DSD+ FL 2.155 Conventional DMR Decode in Scan Mode Sporadic

[AB9NN]

Complete newbie. Two files attached - log files. Use three RTL SDRs and the following bat files:

FMP24 -i2 -o20003 -P0.0 -s1 -b4

DSDPlus -e -fr -i20003 -o1

I have a scanlist and frequencies files populated and correctly formatted with the same frequencies obtained from here:
Digital Frequency Quick Import

The two programs load. I get a solid RF display on Source. I see the scan list being processed and scrolling and occasional stops and brief waveforms on source.
There is audio decode, human voice, but only for a second or so. The scan continues.
Thinking weak signals (probably not - good antenna), filter settings or some mode setting or something? Tried changing -fr to -fa and tried deleting -b4. After changes I got a slightly longer decode but not good quality audio.

 

[dave3825]

I have a scanlist and frequencies files populated and correctly formatted with the same frequencies obtained from here:
Digital Frequency Quick Import

That site is a great site and the way it works when you search, is, it goes thru all the FCC data and displays results based on your search criteria. The only problem is as it does display FCC results, it also lists the many errors contained in the FCC data.

What that means is, the FCC is full of errors. ie: freqs with wrong emissions listed, freqs with more than one emission's listed, wrong site locations, etc. It also lists licenses that may be new, and not yet built out. Even licenses that are no longer in use. It is no fault of the Digital freq search site, but more the FCC.

Justin's site does a remarkable job at displaying that FCC data in many formats recognized by today's scanners (software) and by DSDPlus.

My only advice is if you are going to create scan lists, to not have high expectations of hearing voice on everything listed in that output file. It is best to create your scan list, and then compare it to confirmed results here on radio reference. Then you should get an idea of what you should be hearing voice on because others have confirmed it. I am not saying that you will not hear voice on something that's not confirmed here. Just saying that because it does not know who is "actually " using what emission, on what freq, it can be confusing to new users and overwhelms many just getting started in the hobby.

After changes I got a slightly longer decode but not good quality audio.

Your scan list has both VHf and UHf freqs in it. What antenna are you using?

 

[AB9NN]

dave3825 - Thanks. See attached photos of my TV beam antenna, wire antenna and ham radio antenna. It seems to work well for many things other than TV such as weather satellite decoding to UHF and VHF reception. I also have a ham radio 2 meter and 70 cm antenna (vertical) and an approximately 150' wire antenna for HF. A bit unconventional but working with what I have. If I get my decoding working a little better I may move on to some antenna building projects over the winter with installs this spring or as weather permits in NW Lower MI.

I will review my scan list and focus on a few key frequencies of various services and see what happens.

 

[AB9NN]

FYI - In my FMP24.cfg file I doubled the spectrum update rate from 10 to 20. The FMP.txt file documented:
"Reasonable" range is 5 to 20.
Lower values use less CPU resources.
Higher values better catch brief transmissions on the spectrum display

This seems to have substantially improved the couple of brief transmissions that I have heard. When I read that it would "better catch brief transmissions on the spectrum display" I was left to wonder if that meant that it would just have some better visual display of the data or if it would also affect the audio output. Figuring that I had a reasonably fast computer and out of options I might as well give it a try. So far DMR seems to be decoding and audio has improved, although there doesn't seem to be a lot of traffic. That could be for a multitude of reasons. Still can be improved but pleased with the incremental progress.

 

[slicerwizard]

So which antenna are you using? A horizontally polarized TV antenna sounds like a problematic setup.

 

[AB9NN]

In radio theory - I agree. I probably intersects a small cross section of the vertically polarized signals and logic would dictate that it should produce an inferior signal. The fact that it has some height, has a lot of "metal in the air" and is backed by a strong amplifier at the antenna produces generally acceptable to good signals. I am listening to decodes that sound pretty good. I may try the ham radio antenna at some point. I also have run a multi-band sloper with multiple coils back in the day - wonderful SWL antenna. I also have run a classical discone scanner antenna. It was quite wide banded but after moving from place to place over 30 years or so lost so many of it's radials that it became a wonderful donation to the recyclers of the metal world! chuckle... Best antenna to buy? Best antenna to build?

 

[dave3825]

It's always best to use an antenna tuned for the freqs you monitor. I was having issues with certain freqs and realized that most of the stuff I wanted was all to my west and was not getting the best signal. My apartment window faces east and that's where my antenna is sitting. So I made 2 moxon antennas. A 470mhz and a 700mhz one. I am in Eastern Long Island and with a moxon tuned for uhf, facing west, I pulled in a dmr TIII site from Bergen, NJ , 42 miles line of site, with an indoor antenna...

 

[AB9NN]

I agree on tuned antennas. My MFJ-269 antenna analyzer is very helpful in that regard. I've worked a lot of mobile HF in the 80 meter and up to 10 meter ham bands. Amateur Extra license 10 years or so. Having a tuned, well RF grounded antenna on a car or truck is vital! Fun to talk to other countries from your car without a cell phone! 43 countries contacted so far. I have a Horse Fence ham radio antenna sitting in a box that is not yet deployed. And my wire antenna has other possibilities. Perhaps if we raise our antennas there may be room for more. Having a rotor is quite nice and I did notice a significant improvement after I spun the scan list down and aimed the beam at a specific county. The beam at the time was or nearly was the highest gain beam for TV that I could find and I think the amp up there is around 25 dB gain or so. So - although it does take that thin slice of the vertical RF, the amplification effect of the beam itself and the amp is huge. Every 3 dB of gain in an amp is effectively a double. Figure out the number of times that small slice of RF doubles inside the TV amp and, as long as the noise figures are ok - it produces some nice results. Summary - not the optimal tuned antenna system, but I work with what I have at the time.

 

[DRL-XM43]

What I do is run HDSDR or likewise and tune to the the frequency of interest, from there I fuss with antennas, gain and so forth until I have achieved optimum receive for the frequency, then I run my decoding software using that orientation/settings. It seems like a good method or process rather than all the random trial and error. Just a thought....

 

[AB9NN]

Sounds like a plan. And what if an interest is in scanning multiple frequencies from multiple directions? My testing is anything BUT random trial and error. Since my antenna usage is a bit out of the box I expect it to seem very odd to many and perhaps utterly unacceptable to some. For me, experimentation with using what I have in unconventional ways is part of the interest in radio - and photography and other interests as well. But that's just me. Also DSDTune is not up to date, as of this date, for DSD+ FastLane as was noted in a response to one of my posts. Therefore, that portion of the precision tuning process was never completed. Scanning still seems to work though...

 

[dave3825]

And what if an interest is in scanning multiple frequencies from multiple directions? My testing is anything BUT random trial and error

That's where I am at. So many frequencies , so little time. I like vhf stuff and of course uhf stuff, but let's not forget 700/800 stuff too. I am looking into a triplexer for using 3 different band antennas, with one feed line to my scanner and sdr dongles. Most of my listening is to my west so moxon's will work for me as they are somewhat directional. For all around, omni directional should work.

Actually saw it discussed here. https://forums.radioreference.com/threads/antenna-for-military-and-civilian-air.381736/#post-3049740 Erico listens to airband with an airband antenna, and mil aircraft with an antenna tuned to that. He uses a diplexer. I want to try a triplexer or atleast start with a diplexer for VHF input: 47 ~ 230 MHz and UHF input: 470 ~ 862 MHz

.

 

[AB9NN]

Cool. I ran a DX Engineering duplexer in my car for a time. I had a Comet UHV-6 antenna to start. If I recall it handled everything from 70 cm down to 40 meters. Worked great for many years, many highway miles, lots of Wisconsin and Michigan summer and winter storms, salt, etc.. When it met it's match (pardon the pun) on some chunk of concrete I ran some Ugly Stik type single band antennas - mostly 20 meters. Really good for the money! Later, when I became the Emergency Coordinator for Outagamie County, WI I wanted a fast deployable HF station and so ran a 108" steel whip with ball and spring mount and lavish RF strap grounding for 80 meters on up. Loved working the WI ARES / RACES Sunday morning training nets from some static free locations. One question - I presume your SDR has a 75 ohm RF input - or 50? I run my TV cable direct from the amp at the top of the mast down to a splitter in the basement and then to a Y cable to feed two of the RTL-SDRs with no Balun, etc.. The other RTL-SDR has the little 9:1 balun in front of the SpyVerter and is fed directly by the 150' or so wire antenna. With the Moxons, how do you handle matches or do you need to?

 

[DRL-XM43]

Sounds like a plan. And what if an interest is in scanning multiple frequencies from multiple directions? My testing is anything BUT random trial and error. Since my antenna usage is a bit out of the box I expect it to seem very odd to many and perhaps utterly unacceptable to some. For me, experimentation with using what I have in unconventional ways is part of the interest in radio - and photography and other interests as well. But that's just me. Also DSDTune is not up to date, as of this date, for DSD+ FastLane as was noted in a response to one of my posts. Therefore, that portion of the precision tuning process was never completed. Scanning still seems to work though...

Sorry then, it just seemed like you were perhaps struggling by all the questions and comments you had about poor quality results.

I am in a very difficult location at basement level with no chance for a proper antenna setup, with persistence though I am able to receive and decode with absolute clarity towers located more than 30 miles away P25 phase 1 and 2, NXDN NEXEDGE 4800, Motorola Type II SmartZone, DMR Motorola Capacity Plus Single Site, DMR Motorola Connect Plus (TRBO), DMR Conventional, D-Star and of course commercial wide FM, airband and marine as well as ACARS, FLEX and so foth, I also feed dump1090.

My lead off assumption is the tools like FMP24/DSDplus OP25 and other tools are not the problem, they all work very well, so any issues are almost always with my end of the bargain. So I move forward with the presumption difficulties lie with my setup's. This forum has helped me tremendously and I am thnkful for all the support.

Anyway good look on your quest.

 

[slicerwizard]

And what if an interest is in scanning multiple frequencies from multiple directions?

When the weather improves, switch to a vertical omni / discone?

Also DSDTune is not up to date, as of this date, for DSD+ FastLane as was noted in a response to one of my posts. Therefore, that portion of the precision tuning process was never completed.

DSDTune 0.1.2 works fine.