GPS signal loss

[YYC650]

I have a Dynon HDX primary display, with a SV-GPS-2020 connected through an Advanced ACM "red box." On several locations I've had a complete loss of GPS signal in areas where there is no reason for a signal loss. I checked the user data log (half second recording intervals) and it would go from 8 or 9 satellites to zero over one record step (half a second). The signal loss typically lasts about 15 seconds, at which point it starts acquiring satellites again. I've checked the connections on the antenna and can't find any issues. This has happened about 4 times over the past 2 years.

Has anyone else experienced this? Any other ideas for troubleshooting? I really don't want this to happen at night or in marginal weather.

 

[jakej]

Same as your other post - Other than a 'box' issue the easiest checks are for an intermittent connection. Are there any butt splices or spade connectors involved ? I'd also spray the connections with contact cleaner.

 

[swatson999]

GPS signal losses can be caused by RF interference, too, either from within your ship, or from nearby facilities radiating at any of a number of frequencies which cause destructive interference with the GPS frequency.

 

[YYC650]

GPS signal losses can be caused by RF interference, too, either from within your ship, or from nearby facilities radiating at any of a number of frequencies which cause destructive interference with the GPS frequency.

That is an interesting idea, though in all the cases of GPS signal loss I was flying in remote areas of Canada where there are no sources that I am aware of that would cause interference - I was distant from major cities, very far from any military installation, etc. If it happens again I will keep that in mind and investigate a potential external cause, and see if any other nearby aircraft had a signal loss.

 

[swatson999]

The first suggestion is probably correct...wiring. But don't ignore potential interference from your own electronics. My SPOT tracker's first test location knocked out all GPS reception every 2.5 minutes, e.g. Other avionics can do the same. Look up the frequencies (about a dozen) that can cause dropouts when receiving or transmitting, as well.