Rate of Climb Via GPS Software?

[Steve McBride]

Are there any software application that provide a rate of climb via GPS? I have a couple that rely on BP sensors, but none that rely on GPS data.

I know there are handheld units for balooning and soaring that use GPS for Rate-of-Climb, but software for us that use real-time GPS telemetry?

Thanks again for helping guys - I know I ask a lot of questions.

Steve

[clolson]

My Garmin Vista shows rate of climb/decent. It uses a compination of pressure altitude slowly corrected/updated over time with a moving average of gps altitude to try to auto correct for atmospheric changes.

That said, you could just compute rate of climb as (current altitude - previous altitude) / time step.

People here are coming from so many directions and backgrounds it's hard to know what is obvious and not obvious, I hope you don't take this formula as an insult. There are plenty of 'obvious' hardware/electronic things that leave me clueless.

[Steve McBride]

I appreciate the response very much. I guess I should have shared some background.

I currently have an airborn GPS module (Lassen IQ) sending NMEA GPS data via wireless serial modem to a ground modem that provides position, moving map, speed, altitude, etc. on a notebook PC. I don't have the skills to create the necessary software to provide the rate of climb user interface that I desire so I am looking for a commercial solution. Several software applications will do this, but only with propriatary telemetry data and not GPS NMEA data. Like you mention, it would be a matter of computing altitude over time to get the rate of climb or descent.

The handheld solutions won't help me in this instance unelss they have available PC software that would work with NMEA GPS data. Do you know if your Garmin Vista has optional software that will show rate of climb?

Thanks so much for the help!

Steve

[clolson]

I have an application here (currently linux based) that will take a saved nmea stream and replay it via FlightGear to produce a nice 3d visualization. FlightGear can overlay instruments so you can see altitude, speed, heading, rate of climb, attitude, etc. It will approximate roll and pitch attitude from the climb rate and rate of turn (crude hack.) Yaw angle is based on ground direction. It will interpolate between data points so you get a nice smooth animation.

It would be a bit of effort (but doable) to port this to windows, and would be possible to run in real time if you can put up with some delays or prediction errors. Standard nmea strings come in once every second (or sometimes once every other second) so there will be quite a delay in the rate of climb output. If I set this up to run in real time, you could see the rate of climb and other data on realistic "steam gauges". There is a variety of ways you can configure FlightGear, so you could do panel only, or also show a synthetic view of your area from the aircraft perspective. Or synthetic view + hud, etc.

I've posted this link before, but scroll down to the Oct 27, 2005 entry to get a better idea of what I'm blabbering about:

http://www.flightgear.org/~curt/Models/Special/Rascal110_2/

Also look at the July 2, 2005 entry here:

http://www.flightgear.org/~curt/Models/Special/Rascal110_1/Flight/

And finally check out Phil Cobbin's page:

http://www.cobbin.com/

Follow the links to the synthetic vision page and look at some of his pictures. He is doing all his work within flightgear with very little additional coding. He's now working on overlaying translucent instruments on top of the synthetic world display. Really cool stuff ...

Curt.

[Steve McBride]

That is some cool stuff there. I'll keep an eye on the progress. FWIW, I don't have a problem running Linux on my notebook ;)

Thanks again for the info.

Steve