PowerFlarm at Uvalde?

At 21:48 09 August 2011, Luke wrote:
On 08/09/2011 5:42 PM, Eric Greenwell wrote:
On 8/9/2011 1:01 PM, Luke wrote:
On 08/09/2011 12:58 AM, Rob Cluxton wrote:

Where are your GPS antenas located? 30cm away from GPS antennas AND
the
compass is not realistic in most gliders...

How can the compass interfere with the GPS signal?

I'm not sure but here is a quote from the manual:


"The PowerFLARM� and any associated aerials should be located as far
away as possible -- at least 30 cm (1 ft) -- away from any other GPS
aerial and the magnetic compass."

Luke


You guys ARE joking, right??

Cookie

"The PowerFLARM� and any associated aerials should be located as far
away as possible -- at least 30 cm (1 ft) -- away from any other GPS
aerial and the magnetic compass."

Luke


You guys ARE joking, right??

Cookie

No one is joking but it is very disturbing to be told about this
installation constraint after having placed an order and sent in a
payment.

The constraint, if complied with, will make it almost impossible to fit the
unit in a glider equipped for contest flying.


Andy

Andy Durbin wrote:
"The PowerFLARM� and any associated aerials should be located as
far
away as possible -- at least 30 cm (1 ft) -- away from any other GPS

aerial and the magnetic compass."

Luke


You guys ARE joking, right??

Cookie

No one is joking but it is very disturbing to be told about this
installation constraint after having placed an order and sent in a
payment.

The constraint, if complied with, will make it almost impossible to
fit the
unit in a glider equipped for contest flying.


Andy

This should not surprise anybody and I can think of a lot more to be
"highly disturbed" about in life than this. C'mon we really are not
whining about this are we?

You cannot undo the laws of electrodynamics. The compass is going to be
affected by components in the PowerFLARM and by electrical currents.
Cautious advice like this from a vendor is entirely appropriate for a
device that might well get put up on a glareshield near the compass in a
certified (even IFR) aircraft.

Now why is it a worry? How many of us rely on our compasses? To high
accuracy? The manual is just providing a suitable caution and covering
FLARM's ass.

What is actually much more important is the correct installation with
respect to the antennas being free of conductive obstructions/surfaces
as the manual warns. Still I just know we'll stumble across these units
and antennas buried behind panels with owners unsure why they don't work
properly.

Darryl

At 20:18 10 August 2011, Darryl Ramm wrote:
This should not surprise anybody and I can think of a lot more to be
"highly disturbed" about in life than this. C'mon we really are not
whining about this are we?

You cannot undo the laws of electrodynamics. The compass is going to be
affected by components in the PowerFLARM and by electrical currents.
Cautious advice like this from a vendor is entirely appropriate for a
device that might well get put up on a glareshield near the compass in a
certified (even IFR) aircraft.

Now why is it a worry? How many of us rely on our compasses? To high
accuracy? The manual is just providing a suitable caution and covering
FLARM's ass.

What is actually much more important is the correct installation with
respect to the antennas being free of conductive obstructions/surfaces
as the manual warns. Still I just know we'll stumble across these units
and antennas buried behind panels with owners unsure why they don't work
properly.

Darryl


Who said anyone was "highly disturbed"? I didn't.

Can you cite any other GPS based gliding equipment that requires the GPS
antenna to be installed more than 30cm from any other GPS antenna? I don't
give a rat's arse about the compass but I do care that my other GPS
receivers (currently 3 of them behind or on the panel) continue to work and
there are reports from Uvalde of interference to other GPS based equipment.


Sure FLARM is covering their arse. If there are problems of interference
with other equipment the first question will be "Did you meet the antenna
separation requirements?"

Why would anyone buy a piece of equipment knowing that they could not meet
the installation requirements? Why would anyone build equipment with
strict antenna separation requirements and then make the radiating antenna
non removable thus preventing it's relocation?

PowerFLARM has to work with closer antenna separation that 30cm. If it
cannot, it needs a design change. If it can, the user manual needs to be
revised.

Andy

On 8/10/2011 2:41 PM, Andy Durbin wrote:


Can you cite any other GPS based gliding equipment that requires the GPS
antenna to be installed more than 30cm from any other GPS antenna?

I've been told by Cambridge to separate the 302 GPS antenna from other
GPS antennas by "more than a foot" and "as much as possible".

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz

[snip]

Who said anyone was "highly disturbed"? I didn't.

OK you said "very disturbing". I am highly disturbed at all the
melodrama.

Can you cite any other GPS based gliding equipment that requires the
GPS
antenna to be installed more than 30cm from any other GPS antenna?

Classic FLARM product documentation for years has talked about 25cm
separation. So hopefully this type of spec is not a surprise to many
folks who have been interested in FLARM for a while. And there are
thousands and thousands of classic FLARM systems flying and those pilots
have managed to live with 25cm separation specs and the very occasional
need to jigger things around to reduce any interference issues.

The Flarm transmitter is ~1Ghz (~915 MHz in the USA). GPS receivers are
very sensitive and operate on 1.2/1.5 GHz and when you mix these things
together in a close environment there is just always going to be some
chance of interference. And I am not as worried about the engineering of
FLARM products as much as I am that of other systems that might suffer
interference. There are many shoddy/badly designed and installed devices
out there in the wild wild west of glider cockpit avionics.

The need in the USA for a permanently attached FLARM antenna was the
FCC's requirement not something FLARM wanted to do.

give a rat's arse about the compass but I do care that my other GPS
receivers (currently 3 of them behind or on the panel) continue to
work and
there are reports from Uvalde of interference to other GPS based
equipment.

Sure FLARM is covering their arse. If there are problems of
interference
with other equipment the first question will be "Did you meet the
antenna
separation requirements?"

Just install the unit, in the unlikely event you do have interference
issues move the GPS antennas and fix it. FLARM just cannot engineer a
transmitter that is guaranteed not to interfere with any random GPS or
other electronic product out there. And the first response from any
vendor in that type environment (where they have no control over the
engineering and installation of the other boxes) had to be to tell users
to first try separating the antennas.

I expect many pilots may well replace one existing GPS receiver as they
want the FLARM enhanced NMEA data. That obviously does not remove need
for other receivers or backup receivers but if you do happen to end up a
having problems and have three existing GPSAnyhow just install the unit,
in the unlikely chance you do have interference issues move the GPSs
antennas and fix it. FLARM just cannot engineer a transmitter that is
guaranteed not to interfere with any random GPS or other electronic
product out there. And the first response from any vendor in that type
environment (where they have no control over the engineering of the
other boxes) had to be to tell users to first try separating the
antennas.

if you do happen to end up with problems and really have three existing
receivers and a fourth in the FLARM it may be time to clean up/simplify
your avionics!

Why would anyone buy a piece of equipment knowing that they could not
meet
the installation requirements? Why would anyone build equipment with
strict antenna separation requirements and then make the radiating
antenna
non removable thus preventing it's relocation?

PowerFLARM has to work with closer antenna separation that 30cm. If
it
cannot, it needs a design change. If it can, the user manual needs to
be
revised.

The user manual could better explain the reasons these limits are there.


Darryl

On Aug 10, 6:26*pm, Darryl Ramm wrote:

The need in the USA for a permanently attached FLARM antenna was the
FCC's requirement not something FLARM wanted to do.

How did you arrive at that conclusion?

The documentation on file at FCC clearly indicates that the reason the
antenna is locked into position is that the connector type is not FCC
approved. It is my conclusion that FLARM chose this compromise to
avoid the delay of changing to an approved connector.

https://fjallfoss.fcc.gov/eas/GetApp...tml?id=1491689

As Andy points out, perhaps this is one of the reasons for the delay
on the "brick" version. If the "brick" doesn't come with antenna
connectors on the back, there won't be much point. Perhaps a retrofit
of the approved connector can be done on the set-top boxes... We can
hope.

I went with the "brick" as soon as it became a concept, knowing
PowerFLARM is taller than the OzFLARM and how little I like anything
above the glare shield - compass, mirror, top of IPAQ, Plastic Jesus,
etc.

Many people install the OzFLARM or Swiss FLARM in a cutout at the top
of the panel, making the top of the unit flush with or under the glare
shield. An LS-6 I sometimes fly (VH-KYL, in which Brad Edwards won 15m
at Uvalde Worlds 20 years ago) has it under the glare shield.

Any of the Australian competitors at Uvalde will have input on the use
of FLARM, as they have flown many "FLARM mandatory" contests.

Steve, don't let the authorities see the quick disconnnect on the
stick-on antenna. Likely non-approved.
Jim

On 8/12/11 6:46 AM, Andy wrote:
On Aug 10, 6:26 pm, Darryl wrote:

The need in the USA for a permanently attached FLARM antenna was the
FCC's requirement not something FLARM wanted to do.

How did you arrive at that conclusion?

The documentation on file at FCC clearly indicates that the reason the
antenna is locked into position is that the connector type is not FCC
approved. It is my conclusion that FLARM chose this compromise to
avoid the delay of changing to an approved connector.

To be clear (maybe to other readers) it is not an "FCC approved
connector" in that sense like they are using some cheap connector now
and need a technically better one, they require a connector that
prevents the user swapping the antenna for another non-approved one
(i.e. one different than the device passes FCC tests with). Its CFR 47
Sec. 15.203 - that rule exists because of the concern about users
substituting higher gain antennas and exceeding the radiated power and
other specs within the IMS band (in this case). The whole
fixed/removable antenna comes up in other FCC approved/unregulated
consumer devices e.g. with consumer FRS vs. licensed GMRS radios. In
most consumer (e.g. non-licensed user) devices this usually results in
the antenna or cable being permanently attached to the device. Some of
the FCC enforcement/interpretation of this stuff gets a bit head-scratching.

Darryl

On Aug 12, 6:46*am, Andy wrote:

That link to the single document does not seem to work. The following
should allow the complete document set to be viewed.

http://tinyurl.com/3m3mjx8

Andy