Loss of GPS signal

[modelman]

I have noticed using my (old) GPSMAP 195 that it occasionally messages 'poor gps coverage' but seems to recover.I am using a simple passive antenna that I rest on the coaming pointing skywards.
Do more modern units suffer this/any recommendation for antenna etc?
I noticed that the a/c I was flying on Sunday had a BNC socket and cable for a built in antenna but it is really short and on the RH 'A' pillar and my unit only has a MMC socket. ( can you get a 1 metre adaptor cable?)

MM

[jez d]

Yes, adaptor cables are available. Look on Garmin's website under discontinued, portable, aviation GPSs.

jez

[Tall_guy_in_a_152]

Current GPS chipsets such as SIRF III work well with weaker signals than older units, but are dependant on good design of the RF front-end so there is no guarantee.

My two year old Lowrance gets a 3D fix indoors (within reason) or anywhere in the cockpit, but the older Garmin needs to be on the window-sill or coaming.

[znww5]

The answer is to use an active (ie amplified) aerial - the older GPS units tend to be a bit 'deaf' compared with the newer technologies. The GPS 195 has 5 volts available on its aerial socket and this supply powers the amplifier in the antenna.

Have a look for a Garmin GA27 remote aerial on eBay (mine cost about £15), mount it with as good a view of the sky (normally well forward on the 'dash' at the bottom of the screen) and you should lose the 'poor signal' warning!

[Sir George Cayley]

There's a site to do with this sort of thing you might want to look at.

nano - Report navigation anomalies and help make flying safer (http://www.nano.aero) (I think)

Might be worth tuning in?

Sir George Cayley

[modelman]

znww5 wrote:

Have a look for a Garmin GA27 remote aerial on eBay (mine cost about £15)
Thanks for the info,struggling to find one on ebay (or anywhere).There is one of Chinese origin but I would prefer OEM stuff
I have seen advertised GA27C Low profile antenna-is this the same thing?

Thanks for all comments anyway.
MM

[Fuji Abound]

I have 1,000s of hours on my 195 and it is still my backup GPS.

Only once have a lost the signal with the 195 during a period when I was not using an external aerial.

Simply put use an external aerial and you will never have a problem, use an aerial on the combing and you might very occasionally not receive a signal - some aircraft seem more prevalent to this than others.

[Possum3]

I once lost the signal on my 196 because I inadvertantly left my mobile phone on the coming beside it (it was a deep coaming!). Anything similar may affect the signal.

[7AC]

I used to have this problem with a Garmin 90 and a Pilot III.
The problem turned out to be a faulty alternator. I discovered the problem
by accident when the alternator tripped out and the GPS started to work
perfectly.
Just something for you to check out before blaming the receiver.