LAT/LON of glideslope transmitter

[metamarty]

Hello,

For a datalogger, I am using offsets 85C and 864 to determine the LAT/LON of the glideslope transmitter to determine the altitude deviation from the glideslope. Some runways like EHRD 06/24 are using one ILS frequency that hosts one localiser and two glideslope transmitters. I figured that FSUIPC would check the course1/course2 setting to determine which of the transmitters would be picked, but it appears that I always get one of two transmitters randomly. This problem seems to happen at a lot of airports.

This is the testing condition:

FSUIPC 4.853 in FSX

Position: 10 NM final EHRD runway 6 (using aerosoft EHRD scenery, but default also shows this problem)

I tune in the ILS frequency of the runway and monitor offset 0x85c and 0x864.

When toggling between active and standby frequency to switch on/off reception of the ILS, the value of the offsets pick either of the two glideslope transmitter locations, but you never know which one you'll get.

Is there any condition that FSUIPC checks, or can I tell it which one to pick?

Thanks,

Marty

[Pete Dowson]

For a datalogger, I am using offsets 85C and 864 to determine the LAT/LON of the glideslope transmitter to determine the altitude deviation from the glideslope. Some runways like EHRD 06/24 are using one ILS frequency that hosts one localiser and two glideslope transmitters. I figured that FSUIPC would check the course1/course2 setting to determine which of the transmitters would be picked, but it appears that I always get one of two transmitters randomly. This problem seems to happen at a lot of airports.

FSUIPC can only use the information provided by FSX. 0858 is from the SimConnect variable "NAV GS LATLONALT:2" and 085C from "NAV GS LATLONALT:1". The locations it provides must surely always be the one you are currently or have most recently been receiving, which is related to your aircraft position not the Course settings -- which aren't relevant to the reception of radio but only the deflection of the needle.

Is there any condition that FSUIPC checks, or can I tell it which one to pick?

You can't pick which one you are (or would be) receiving, FS does that for you. I am sure it is only based on your aircraft's position with respect to the runway orientation and ILS positions. There will obviously be ambiguous positions which are not receiving either very well and may therefore appear rather random.

Regards

Pete

[metamarty]

Thanks for this information. I will investigate further.