SDS200 "filter" settings
- Thread starter Emoney250
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I've seen smatterings here and there that basically indicate "choose what works best for you" - however I as well have yet to see a well put together technical reference or article that describes each of the filter settings and what they actually do/mean etc.
It seems appropriate that for advanced users an article or explanation should exist. Each filter setting should have a description of what the developer's intended result was (why invert vs normal) and other (why wide vs non-wide) and why normal vs off might be appropriate, as well as what each filter is actually doing internally.
Unless I'm missing something, right now we're just in trial and error mode.
It seems appropriate that for advanced users an article or explanation should exist. Each filter setting should have a description of what the developer's intended result was (why invert vs normal) and other (why wide vs non-wide) and why normal vs off might be appropriate, as well as what each filter is actually doing internally.
Unless I'm missing something, right now we're just in trial and error mode.
Also what would be helpful is if Uniden published a procedure for determine how to figure out which filter setting is appropriate in your own environment. Answers to the above questions would be a good start, but then a procedure for getting to the proper setting given your configuration would be good.
xusmarine1979
Active Member
I found the user manual on-line hoping to find something but there wasn't even a mention of them let alone an explanation. Only 60 pages? I wonder how big it will eventually become!
Unfortunately, trial and error. Try each setting, the one that works best is the one to use (at that location).
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
http://info.uniden.com/twiki/bin/view/UnidenMan4/SDS200FirmwareUpdate
xusmarine1979
Active Member
I'll have to try that. I've been playing around with them as well but just cannot seem to find any real difference in the various settings. Thanks for the tip!
But I think it would be helpful to understand the filters in a little more detail.
What does Invert Mean? Invert what?
What does the normal filter do? When inverted what does it do?
Wide? Wide what?
I've seen various references to high bandpass filters.. but what are the parameters around that?
Normal is high pass. Invert is low pass. Wide is wider pass frequency.
First I can give you what I use. This is both units I have sds100/200. When uhf/vhf some 700/800 I use Wide Normal. On SLERS System 800 I use Wide Invert. I did a test last weekend for other areas out of town on SLERS and Wide Invert seem to work. When I do custom search I use Wide Normal. If I use Global the signal is weak and barely hear that channel. I would make a list on each filter see what is the best for you.
Global means it is set to whatever the global filter setting is set to.
My Global Setting is Wide Normal which works best for what I listen to. Some seemed confused what Global means
The right combination of filters and IFX if necessary does work, but it is interesting to read this. The hardware filters I have used, such as the ones from Par Electronics, are high pass, low pass, or notch. But in each case there is an actual frequency that signals above or below can pass, or a frequency or area of frequencies that can be notched out, such as the FM broadcast band. How does the SDS200 know where to start I guess for lack of better wording? My offending frequency is a strong Mot Type II control channel at 855.5375, and my frequencies that are affected by it were 855.4625, 855.2375, and 855.1125. So, if the SDS200 magically knows this I understand why the invert setting works (but with help from the IFX which is what really made the difference as I previously stated).
Other than that I'm completely missing something, which is entirely possible, or it truly is hit or miss. But as said the right combo DOES work, most importantly. This is why I'm curious as to a more in-depth description at some point about how they work. Thanks Paul.
What are the high, low, and wide/normal frequency thresholds?
xusmarine1979
Active Member
It may be my imagination, but I have noticed during other tests that the ifx seems to attenuate/ lessen the signals on 700/800 MHz by just a bit. Because with ifx off I can normally pick up the neighboring counties while at home but not so much with it on.
As far as filters go I have mine globally off. Until and unless I perceive a problem with a signal I just leave it be. The farthest we can drill down with filter settings is to the Department level of programming so that filter setting could have negative effects on anything else being scanned within the department. In my case they are sorted by public safety for municipalities so I was able to minimize those side-effects. The IFX level though is programmable by channel/frequency though so I don't think it would cause any grief elsewhere. It would be nice at some point to get the filter settings down to the channel level if that's possible.
Is "Wide" wider than Normal or does Wide sit between Normal and Invert?
What on the display should I watch to see if there is an improvement when changing the filters or is it all by ear listening. Why would Uniden add the feature with no explanation, not everyone has attended Uniden University!
When used properly they should improve the sound noticeably if needed. Before filters were even being discussed most users claimed the SDS series scanners sounded perfect. If you're one of those people you need not worry about using filters.
Keep in mind the SDS series are a 'work-in-progress'. They were pretty much released in a beta state (still in development) as with the case with most all scanners these days. As new features are discovered and improvements are discovered, new firmware releases become available. That's the nature of the hobby and sometimes half the fun!
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