SDS100/SDS200: What is the difference with all the filters in the sds100 scanner?

[One13Truck]

I’ve only noticed some filter settings have a negative impact on some stuff I monitor. Never saw any improvement when using them. At this point I’ve decided they’re more trouble than anything and just turned them off. But as always YMMV. Great for all those that they have helped out though.

 

[Ubbe]

I’ve only noticed some filter settings have a negative impact on some stuff I monitor.

It's a 10MHz wide window that you can move either up or down in frequency but you cannot make it more narrow to pass fewer interfering signals. If you are listening to 160MHz and move the window to allow 150MHz to pass but block 160MHz you could let strong 150MHz pager transmitters reach the receiver that interfere with reception and loose sensitivity or get mixing products from several transmitters. The SDS receiver chip are much more sensitive to get interfered from signals in the same frequency bands than conventional receivers, that can't handle simulcast, that are more or less immune to that.

/Ubbe

 

[One13Truck]

Like I said some people have had great luck by messing with the filters. I’ve only seen some make it worse for me. After I turned them back off again I’m picking up more than I was with them on. Maybe I just got lucky with the location and if I move the scanner I’ll need them. Who knows. But for now keeping them off is working much better for me so I’m not messing with them unless something changes and I need to. As always YMMV.

 

[werinshades]

Like I said some people have had great luck by messing with the filters. I’ve only seen some make it worse for me. After I turned them back off again I’m picking up more than I was with them on. Maybe I just got lucky with the location and if I move the scanner I’ll need them. Who knows. But for now keeping them off is working much better for me so I’m not messing with them unless something changes and I need to. As always YMMV.

Exactly what was said when they first came out...if you need them you have them, if you don't turn them off.

 

[werinshades]

SDS100FirmwareUpdate < UnidenMan4 < TWiki

info.uniden.com

Scroll down and you'll see the information when the filters were added.

 

[Ubbe]

Keep in mind that you have 9 different settings to try if you suspect that a frequency are interfered, 5 for each IFX mode, excluding the one you are currently using. If a site or conventional department have frequencies that are more than 3MHz apart then it might happen that when one frequency have been set to a correct filter another frequency starts to be interfered by that filter setting. The current user interface are not best one but hopefully it will be developed to be more advanced in the future.

The reason Uniden use 10MHz wide IF filters in SDS scanner has to be that they are the same ones they use in all other scanners. I looked at the cost for a 400MHz filter that where 1MHz wide, that had a center frequency loss of 5dB instead of 1dB, and it was less then $2.

/Ubbe

 

[Whiskey3JMC]

Bottom line is filters yield different results for different users. Not all systems and RF environments are created equal. Experimentation is key. If one filter doesn't bring in signals more optimally, move onto the next...

 

[JoeBearcat]

It is my understanding the filter settings were initially bench test tools, available only within the company. But Uniden made them available to all after there were concerns over such complaints as “lost signals” or “scanner hears only one side of the conversation”. Maybe they help, maybe they don’t.

That is exactly correct. To compound the issue, the RF environment changes with each system and even each location with each system, so the testing every case is not very practical. There have historically been several times test tools were made available to the public in order to get as much data as possible. In this case, there is no one-size-fits-all solution possible within the constraints of the budget and design goals.

 

[JoeBearcat]

I made the suggestion several months ago that there should be an easy way to just flip through each filter individually while monitoring a system rather then going through the menu system. My recollection is that he said that he would add it to "the list".

This is also accurate. (and is on the list of feature requests if it is possible to do)

 

[JoeBearcat]

There's no doubt that the SDS100 where rushed as the big battery where an afterthought and the filters also where an afterthought that where available first after firmware upgrades. The beta testers where not experienced enough or not knowledgable enough to catch the problem with using a sat dish receiver chip that are used in some $10 SDR dongle receivers. Uniden probably didn't inform about the receiver chips performance that the RF AGC reacts to signals 7MHz away from the monitored frequency and the interferencies can occure from signals 5MHz away and 10 MHz when Normal or Invert filter settings are used.

The battery issue solution was in progress even before the release of the scanner. They simply could not be made fast enough to ship with the first units. It was not an afterthought, but was a result of testing in the real world by the "inexperienced beta testers" as you call them. And no, the component specs were not shared with the beta testers. Even with the testing in over a dozen locations, not all areas could be tested. The only way to do that is to make everyone a beta tester which I have zero doubt would receive even more criticism from the usual suspects. In a way, these filters are proving to be a flaw rather than the benefit they were meant to be. So, you are darned if you do and darned if you don't.

And as usual, the private sector is proving to be much more informed than many 'in the loop'.

 

[One13Truck]

As an early buyer I loved getting the smaller battery and then the replacement full sized one. Now I have a spare I can use in case of emergency.

 

[werinshades]

As an early buyer I loved getting the smaller battery and then the replacement full sized one. Now I have a spare I can use in case of emergency.

Yes it was, and have been charging the batteries in the scanner since Day 1 too.

 

[One13Truck]

Yes it was, and have been charging the batteries in the scanner since Day 1 too.

So do I. I’ve been doing it that way since the 80’s despite what the take the batteries out people scream and yell. I’ve yet to see my doing this cause Godzilla to rise out of my pool or cause California to fall into the ocean.

Also decided to do more filter testing with no noticeable results once again. But as always what works for me here at my QTH/10-20 could be totally different just down the street. I’ll keep testing once in a while but will be sticking with what works right now.

 

[werinshades]

So do I. I’ve been doing it that way since the 80’s despite what the take the batteries out people scream and yell. I’ve yet to see my doing this cause Godzilla to rise out of my pool or cause California to fall into the ocean.

Also decided to do more filter testing with no noticeable results once again. But as always what works for me here at my QTH/10-20 could be totally different just down the street. I’ll keep testing once in a while but will be sticking with what works right now.

A few of us here have reported Wide Invert made a significannt improvement on our 700 Mhz. trunking systems, if that means anything.

 

[trentbob]

The battery issue solution was in progress even before the release of the scanner. They simply could not be made fast enough to ship with the first units. It was not an afterthought, but was a result of testing in the real world by the "inexperienced beta testers" as you call them. And no, the component specs were not shared with the beta testers. Even with the testing in over a dozen locations, not all areas could be tested. The only way to do that is to make everyone a beta tester which I have zero doubt would receive even more criticism from the usual suspects. In a way, these filters are proving to be a flaw rather than the benefit they were meant to be. So, you are darned if you do and darned if you don't.

And as usual, the private sector is proving to be much more informed than many 'in the loop'.

Sticking to the topic of the thread in regard to the filters I think they were most valuable to add to the radio. In no way are the filters a flaw, the flaw is not understanding how to apply them properly and efficiently.

As I stated before, I got one of the first radios, pretty sure it was the second batch in June 2018, no CSJ so far but rotary dial issues and Battery clip came apart in my hand.

My tdma phase ll system with one site called simulcast + 26 simulcast towers, all very close to each other here in simulcast distortion hell secondary to LSM did not work on the sds100. Nothing but clipped and missed transmissions even with a 2 second system hold time.

Since the radio was a work in progress with regular firmware updates I put it in a drawer and went back to using my mot gear.

When Paul introduced the first set of filters it was a freaking miracle, I applied invert to that one simulcast site and was extremely pleased to find that the clipping and missed transmissions were resolved. On the second set of filters wide invert made for an even better error rate. I was able to remove the two second system hold time.

If it wasn't for the introduction of the filters I would not own the radio today, or the sds200.

 

[JoeBearcat]

I did say "in a way". They are being used as a criticism of the scanner.

Yes, in other ways they are a huge benefit as you pointed out.

My point was that either way (including them or not) will draw criticism, so there is no winning choice.

 

[werinshades]

I did say "in a way". They are being used as a criticism of the scanner.

Yes, in other ways they are a huge benefit as you pointed out.

My point was that either way (including them or not) will draw criticism, so there is no winning choice.

The best part I've seen is they are Department/Site/ or can be used Globally for all systems. A dedicated tutorial for new users might be beneficial too. Maybe a new You Tube page or a continuation of one?

 

[trentbob]

The best part I've seen is they are Department/Site/ or can be used Globally for all systems. A dedicated tutorial for new users might be beneficial too. Maybe a new You Tube page or a continuation of one?

LOL, try looking at my multiple post in the past on the proper application of filters. Using global, invert, wide invert, wide normal.... forget about normal as that is what you use by default and forget about Auto as it slows down scanning because it samples every filter. Don't worry about no filter at all unless you live in the county of Nye.

Once you find the proper filter on the radio using real-time results of RSSI, YES, RSSI and noise level and error rate then return Global to normal by default as it affects every object on the radio and you don't want to compromise their results with a different filter.

Drill down on the menu to site options and apply the filter that works best during your sampling global.

Make sure that you connect to Sentinel and transfer your card to your profile first thing to save any
changes you made on the radio itself.

If you start to get good results with filters it's important to add filter indicator to your display.

HTH... Bob.

 

[Ubbe]

Don't worry about no filter at all unless you live in the county of Nye.

The physical filter are always in line and cannot be omitted. The Off setting means that the filter are not offset and are centered. Here's a picture from Steve Holloways Facebook page where he lets his bandscope program sample the signals over time with his SDS200 to produce a view of the filters bandwidth and signal attenuation. The names and colors are not the proper ones and the diagram are not an exact representation but shows the principal.

The green line at the top of the curve are the Off setting, where you also will have the best sensitivity in the scanner for weak signal monitoring.
The black line to the furthest right are the Normal setting, where the signal will be be some 6-10dB weaker but will block higher frequencies.
The red line to the left are the Invert filter where it blocks lower frequencies but the signal strength will also be reduced.
The blue line just right of the center line are the Wide setting that doesn't reduce the received signal much but still has some attenuation of higher frequencies.
The filter are always 10MHz wide and it is 10MHz between the left line, at 75, and the right line, at 100.

When you run the Normal setting you will receive your tuned frequency at the black line and will pass a lot of lower frequencies to the receivers IF stage. If those frequencies are too strong, probably cell phone towers will have the biggest signals, they could overload or create too many mixing products that interfere with the tuned frequency. Choosing Invert will attenuate those interfering signals but will also open up for higher frequencies that might then cause overload and mixing products.

If you login to Steves Facebook page you can see him demonstrate his bandscope program. He tunes around in the FM broadcast band and you can see that when he tunes to a strong station there are several internal mixing products that moves in the opposite direction and at some point are exactly at the received stations frequency and will interfere depending of how strong the stations signal are. When using different filters and IFX those mixing products moves differently and to other frequencies.

The bandscope program could be used to tune around a suspected frequency that has issues to see if a mixing product are too close to the received frequency and then change filter or IFX setting and see if there's a setting that has those interferencies far enough away to not cause any problems.

Steve Holloways FB page "Free Scanner Software" (needs login)

/Ubbe

 

[trentbob]

I often change filters on the run secondary to changing RF conditions. Although we all agree that what works for one isn't going to work for another and it is location-specific with regard to your environment, I have actually seen a pattern. First of all I have never seen no filter at all improve anything, the normal filter which is called normal for a reason usually does well.

I have seen though the pattern of, wide normal improving VHF high performance and wide invert working best on tdma Phase ll systems. In my particular area, Aviation frequencies are deaf unless I apply IFX to every one, leaving normal as the global setting of course. That doesn't apply to military Aviation frequencies. Default normal works best for them.