gps fyi

[bobnoffs]

i have 2 gps antennas under the cowl and i have forgotten which drives which nav radio. i put a square 3/16'' piece of steel plate over one antenna at a time and taxiied around waiting for the signal to drop off. i still dont know which antenna is which as neither radio ever dropped its signal.didnt expect that.

 

[mstrauss]

i have 2 gps antennas under the cowl and i have forgotten which drives which nav radio. i put a square 3/16'' piece of steel plate over one antenna at a time and taxiied around waiting for the signal to drop off. i still dont know which antenna is which as neither radio ever dropped its signal.didnt expect that.

Why don’t you just disconnect one? It’s not like the antenna is used for transmitting. No risk to the unit.

 

[BobTurner]

i have 2 gps antennas under the cowl and i have forgotten which drives which nav radio. i put a square 3/16'' piece of steel plate over one antenna at a time and taxiied around waiting for the signal to drop off. i still dont know which antenna is which as neither radio ever dropped its signal.didnt expect that.

How big is the plate? The wavelength for GPS is about 20 cm (8”) so you’ll get a lot of diffraction around any plate smaller than that. Many gps boxes have a built in satellite strength display. That would give you more quantitative data than ‘it still works’.

 

[bobnoffs]

plates were size of gps antenna, a couple inches square.
to unplug units i would have to go another layer down, into the avionics bay. and once i unplugged it i would have no idea what antenna i was disconnecting.

 

[nitrohog]

We used to watch the GPS status page and cover one with our hands, you can see an almost instantaneous drop in signal strength.

 

[Dugaru]

Aluminum foil, formed over an antenna, worked perfectly to block the signal when I was troubleshooting recently. Mine was leaking a “jamming” frequency however.

 

[bjdecker]

Why don’t you just disconnect one? It’s not like the antenna is used for transmitting. No risk to the unit.

...and if the GPS receiver is worth its salt it will indicate that the antenna is disconnected...