0
OG-Tahiti

FlySight GPS

Recommended Posts

Quote

just wondering if this thing is waterproof/resistant?
u know we like chasing down those puffies!



It is not waterproof, but I wouldn't be concerned about jumping in clouds and general freefall moisture. If you're coming down from the jump soaking wet, then I'd be worried.

Michael

Share this post


Link to post
Share on other sites
is there any way we might be able to make it waterproof in the future?

just wondering about running some silicone around the housing then putting it back together?

im a florida jumper and have been caught by some fronts before, exited in the rain a few times.

its funny seeing the freefliers with red arms and necks from getting pelted, then you land with your nylon skin without damage and laugh!
Flock University FWC / ZFlock
B.A.S.E. 1580
Aussie BASE 121

Share this post


Link to post
Share on other sites
Quote

is there any way we might be able to make it waterproof in the future?

just wondering about running some silicone around the housing then putting it back together?



It's possible. One of the biggest issues right now is probably the sliding switch. It's got a nice tactile feel, but would be very difficult to waterproof. Otherwise, I think a sufficiently motivated user would have no problem beefing up the water resistance on the current model.

Michael

Share this post


Link to post
Share on other sites
Sweet.

I see the CSV-file is also working now.
But i get confused about the data.
First off: What is velN, velE, velD, hAcc, vAcc, sAcc, gpsFix, numSV?

The velocityreadings say they are in m/s, are you sure its not m/0.2s?
The speeds look very slow for beeing 1 second.

Share this post


Link to post
Share on other sites
Quote

First off: What is velN, velE, velD, hAcc, vAcc, sAcc, gpsFix, numSV?



Ah, yes. The columns are as follows:

time      Time in ISO8601 format

lat Latitude (degrees)
lon Longitude (degrees)
hMSL Height above sea level (m)
velN Velocity north (m/s)
velE Velocity east (m/s)
velD Velocity down (m/s)
hAcc Horizontal accuracy (m)
vAcc Vertical accuracy (m)
sAcc Speed accuracy (m/s)
gpsFix GPS fix type (3 = 3D)
numSV Number of satellites used in fix


Quote

The velocityreadings say they are in m/s, are you sure its not m/0.2s? The speeds look very slow for beeing 1 second.



During the jump, you can see downward speeds of about 30 m/s, which sounds about right. Possibly you were looking at the wrong column?

Michael

Share this post


Link to post
Share on other sites
Ok, thanks.

Yes i was looking in the wrong column :$
So you have split the speeds in three parts, hmm...
So if you want to know your speed in the direction you are flying (if not straight north/east) you have to calculate the speed.

The accuracy columns, lets take one of the rows as an example. It says hMSL 2193.68, and hAcc 1.01.
So does that mean your altitude at that moment could be anywhere between 2194.69 and 2192.67?
Thats cool. I guess the vAcc and sAcc is the same.

This csv-file is that created directly in the GPS or is it something thats created in the computer?
I miss some data in the file, such as hDistance, velH (independent of direction) and Glideratio.

EDIT: noticed a misstake in the calculations, replaced attached file

Share this post


Link to post
Share on other sites
Quote


This csv-file is that created directly in the GPS or is it something thats created in the computer?



The csv files are created in the GPS. When connected by USB it mounts like a memory stick and you can open\copy the files.

Try Paralog http://www.paralog.net/ for calculating everything you can think of from the recorded data.

Share this post


Link to post
Share on other sites
As LukeH indicated, the CSV file is the raw data stored by the FlySight on its internal drive, and isn't really intended for (average) human consumption. To analyze the data, I'd recommend either the FlySight Viewer or Paralog.

However, looking at your spreadsheet... If you want to know your total horizontal speed, the easiest way is to take SQRT(En*En+Fn*Fn). The velocities stored in the file come directly from Doppler calculations in the GPS receiver, and are a great deal more accurate than taking differences in position.

Similarly, if you want to know the horizontal distance traveled, you're likely better off to take the sum of these horizontal speeds, rather than the sum of differences in position.

Your interpretation of the accuracy figures is more or less correct. The only issue is that it's not really a hard bound, but more like a standard deviation.

Michael

Share this post


Link to post
Share on other sites
Intressting.

I tried the pythagorean equation to calculate the speed and it did show a different speed than what i calculated based on the GPS position.

Also calculated the distance based on the speed, and it to showd a slight difference.

I attached a new spreadsheet.


velH The velocity calculated by using the distance between to GPS positions.
velSQRT The velocity calculated by SQRTequation you suggested.
velDiff Difference in % between the calculations

hDistance Distance traveld based on GPS position.
hDistVel Distance based on the speed readings.
hDistDiff Difference in %


I can understand the difference in the begining is bigger due to the number of sattelites, but as you can see i redlined two rows which is very odd.
Its kind of obvious that its the GPS position that has been off and it "bumped" itself in to position, but why and how come we dont see the same in the velocitycalculations.
If we exclude the red lines all other differences are within the sAcc.

But the distance traveld differs more than the hAcc.
Could that be because of the altitude?
The longitude/latitude grid is (as far as i know) on the ground, and when you go up you get a "lower resolution"?
In the calculations i make based on GPS position i take altitude in to the formula, how does the velocitys the GPS gives do?

Sorry if i bother you with this, i just find it odd that there is that much difference.


And i got my FlySight in the mail today :D
Thanks!

I had to save it as xlsx (2007 version) because the file would exceed file size limits in 2003 version

Share this post


Link to post
Share on other sites
Got it. If you look at the time column, it appears that the GPS skips one record in the two rows you've noted, so the time between samples is 0.4 seconds instead of 0.2.

Distance traveled will definitely have a larger error. The individual positions should be within hAcc, but when you integrate, the error in distance traveled will be something like sqrt(n * hAcc), where n is the number of terms which have been integrated to get that distance.

Otherwise, the spreadsheet looks good. Your equation for horizontal distance seems spot on, and I'm happy to see that it agrees reasonably well with integrating the horizontal velocities.

The velocities reported by the FlySight are derived from Doppler shifts. Basically, once the GPS has a lock on the satellite's signal, it keeps track of small time differences that result from Doppler shift (i.e. time shifts in the signal due to your motion relative to the satellite). As it turns out, the GPS can do this very accurately, so Doppler-derived speeds are considerably more accurate (and robust) than those based on difference in position.

Michael

Share this post


Link to post
Share on other sites
Gah! I should have seen that. I have had the same problem with my other GPS logger so i should have looked at that.

You are correct, i didnt think of the hAcc the correct way.

The software for the GPS, will it be avalible for Windows also?

Share this post


Link to post
Share on other sites
I bought one of these and it has arrived; just in time for the 25-way WS diamond event at Sibson this weekend, where I hope to be putting it through its paces! Anybody who is interested in having a look, please ask.
Skydiving Fatalities - Cease not to learn 'til thou cease to live

Share this post


Link to post
Share on other sites
Quote

will it be avalible for Windows also?



I've heard MAC OS can support some Windows applications... is there a similar method for Windows w/MAC apps?

Since the logger creates the CSV file (easily opened in MS office) and the config file is a TXT (easily does your PC even matter?

Does windows recognize the flysight as a drive?
This isn't flying, its falling with style.

Share this post


Link to post
Share on other sites
Quote

Quote

will it be avalible for Windows also?



I've heard MAC OS can support some Windows applications... is there a similar method for Windows w/MAC apps?



Until now, i dont think it has ever been needed or wanted :P


Quote


Since the logger creates the CSV file (easily opened in MS office) and the config file is a TXT (easily does your PC even matter?

Does windows recognize the flysight as a drive?



Yes, you can open it in Excel, but the thing i was looking for was the graphs that the flysight software creates.
Oh well, i can do that in Excel also. B|

Share this post


Link to post
Share on other sites
Quote

Yes, you can open it in Excel, but the thing i was looking for was the graphs that the flysight software creates.
Oh well, i can do that in Excel also.



Yeah. it took me about five minutes to make the same graphs within the excel sheet.
I'm working on a conversion loop from that cvs to a gpx/or a kml track for a google earth track.

I'm $250 poorer now too... ;)
This isn't flying, its falling with style.

Share this post


Link to post
Share on other sites
Quote


I am hoping to put together a similar bit of software for Windows, but unfortunately it's a little ways down the priority list.



Is the file format used by FlySight unique? If not is it available in GPS Babel? If it is unique would you submit it to GPS Babel for inclusion so people can convert to KML and GPX easily?

Share this post


Link to post
Share on other sites
If you clean up the csv file to look like this (universal csv with field structure in the first line) it'll be fine in gpsabel:

lat,lon,alt,speed
53.6322164,-114.1941555,4443.29,33.84814323

ps. I have an old gpsbabel so the flysight csv may be supported fully in a newer version

edit: guess it's not supported... file conversion is super easy though and I'm eager to plot my wingsuit flailing in 5hz google earth glory :)
This isn't flying, its falling with style.

Share this post


Link to post
Share on other sites
Unfortunately, the GPSBabel CSV format seems to omit a few pieces of information which I think are important. In particular, I don't see time or velocity data in there.

Arguably, velocity can be calculated from position data, but this isn't a very accurate way of doing things. FlySight stores velocities derived from Doppler shifts, which results in much more accurate results.

I've submitted a request to the GPSBabel mailing list. Reading through their FAQ, it seems like FlySight's CSV file should be a piece of cake for them to add. I poked around a little thinking I might be able to add it myself, but I think it may be better if a developer more familiar with the project does it.

Michael

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account. It's free!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
0