Optimizing Filters

[Alain]

In another forum, someone recently brought up the [above] subject that this beginner, currently, has no understanding of.

The Uniden manual is useful for swatting flies...not much more. Went to Mark's Scanners [SDS Sentinel Software Manual], looked for "filters" in the index and couldn't find any info. Any tutorials available?

Questions: where are these filters? How do I use them? What [and how] will they impact the received signals?

What am I hoping to effect? [screen shots would be a +!]

Many thanks for taking the time to respond!

 

[iMONITOR]

Welcome to the club! The SDS200 is the only radio I've ever known that utilizes some kind of filters with no explanation as to what they actually do, how they work, or how do use them.

There are all kinds of filter used in radio. Audio and RF filters. In most all cases there is a complete understanding of them. If you don't know, there are numerous references to read up on. Uniden left it to be a "shoot from the hip" and see if you hit something approach. I have no idea why that is! If no one at Uniden U.S. understands them, why don't the design engineers in Japan release some information, translate it and print an addendum to the manual?

 

[nessnet]

On this forum, there has been quite a number of posts on this subject. May I suggest a look at the past posts on this - a ton of great information is there.

First thing to remember, is that what filters to use is completely unique to your location and RF situation. It is truly an experiment and see.

 

[Alain]

Nessnet said,

" It is truly an experiment and see..."

O.K., where do I go to begin the experiment? During experimentation, just what am I trying to accomplish?

By that I mean I can currently hear most channels with 5/9 copy, but some of the fire agencies [on AM] tend to need audio help. Some of the "simulcast" channels have problems "breaking up" during transmission. Do filters help in that regard, as well as P25 Phase II? I assume that the filters work on AM & NFM as well?

First step [I assume] is to get the scanner to scan. O.K. it's scanning...now what? I assume that I hold on a channel, correct?

Nessnet, you can sense I'm trying to establish some basic steps of operation for accessing/using the filters, but I do NOT wish to assume too much!

So, having paused the scanner, now holding on a channel [if this is the correct procedure] what are the next steps after that??

I hope I haven't overwhelmed with questions?! Again...many thanks!

iMONITOR, I am pleased that there are others [I consider you a far advanced user than myself, iMONITOR] who are somewhat uncertain of their knowledge and usage of these filters. Thank you for your comment!

 

[IAmSixNine]

I had similar questions as you did but when i got my SDS100 a month or so ago i did a lot of searching in the forum and found lots of answers. So many that i didnt need to post questions asking.

If you have read those threads and still need help let us know. The answers are there.
I will apologize up front if this sounds rude or negative, its not meant to be.

 

[fxdscon]

Nessnet said,

" It is truly an experiment and see..."

O.K., where do I go to begin the experiment? During experimentation, just what am I trying to accomplish?

First...... be absolutely certain you are using the latest version of Sentinel, and the latest version of firmware for the SDS200


Filter settings are available in both Sentinel (in the favorites list editor),

and in the scanner's menu system:

MENU --> SETTINGS --> GLOBAL AUTO FILTER
⦁ Normal (always use HPF)
⦁ Invert (always use inverted HPF)
⦁ Auto (try HPF then if no signal detected to open squelch, try inverted HPF)
Note: If Auto is selected, conventional scan and search speed will be greatly slowed, as every frequency on which a signal is not detected on first pass will be rescanned using the inverted HPF setting.

MENU --> MANAGE FAVORITES --> REVIEW/EDIT SYSTEM --> EDIT SITE --> SET FILTER (Setting menu for trunked systems)
⦁ Global (use the setting from GLOBAL AUTO FILTER)
⦁ Normal
⦁ Invert
⦁ Auto

MENU --> MANAGE FAVORITES --> REVIEW/EDIT SYSTEM --> EDIT DEPARTMENT --> SET FILTER (Setting menu for conventional systems)
⦁ Global (use the setting from GLOBAL AUTO FILTER)
⦁ Normal
⦁ Invert
⦁ Auto

MENU --> SRCH/CLOCALL OPT --> SET FILTER (Setting menu for Close Call and Search)
⦁ Global (use the setting from GLOBAL AUTO FILTER)
⦁ Normal
⦁ Invert
⦁ Auto

 

[nessnet]

O.K., where do I go to begin the experiment? During experimentation, just what am I trying to accomplish?

Seriously, you really need to read the many previous posts (here) on the filters subject. This all has been covered - probably 4-5 times now.

Not trying to be an Adam Henry. Those previous posts contain a TON of information and if you read them, you will be much more familiar with filters, how they work and recommended steps to 'experiment".

 

[wowologist]

" By that I mean I can currently hear most channels with 5/9 copy, but some of the fire agencies [on AM] tend to need audio help. "
whoa fire agencies are using AM? In the 21st century?

 

[Ubbe]

O.K., where do I go to begin the experiment? During experimentation, just what am I trying to accomplish?

SDS scanners use a 10MHz wide filter (or was it 12 or 15Mhz?) that in the filters Off setting will pass all frequencies up to 5Mhz lower and 5MHz higher from the one you are monitoring. If you have another frequency inside that 5MHz that are strong enough it could interfere with your monitored frequency that will make analog signals sound distorted and digital signals to have drop outs or not even decode at all.

You could enable the display to show D-ERROR and NOISE levels to aid in the experiments. You have to suspect that a frequency are compromised and work with that frequency. When you receive an analog signal you would like to get the NOISE level as low as possible and you don't really need to look at the signal level. But if you do you probably need the signal level strenght to be as weak as possible, as it then are having less interference from other frequencies. Digital signals needs to have as low D-ERROR as possible, and probably weakest possible signal strenght.

If you change the filter setting to Normal or Invert it will move the filters frequency to one side, so that it opens up up to 10MHz at one side but block all frequencies at the other side. Which side, above or below your monitored frequency, depends of if it is Normal or Invert that are used.

The Wide settings are variations of this and only change the filter halfways, 3MHz to one side and 7MHz to the other.

To a normal user it is impossible to know which filter to use and it has to be tested out. One culprit are that filter settings apply to all frequencies in a site or a whole departments analog frequencies. So it might be impossible to find a suitable filter settings. Also you can use IFX on a frequency that will switch to another filter, there are two in the scanner, that works at another frequency and might change how the filters manage to block out interfering frequencies. So if different filter settings just change which of two frequencies in a site that are interfered, then doing IFX to one of them might solve it.

/Ubbe

 

[Alain]

fxdscon...

This is what I have been seeking!

SDS scanners use a 10MHz wide filter (or was it 12 or 15Mhz?) that in the filters Off setting will pass all frequencies up to 5Mhz lower and 5MHz higher from the one you are monitoring. If you have another frequency inside that 5MHz that are strong enough it could interfere with your monitored frequency that will make analog signals sound distorted and digital signals to have drop outs or not even decode at all.

You could enable the display to show D-ERROR and NOISE levels to aid in the experiments. You have to suspect that a frequency are compromised and work with that frequency. When you receive an analog signal you would like to get the NOISE level as low as possible and you don't really need to look at the signal level. But if you do you probably need the signal level strenght to be as weak as possible, as it then are having less interference from other frequencies. Digital signals needs to have as low D-ERROR as possible, and probably weakest possible signal strenght.

If you change the filter setting to Normal or Invert it will move the filters frequency to one side, so that it opens up up to 10MHz at one side but block all frequencies at the other side. Which side, above or below your monitored frequency, depends of if it is Normal or Invert that are used.

The Wide settings are variations of this and only change the filter halfways, 3MHz to one side and 7MHz to the other.

To a normal user it is impossible to know which filter to use and it has to be tested out. One culprit are that filter settings apply to all frequencies in a site or a whole departments analog frequencies. So it might be impossible to find a suitable filter settings. Also you can use IFX on a frequency that will switch to another filter, there are two in the scanner, that works at another frequency and might change how the filters manage to block out interfering frequencies. So if different filter settings just change which of two frequencies in a site that are interfered, then doing IFX to one of them might solve it.

/Ubbe

 

[iMONITOR]

fxdscon & Ubbe best explanations I've seen to date, thank you for posting!

 

[Anderegg]

fxdscon...

This is what I have been seeking!

To be perfectly blunt on this subject, it really DOES NOT MATTER (at least an explaination) what the filters do, their range, up down etc, because as others have posted, it really is just trial and error.

MY RECOMMENDATION is to set everything to GLOBAL, which allows you to HOLD on a channel or system, and quickly change the GLOBAL AUTO FILTER in the main easy to get to SETTINGS menu. Use the dBm meter and ERR rate to HOLD and change to each filter and determine which filter gives the best performance for the specific signal/system. Once you determine the best filter, manual program that filter into the site/department (filter settings are stoted per site/department) instead of GLOBAL. Continue doing this for all your other systems and frequencies. Using GLOBAL for those not yet determined simply makes it easier to toggle different filters, because digging down into the menu for each site/departments filter settings takes way way too many button presses!

Paul

 

[trentbob]

So yes filters are different for everybody in accordance with your RF environment. Here's the method I use. If you do it right it's certainly is not hit or miss. I see filter selection as more of a troubleshooting Aid oh, it doesn't have to be set for every object.

Global filters are not permanent applications, they are used as a temporary sampler. Default for Global filters is normal. Global filters affect every object on your radio unless you go in and manually change that object in site options or Department options...

Filters should be sampled on the radio itself so you see real-time results from RSSI and noise levels and and error rates so make sure your radio is on detailed display.

Sit on a TG in a trunked system. You should be able to see the signal bars, RSSI and noise level and error rate on your display. Go to menu, settings, Global filters and try invert, back out of menu and jot down your RSSI and noise levels while on invert. Note that you've already sampled normal filter as that's the default. After listening to invert for a while go back into menu, settings, Global filters and try wide normal then back out of menu. Look at your results on wide normal for a while, you're looking for an improved RSSI and noise level, noise level is really what you want to focus on. Go back into menu, settings, Global filters and try wide invert. Repeat the process with filters off also. Note your findings and see what filter produce the best RSSI and noise levels. You noticed that we avoided using the auto filters as they sample every filter every time on every object and slow scanning way down and you never know what filter did the trick anyway.

If you find a filter that did better than other filters on that system then go into menu, settings and Global filters and return Global filter to normal. You don't want to use Global filters to accommodate just one system as it will compromise other objects that do well on normal which is default for a reason.

Now go into menu, manage favorites, go to the favorites list that system is in, review edit system, go to that system, edit site, pick a site, preferably you should have the least amount of sites you have to have, set filter, by default it should be on global now you're going to apply the filter that you found was the best choice when you did your sampling. Backup 1 in menu and pick the next site and apply the same filter until all the sites have the filter applied. Back out of menu and you have customized that particular system with the best filter from your global sampling.

Applying conventional filters is a little more tedious as you have to wait for transmissions on that conventional frequency. You will use the same method of sampling the global filters. Just normal, invert, wide normal, wide invert and no filter at all. When you have picked your best filter go back to Global filters and return it to normal which is the default.

Go to menu, manage favorites, pick the favorites list that conventional object is in, review edit system, pick the system that conventional object is in, edit Department, pick the department that conventional object is in, set filter, it will be on global by default, apply the filter you found best during your sampling.

No, you cannot apply a filter to one single Channel. The filter you choose will apply to all the conventional items in that department. You get around that by the way you program your radio. If you have a fire department with five VHF High frequencies, or you are listening to Marine broadcast, or you're listening to Railroad you want to put all of those conventional items in the same Department as they're all going to call for... The same filter.

It is helpful if you add the filter indicator on your display as it will help you to keep track. Because you reset Global filters to normal most objects and systems will have normal indicated. You only went in and made a change because of poor reception or problems with that particular system or Channel and those items will indicate the new filter you applied on the display.

I found this is the most efficient way to apply filters.

PS. I almost forgot, when you're done make sure you hook up to Sentinel and transfer all the changes to your profile so as not to lose them LOL.

 

[Anderegg]

And don't use Auto or Wide Auto...from what I have read, those slow down the scanning process.

Paul

 

[pb_lonny]

What is the issue you are trying to resolve?

 

[Anderegg]

What is the issue you are trying to resolve?

Is non-optimized not an issue?

Paul

 

[trentbob]

And don't use Auto or Wide Auto...from what I have read, those slow down the scanning process.

Paul

What is the issue you are trying to resolve?

That is correct Paul as I indicated in my post... the reason that you would apply a different filter than the default normal is poor reception. Many people have complained about VHF and UHF performance. By changing the filter permanently on that problematic object it can improve reception and performance.

Just to put it in context. I got one of the first SDS 100 units. We have been using Motorola apx 7000s for my P2 simulcast system since 2015 as we had many problems with the x36 and whistlers didn't work a lick.

I was extremely disappointed with the SDS 100, transmissions were clipped and there were many missed transmissions, the radio would scan right through them. Also conventional performance at that time was awful. I used a trick that we used to use on the X36. I applied a system hold time of 255 seconds and it improve things a little bit but of course I couldn't scan anything else other than the one P2 system. The radio ended up going in a drawer. I held onto it because I knew many improvements would be coming as Paul was actively monitoring the situation and adding frequent firmware updates.

One of the updates slowed scanning down improving the reaction from the SDR chip but the radio is a very slow scanner as we all know. Paul also made adjustments to VHF crackling. Some improvement but...

Then we had the firmware update that introduced normal and invert filters... I took the radio out of the drawer and dusted It Off and applied invert filter. I swear it was like a freaking miracle. What great performance on my P2 system. It was terrific. I actually was able to use the radio again that I had totally written off as worthless. Soon after there was another set of filters that came out that included the wide invert and wide normal option, the radio worked even better on wide invert. I did leave on a 1 second system hold time on the system, I've actually now changed it to zero and never have any missed transmissions. It works terrific on my P2 simulcast system.

I also found marked improvement on conventional frequencies also applying filters. The system that I use is basically as Paul had described how to do it.

 

[Anderegg]

trentbob, try throwing troublesome trunking frequencies into your IFX list...I had to fill my list with 700/800 LSM frequencies that were just knocked off the air by my local (100 feet away...yes, seriously...) cell phone tower. IFX made the difference between the freq blinking on and off with no RX of talkgroup, to at least receivable if sometimes garbled digital reception. I identified troubled frequencies by recordign the SDS screen as freq's would blinkl on and off faster than you can see, and paused the video to see which freq's to add to the IFX list. It really did make a huge diff, especially considering my CC is on an IFX required frequency!

Paul

 

[trentbob]

trentbob, try throwing troublesome trunking frequencies into your IFX list...I had to fill my list with 700/800 LSM frequencies that were just knocked off the air by my local (100 feet away...yes, seriously...) cell phone tower. IFX made the difference between the freq blinking on and off with no RX of talkgroup, to at least receivable if sometimes garbled digital reception. I identified troubled frequencies by recordign the SDS screen as freq's would blinkl on and off faster than you can see, and paused the video to see which freq's to add to the IFX list. It really did make a huge diff, especially considering my CC is on an IFX required frequency!

Paul

Yep very familiar with ifx... When I first got the radio I went to NOAA Weather Radio in my area. We have at least four channels that you can pick up all the time as I live on the east coast near the water. Couldn't pick up a damn thing on NOAA Weather Radio. Simply toggled function 7 and it came in great. I also noticed, since I listen to our Philly area umbrella Helo Unicom frequency and our news Chopper air-to-air coordination frequency everyday that Aviation was terrible. I simply add ifx to every Aviation frequency on the radio, night and day receptions.

 

[4436time]

Set my SDS200 filter to Auto and it's working better overall. What the scanner really needs when set to Auto is to display the filter in use for each system so you can set each one accordingly without guessing. Pie in the sky........