MDASAT-2(?) - Satellite hunting

A tweet a couple of hours ago by @N6RFM:

It shows the existence of MDASAT-2, but it is unknown which object is.

Checking in DB we have 3 unidentified entries, but identified in catalog:

All of them were added with transmitter at 401.075 which was the middle frequency from the published ITU range. However it looks like that at least for one of these satellites, MDASAT-1C it was chosen the frequency that @N6RFM’s observed, which is inside the ITU range. The verification comes from @PE0SAT strf observation shown below:

So, let’s change the transmitters to all three in order to check if this frequency is valid for all of them.

There is always the chance that what @N6RFM observed to be one of them, as all three of them were over US at that time. But let’s wait for confirmation that they were in his field of view (FOV) and also some more decodes to verify that one of them transmits as MDASAT-2. Until then let’s keep the scenario that a 4th unknown satellite could be the one received as MDASAT-2.


Thanks Fredy! I’ve also sent a message to the team in South Africa. Hoping for a reply. :slight_smile: Will keep this group posted for sure.


This is one of the frames I got by demodulating with direwolf this observation by @vk5qi station.

[0.3] MDASAT-2>CPUTGS:<0x08><0x02>�(<0x00>I<0x10><0x03><0x19><0x01>eb��<0x00>B<0x0c>�<0x01><0x01><0x10><0x0f>�]oz<0x01>�@(<0x03><0x01><0x00>0<0x08><0x00><0x00><0x00><0x00><0x00><0x00><0x00><0x00><0x00><0x00><0x00><0x03>��\�<0x05>DQ<0x01><0x00><0x0a>k��� �)p4�ĩ�<0x00><0x00><0x03>�<0x00><0x00><0x00>ud
U frame UI: p/f=0, No layer 3 protocol implemented., length = 96
 dest    CPUTGS  0 c/r=1 res=3 last=0
 source  MDASAT  2 c/r=0 res=3 last=1
  000:  86 a0 aa a8 8e a6 e0 9a 88 82 a6 82 a8 65 03 f0  .............e..
  010:  08 02 e1 28 00 49 10 03 19 01 65 62 8a cc 00 42  ...(.I....eb...B
  020:  0c bd 01 01 10 0f e4 b0 5d 6f 7a 01 83 40 28 03  ........]oz..@(.
  030:  01 00 30 08 00 00 00 00 00 00 00 00 00 00 00 03  ..0.............
  040:  82 eb 5c ad 05 44 51 01 00 0a 6b 81 c0 b2 20 9c  ..\..DQ...k... .
  050:  29 70 34 a9 c4 a9 c4 00 00 03 c8 00 00 00 75 64  )p4...........ud

The -2 is how direwolf show the Source SSID when it is not 0, in the second part which shows the frame with each header and in hex format, it is clearer.

Here is an older example of observation and how it is shown in direwolf:

U frame UI: p/f=0, No layer 3 protocol implemented., length = 34
 dest    APOFF   0 c/r=0 res=3 last=0
 source  USNAP1  1 c/r=0 res=3 last=0
 digi 1  ARISS   0   h=0 res=3 last=1
  000:  82 a0 9e 8c 8c 40 60 aa a6 9c 82 a0 62 62 82 a4  .....@`
  010:  92 a6 a6 40 61 03 f0 3e 42 61 6e 6b 30 2d 53 41  ...@a..>Bank0-SA
  020:  46 45                                            FE

In other words @N6RFM you probably got MDASAT-1C, which seems to be active from the three (need to confirm that the other two are not transmitting either on this frequency or at all).

So, MDASAT-2 doesn’t exist (yet?), however your observation was useful to find the right frequency for the other satellites and identify at least MDASAT-1C. :slight_smile:

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Thanks Fredy! Much appreciated. :slight_smile: :+1:

I’m monitoring NORAD 51038 for tonight’s pass. Let’s see if this repeats!

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Here’s from a pass just a few minutes ago. tracking 51038. TLEs not perfect but close. Had to fine tune to get decodes from IQ replay. Time is USA EST. 401.050 MHz

While I understand the explanation of Direwolf source SSID, I’m puzzled that UZ7HO would behave the same way? Unless, -1A = MDASAT-0, -1B = MDASAT-1, and -1C = MDASAT-2?
Frames uploaded to Satnogs 99465.