Hello all,,
Can anyone break this HFDL message down and explain what each line means? I have added my assumptions next to the line in RED, can you confirm my assumptions? Big ones I would like to know is if its an AC transmitting to SFO, or is it SFO Transmitting to an AC? Interestinbg enough I got this on 17.919 Mhz which is supposed to Riverhead not SFO ?
<300 bps 1.8 sec 1442 Hz> 02/01/2024 17:24:29 (date and time, 300 bps speed 1.8 sec? 1442 hz?)
MPDU CRC control: OK (MPDU CRC OK)
MPDU (Media access control Protocol Data Unit) - Downlink (downlink from an aircraft?)
00 Ground Station Identifier: 1 - San Francisco CALIFORNIA, USA (121-45-34W 38-22-48N) Synchronized to UTC time (xmitted to SFO station)
01 Aircraft Identifier: 255 (AC ID# ID# of transmiting AC?)
02 Number of medium priority slots: 0 Low priority slots: 0 (Slots? No idea?)
03 Uplink data rate: 600 bits/s U(R): 0 LPDU [ U(R) Vect + 1..8 ]: 00000000 (no idea?)
04 Number of LPDU: 1 LPDU Sizes: 21 ( No Idea?)
LPDU CRC control: OK ( LPDU CRC OK )
[LPDU log-on request (DLS)] Aircraft ICAO address (hex): A2DA60 (log on request, what are they requesting to log on to? ICAO info in hex)
Line 1 - This transmission from the aircraft is at 300bps rate 1.8 secs duration at this timestamp
Line 2 - The CRC is good (Cyclic Redundancy Check) i.e. are all the bits of the message received OK?
Line 3 - This is a downlink from aircraft to ground station
Line 4 - Ground station to which this message is addressed
Line 5 - HFDL network ID of this aircraft
Line 6 - The aircraft has not requested any slot frames
Line 7 - The uplink rate is 600bps U(R) 0 means no uplinks received and I guess referring to the 1.8secs transmission period
Line 8 - Link Protocol Data Unit stuff
Line 9 - LPDU CRC is good
Line 10 - Log on to the HFDL network with this ground station is requested. If you can see the G/S uplinks you may see the acknowledgement sent AND the ICAO HEX code for the airframe
