"Flarm, no GPS"

I am getting this bitching Betty alarm every so often. It may do it for a minute or so, then goes away, then comes again.

Looking at the Flarm IGC file, there are comment lines that look like this:

LFLA213757GPS 7 45

Which I believe represents GPS status (7 satellites?)

Then I get some that look like this:

LFLA213857GPS 0 0

No satellites? The B field time stamps show a lat and long 4 seconds before and 4 seconds after. In the flight today I got 14 of these and about that many warnings (I didn't count the warnings).

This didn't happen last year, started coincident with the 6.0.2 firmware "upgrade".

Can anyone shed any light on this? Can't find any spec from Flarm that describes it.

On Thursday, July 2, 2015 at 10:12:49 PM UTC-7, jfitch wrote:
I am getting this bitching Betty alarm every so often. It may do it for a minute or so, then goes away, then comes again.

Looking at the Flarm IGC file, there are comment lines that look like this:

LFLA213757GPS 7 45

Which I believe represents GPS status (7 satellites?)

Then I get some that look like this:

LFLA213857GPS 0 0

No satellites? The B field time stamps show a lat and long 4 seconds before and 4 seconds after. In the flight today I got 14 of these and about that many warnings (I didn't count the warnings).

This didn't happen last year, started coincident with the 6.0.2 firmware "upgrade".

Can anyone shed any light on this? Can't find any spec from Flarm that describes it.

I note in looking at IGC logs from prior years (before the 6.0 firmware) that these comment sentences didn't exist. I wonder if someone could look at a post 6.0 firmware IGC log from their PowerFlarm, and see if there are some "LFLAxxxxxxGPS 0 0" entries. Can't tell if this is normal or not.

On Thursday, July 2, 2015 at 10:12:49 PM UTC-7, jfitch wrote:
I am getting this bitching Betty alarm every so often. It may do it for a minute or so, then goes away, then comes again.

Looking at the Flarm IGC file, there are comment lines that look like this:

LFLA213757GPS 7 45

Which I believe represents GPS status (7 satellites?)

Then I get some that look like this:

LFLA213857GPS 0 0

No satellites? The B field time stamps show a lat and long 4 seconds before and 4 seconds after. In the flight today I got 14 of these and about that many warnings (I didn't count the warnings).

This didn't happen last year, started coincident with the 6.0.2 firmware "upgrade".

Can anyone shed any light on this? Can't find any spec from Flarm that describes it.

was there military GPS jamming going on at the time?. I got lots of dropouts and a blackout for 40 minutes near mono lake last week. My backup Oudie GPS also showed dropouts.

Matt

On Friday, July 3, 2015 at 8:00:52 AM UTC-7, Matt Herron Jr. wrote:
On Thursday, July 2, 2015 at 10:12:49 PM UTC-7, jfitch wrote:
I am getting this bitching Betty alarm every so often. It may do it for a minute or so, then goes away, then comes again.

Looking at the Flarm IGC file, there are comment lines that look like this:

LFLA213757GPS 7 45

Which I believe represents GPS status (7 satellites?)

Then I get some that look like this:

LFLA213857GPS 0 0

No satellites? The B field time stamps show a lat and long 4 seconds before and 4 seconds after. In the flight today I got 14 of these and about that many warnings (I didn't count the warnings).

This didn't happen last year, started coincident with the 6.0.2 firmware "upgrade".

Can anyone shed any light on this? Can't find any spec from Flarm that describes it.

was there military GPS jamming going on at the time?. I got lots of dropouts and a blackout for 40 minutes near mono lake last week. My backup Oudie GPS also showed dropouts.

Matt

In the Flarm IGC file there appear to be no skipped Lat Long records around these messages. Time correlating to the Air Av IGC log, at each of the instances there are no missing fixes.

My guess is that it is a Air (Butterfly) vario thing. The Flarm NMEA stream must have changed to introduce some new stuff at the 6.0 change, and the vario is choosing to warn about things that might be better unsaid. But I was trying to get more info on the PowerFlarm first.

I have the same problem. I just turned down the voice volume to 0. A better solution would be nice.
Dale

On Friday, July 3, 2015 at 8:40:05 AM UTC-7, wrote:
I have the same problem. I just turned down the voice volume to 0. A better solution would be nice.
Dale

The GPS rx threshold for these messages seems too low. I've had the same message in the Air vario while using one antenna for three devices. The other devices were perfectly happy.
Incrementally tilting the instrument panel up will provide the message before other devices lose GPS.
Personally wouldn't turn the messages down, no longer use FLARM visual displays.
Jim

Jon,

I flew 3 hours today, and my Butterfly vario was happy with all of the messages from my Flarm (v6.03). My messages typically look like LFLA185213GPS 10 45.

I'm in PA, so maybe there's something to Matt's GPS jamming theory.

-John, Q3

On Friday, July 3, 2015 at 11:26:00 AM UTC-4, jfitch wrote:
In the Flarm IGC file there appear to be no skipped Lat Long records around these messages. Time correlating to the Air Av IGC log, at each of the instances there are no missing fixes.

My guess is that it is a Air (Butterfly) vario thing. The Flarm NMEA stream must have changed to introduce some new stuff at the 6.0 change, and the vario is choosing to warn about things that might be better unsaid. But I was trying to get more info on the PowerFlarm first.

Aaaargh - correction. V6.02, not v6.03. And there were no messages at all of the form LFLAxxxxxxGPS 0 0. For what it's worth, my hardware is v1.1.

-John, Q3

On Friday, July 3, 2015 at 11:18:55 PM UTC-4, John Carlyle wrote:
Jon,

I flew 3 hours today, and my Butterfly vario was happy with all of the messages from my Flarm (v6.03). My messages typically look like LFLA185213GPS 10 45.

I'm in PA, so maybe there's something to Matt's GPS jamming theory.

-John, Q3

On Friday, July 3, 2015 at 9:38:17 AM UTC-7, JS wrote:
On Friday, July 3, 2015 at 8:40:05 AM UTC-7, wrote:
I have the same problem. I just turned down the voice volume to 0. A better solution would be nice.
Dale

The GPS rx threshold for these messages seems too low. I've had the same message in the Air vario while using one antenna for three devices. The other devices were perfectly happy.
Incrementally tilting the instrument panel up will provide the message before other devices lose GPS.
Personally wouldn't turn the messages down, no longer use FLARM visual displays.
Jim

More to this, of more general interest.

I flew today and got some extended periods of "no GPS" warnings. Again the IGC file looks ok, but there are the "GPS 0 0" messages where I was getting the voice warnings. I then overlaid the flight logs from the Flarm and the Triadis logger in Seeyou, and it is obvious that in fact the Flarm does not have a fix, and is merely filling in interpolated fixes after the fact to generate a straight line between the valid ones. This is quite obvious in SeeYou. Looking at yesterday's traces, same thing. Looking at some traces from last year, they overlay exactly. In the SeeYou graph, you can display fix accuracy and see it as well, large intervals of essentially no accuracy.

So something has gone wrong with my Flarm, either the firmware update or winter storage has caused it to be unreliable. If you did not recognize this, you would turn in a file at a contest and get short changed because corners are cut. Or maybe the scoring software would throw it out.

On Friday, July 3, 2015 at 9:38:17 AM UTC-7, JS wrote:
On Friday, July 3, 2015 at 8:40:05 AM UTC-7, wrote:
I have the same problem. I just turned down the voice volume to 0. A better solution would be nice.
Dale

The GPS rx threshold for these messages seems too low. I've had the same message in the Air vario while using one antenna for three devices. The other devices were perfectly happy.
Incrementally tilting the instrument panel up will provide the message before other devices lose GPS.
Personally wouldn't turn the messages down, no longer use FLARM visual displays.
Jim

Dale and Jim, if you overlay the Flarm IGC file on the Air Vario IGC file from the same flight in SeeYou, do you see problems? Or can you email the files to me and I can try it?