Homemade On board telemetry System

[Barry_Cole]

Or you could just but a Taranis, and make life easy....

Sorry, but I had to say it.



BC

[jimbo]

[quote="Barry_Cole"]Or you could just but a Taranis, and make life easy....

Sorry, but I had to say it.



BC[/quote]
I was wondering when the taranis quote would appear !

Anyway, ive done nothing as i think i blew up an arduino with my voltage divider, when i connect to a lipo rather that the USB, i get 6.5V across the 5V pin, currently ive ordered a replacement nano and waiting for the slow boat from china to bring it.
I can still test it on board but my reference voltage is no longer 5V it varies with the state of the lipo (which means my read voltage is screwy), but ive not had the inclination anyway in the cold north and easterly winds.

[jimbo]

[quote="Peter Balcombe"]
Note that a 1/4 wave aerial length for 433MHz is 173mm, so this needs to be kept straight in the fuselage.[/quote]
I tried it before an aerial was added and after the correct aerial was added - the range went from 2ft, to in the order of 50m (along the ground outside). Im hoping to an overhead object range will be improved further.

[Peter Balcombe]

Jimbo,
You will get best performance if the antenna wire is at 90 degrees to the board ground plane, thus the wire should be sticking straight out of the board connection pad hole. Also, as for our normal TX antenna, the maximum signal strength will be at 90 degrees to the axis of the wire/antenna rod as it radiates out in a doughnut pattern around the antenna axis.
(Think of a ring doughnut slid over the antenna & the radiation pattern being similar to the shape of the doughnut - highest where the doughnut is thickest!!)
This is why 2.4GHz aerials should always be cranked at 90 degrees - to give maximum radiation in the likely direction of the model.
If you now get 50m range with direct line of sight signal path (no walls/physical obstructions in the way) then I wouldn't expect too much more in the air.
Remember that the 433MHz units you are using are quite low Tx output power & Rx sensitivity and intended for the sort of range you are now achieving. This is why I mentioned higher power/sensitivity alternatives earlier.

Using a telemetry equipped radio may not be that expensive an option at the end of the day as you should at least get a proven setup with off the shelf sensors etc. However, there is always the challenge of brewing your own

[Barry_Cole]

Using a telemetry equipped radio may not be that expensive an option at the end of the day as you should at least get a proven setup with off the shelf sensors etc. However, there is always the challenge of brewing your own

See post below....

Sorry Jim.



BC

[jimbo]

Barry, Why would I want to change my radio when I am completely happy with the one I have at he moment, I have many receivers, i will save 400 quid if I don't replace(tx plus enough receivers) and as I have detailed above I can make my own for a few quid!

[Barry_Cole]

It worked for me...



BC

[jimbo]

Test bed will be swift S1. Its gonna fly nose heavy, but i have it set up with rearward CG anyway so, should be OK.
New Uno fixed the problem with the voltage divider, now reading bang on.

[Peter Balcombe]

Good luck Jimbo,
It will be interesting to see what airborne range you get.
Peter

[jimbo]

Hi peter, I'll be estimating the range as its simply battery voltage, no altimeter. I should be able to get a rough approximation based on model size, tbh large models at Aggies spec out at 800ft max, wont go higher in the slope lift, itll be fact finding mission to see if with the current radio set it will be usable. The general idea is to get to a decent altitude and see it we still receive. Model is about 2,8m span so I think if I spec that it'd be 400ft. Starting looking about for a GPS, for speed and altitude measurements.