I’m building a model rocket, and in it I have a custom Arduino powered datalogger. The unit works great, can log onto a micro SD altitude and acceleration data at a fast rate.
Now I wrote a software simulation in python and predicted on D sized motors my model should fly up to 1100ft. Now the chance of losing that is reasonable and I would like a low-weight solution to potentially find this model if it were to go out of sight.
Requirements would be:
Low weight, my data logger with Lipo is 10g so as low as reasonably practicable
Can run from a 1s Lipo and run from a 3.3v Arduino
Fits into a small space, body tube is 40mm internal diameter by 70mm long.
Doesn’t require expensive ground equipment to track it.
Can detect a signal from 200m away. No data transfer is required just signal detection.
Now I was thinking about a small 433MHz Rx and Tx unit, add the Tx unit to the data logger and build an Arduino powered ground unit with a highly directional antenna so I can sweep the antenna around and hopefully find it. But keen to hear other ideas or thoughts.
It shouldn't be too difficult to find it with a good directional antenna given it's only going to be about 1 km away. Have you considered using a low cost gps module because they can be very small and give you a far better accuracy. The additional info they provide could also be useful and logged by your system.
A 434Mhz transmitter that puts out an pseudo FM tone can be received with a low cost Baofeng UHF handheld.
With a directional antenna such as a yagi or with a low tech 'body fade' technique you can get reasonable fix on the remote transmitters.
I guess most of the 434Mhz radio modules that have FSK capability can be used for this, I know the RFM22\Si4432 can and the LoRa modules also.
For real long distance radio direction finding persuading the radio module to send a plain FSK carrier can extend the direction finding capability quite a bit.
The thing is, if your main interest is rocketry then I'd suggest using an off the shelf gps unit rather like a dog tracker and that would probably be a lot cheaper than buying all the various bit's and get you where you want to be quicker.
jaddion82052:
Now I was thinking about a small 433MHz Rx and Tx unit, add the Tx unit to the data logger and build an Arduino powered ground unit with a highly directional antenna so I can sweep the antenna around and hopefully find it.
The receiver end has nothing to do with Arduinox.
srnet:
With a directional antenna such as a yagi or with a low tech 'body fade' technique you can get reasonable fix on the remote transmitters.
Yes on the Yagi but I have found the "low tech 'body fade' technique" painfully tedious, certainly almost useless in competitive hunting.
jaddion82052:
Doesn’t require expensive ground equipment to track it.
Well, the Baofeng certainly is cheap enough, at least pre-Covid.
You might google for animal tracking transmitters. In the past I think I've seen some fairly simple schematics. You will need to take into account how you will be able to detect the signal and its direction. in the amateur radio world you might google fox hunt transmitter and similar.
I do suggest that if you want stupid long distance radio direction finding, then detecting an FSK with a UHF handheld carrier is well worth a go.
Turn of the squelch on a UHF handheld and when it receives the FSK carrier it gets confused and goes quiet. Sweep a directional antenna like a yagi either side of the direction of the transmitter and the noise level rises either side. So you point the antenna for minimum noise. Its heaps easier to get an accurate fix this way versus pointing the antenna for maximum volume on a tone.
srnet:
Sweep a directional antenna like a yagi either side of the direction of the transmitter and the noise level rises either side. So you point the antenna for minimum noise. Its heaps easier to get an accurate fix this way versus pointing the antenna for maximum volume on a tone.
Of course that does not work at all when you get close to the transmitter.
You need a step attenuator (or dual gate pre-amp with gain control on G2) and the radio housed in a tin can!
