SDS100/SDS200: The Art of Filtering

[trentbob]

Well we all know that there are so many factors and so many things that can interfere or cause a problem with reception. It's not just limited to another agency close to you. In today's world it can be anything, including topographical, that's why what works for you may not work for me.

 

[gary123]

To add to trentbobs post. When using as a portable or mobile rather than a base. Interfering signals come and go. What works fine in one area my be terrible one block away.

The first step in fixing any interference problem is to identify what is interfering, where its interfering and how bad its interfering and also WHEN its interfering. Again in a non technical way its like a traffic jam. Sometimes its always jammed other times its jammed once due to some idiot learning to drive LOL.

 

[Ubbe]

So then these filters are the equivalent of an IF Shift on a communications receiver or Ham transceiver, and are designed to reduce adjacent channel interference?

That's exactly what it is.

But it has only two fixed minus settings and two plus settings and not variable over the whole range like HAM receivers normally have. My R75 also have shift of the second IF that can be cross set to the first IF making it really narrow. But then you also have the non controllable RF AGC in the front end of the SDS receiver that sometimes ruins any kind of user settings, except maybe the Attenuator setting.

/Ubbe

 

[Ensnared]

At present, my radio is working well in McLennan and Bell counties. Generally speaking, are there any filters that are generally used on trunking systems? I don't seem to be missing any transmissions. However, I want to be prepared for other cities that may need filter adjustment.

 

[werinshades]

At present, my radio is working well in McLennan and Bell counties. Generally speaking, are there any filters that are generally used on trunking systems? I don't seem to be missing any transmissions. However, I want to be prepared for other cities that may need filter adjustment.

Like we've been saying, your results may vary. If you're having issues, try them all out.

 

[trentbob]

At present, my radio is working well in McLennan and Bell counties. Generally speaking, are there any filters that are generally used on trunking systems? I don't seem to be missing any transmissions. However, I want to be prepared for other cities that may need filter adjustment.

Honestly, there is no pattern. It's location and situation. All of the phase1 or Phase 2 simulcast systems I listen to, not at the same time but as I'm mobile using a Larsen tri-band, require a filter other than the default of normal.

Try to get familiar with the system I described on post 6. The more you do it, the smoother and easier it gets. I do it all the time and it's just bing bang bada boom.

 

[Ensnared]

Honestly, there is no pattern. It's location and situation. All of the phase1 or Phase 2 simulcast systems I listen to, not at the same time but as I'm mobile using a Larsen tri-band, require a filter other than the default of normal.

Try to get familiar with the system I described on post 6. The more you do it, the smoother and easier it gets. I do it all the time and it's just bing bang bada boom.

Last night, I got a bit adventurous. I got out my SDS 100 and proceeded to go through the filters for one Favorite, Waco PD HOTRRS. I got to "Wide Normal." However, as I was loading this up, I committed the unpardonable sin. I cancelled the download, mid-stream. I corrupted my 32DB micro SD. I attempted to save it by using the ScanDisk software to no avail. Now, the card is invisible on my computer when the card is inserted into the card reader or through the radio connected to the computer. I did this when I first bought my 436HP.

I will tackle this task later, after NY Eve, my favorite day of the year for scanning. One more thing. I love the Larsen Tri-band. I have mine sitting on a Tram base.

 

[MStep]

Last night, I got a bit adventurous. I got out my SDS 100 and proceeded to go through the filters for one Favorite, Waco PD HOTRRS. I got to "Wide Normal." However, as I was loading this up, I committed the unpardonable sin. I cancelled the download, mid-stream. I corrupted my 32DB micro SD. I attempted to save it by using the ScanDisk software to no avail. Now, the card is invisible on my computer when the card is inserted into the card reader or through the radio connected to the computer. I did this when I first bought my 436HP.

I will tackle this task later, after NY Eve, my favorite day of the year for scanning. One more thing. I love the Larsen Tri-band. I have mine sitting on a Tram base.

Some of my cards have suddenly come up with various error while just going through the radio's normal operation. Spare Micro SD cards are good too keep around, but if you've screwed up your card, you could try doing one or two full reformats on the card and then doing the "Clear User Data" and trying that card again.

Sometimes it takes several attempts, but I have been able to "resurrect" cards that I thought were shot and got them working just fine again.

 

[DeaconHarry16]

Should we change the filters with every oil change?

 

[MStep]

Should we change the filters with every oil change?

Sounds more like you would be getting a "lube job".

 

[trentbob]

Ensnared... so it sounds like you were using Sentinel to sample filters? Maybe I didn't read that right? As I had explained you sample filters on the radio itself using the keyboard and the menu button for real-time results of reception indicators.

First you use Global filters of wide normal, invert and wide invert. You already know what normal does because that's default. Global filter affects every object on the radio so no matter what system you are testing it will apply the filter to everything. Once you find a better filter put Global back on normal which is default which affects every object unless you go in and apply another filter to the sites of a system

After you're done adding the new filter to the sites of the system you want using the keyboard and menu button, then you hook up to Sentinel and transfer information from the radio to your profile so as to keep the changes permanent on Sentinel.

Is this where the card became corrupted because you interrupted the transfer of data from the card to the computer?

 

[Ubbe]

Maybe a method to use might be, as filters can be individually set to each site, to copy a site 4 times and set the 5 different filter settings to the sites. Then when one site sounds distorted or behaves strange then lock that out, or turn the dial to continue scanning, and try the next copy of the site. You will need to have the filter setting show in the display or name each site slightly differently. You could mark each good site with an exclamation mark and see that it continues to sound good at all its voice frequencies.

But you would probably first try and set IFX to a frequency that has problems to see if that helps and first after that begin with the filter testing.

/Ubbe

 

[trentbob]

Maybe a method to use might be, as filters can be individually set to each site, to copy a site 4 times and set the 5 different filter settings to the sites. Then when one site sounds distorted or behaves strange then lock that out, or turn the dial to continue scanning, and try the next copy of the site. You will need to have the filter setting show in the display or name each site slightly differently. You could mark each good site with an exclamation mark and see that it continues to sound good at all its voice frequencies.

But you would probably first try and set IFX to a frequency that has problems to see if that helps and first after that begin with the filter testing.

/Ubbe

I have thought about that Ubbe. It's a little difficult to convey in words but I understand what you're saying. With the few systems and the consistent conventional objects I listen to I don't really do too much changing up of anything and I don't drive all that much out of my area.

I think we remember Paul referring to the auto filters to rectify listening to a system as you travel around mobile but he did emphasize that it did slow scanning way down just by the nature of sampling each filter on every object within the system it is applied to.

It is certainly something to investigate, if they need arises. Strangely enough, the filter that works best on my counties Phase ll simulcast system works on the same filter the best, no matter where you are in the county in a mobile application. You've got to wonder if the system itself also dictates the filter chosen?

 

[Ubbe]

You've got to wonder if the system itself also dictates the filter chosen?

It does, if the systems frequencies are spread over a wider frequency range. As it is the exact same frequencies used in all sites in a simulcast system you could end up using the same filter setting for the systems whole coverage area, if the system are interfering with itself in the scanner when using another filter setting.

/Ubbe

 

[JoeBearcat]

Now, the card is invisible on my computer when the card is inserted into the card reader or through the radio connected to the computer.

In Sentinel, there should be an option to 'show all drives'.

I've had the same happen with stand-alone flash drives.

 

[Ensnared]

I used the "Invert" filter on HOTRRS and Bell County P25. It noticed less dropped transmissions. I am still attempting to find IFX in Sentinel. I suspect this is adjusted on the radio.

I was quite pleased to see a filter adjustment in the SDS 100 menu. Previously, I was changing filters by shooting each filter adjustment from Sentinel into the radio. This was a great discovery. Thanks for the help.

 

[DudleyG]

IFX in located in the profile. Edit your profile, click on the right tab called Miscellaneous, look in the lower right corner and there it is. You edit and/or add or delete which frequencies you want to use IFX. It applies to anywhere in the scanner that uses that frequency, not just the use in one favorite but in all favorites plus location scanning.

 

[trentbob]

Again it's better to make adjustments like ifx on the radio itself so that you can listen to real time results. While sitting on a conventional object toggle function seven. It will add or take away ifx. If it doesn't work toggle It Off but make sure if you do add it to a conventional frequency that you hook up to Sentinel and transfer your data card to your profile so as to keep the setting permanent.

Glad you are having success with the filters

 

[ten13]

FWIW, I had a very hard time trying to receive the Jersey City PD (on a 400 Trunked system, with only one site), while living in lower Bergen County, NJ., a distance of about 10 miles in an urban/suburban area. It was often broken up, or not received it at all. I changed outdoor antennae, its location, etc,...NG.

I was about to give up but, after reading the posts here about the filters, I played with them, and finally landed on "wide-normal" and now I get a consistently good and readable signal for the past two or three days.

Could it be because of "atmospherics" improving the signal? Maybe.

But with the filter change, so far, so good.