming from. And especially when mobile. Since the two counties I travel into are simulcast there isn't too bad of an issue. Not too much RF but having a better understanding about the features sure does help. Thanks again, guys.

 

[iMONITOR]

It's hard to understand why Uniden didn't supply an addendum to the manual regarding these filters. I would think they could give some explanation of what they do and when to use them. I fully understand it would vary by location and particular requirements.

Imagine if the did such a thing with our new computerized vehicles. Just toss half a dozen switches, knobs, or Icons in there and give you no idea what they do or when to use them.

 

[iMONITOR]

xusmarine1979

Thank you for your service Jon!

 

[xusmarine1979]

It's hard to understand why Uniden didn't supply an addendum to the manual regarding these filters. I would think they could give some explanation of what they do and when to use them. I fully understand it would vary by location and particular requirements.

Imagine if the did such a thing with our new computerized vehicles. Just toss half a dozen switches, knobs, or Icons in there and give you no idea what they do or when to use them.

I definitely don't have any complaints, it does do an outstanding job on simulcast and that's what I mostly listen to. But I know there's always room for improvements. I also hope to see more updates in the near future, I know a lot of folks have a lot of requests.

 

[xusmarine1979]

xusmarine1979

Thank you for your service Jon!

Thank you!!

 

[trentbob]

It's hard to understand why Uniden didn't supply an addendum to the manual regarding these filters. I would think they could give some explanation of what they do and when to use them. I fully understand it would vary by location and particular requirements.

Imagine if the did such a thing with our new computerized vehicles. Just toss half a dozen switches, knobs, or Icons in there and give you no idea what they do or when to use them.

Yep I agree, we have RR but not all the information about filters has been accurate, especially how to properly apply them.

I took to the filters like a duck to water the first day the first set was introduced through firmware.

I just went by Paul's firmware description the morning that he introduced them. I was having a lot of problems with my P2 simulcast system with clipped transmissions and totally missed transmissions and it wasn't housekeeping and "system" hold didn't work either. Using invert filter was like a friggin miracle.

I'm sure Paul had intentions of making an addendum for future manuals but just never got time to get around to it.

He would be the best qualified one to describe the use of the filters and would be the one to write the addendum... haven't heard too much from Uniden themselves regarding proper techniques and use.

They made all the difference with my radio.

 

[iMONITOR]

I was having a lot of problems with my P2 simulcast system with clipped transmissions and totally missed transmissions and it wasn't housekeeping and "system" hold didn't work either. Using invert filter was like a friggin miracle.

For the often problematic simulcast system in Macomb County, Mich. I chose the Wide Invert filter but it was by trial and error and it worked great!

I didn't mean to imply that Paul dropped the ball. I'm pretty certain he had a staff contributing to the scanner division. I would think the manual addendum would have been something he would have delegated to a product marketing/specification group after passing on technical notes to them.

 

[Ubbe]

As for the filter settings, which filter (wide or not) actually creates a tighter or smaller window to the frequency being monitored.

It's the one and same filter that are used for all settings. It is a 10MHz wide filter and cannot be changed to be more narrow or wider. What happens with the different settings are that the filters 10Mhz window are moved to either side of the frequency.

When in the Off position it works as a normal filter and pass +/-5Mhz of the spectrum with your monitored frequency in the middle.
In Normal the IF frequency are shifted so that the filter are open 10Mhz below the monitored frequency and less than one MHz above. It is used when you have an interfering frequency that are higher in frequency than the one you monitor.
When set to Invert it opens up for all frequencies up to 10Mhz higher in frequency and hardly anything below your monitored frequency.
The different Wide settings are only shifting halfways, something like 7Mhz at one direction and 3Mhz in the other.

Only the Off setting will give highest sensitivity for weak signal monitoring and other settings will give worse sensitivity, but could be a good thing in some cases. The reason for the 10Mhz wide filter are that it is the same one used in Unidens other scanners and are cheap. Of course the SDS scanner would have benefit from a much narrower filter but would probably also have made the scanner cost too much. Scanner, or receivers, that have good narrow filters like Icom8600 costs $5000.

There are other functions in the SDS scanner like an Automatic Gain Control that senses the total radiosignal energy over something like +/-10MHz, or perhaps more, and reduce sensitivity if the signal are considered too strong. So a strong pager signal or cellular tower 10MHz away in frequency from the one you are monitoring will make the scanner loose sensitivity and your monitored signal could dissapear completly.

/Ubbe

 

[iMONITOR]

What does "invert" do?

 

[Ubbe]

What does "invert" do?

When set to Invert it opens up for all frequencies up to 10Mhz higher in frequency and hardly anything below your monitored frequency.

/Ubbe

 

[TangoBlue]

This thread has been very helpful.

I recently recieved the SDS100 and added the noise display option to be horrified at the levels shown.

With the normal filter I see it fluctuate between 700-50,000 while it is scanning. Unfortunately the 700 is rare with most looking to be in the 20,000 range.

I have swapped antenna, but did not observe a difference so far, so I am going to experiment with filters after reading this thread.

I am in an apartment building in a dense area so other than filters are there any other way to try and reduce noise?

Reading through threads it looks like less than, 500 is good?

I saw threads from @Ubbe about interpretation of the debug logs which may yield some insights, but I did not find anything detailed on how to interpret them? I want to make sure the high noise is not an underlying hardware issue if possible.

Thanks

 

[Ubbe]

When you scan and there's no signal on a frequency then an empty channel will indicate something like 50.000 in noise level.
Normal squelch opening are probably at 1.000 so 500 are a pretty weak signal. A good signal are probably at the 100 level and you can only use the Noise value when a transmitter are sending out a carrier.

Digital signals are best measured by D-ERROR that should have as few errors as possible.
There's also the IFX setting to be considered when trying out different filters.

/Ubbe

 

[xusmarine1979]

I can see where the filters definitely come in handy but after experimenting a bit last night at home I'm still a bit baffled. When I''m home it's pretty quiet. I don't get too much rf noise. So I figured just leaving the filter for MARCS off would just simply balance it out since I don't have any cell towers or anything near by to offend it. But for some odd reason having it on wide-invert I pretty much get zero errors. but switching it to anything else the errors will jump around. But the reason I know that there isn't anything in or around the house is I'll take both my GRE and the SDS, set it to a random frequency in the system I'm monitoring, open up the squelch and walk around. I don't see anything at all pop up, but I know this method works because I'll go up and down the highway doing this and when I go near a cell tower it'll max out the signal bar.

Sorry for rambling there, but I'm wondering if anyone else gets the same outcome.

 

[xusmarine1979]

It's the one and same filter that are used for all settings. It is a 10MHz wide filter and cannot be changed to be more narrow or wider. What happens with the different settings are that the filters 10Mhz window are moved to either side of the frequency.

When in the Off position it works as a normal filter and pass +/-5Mhz of the spectrum with your monitored frequency in the middle.
In Normal the IF frequency are shifted so that the filter are open 10Mhz below the monitored frequency and less than one MHz above. It is used when you have an interfering frequency that are higher in frequency than the one you monitor.
When set to Invert it opens up for all frequencies up to 10Mhz higher in frequency and hardly anything below your monitored frequency.
The different Wide settings are only shifting halfways, something like 7Mhz at one direction and 3Mhz in the other.

Only the Off setting will give highest sensitivity for weak signal monitoring and other settings will give worse sensitivity, but could be a good thing in some cases. The reason for the 10Mhz wide filter are that it is the same one used in Unidens other scanners and are cheap. Of course the SDS scanner would have benefit from a much narrower filter but would probably also have made the scanner cost too much. Scanner, or receivers, that have good narrow filters like Icom8600 costs $5000.

There are other functions in the SDS scanner like an Automatic Gain Control that senses the total radiosignal energy over something like +/-10MHz, or perhaps more, and reduce sensitivity if the signal are considered too strong. So a strong pager signal or cellular tower 10MHz away in frequency from the one you are monitoring will make the scanner loose sensitivity and your monitored signal could dissapear completly.

/Ubbe

I gotchya, and that's what I thought. I'm becoming a fan of yours, Ubbe. Thank you for your help as always.

 

[Ubbe]

You get interferencies from signals as low as -80dBm, usually from the other frequencies from the site you are receiving. And that RSSI signal level with the associated signal strenght bars are a joke:

SDS100/SDS200: - Global Auto Filter Vs. Global Attenuation

I was reading through some previous posts and I am unclear on the difference between Global Auto Filter and Global Attenuation. What I have been doing recently is scanning groups of frequencies in sequential order to determine what DMR Color Codes are being used. On a few UHF frequencies in...

forums.radioreference.com

/Ubbe

 

[TangoBlue]

So I turned the global filter to off to monitor over time as a baseline since I'm logging activity with Proscan. Unfortunately it doesn't log noise levels it looks like. It would be nice if I could track the noise during active transmission, so I could then test each filter to see their effect.

I see the noise is in the stream coming into proscan, so I wonder if I can get access to log it. I'll see if I can make a feature request to log the average noise for the length of the transaction.