Ground vehicles with valid ICAO addresses will not be tracked if they use DF18 CF1 instead of CF0

Ground vehicles, buildings and obstructions at an airport can have transmitters fitted that transmit ADSB messages. These transmitters do not necessarily need to use ICAO addresses. If they have been allocated an ICAO address then they should transmit their ADSB using DF18 CF0, if they have a non-ICAO address then they should use DF18 CF1 (by my reading of the documentation, I could well be wrong).

VRS accepts ICAO addresses from DF18 CF0 but ignores non-ICAO addresses from DF18 CF1. Consequently CF1 vehicles are not tracked.

However, it turns out that at least one airport has a mix of vehicles that transmit CF0 and CF1, even though all of them clearly have addresses allocated from the same small range of valid ICAO addresses. It's possible the CF1s are transmitting private addresses but if they are then they were chosen to be confusingly close to the addresses used by the CF0 vehicles. I think it's more likely that the transmitters on the CF1 vehicles are misconfigured and should really be sending CF0.

To address this there should be a new setting under the raw decoding settings to control whether DF18 CF1 addresses are accepted as ICAO addresses. If this is set to true then treat them the same way as CF0.

The option to configure the settings for strict ICAO decoding should turn the option off. However, I think by default the option should be turned on. I suspect the new addresses that get shown will be very obviously ground vehicles or buildings, if the address isn't ICAO then some bits of information will be a bit freaky but it's probably still preferable to show them rather than hide them.

vradarserver / vrs

Ground vehicles with valid ICAO addresses will not be tracked if they use DF18 CF1 instead of CF0 #20