In below observation, I can see it decoded in AX.25 frame, but the frame structure is not visible in data the ground station decoded. How does it getting data in AX.25 frame?
https://network.satnogs.org/observations/10582647/
To put more in detail, it decoded SC2314 (53 43 32 33 31 34), R2ANF (52 32 41 4E 46) but I can’t find them in nowhere in decoded data.
Any help will be appreciated.
R2ANF is A4 64 82 9C 8C
SC2314 is A6 86 64 66 62 68
You have to shift it 1 bit.
A4 64 82 9C 8C 40 60 A6 86 64 66 62 68 63 00 F0 46 42 02 00 01 00 19 00 14 00 FF 70 21 19 F0 0E A5 5E 36 67 2E 5F 81 00 60 09 00 00 25 00 10 1E 01 21 ED 04 00 01 00 30 00 09 00 16 00 23 00 01 00 02 00 05 00 59 FE 55 00 34 00 B4 00 08 01 2A 00 B6 04 14 05 01 05 26 05 00 E0 53 00 58 1E 2A 81 81 00 D8 66 15 5B D4 24
Thank you! Do you know why 1 bit is shifted?
The HDLC address field is extended beyond one octet by assigning the least-significant bit of each octet to be an “extension bit”. The extension bit of each octet is set to zero, to indicate the next octet contains more address information, or one, to indicate this is the last octet of the HDLC address field. To make room for this extension bit, the amateur Radio call sign information is shifted one bit left.
While in decoding sequence, found out that DESTINATION SSID is 6 and extension bit is 0000. But in the decoded data, it the DESTINATION SSID is set to 0. Do you think it’s wrong? I appreciate your help.
The SSID is part of the 7th byte of a callsign.
Looking at the bits of the 7th byte, the SSID is on the S marked bits:
7654 3210
CRRS SSSE
For 0x60 = 0b0110 0000 the SSID is 0.
C = Command or Response
R = Reserved
E = Extension bit
