XCSoar wind calculation

[Martin Gregorie[_5_]]

BTW, on Friday I was flying with LK8000a9 and noticed that while I was
thermaling the wind was being reported as 4 kts @ 260-270, but after I'd
been in cruise for a while it had switched to 11 kts @ 350. This switch
was consistent through the flight. The IGC trace shows that the
thermaling wind parameters were correct, so no surprise there.

Has anybody else seen this happening and, if so, which version were you
running? I'm curious to know whether its LK8000 specific or if it affects
the main branch code (5.2.3 / 5.2.4) as well.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[PCool]

Martin,
there were no changes for wind calculations in the code, and
normally we found the wind calculation in xcsoar to be very accurate while
thermalling...but only if we have a good and correct position reporting from
gps. It has come to my attention the fact that there is an important problem
with the 31X gps (made for car navigation, and not for air navigation).
I am trying to fix it adjusting internal parameters in the Sirf-Titan
chipset, but it's not trivial.
Since the problem does not appear in straight flight, I'm going to add wind
calculation for straight flying which should solve the problem once forever.
Otherwise, check your gps antenna if you are not using a 31X.

paolo


"Martin Gregorie" > ha scritto nel messaggio
...
> BTW, on Friday I was flying with LK8000a9 and noticed that while I was
> thermaling the wind was being reported as 4 kts @ 260-270, but after I'd
> been in cruise for a while it had switched to 11 kts @ 350. This switch
> was consistent through the flight. The IGC trace shows that the
> thermaling wind parameters were correct, so no surprise there.
>
> Has anybody else seen this happening and, if so, which version were you
> running? I'm curious to know whether its LK8000 specific or if it affects
> the main branch code (5.2.3 / 5.2.4) as well.
>
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |

[Martin Gregorie[_5_]]

On Sun, 27 Sep 2009 14:52:10 +0000, PCool wrote:

Hi Paolo,

> There were no changes for wind calculations in the code, and
> normally we found the wind calculation in xcsoar to be very accurate
> while thermalling...but only if we have a good and correct position
> reporting from gps.
>
Thanks for confirmation that there are no forks in the wind calculation
code.

I wouldn't expect wind calculations in cruise to be as good as my C4
since it has TAS to work with (pitot+static and an internal altimeter,
hence TAS), but I was somewhat disturbed by the 90 degree wind direction
switching and the accompanying 50% variation in reported wind speed.

> Otherwise, check your gps antenna if you are not using a 31X.
>
It seems OK - I've never had GPS drop-outs in flight though most (all?)
XCSoar log files have at least one irregular log interval reported by
EWView when I'm reviewing the flight.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Adam]

On Sep 27, 9:52*am, "PCool" > wrote:
> Martin,
> * * * * * * *there were no changes for wind calculations in the code, and
> normally we found the wind calculation in xcsoar to be very accurate while
> thermalling...but only if we have a good and correct position reporting from
> gps. It has come to my attention the fact that there is an important problem
> with the 31X gps (made for car navigation, and not for air navigation).
> I am trying to fix it adjusting internal parameters in the Sirf-Titan
> chipset, but it's not trivial.
> Since the problem does not appear in straight flight, I'm going to add wind
> calculation for straight flying which should solve the problem once forever.
> Otherwise, check your gps antenna if you are not using a 31X.
>
> paolo
>
> "Martin Gregorie" > ha scritto nel .. .
>
> > BTW, on Friday I was flying with LK8000a9 and noticed that while I was
> > thermaling the wind was being reported as 4 kts @ 260-270, but after I'd
> > been in cruise for a while it had switched to 11 kts @ 350. This switch
> > was consistent through the flight. The IGC trace shows that the
> > thermaling wind parameters were correct, so no surprise there.
>
> > Has anybody else seen this happening and, if so, which version were you
> > running? I'm curious to know whether its LK8000 specific or if it affects
> > the main branch code (5.2.3 / 5.2.4) as well.
>
> > --
> > martin@ * | Martin Gregorie
> > gregorie. | Essex, UK
> > org * * * |

Can anyone explain why my wind calculation always reads "0". I can set
it manually but cannot seem to get the autocalc to work. My old setup
on another PDA worked fine.

Thanks in advance!
Adam

[Uncle Fuzzy]

On Sep 30, 7:28*pm, Adam > wrote:
> On Sep 27, 9:52*am, "PCool" > wrote:
>
>
>
>
>
> > Martin,
> > * * * * * * *there were no changes for wind calculations in the code, and
> > normally we found the wind calculation in xcsoar to be very accurate while
> > thermalling...but only if we have a good and correct position reporting from
> > gps. It has come to my attention the fact that there is an important problem
> > with the 31X gps (made for car navigation, and not for air navigation).
> > I am trying to fix it adjusting internal parameters in the Sirf-Titan
> > chipset, but it's not trivial.
> > Since the problem does not appear in straight flight, I'm going to add wind
> > calculation for straight flying which should solve the problem once forever.
> > Otherwise, check your gps antenna if you are not using a 31X.
>
> > paolo
>
> > "Martin Gregorie" > ha scritto nel .. .
>
> > > BTW, on Friday I was flying with LK8000a9 and noticed that while I was
> > > thermaling the wind was being reported as 4 kts @ 260-270, but after I'd
> > > been in cruise for a while it had switched to 11 kts @ 350. This switch
> > > was consistent through the flight. The IGC trace shows that the
> > > thermaling wind parameters were correct, so no surprise there.
>
> > > Has anybody else seen this happening and, if so, which version were you
> > > running? I'm curious to know whether its LK8000 specific or if it affects
> > > the main branch code (5.2.3 / 5.2.4) as well.
>
> > > --
> > > martin@ * | Martin Gregorie
> > > gregorie. | Essex, UK
> > > org * * * |
>
> Can anyone explain why my wind calculation always reads "0". I can set
> it manually but cannot seem to get the autocalc to work. My old setup
> on another PDA worked fine.
>
> Thanks in advance!
> Adam- Hide quoted text -
>
> - Show quoted text -

From "config" to "setup system" go to page 5 "Glide Computer". The
Auto Wind is probably set to 'manual'. I use 'Both' (zigzag and
circling) but anything other than 'manual' will make it change
automatically.

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Abigel Edward

[Abigel Edward]

Dear Sir.

How are you sir hope everything is moving well.
My name is Abigel Edward i am 19 years old from ivory coast west
Africa,Sir i am requesting for your assistance for an investiment in your
country which i will want my money to be transferd to your account for an
investment pupose, if you are willng to assist me and my brother to come
over to you after the money most have been to your account i will be very
very greaful and will uplift you more and more.we are orphans and we
don't know what to do with this money which our late father left before
he died that is why we need your advice and to gueide us so that our
$7.5million dollars will not lost in a wroung hand.I will be waiting for
your Urgent respons.

This is my private email contact me here for an easy commucations



Thanks and God bless you.

Sincerly
Abigel Edward

[Martin Gregorie[_5_]]

On Sun, 27 Sep 2009 22:16:51 +0000, Martin Gregorie wrote:

Following myself up: it turns out I'd left wind calculations configured
as 'Both' in a PNA, which lacks ASI connections or a compass. Dave Salmon
gave me the pointer to figuring this out. I've now changed the wind
calculation setting to 'circling' but have yet to fly with the new
configuration. I was surprised (but probably should not have been) that
the PNA default is 'Both'.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Martin Gregorie[_5_]]

On Thu, 01 Oct 2009 04:30:12 -0700, Uncle Fuzzy wrote:

>
> From "config" to "setup system" go to page 5 "Glide Computer". The Auto
> Wind is probably set to 'manual'. I use 'Both' (zigzag and circling)
> but anything other than 'manual' will make it change automatically.
>
It defaulted to 'both', which is odd since its a vanilla PNA and the
zigzag calculation is described as needing ASI input. I've changed it to
'Circling' but not flown with it since then.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[PCool]

PNA version behaves exactly ad PDA version concerning the wind, and also
concerning the configuration of wind.
I guess it hasn't been touched since years.
The fact that wind is not calculated means that either you are not
thermalling with a constant bank angle, or that there is a very strong wind,
or - most probably - that your gps is not passing correct positions to the
software due to an antenna problem (weak signal reception, sufficient with
no banking, but not sufficient while thermalling with high bank angles).
Hp310-314 has this problem for instance.
Having "both" will not make any difference since if there is no ASI input
the zigzag is not calculated, and in any case zigzag and circling are "both"
used in case you select "both" (of course!).

Our investigations on this matter showed that using an external SirfIII
bluetooth antenna made the problem of "no wind" disappear.
We still have to understand if that's because of the position of the
antenna, or the quality of the chipset inside the gps receiver.
In either case, that was not a software problem.

If you use some other software, you may have a wind calculation no matter if
data from gps is wrong. Of course this calculation IS wrong.
The difference in this case is the fact that xcs has a quite good filtering
algorithm that will not parse spurious data.

Paolo




"Martin Gregorie" > ha scritto nel messaggio
...
> On Thu, 01 Oct 2009 04:30:12 -0700, Uncle Fuzzy wrote:
>
>>
>> From "config" to "setup system" go to page 5 "Glide Computer". The Auto
>> Wind is probably set to 'manual'. I use 'Both' (zigzag and circling)
>> but anything other than 'manual' will make it change automatically.
>>
> It defaulted to 'both', which is odd since its a vanilla PNA and the
> zigzag calculation is described as needing ASI input. I've changed it to
> 'Circling' but not flown with it since then.
>
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |

[Martin Gregorie[_5_]]

On Thu, 01 Oct 2009 14:20:57 +0000, PCool wrote:

> The fact that wind is not calculated means that either you are not
> thermalling with a constant bank angle, or that there is a very strong
> wind, or - most probably - that your gps is not passing correct
> positions to the software due to an antenna problem (weak signal
> reception, sufficient with no banking, but not sufficient while
> thermalling with high bank angles). Hp310-314 has this problem
> for instance.

Not quite!

The help screen (once I read it) says in no uncertain terms that zigzag
wind calculation doesn't work if the only input is GPS.

My PNA was certainly not producing sensible cruise calculated wind and,
as it has a GPS as its only sensor, 'Both' must be incorrect since it
uses 'Circle' while climbing and 'zigzag' in cruise. So, I've set the
wind calculation to 'Circle' like the help page suggested.

I'll report back once I've flown in 'Circle' mode. Should have been
today, but a balky online bank and a misread forecast put paid to that.
Rats!


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Adam]

On Oct 1, 7:38*pm, Martin Gregorie >
wrote:
> On Thu, 01 Oct 2009 14:20:57 +0000, PCool wrote:
> > The fact that wind is not calculated means that either you are not
> > thermalling with a constant bank angle, or that there is a very strong
> > wind, or - most probably - that your gps is not passing correct
> > positions to the software due to an antenna problem (weak signal
> > reception, sufficient with no banking, but not sufficient while
> > thermalling with high bank angles). Hp310-314 has this problem
> > for instance.
>
> Not quite!
>
> The help screen (once I read it) says in no uncertain terms that zigzag
> wind calculation doesn't work if the only input is GPS.
>
> My PNA was certainly not producing sensible cruise calculated wind and,
> as it has a GPS as its only sensor, 'Both' must be incorrect since it
> uses 'Circle' while climbing and 'zigzag' in cruise. So, I've set the
> wind calculation to 'Circle' like the help page suggested.
>
> I'll report back once I've flown in 'Circle' mode. Should have been
> today, but a balky online bank and a misread forecast put paid to that.
> Rats!
>
> --
> martin@ * | Martin Gregorie
> gregorie. | Essex, UK
> org * * * |

Mine is and has always been set to "circling". In the same plane it
all worked great on another PDA with the same settings. I will try to
reposition the GPS dongle next time out but note that when I examine
my flights in See You, the GPS appears to work fine with no brownouts/
missing data points. FWIW, the logger time steps are set to 5 seconds
cruise, 1 second thermalling.

/Adam