Paul,
No sign of your posting on the OGN forum, however a couple of
points occur to me,
The Flarm is probably faulty if the frequency is that unstable, I
have seen units where the frequency offset has been close to
unacceptable, but they don’t normally change much in use, as a
workaround you could ask the owner of the ground station to
increase the bandwidth that they receive on, this has the
downside of higher cpu load and greater noise but will pick up off-
frequency units better (perhaps set the demodulator ScanMargin
to around 20 or 25)
But in the long term you will probably need to get the Flarm unit
checked by the manufacturer as it doesn’t look right to me.
Ben. (U.K. OGN station Aldersht2)


At 01:17 18 August 2018, Glidingstuff wrote:
Thanks for the quick reply Dan.

Have you updated the FLARM to the latest firmware (6.60)?
Yes. Both units are running 6.60
What kind of coax did you use to connect the antennae to the
FLARM and
how long are the runs?
Aviation quality and about three meters
Have you tried a factory reset of the FLARM?
Yes. Its just back from being reset. But they admit they didn't
check the
freq performance.
Does the towplane have a metal tint on the plexiglass
windscreen?
No

I haven't ever seen the frequency offset move that quickly.

We had a FLARM CORE in the club which went for repair and
the transmit
section was replaced; it could only be seen for 100m or so. Now,
range like
all the others (OGN ranges of greater than 40 km).

A great resource is the forum for the OGN; it is at
https://groups.google.com/forum/#!fo...nglidernetwork .
Details on
joining it are at http://wiki.glidernet.org/contact .

Cheers
Dan

I have sent the above data to the OGN people but no reply from
them as yet
either.

Paul