SDRTrunk

[DSheirer]

I had a few minutes to work on this tonight and I've got the Tait 1200 CCDI GPS messages decoding and plotting on the map. I have the whole degree values for latitude and longitude parsing good, but I don't think I have the fractional values correct yet.

What radio group is this (FPP?), and how large would their coverage area be? Would they be located mainly on the roads, or do they venture off the main highways?

Denny

 

[whitfords]

Hi Denny and thanks. More examples uploading to dropbox now. They venture off the main highways a lot. Pretty much Perth City to approx 150 km North, 150 km East, 200km South...
I am not sure of the FPP, they use Tait 8260 units, programmed probably 5 years ago.

 

[DSheirer]

I posted a new build (sdrtrunk_20150110_1526_tait1200_test.zip) with the Tait 1200 GPS and SELCAL message parsing. However, it doesn't seem to decode the SELCAL examples that you posted very well. The protocol uses a very short bit rev period and my FSK symbol and message framer have a hard time sync'ing up with the messages. I'll play with it some more later after I finish a P25 viterbi decoder I've been working on. If you produce any decode logs, please post to your dropbox.

Denny

 

[whitfords]

Hi again, I don't remember putting any SELCALL in there, maybe some rogue DTMF tones? They rarely use SELCALL so probably not worth looking at unless I can find some real examples of it. I am decoding at the moment and will update you soon Thanks again from Down Under!

 

[whitfords]

Hey Denny, it's not catching all the data transmissions. Do you recommend the Gain to be Auto? What is the best sample rate please?
Thanks

 

[whitfords]

Hi again,
OK, been decoding for a while. I think the calculation from NMEA Lat/Long to GPS placement on the map (Decimal Lat/Long) is placing the units about 15-20km South West of where they really are. I have placed a map in the dropbox along with some logs. How do they come out when you decode them from binary? DDmm.mmmm ? Cheers

 

[DSheirer]

Hey Denny, it's not catching all the data transmissions. Do you recommend the Gain to be Auto? What is the best sample rate please?
Thanks

Which receiver are you using?

If you're using one of the RTL-2832 based dongles, set the manual gain to the lowest setting and then incrementally increase the gain up to the point that the noise floor starts to rise.

Set the sample rate to the lowest rate (240k or 288k) until you get everything adjusted.

 

[DSheirer]

Hi again,
OK, been decoding for a while. I think the calculation from NMEA Lat/Long to GPS placement on the map (Decimal Lat/Long) is placing the units about 15-20km South West of where they really are. I have placed a map in the dropbox along with some logs. How do they come out when you decode them from binary? DDmm.mmmm ? Cheers

I looked in your dropbox ... no new logs/files?

I think I'm not decoding the location fractional degree values correct, which would be causing the 15-20km errors that you're seeing. I'll take a look at it again.

 

[whitfords]

Whoops, didn't have the Dropbox syncing properly. Try now. The logs should be in the folders.

 

[whitfords]

Oh, and the Simoco 9000 series Dispatch and AVL program are in there too if that is any assistance. I am not sure if Simoco use the same protocol for ANI and GPS FFSK data transmissions as TAIT...

 

[DSheirer]

I figured out the fractional lat/long values. I'm trying to get the heading and speed values now.

Are these Bush Fire Bridage vehicles that you're following?

https://www.google.com/maps/@-32.16...ata=!3m4!1e1!3m2!1sNGKB08Pl5TyE6_GessIMnw!2e0

The google street view images make it look very dry there ... I'd imagine the fire departments stay very busy.

 

[DSheirer]

Latest test build with corrected gps location and speed parsing posted ( sdrtrunk_20150111_1404_tait1200_test.zip). I changed the message B format to read ANI instead of SELCALL.

Denny

 

[whitfords]

Fantastic. Will try it now. Yes, that is certainly what they are.
Some photo's...
http://www.abc.net.au/news/image/4472334-3x2-940x627.jpg
https://pbs.twimg.com/media/B7BLGBNCYAEEQLG.jpg:large
Firefighters control Bullsbrook bushfire, warning downgraded to watch and act - ABC News (Australian Broadcasting Corporation)
http://9news.static9.net.au/~/media/images/2015/january/12/1201bullsbrookfire2tw.ashx?w=603
http://resources1.news.com.au/image...0749-d50ca192-924e-11e4-a068-35e4e5c4fad4.jpg
https://pbs.twimg.com/media/B6-9zQrCQAA5MIv.jpg
https://pbs.twimg.com/media/B6_Hm4PCUAE-4kE.jpg:large
https://s.yimg.com/ea/img/-/130301/280213gendfes2_18ivldl-18ivldo.jpg

 

[whitfords]

Fantastic. Will try it now. Yes, that is certainly what they are.
Some photo's...
http://www.abc.net.au/news/image/4472334-3x2-940x627.jpg
https://pbs.twimg.com/media/B7BLGBNCYAEEQLG.jpg:large
Firefighters control Bullsbrook bushfire, warning downgraded to watch and act - ABC News (Australian Broadcasting Corporation)
http://9news.static9.net.au/~/media/images/2015/january/12/1201bullsbrookfire2tw.ashx?w=603
http://resources1.news.com.au/image...0749-d50ca192-924e-11e4-a068-35e4e5c4fad4.jpg
https://pbs.twimg.com/media/B6-9zQrCQAA5MIv.jpg
https://pbs.twimg.com/media/B6_Hm4PCUAE-4kE.jpg:large
https://s.yimg.com/ea/img/-/130301/280213gendfes2_18ivldl-18ivldo.jpg

 

[whitfords]

Not sure if it is a common avl issue, but what I am listening to is over a series of linked repeaters through a network, and only the units that transmit on the repeater I am monitoring seem to be decoded. I still hear the data from the units transmitting on other repeaters in the network, but for some reason the audio must be compressed or changed enough for it to not decode. Did you have that with some of the audio files I put in the dropbox (some not decoding)?
Thanks
P.S. It seems the lat/longs may be correct now, but I will know more soon hopefully!!

Thanks again!!

 

[DSheirer]

Not sure if it is a common avl issue, but what I am listening to is over a series of linked repeaters through a network, and only the units that transmit on the repeater I am monitoring seem to be decoded. I still hear the data from the units transmitting on other repeaters in the network, but for some reason the audio must be compressed or changed enough for it to not decode. Did you have that with some of the audio files I put in the dropbox (some not decoding)?
Thanks
P.S. It seems the lat/longs may be correct now, but I will know more soon hopefully!!

Thanks again!!

Yes, I had the same issue with poor/no decoding of most of the data bursts that you sent. The signals appear to be strong, but somewhat distorted, possibly from the repeaters. I tried adding more filtering but that didn't seem to help.

That issue is compounded by the Tait signal using a short bit reversal period ( 8 reversals) which is designed to allow the decoder to synchronize with the bit stream. This is less than half of what the other FFSK signals like Fleetsync and MDC1200 use and it causes my decoder to miss many of the message bursts. I experimented with changing some of the settings in my FSK decoder to allow it to sync/align more quickly, but that seemed to induce more errors later in the message. I'll do some more experimenting to see if I can improve the decoding.

 

[whitfords]

You have done an awesome job as it is!! I am currently decoding using the soundcard input and running SDR Sharp standalone. In the command window it is showing the messages being decoded, but it isn't coming up in the messages window, yet it seems to place the icon on the map OK.

I do have some other questions which are low priority though. Seems I can't adjust the size of the inner windows anymore. Not sure what changed. (edit : a restart fixed it)

Also, some stage down the track will there be a way to have the map open in a separate window ( or parse to google maps)?

I am not sure how to assign names / callsigns to the ID of the transmissions using Aliases either. Is there a way to associate a callsign with an ID so the callsign is on the map instead?

Thanks again. I will drop the logs etc into the dropbox for you in 5 min.

 

[DSheirer]

In the command window it is showing the messages being decoded, but it isn't coming up in the messages window, yet it seems to place the icon on the map OK.

Left-click on the decoding channel window (left-side) and that will make the messages from that channel display in the messages tab.

Also, some stage down the track will there be a way to have the map open in a separate window ( or parse to google maps)?

I only added enough functionality to the map to allow me to see Fleetsync GPS messages and then moved onto other parts of the program. I plan to update/enhance the map at some point.

I am not sure how to assign names / callsigns to the ID of the transmissions using Aliases either. Is there a way to associate a callsign with an ID so the callsign is on the map instead?

1. Create an AliasList (right-click on Playlist > Alias Lists in configuration tab).
2. Add an alias to the alias list using the callsign as the name.
2a. Select an icon to use for the alias. You can import your own icons via the IconManager.
3. Add one or more Talkgroup identifiers to the alias. For Tait, the talkgroup format should be the full 8-character ident that you see in the decoded message. You can alias both the FROM and the TO idents.
4. Assign the alias list to the decoding channel in the channel configuration editor.
5. Restart the channel.

 

[whitfords]

Thanks again Denny ! I'll try it out in the morning! zzzzzzz

 

[Gilligan]

Hey Denny,

I noticed that you have recording capability in SDR-Trunk, however it seems to run continuously. I was wondering if it would be possible for you to start/stop recordings triggered by CALL events and then add the timestamp and talkgroup into the filename? This would make it SO easy to sort out transmissions by talkgroup and then figure out who is using each. What do you think?