AIS Slot map

[lucasb]

AIS Slot Map
In the AIS system, one minute is called a frame, divided into 2250 time slots, each time slot is 26.67ms

I am interested to get the AIS slot map from SDRAngel data
In current SDRAngel configuration the time recorded is in the format HH:MM;SS

What I would like is the option in SDRAngel to show the received frame in slot number or in milliseconds after the frame started. ??
Can somebody please provide a solution?
Best regards

Lucas

[srcejon]

I can add an extra column to the table, with a calculated slot time, based on when a message is decoded, but the time between data being received by an SDR and when it is processed in SDRangel is somewhat of an unknown (varies with SDR, O/S, buffering etc), so the calculated slot could well be wrong.

[lucasb]

Hi srcejon

I am very happy with your quick replay and your solution ! Yes what you propose would be very good and I think workable - Of course there will be processing delay of the SDR but that is not important - What I am looking for is the actual load on the AIS channel and see when there is a point of saturation - Thanks so much
Lucas Guyancourt France

[srcejon]

Give this a try: https://github.com/f4exb/sdrangel/pull/1664

[lucasb]

Dear Friend, I am very surprised how fast you made the code for AIS slot map- I will have now a look at what you made - I am 77 years of age and fascinated with SDR and AIS applications . I keep you posted THANKS

[lucasb]

I am impressed !

[lucasb]

I made a new record of 50 ATON's
The recorded time slots are around 100 slots behind ( due to SDR latency) but the slot distance between two AIS ATON sentences is correct ( 20 slots spacing between each ATON) Thus it works perfect - I will do some further testing - Thanks !!

[srcejon]

Would a slot map image be useful? This is a 50x45 (=2250 slots) image, where one dot/pixel is drawn for each used slot.

SlotMap.png (135.49 KiB) Viewed 281 times

It's using a different colour for each different MMSI, but maybe that's a bit confusing as there are so many different ships.

Gives a rough idea of congestion though.

[lucasb]

Dear Friend,

I am amazed, really, you made what I had in mind - It looks beautiful.
A small comment, No need to make a color for each flag or MMSI.
It would be prefect to show Class A Color A , Class B vessels color B and Fixed ATON color C, Virtual ATON color D.there are not so many types .
That would be perfect for my small project for inland waters AIS systems .
Could you make it this way .. ?? Can I get in contact with you personally ? my email lucas.beumer@free.fr. I wish I could tank you in person !! Thank you so much !! Lucas

[srcejon]

Here we have:

Red=class A
Blue=class B
Green=Base station
No AtoNs near me, but they'd be in different shades of yellow, for fixed/virtual/mobile.

SlotMap2.png (105.42 KiB) Viewed 267 times