ModeSDeco2 and ModeSMixer2 - console programs for RTLSDR and transcoding

[Anmer]

how sould you notice it?

Since they outperform the specialist receivers, in aircraft tracked, I'm assuming the alleged "noise" is not adversely affecting the RPi based ones.

[Oldfella]

Hi Anmer

The aircraft were also not showing on the Skyview map.   The missing aircraft are up to about 15nm from my location.   Another friend of mine appears to have a similar problem when using the Stretch version of
the software.

I have gone back to using the FlightAware dongle with ModesDeco plugged straight into the USB port of my notebook.   All working fine and all aircraft displaying.   The only thing is I now do not have the advantage of the MLAT aircraft being displayed.

I tend to think that there is an issue with the Stretch/ModeSMixer2 software for now.

Cheers
Mark

Following on from Mark's posting, I too am experiencing the same symptoms and can report it affects the Skyview map as well.

My setup is as follows:-

1. PC Intel CPU i7-7700, 16GB RAM with Windows 10 Pro 64bit connected to router via Ethernet
2. Raspberry Pi 3 running Stretch o/s connected to router via Ethernet
3. DPD ADS-B Antenna 1.8m above roof and 100m above sea level.
4. 7m of LMR400 coax feeding FlightAware Pro Stick connected to Pi
5. Sergsero's test version of modesmixer2_rpi2-3_deb9_20180311 installed on the Pi along with PiAware 3.6.2 (dump1090-fa), FR24 and Plane Finder 4.1.1
6. Running BaseStation ver 185, PlanePlotter 6.4.6.9 and PBLink3, max range 233nm.

Aircraft within the general area are normally shown with a steady trail however, as an aircraft approaches my location, their trail will change to a stream of dots which become further apart before disappearing all together then to reappear as they retreat. This normally occurs within a 8nm radius of my location but could vary depending on altitude and aircraft types. Light aircraft can be within 2 to 3nm, usually at 1500ft, before loss of signal occurs. Observation of the situation over the past couple of days has shown a real hit and miss of these symptoms with some RPT aircraft getting within 3nm while others could occur up to 10 to 12nm.

I cannot put a time when this started to occur, upgrading the Pi from Jessie to Stretch, installing the test version of Modesmixer2 or running PiAware 3.5.3 (3.6.2 installed 2 days ago). My take on the situation is that my system appears to get overloaded when some aircraft come close to my location. I noted that there has been recent discussion on the FlightAware forum about gain control and I wonder if the FlightAware Pro Stick along with improvements to the various software could be causing this problem.

Would be interested to hear from any other member who is also experiencing these symptoms.

[Anmer]

Thanks for sharing this.

Do the "missing" aircraft reappear on Skyview if ModeSMixer isn't being used?

[sergsero]

Hello,

Unlike SDR program, such as dump1090 or MD2, the main task of which is to extract Mode S messages from received radio signals and send them to a network, the visualization programs like VRS and MM2 display data on map contained in incoming messages from outside sources. Also them can perform conversion of message formats when it is set by user.

But they operate only with the information that comes in input messages.

The trail of track in form of dots occurs when no longer receive messages containing coordinates of the aircraft. Or the decoded coordinates are invalidated for some reason, for example, you received a new position message within exceeded the time limit between odd/even pair of position messages and etc.

This may be due to overload of receiver by strong signal from close aircraft when receiver has insufficient dynamic range and high sensitivity. The R820T2 receiver chip exhibits very high sensitivity, around -120 dBm typically.
The dynamic range is the relation between the strongest signal and weakest signal (noise floor) that can be digitized without distortion.  But SDR-chip RTL2832U has only 8 bit ADC (analog-to-digital converter) and this low number of bits limited his dynamic range.

Do you use the FlightAware Prostick (without internal filter) or their last version - FlightAware Prostick Plus?
Check, when labels of the aircraft hide on map, whether this aircraft remain in the table?
Check the signal level at border where label stops being displayed.

By default settings of piaware configure file for dump1090 are usually set gain value "-10" which means use of automatic mode.
Try to change this value to some possible values for the R820T2 chip gradually decreasing it from maximum of 49.6 and check to see if this restores the display of aircraft near your location.
(Not perhaps during this test, due to the gain reduction, you will not be able to receive signals from the most remote aircraft on the coverage border.)

Best regards,
sergsero

[Oldfella]

Thanks for sharing this.

Do the "missing" aircraft reappear on Skyview if ModeSMixer isn't being used?

Thanks Anmer for your reply. With just the PiAware running and no Modesmixer, the nearby aircraft are still missing in action. It looks like the FlightAware Pro Stick Plus is out performing itself. Spoke to Mark (QF1) this afternoon and think it strange that we are the only two to have come across this problem.

Cheers.

[Oldfella]

By default settings of piaware configure file for dump1090 are usually set gain value "-10" which means use of automatic mode.
Try to change this value to some possible values for the R820T2 chip gradually decreasing it from maximum of 49.6 and check to see if this restores the display of aircraft near your location.
(Not perhaps during this test, due to the gain reduction, you will not be able to receive signals from the most remote aircraft on the coverage border.)

Best regards,
sergsero

Many thanks again Sergsero for your assistance. I'm using the FlightAware Pro Stick Plus dongle and found it very interesting your explanation on how the stick operates. I will start a process of reducing the RF gain in steps from 49.6 to see what effects it has on the missing aircraft and report back.

Best regards.

[Oldfella]

Check, when labels of the aircraft hide on map, whether this aircraft remain in the table?
Check the signal level at border where label stops being displayed.

Hello Sergsero, I have refitted the FlightAware filter and there hasn't been any noticed changes to the previously report circumstances.

With the max gain setting of -10 (49.6), aircraft within 5 to 7nm of my location disappeared off BaseStation. These aircraft still remain on the ModesMixer2 Flights Table and continued to show all data except for lat, lon and distance with the message rate dropping and the SGL reaching 210+. Aircraft at the border will drop off when the SGL goes below 37 with a range of about 199nm.

With the gain set at 40.2 there was no lost of aircraft close in and SGL stayed below the 200 mark. Border aircraft disappeared around the 192nm mark with a SGL of 7. Increasing the gain step by step to a setting of 48.0, there was only the occasional lost of aircraft within the 5 to 7 nm radius on my location. On the border edge, lost of aircraft occurred again at about 199nm with a SGL of 13.

These are average figures which varied over days depending on height and aircraft types. It would seem that a gain of 48.0 is the best overall setting for my setup.

Unfortunately I cannot noted when this event first occurred, either with the upgrade of the Pi from Jessie to Stretch or FlightAware from 3.5.3 to 3.6.2 but before these changes my system showed no signs of lost of aircraft within the 5 to 7nm except the occassional light aircraft passing low overhead. I'm planning to format a SD card with Jessie and install 3.5.3 and do some tests and see if the problem existed under that arrangement.

Thank you again for your program and help, it is very much appreciated.

Noel

[Anmer]

Thanks for sharing this.

Do the "missing" aircraft reappear on Skyview if ModeSMixer isn't being used?

Does altering the gain affect the aircraft shown on Skyview?

[Oldfella]

Does altering the gain affect the aircraft shown on Skyview?

Yes Anmer, it appears that changing the gain effects BaseStation, Skyview, modesmixer2 as well as PlaneFinder. Unfortunately, I haven't got a multi screen set up so it's a case of chasing the views on one monitor and from what I can gather, at max gain (-10), the aircraft within that 5 to 7nm radius all seem to disappear about the same time. With a gain setting of 48.0 there is very little to no lost of signal within the "Bermuda Circle". I'm happy with that setting and now will keep an eye on the max range side of things. So far haven't been able to spot any noticeable change.

Thanks again for Sergsero and your input and as Mark and I have commented, surprised that this effect hasn't been flagged before by members.

Best regards,

Noel

[A380]

Hello,

what is your command line?

Do you have any --valid-adsb option or the default?

I'm living near the Airport and all planes on the screen.

I set have the following vaild setting:   --valid-adsb 1:1 

Kind Regards
Rene

[Oldfella]

Hello,

what is your command line?

Do you have any --valid-adsb option or the default?

I'm living near the Airport and all planes on the screen.

I set have the following vaild setting:   --valid-adsb 1:1 

Kind Regards
Rene

Many thanks Rene for your question. I have always been concerned that I have the right settings in the command line. I have played around with the settings over a period of time and never sure that I got it right.

My current version is as follows

sudo ./modesmixer2 --google-key Axxxxxxxxxxxxxxxxx --inConnect 192.168.13.15:30005 --inConnect 192.168.13.15:30105 -outServer sbs10001:10001 --location -33.xxxxx:151.xxxxx --db/home/pi/ADSB/BaseStation.sqb --frdb /home/pi/ADSB/flightroute.sqb --silhouettes /home/pi/ADSB/OperatorFlags --web 8765

I have only just added the google key and the two sqb databases and the silhouettes folder. I have in the past included both the databases and the silhouettes folder but would always come up with an error and deleted those inclusions. This time it seems to be working well. 

If you see any omissions that should be included please let me know. I would be very appreciative of any advice.

Just to repeat my software arrangements - Pi3 via Etherrnet feeding BaseStation (Address 192.168.13.15 Port 10001), PlanePlotter (RTL dongle RPi dump1090 (192.168.13.15:30105)) then via web browser FlightAware:8080, FR24:8754. PlaneFinder:30053 and ModesMixer2:8765. All working as per the book.

Thank you,
Noel

[QF1]

Hi A380

I am very new to using ModeSMixer2 and I am interested in your suggestion and would like to try it.  Would you mind sharing your command line>
What is the effect of --valid -adsb 1:1

Like Noel (Oldfella) I am having similar problems around Sydney Airport.   It seems to affect aircraft between approx 500 feet and 6000 feet.   Overflights at higher altitudes do not seem to be affected.   I have turned the gain down a little but do not want to lose too much at max range.   I see gaps in the feed from about 6nm from my location.

Cheers
Mark

[dewoert]

Would it be possible to use ModeSMixer2 to filter MLAT traffic from an input source ?
I receive data from an external receiver, and would like to only get the ADS-B flights.
The current data has ADS-B and MLAT combined into one Beast format. MLAT traffice is "tagged", so i can "see" it as MLAT in MM2.
It is not possible for me to change the source, so i would like to split this traffic.
Allready tried different output from MM2, but MLAT traffic will not dissapear.

[abcd567]

Now on modesmixer2 map, Google shows a warning and watermark. I can get rid of it if I add Google key, but I dont want to get a Google key.

Is there an option in ModeSMixer2 to display OpenStreet or leaflet map like VRS or dump1090-fa and dump1090-mutability  now have?

[w7psk]

Now on modesmixer2 map, Google shows a warning and watermark. I can get rid of it if I add Google key, but I dont want to get a Google key.

Is there an option in ModeSMixer2 to display OpenStreet or leaflet map like VRS or dump1090-fa and dump1090-mutability  now have?

I am in the same position. I dont want to pay for Google key,  can we use a different map?