On Wednesday 22 Jun 2005 12:27 am IST, Curtis L. Olson wrote:

CL> Kitts wrote:
CL> 
CL> >PIO's?
CL> >  
CL> >
CL> 
CL> Pilot induced oscillations ...

Oh! ok. Yeah this happens all the time when i use the keyboard in the 
simulator! :-)

CL> >CL> I would just run with --fdm=null and pass in the 
CL> >CL> data that you do have.  Optionally you can compute estimates for 
things 
CL> >CL> you don't have just to make the display prettier.
CL> >
CL> >Optionally i can compute? How? Is it not the FDM that does all that 
CL> >computation?
CL> >  
CL> >
CL> 
CL> The thing you have to remember about the FDM's is that they are self 
CL> contained units that maintain their own internal state.  They aren't 
CL> setup to have their internal values overridden by an external source, 
CL> and there are issues and problems doing that.  For instance if you 
CL> estimate some sequence of positions over a second or two, but you were 
CL> hit with a gust and ended up a long ways off from the estimate, now you 
CL> plug those new values into the FDM, it sees a huge distance travelled 
CL> compaired to the estimate in a very short time frame, and might generate 
CL> huge forces that could ripple through the future calculates and throw 
CL> your estimates off even further.
CL> 
CL> You almost need a way to check point the calculations so you can backup 
CL> to the last known good value when your next good data arrives.
CL> 
CL> It's not trivial, there are a ton of pitfalls, and our FDM's aren't 
CL> setup to be able to do that.
CL> 
CL> Having said that, I don't think any of these things are insurmountable, 
CL> and there might even be easy solutions to many of the challenges, but 
CL> you'd have to go dig into the flight model code with a certain level of 
CL> understanding of what you are doing and what you hope to accomplish 
CL> before you are going to have any success with this approach.

Hmmm... Maybe not right away but as a future thing. For the near future ill 
stick to --fdm=NULL :-)

CL> >I have used 3 devices till date to achieve wireless link. I have used 
RF 
CL> >modules from Linx 
CL> 
>(http://www.linxtechnologies.com/index.php?section=products&category=rf_modules&subcategory=es_series),
> 
CL> >BIM1 modules from Radiometrix 
CL> >(http://www.radiometrix.co.uk/products/bim1.htm) and XStream radio 
modems 
CL> >from maxstream 
CL> >(http://www.maxstream.net/products/xstream/module/9xstream.php).
CL> >
CL> >Of the three, the maxstream module is what i currently use as it has 
CL> >provided me with the most reliable link and longest range. I have 
however, 
CL> >had reasonably good success with the BIM1 modules. It however requires 
CL> >robust error checking algorithms for reliable use. These have the 
advantage 
CL> >of being light weight and giving pretty good range.
CL> >  
CL> >
CL> 
CL> Where can I find a price or someone selling the maxstream module?  I'm 
CL> must be missing the link, or do they not sell to individuals?

Price is available on Digikey. Search for Xstream and follow that link <RF 
Transmitters/REceivers>. There are plenty of variants available in 2 
frequencies. Here is one such variant 
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=195594&Row=517830&Site=US

-- 
Cheers!
Kitts


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