KRAKsat Satellite

New satellite - KRAKsat - was launched today from ISS at 11:50 UTC.
You can find out more about project on (our app for radioamateurs).

KRAKsat is transmitting only AFSK 1200 on 435.500 Mhz. There is a beacon every 15 minutes with some statuses and downlink on request from our station in Warsaw.

If anyone manage to get some data from our satellite, we would like to kindly ask to put it (in txt format) on our platform Any help is welcomed and great!

I’d also like to request a change on KRAKsat satnogs page - there’s a mistake about GFSK modulation. We have only AFSK 1200. Thank you in advance.


Hi @yiea,

Congratulations on your successful deployment!

The satellite is already added and there are some scheduled observations in SatNOGS Network, also I’ve accepted the request on DB about the invalid GFSK mode. Some observations have been scheduled with this mode, I’ll try to modify them to use the AFSK one.

I can see you have details about demodulation of your packets in, however I can not find any details on how to decode the results of the AFSK demodulation to useful data. Are these info publicly available? If not, could you add them in, so to be accessible for radio amateurs?

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Hello! Thank you for the correction and the answer.

Results of AFSK demodulation are decoded by our team after accepting uploaded files and I’ll do my best to show it after the decoding to the person that send it. After decoding it’s also automatically added to our charts pages, so if someone catches the beacon, he will be able to see it decoded on one of the pages. There’s some test data now there but I’ll clear the system today so it’ll be ready for data from radioamateurs :slight_smile:

Shouldn’t the message be decodable by the general public to be using the the Ham bands?


It is - it’s done automatically by app :slight_smile: And you can demodulate it using free tools for AFSK 1200.

closed source data format but open access? Like, let’s AFSK our data packed in password protected 7zip AES text (and send it like binary)? Seems a bit like cryptolocker stuff. You see, when the SatNOGS team get the format they can use Grafana to plot the telemetry 24/7 as data falls into db, simple as that. Sorry for being like that, but …


Can I have this app? Or is it only available to your team. If then you seem to not want anyone but your team decoding the telem from you satellite.

Transmissions between amateur stations in different countries may not be obscured.
[See: RR 25.2A] This means that (1) technical descriptions of all emissions, codes, and
formats must be publicly and widely available; and, that (2) technical descriptions must
be sufficient to enable any technically competent licensed amateur radio operator to use
the system. You may do nothing intended to conceal the meaning of a transmission,
except in the case of space telecommand transmissions for critical spacecraft functions.

Part E of

Yes this document is from 2006 but this rule is still in effect.

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Yes, we are aware of that - app is available and it works online on It’s available for everyone, but every uploaded dataset goes to manual review to avoid errors (like data from Światowid which was deployed at the same time with same frequency). We’ll also publish the documentation with all the information about decoding - days/weeks max - we’re still working on that, I hope you’ll be understanding about the delay :slight_smile:

@yiea To be frank, we really need an engineering document describing all the packets, this should be provided BEFORE the launch. You must have this document since early development stage of the RF comms. We don’t need any eye candy in this document, only raw engineering details about the packets.
Do not forget that your projet must be useful and interesting for the ham radio community, else it’s simply an abuse.


KrakSat is identified as object 44426, however it is object 44427. Verified by this observation. NORAD ID is now changed on both DB and Netowork.


We have some issues with our KRAKsat satellite. As you can see on the SatNOGS waterfalls it’s rebooting constantly and we’re trying to find a way to fix that and reset it to normal state.
I would like to kindly ask you to listen to KRAKsat when it passes above your stations (ID 44427) and upload your audio to SatNOGS. It will be really helpful for our space mission!

If you have any questions, don’t hesitate to ask.

Thank you all in advance,

Have you had time to get the documentation worked out for decoding? (Just asking as its been a month. Plus it would help in figuring out whats up with it.)


@KD9KCK - please, have a look here:
After a restart, KRAKsat is simply transmitting “START U1, START U2, BOOT NR x” and after these messages there should be a beacon (as described in pdf).

Best regards,


As far as I can tell from the frames stored in our DB: not a single beacon has been recorded since. But it reboots a lot! ~500 reboots in ~4h45min, see:

        "time": "2019-08-04 05:47:34",
            "monitor": ":SP6ZWR:        BOOT NR 10561"
        "time": "2019-08-04 01:00:33",
            "monitor": ":SP6ZWR:        BOOT NR 10069"

Unfortunately we do not have any telemetry yet :frowning:

Definitely in a boot loop. Observation 905768: KrakSat (44427)

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Hello Alicja,

As KrakSat seems to get more healthy after a while there are some undocumented beacon contents present in the recorded data. Could you give some more hints on, e.g. ER, CU, EM, etc.?

Best regards,

Hello Patrick,

Yes, we know that unfortunately KRAKsat is now in the boot loop.
Where did you find these beacons? EM, CU and ER are Światowid’s (ID:44426) beacon parameters.

Best regards!

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Ok, so they might have overlapped in an observation. Just wondering: is that still possible?

We have a very basic dashboard, only showing the ASCII strings of the telemetry beacons, at

No filtering, so it might indeed be beacons from other satellites that crossed the KrakSat observation. But there also seem to be some data from KrakSat besides the boot-loop counter…

Maybe they have overlapped, maybe it’s still possible… After the restart there actually should be a beacon from KRAKsat, but as far as I know it manages only to send first line of it (STS with 32-bit 0/1 status) and after that it starts to reboot again. If you encounter a log from KRAKsat with master or radio status (M1;LOG or U1;RL), please let us know - it would be very valuable.

Thank you for your interest and help!

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