Is there something to measure HORIZONTAL distance in realtime/wirelessly?

[oracle_9]

Besides devices measuring altitude, is there something to measure the distance from you and the plane in the horizontal?

[Gary Mortimer]

A simple thing here http://rvosd.rangevideo.com/?page_id=21 would depend how accurate you needed it I guess.

[Peter Seddon]

You can use a GPS to calculate both the ground range and slant range of two sets of co-ordinates.

regards Peter

[Tuner]

You can do this with Time-Of-Flight measurements using radio. However the more accurate the system the more expensive.

One of the difficulties with this technique is when you get multiple reflection of the radio signal arriving at different times.

I know such devices exist however I dont know of any and how big and how expensive.

Good Luck!

[oracle_9]

I was thinking of using the rangevideo visor and an onboard camera in the plane with sensors and all. But the problem is that if you got the visor on, you do not want to travel to far from the transmitter, so if rangevideo has a display showing the distance from you and your plane, then you can return the plan before reaching the other limits of the signal.

[eddymoore]

I would have thought GPS would be the obvious and fairly painless way of doing this. You could quite easily get 4Hz data that was good to, say, <10m. If you need something much more than that, it's going to start getting fairly expensive.

[dmgoedde]

I would have thought GPS would be the obvious and fairly painless way of doing this. You could quite easily get 4Hz data that was good to, say, <10m. If you need something much more than that, it's going to start getting fairly expensive.I agree... could be < $200, here's how: OEM GPS ($100 or less) and simple voltage regulator to make it happy, power it from a battery. Connect serial output of GPS to serial input of wireless modem, perhaps something 10-100mW. Most modems are configured to act as serial cable replacement right out of the box... data into the modem in airplane will appear on the ground modem's serial out. Pass the data into a serial port of your laptop, or via serial-to-USB converter (Parallax Prop Plug works well), and then use GooPs for $15 and Google Earth with area cached for offline use. I do something a bit fancier than this with AttoPilot, however I have done exactly what is described above. I have used the $179 XTend 900 MHz modems, but again, many cheaper modems exist that still give good range, and act as a serial cable replacement right out of the box. Check out www.Sparkfun.com for OEM GPS and modems... they have everything you need.

[eddymoore]

For our high altitude balloons, we get our text telemetry every 10 secs (lat long alt, temps and pressures and other sundries) and that's with a 10mW Tx over 500km away (still have line of sight at balloon altitudes) and the radios cost us about $10. You can do a lot with a little, you just need the appliance of a little science.

[wadiprawita]

Dear eddymoore,

Where can we buy that kind of Tx ?

regards

-doni-

[eddymoore]

wadaprawita:

http://www.radiometrix.co.uk/products/ntx2nrx2.htm

It's not some intelligent transparent link - we actively do line coding and raised cosine pulse shaping and other things on a micro-controller and DAC to feed it. We have a high quality, sensitive receiver on the other end. We had a Yagi antenna at the receiving end when we got to 500km, however we now normally just use whip antennas which are still quite happy 200km away (never tested it practically beyond that).