On Wed, 24 Nov 2004 22:54:46 +1030, you wrote:

>
>One from China, Cheng Jing Electronics. Or Imperial Electronics 
>Technology are both on the little info I have. Again my german friend 
>travels the world and attends most of the Asian trade fares, I source 
>all sorts through him. Try and get a hold of Electronice Components 
>Asia. It is a think catalogue style free to trade magazine that has 
>hundreds of suppliers in it. Most Chinese and many Taiwanese companies 
>are more than happy to trade in small export volumes to try and 
>establish a market presence.
>
>Al

Thanks for that Al. I'm going to build an ultrasonic windspeed sensor
for use particularly with slope soaring RC sailplanes. This should be
a much cheaper and sturdier version than the units that have small
fans inside a housing.

Hi,

> Thanks for that Al. I'm going to build an
ultrasonic windspeed sensor
> for use particularly with slope soaring RC sailplanes. This should be
> a much cheaper and sturdier version than the units that have small
> fans inside a housing.

and what about rain, snow etc.?
Do you shield the sensor or shut of during rain/snow?

And wouldn't be a heatwire + temperature sensor cheaper?

Rolf

Some years ago I had a friend who was quite well renowned in the 
competition soaring world. I proposed to him an electronic system that 
sought out thermals and autoguided the plane towards them. Apparently 
illegal in competition.

Al

dmm wrote:
> On Wed, 24 Nov 2004 22:54:46 +1030, you wrote:
> 
> 
>>One from China, Cheng Jing Electronics. Or Imperial Electronics 
>>Technology are both on the little info I have. Again my german friend 
>>travels the world and attends most of the Asian trade fares, I source 
>>all sorts through him. Try and get a hold of Electronice Components 
>>Asia. It is a think catalogue style free to trade magazine that has 
>>hundreds of suppliers in it. Most Chinese and many Taiwanese companies 
>>are more than happy to trade in small export volumes to try and 
>>establish a market presence.
>>
>>Al
> 
> 
> Thanks for that Al. I'm going to build an ultrasonic windspeed sensor
> for use particularly with slope soaring RC sailplanes. This should be
> a much cheaper and sturdier version than the units that have small
> fans inside a housing.
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 

The heated wire method is not  robust enough for my use, which is 
another reason the mini fan system was scrapped. Ultrasonics have no 
moving parts, no parts that can be readily damaged. Rain can be 
compensated for, and snow can be blown away. This is a very tiny thing 
with one very specific purpose. I doubt that Dave will be flying his 
sailplanes in rain or snow either. In my case the sensor only activates 
for the very short periods it might be needed, perhaps a few minutes 
every day.

Al

rolf.freitag@rolf... wrote:

> Hi,
> 
> 
>>Thanks for that Al. I'm going to build an ultrasonic windspeed
sensor
>>for use particularly with slope soaring RC sailplanes. This should be
>>a much cheaper and sturdier version than the units that have small
>>fans inside a housing.
> 
> 
> and what about rain, snow etc.?
> Do you shield the sensor or shut of during rain/snow?
> 
> And wouldn't be a heatwire + temperature sensor cheaper?
> 
> Rolf
> 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 

At 09:35 AM 25/11/2004, you wrote:

Al,

Have you done any work on measuring velocity in air and water (birds and 
animals)?

Thanks


Peter

>The heated wire method is not  robust enough for my
use, which is
>another reason the mini fan system was scrapped. Ultrasonics have no
>moving parts, no parts that can be readily damaged. Rain can be
>compensated for, and snow can be blown away. This is a very tiny thing
>with one very specific purpose. I doubt that Dave will be flying his
>sailplanes in rain or snow either. In my case the sensor only activates
>for the very short periods it might be needed, perhaps a few minutes
>every day.
>
>Al
>
>rolf.freitag@rolf... wrote:
>
> > Hi,
> >
> >
> >>Thanks for that Al. I'm going to build an ultrasonic windspeed
sensor
> >>for use particularly with slope soaring RC sailplanes. This should
be
> >>a much cheaper and sturdier version than the units that have small
> >>fans inside a housing.
> >
> >
> > and what about rain, snow etc.?
> > Do you shield the sensor or shut of during rain/snow?
> >
> > And wouldn't be a heatwire + temperature sensor cheaper?
> >
> > Rolf
> >
> >
> >
> >
> >
> > .
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>.
>
>
>Yahoo! Groups Links
>
>
>
>

On Wed, 24 Nov 2004 20:49:48 +0100, you wrote:

Hi Rolf
>
>Hi,
>
>> Thanks for that Al. I'm going to build an ultrasonic windspeed
sensor
>> for use particularly with slope soaring RC sailplanes. This should be
>> a much cheaper and sturdier version than the units that have small
>> fans inside a housing.
>
>and what about rain, snow etc.?

I don't fly in areas that have snow, but do fly mostly near the coast. 
And as for rain, well I'd rather be building during that time, but
I've got a 
few electronics designs in progress at the moment, the hand-held windspeed
sensor is just one of them.

>Do you shield the sensor or shut of during
rain/snow?

No, it won't be necessary. My idea is to have a portable and robust unit 
that would be cheap and I could throw in my toolbox. Its not going to be
stand-alone in a field, or on a slope. Although that could be for another
application. A solid state weather station that could be connected to the
internet via a GSM/GPRS modem, together with camera that could show
the conditions, aircraft and personnel on-site.

>And wouldn't be a heatwire + temperature
sensor cheaper?

A heatwire requires power, and since I want this to be battery powered
and want them to last as long as possible, heatwire is out.

>Rolf

Regards
David

At 10.21 25/11/2004, you wrote:
>A heatwire requires power, and since I want this to
be battery powered
>and want them to last as long as possible, heatwire is out.

Uhmm I did design both an ultrasonic windspeed sensor and a heatwire one.
The heatwire actually was less power consuming than the ultrasonic.
That depends mainly on the actual choice of transducers. So it may be 
different for you.
Sorry if I misunderstood something, however. I could not follow the 
complete thread.
regards
A_M 

In air only, as part of a small UAV project. Rather than a pitot tube I 
used INS. Actually my basic system uses a pair of INS systems each with 
different sensor types. In this way I have two sources for orientation 
for example, each with different error characteristics. The project 
started from two sources, one of these was trackign a small sailing 
boat. The rough seas, and low velocities make it very difficult to track 
without the addition of GPS. At that time GPS was too large and 
expensive to be viable.

I certainly see no reason not to use INS underwater. There may be a drop 
in accuracy WRT air, but, short of the gradiometric systems used by 
nuclear subs  it would be hard to find a better way I suspect. And, 
certainly, earlier subs ran on heading, speed, time, current calculations.

Al

Peter Grey wrote:
> At 09:35 AM 25/11/2004, you wrote:
> 
> Al,
> 
> Have you done any work on measuring velocity in air and water (birds and 
> animals)?
> 
> Thanks
> 
> 
> Peter
> 
> 
>>The heated wire method is not  robust enough for my use, which is
>>another reason the mini fan system was scrapped. Ultrasonics have no
>>moving parts, no parts that can be readily damaged. Rain can be
>>compensated for, and snow can be blown away. This is a very tiny thing
>>with one very specific purpose. I doubt that Dave will be flying his
>>sailplanes in rain or snow either. In my case the sensor only activates
>>for the very short periods it might be needed, perhaps a few minutes
>>every day.
>>
>>Al
>>
>>rolf.freitag@rolf... wrote:
>>
>>
>>>Hi,
>>>
>>>
>>>
>>>>Thanks for that Al. I'm going to build an ultrasonic
windspeed sensor
>>>>for use particularly with slope soaring RC sailplanes. This
should be
>>>>a much cheaper and sturdier version than the units that have
small
>>>>fans inside a housing.
>>>
>>>
>>>and what about rain, snow etc.?
>>>Do you shield the sensor or shut of during rain/snow?
>>>
>>>And wouldn't be a heatwire + temperature sensor cheaper?
>>>
>>>Rolf
>>>
>>>
>>>
>>>
>>>
>>>.
>>>
>>>
>>>Yahoo! Groups Links
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>.
>>
>>
>>Yahoo! Groups Links
>>
>>
>>
>>
> 
> 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 

At 10:14 PM 25/11/2004, you wrote:

Thanks Al,

I believe you have selected my Christmas reading subject - INS.

Peter

>In air only, as part of a small UAV project. Rather
than a pitot tube I
>used INS. Actually my basic system uses a pair of INS systems each with
>different sensor types. In this way I have two sources for orientation
>for example, each with different error characteristics. The project
>started from two sources, one of these was trackign a small sailing
>boat. The rough seas, and low velocities make it very difficult to track
>without the addition of GPS. At that time GPS was too large and
>expensive to be viable.
>
>I certainly see no reason not to use INS underwater. There may be a drop
>in accuracy WRT air, but, short of the gradiometric systems used by
>nuclear subs  it would be hard to find a better way I suspect. And,
>certainly, earlier subs ran on heading, speed, time, current calculations.
>
>Al
>
>Peter Grey wrote:
> > At 09:35 AM 25/11/2004, you wrote:
> >
> > Al,
> >
> > Have you done any work on measuring velocity in air and water (birds
and
> > animals)?
> >
> > Thanks
> >
> >
> > Peter
> >
> >
> >>The heated wire method is not  robust enough for my use, which is
> >>another reason the mini fan system was scrapped. Ultrasonics have
no
> >>moving parts, no parts that can be readily damaged. Rain can be
> >>compensated for, and snow can be blown away. This is a very tiny
thing
> >>with one very specific purpose. I doubt that Dave will be flying
his
> >>sailplanes in rain or snow either. In my case the sensor only
activates
> >>for the very short periods it might be needed, perhaps a few
minutes
> >>every day.
> >>
> >>Al
> >>
> >>rolf.freitag@rolf... wrote:
> >>
> >>
> >>>Hi,
> >>>
> >>>
> >>>
> >>>>Thanks for that Al. I'm going to build an ultrasonic
windspeed sensor
> >>>>for use particularly with slope soaring RC sailplanes. This
should be
> >>>>a much cheaper and sturdier version than the units that
have small
> >>>>fans inside a housing.
> >>>
> >>>
> >>>and what about rain, snow etc.?
> >>>Do you shield the sensor or shut of during rain/snow?
> >>>
> >>>And wouldn't be a heatwire + temperature sensor cheaper?
> >>>
> >>>Rolf
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>.
> >>>
> >>>
> >>>Yahoo! Groups Links
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >>
> >>
> >>.
> >>
> >>
> >>Yahoo! Groups Links
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
> > .
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>.
>
>
>Yahoo! Groups Links
>
>
>
>

At 11:01 AM 26-12-04, you wrote:

Thanks Al, A good simple answer even I can understand!

Peter

>The basics of INS are simple. You start at point X.
You measure
>orientation in 3D, using FGM's or gyro's. You measure acceleration
with
>accelerometers in 3D, you obviously must know the calibration factors
>for all sensors. Having taken the acceleration readings you must
>normalise them against the calibration data. You do the same with the
>orientation sensors. Once you know the 3 orientation vectors (assuming
>you have DC accelerometers) you can compensate the g readings against
>that axis orientaion, having first compensated for any axial
>misalignments of and between the two sensors. This will yield an
>absolute +/-g vector, the integral of this is velocity, the integral of
>that is distance. Repeat this and accumulate the results. Reading to
>reading is very precise, error becomes huge over time, so needs
>periodically correcting.
>
>By using two separate INS systems you reduce the rate of error
>accumulation, and improve the overall accuracy.
>
>That's really it for the basics. You can readily determine your
location
>relative to point X, then relative to each subsequent reecorrection
>point. Bear in mind that you must account for the existing velocity and
>angles after each correction.
>
>There are quite a few extra things I employ to improve the precision of
>my own systems, but they are my bread and butter, so I hope the little
>I've written is of use.
>
>Al
>
>Peter Grey wrote:
>
> > At 10:14 PM 25/11/2004, you wrote:
> >
> > Thanks Al,
> >
> > I believe you have selected my Christmas reading subject - INS.
> >
> > Peter
> >
> >
> >>In air only, as part of a small UAV project. Rather than a pitot
tube I
> >>used INS. Actually my basic system uses a pair of INS systems each
with
> >>different sensor types. In this way I have two sources for
orientation
> >>for example, each with different error characteristics. The project
> >>started from two sources, one of these was trackign a small sailing
> >>boat. The rough seas, and low velocities make it very difficult to
track
> >>without the addition of GPS. At that time GPS was too large and
> >>expensive to be viable.
> >>
> >>I certainly see no reason not to use INS underwater. There may be a
drop
> >>in accuracy WRT air, but, short of the gradiometric systems used by
> >>nuclear subs  it would be hard to find a better way I suspect. And,
> >>certainly, earlier subs ran on heading, speed, time, current
calculations.
> >>
> >>Al
> >>
> >>Peter Grey wrote:
> >>
> >>>At 09:35 AM 25/11/2004, you wrote:
> >>>
> >>>Al,
> >>>
> >>>Have you done any work on measuring velocity in air and water
(birds and
> >>>animals)?
> >>>
> >>>Thanks
> >>>
> >>>
> >>>Peter
> >>>
> >>>
> >>>
> >>>>The heated wire method is not  robust enough for my use,
which is
> >>>>another reason the mini fan system was scrapped.
Ultrasonics have no
> >>>>moving parts, no parts that can be readily damaged. Rain
can be
> >>>>compensated for, and snow can be blown away. This is a very
tiny thing
> >>>>with one very specific purpose. I doubt that Dave will be
flying his
> >>>>sailplanes in rain or snow either. In my case the sensor
only activates
> >>>>for the very short periods it might be needed, perhaps a
few minutes
> >>>>every day.
> >>>>
> >>>>Al
> >>>>
> >>>>rolf.freitag@rolf... wrote:
> >>>>
> >>>>
> >>>>
> >>>>>Hi,
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>>Thanks for that Al. I'm going to build an
ultrasonic windspeed sensor
> >>>>>>for use particularly with slope soaring RC
sailplanes. This should be
> >>>>>>a much cheaper and sturdier version than the units
that have small
> >>>>>>fans inside a housing.
> >>>>>
> >>>>>
> >>>>>and what about rain, snow etc.?
> >>>>>Do you shield the sensor or shut of during rain/snow?
> >>>>>
> >>>>>And wouldn't be a heatwire + temperature sensor
cheaper?
> >>>>>
> >>>>>Rolf
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>.
> >>>>>
> >>>>>
> >>>>>Yahoo! Groups Links
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>.
> >>>>
> >>>>
> >>>>Yahoo! Groups Links
> >>>>
> >>>>
> >>>>
> >>>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>.
> >>>
> >>>
> >>>Yahoo! Groups Links
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >>
> >>
> >>.
> >>
> >>
> >>Yahoo! Groups Links
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
> > .
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>.
>
>
>Yahoo! Groups Links
>
>
>
>