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flight:hfdl-wrong-hexes

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flight:hfdl-wrong-hexes [2024/02/23 09:34] – 2m0iigflight:hfdl-wrong-hexes [2024/02/23 10:07] (current) – 2m0iig
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 Without going into too much detail both of these types of signals contain all sorts of information, and are usually accompanied by an aircraft's 24-bit ICAO address. This is a 6 character hexadecimal ID that identifies a specific aircraft on the planet. However, these codes are not immutable. If a plane's registration/country is changed then a new hex is assigned, according to the registration country of the aircraft. Different blocks (ie, the characters the code starts with) exist for different countries. Without going into too much detail both of these types of signals contain all sorts of information, and are usually accompanied by an aircraft's 24-bit ICAO address. This is a 6 character hexadecimal ID that identifies a specific aircraft on the planet. However, these codes are not immutable. If a plane's registration/country is changed then a new hex is assigned, according to the registration country of the aircraft. Different blocks (ie, the characters the code starts with) exist for different countries.
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-[img-aircraft comms] 
  
 Along with ACARS via satellite comms and VHF airband @ around 136 MHz, this means that there are usually 4 different systems pinging away. And usually everything is fine and dandy. However, I spotted an issue the other week that caused me a small amount of interest: it seems that sometimes these 4 systems don't always have the same hex ID. Along with ACARS via satellite comms and VHF airband @ around 136 MHz, this means that there are usually 4 different systems pinging away. And usually everything is fine and dandy. However, I spotted an issue the other week that caused me a small amount of interest: it seems that sometimes these 4 systems don't always have the same hex ID.
  
-[hf wrong track]+[hfdl/ads-b track of same plane side by side]
  
 I spotted a HFDL track going through my ADS-B range that didn't switch to an ADS-B track - the track was HFDL-only. The plane would definitely have been pinging ADS-B or Mode S, so I checked on my feeder to see what plane was in the same area on ADS-B/Mode S at the same time as the HFDL ping. And to my surprise, I found a totally different hex ID, with a similar callsign to the HFDL ping (OCNxxx/LHxxxx). The callsign being different (even though some numbers were the same, allowing me to make a match) is explained by the difference between ICAO and IATA callsign prefixes, and is outside of the scope of this article. The hex ID, however, is a different proposition. I spotted a HFDL track going through my ADS-B range that didn't switch to an ADS-B track - the track was HFDL-only. The plane would definitely have been pinging ADS-B or Mode S, so I checked on my feeder to see what plane was in the same area on ADS-B/Mode S at the same time as the HFDL ping. And to my surprise, I found a totally different hex ID, with a similar callsign to the HFDL ping (OCNxxx/LHxxxx). The callsign being different (even though some numbers were the same, allowing me to make a match) is explained by the difference between ICAO and IATA callsign prefixes, and is outside of the scope of this article. The hex ID, however, is a different proposition.
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-[ads-b of same plane] 
  
 Why does this matter, though? Well, it'd be nice to see an entire line as a plane's signal is received in different modes and have a complete, unbroken track. With this issue we'd have two separate, unconnected tracks. This is a bit of a pain when analysing data and looking at the entire route of an aircraft. Here's one that worked fine, showing the HF points, then a dotted line to connect it to the ADS-B track. Why does this matter, though? Well, it'd be nice to see an entire line as a plane's signal is received in different modes and have a complete, unbroken track. With this issue we'd have two separate, unconnected tracks. This is a bit of a pain when analysing data and looking at the entire route of an aircraft. Here's one that worked fine, showing the HF points, then a dotted line to connect it to the ADS-B track.
flight/hfdl-wrong-hexes.1708680893.txt.gz · Last modified: 2024/02/23 09:34 by 2m0iig