459MHz UHF legal Tx and Rx - Arduino based programability.

Miles · July 19, 2011, 08:56:19 AM

Quote from: Devonian on July 14, 2011, 12:13:42 AM
@ Badwolve1
60 miles on 100 mW is going to be difficult I can assure you, aside from the fact that an FPV spotter would be visually disadvantaged!
I'm also a radio amateur and at 433MHz (70cm band) I'd be struggling to make reliable contact with under 3 watts and would probably turn the wick up to my legally allowed limit of 400 watts :D
That's another good reason to get away from the 433MHz band for model control as you never know who'll be pointing their flame thrower in your direction.

Nigel.

I know a friend of mine is working with the MOD to produce long-range drones. I don't know what frequency he is using, based on the RX equipment he has, I think he is on 400MHZ and can maintain RC manual control 50KM away, and can continue flying on an auto pilot for 100KM before refuelling. He has also got licenses that mean he doesn't need a spotter ETC from the MOD, but he only tests them on MOD sites anyway. If there is anything you want me to talk to him about for you, please say and I will be happy to help :)
Thanks
BW

thundead · July 19, 2011, 12:15:15 PM

Hi Nigel,
I've been watching the progress of this proj for a while and would like to give a hand since I also want a sollution to our 459mhz limitation.

I've got decent skills in arduino programming (messing with my mega board all the time) and want to order myself an open lrs system to play with.

the only thing I can't figure out is how to connect the openlrs to my pc. my arduino mega simply hooks via usb.

do I need to get a special programmer and if u could point me in the right direction.

Cheers,
Mihai

Devonian · July 19, 2011, 02:06:20 PM

Hi Mihai,

Welcome and great first post!

I use a 'normal' FTDI USB interface for programming, the same that is used for lots of Arduino projects.
http://www.skpang.co.uk/catalog/ftdi-basic-breakout-5v-p-442.html

I made an interface cable to suit the OpenLRS Tx and the Rx (as the pinouts are different on both boards at present!).
They are simple enough as it's just 3 wires -- Tx, Rx & Gnd.

I cut a small slot in the Tx casing to easily connect my programming lead whilst it's still plugged in the back of my Futaba T9.

Nigel.

thundead · July 19, 2011, 02:16:33 PM

Aaa oki, thought that was it.
Think I saw one of those on the flytron website aswell so I can might aswell get everything in one go. Does that adapter in your post has a mini usb port?

Cheers,
Mihai

Devonian · July 19, 2011, 02:24:16 PM

Yes, mine has mini USB and the one on Flytron site is not as nice as the one I linked to ;)

Nigel.

thundead · July 19, 2011, 03:11:43 PM

Oki I ordered myself evertlything I need ( I hope haha).

Ill let youknow when I've started playing with the openlrs :)
In the meantime if you have any arduino related questions let me know how can I help.

Cheers,
Mihai

Shikra · July 19, 2011, 03:27:11 PM

Bit of a lapsed programmer I'm afraid. Not had to do anything for a few years. No call in work anymore....

Recently restarted a Diversity project that I left off about 3 years ago so starting to realise how much I've forgotten already! Anyway looks like you have a new guy on the block. Hope he has more time than me!

I've not had a look at the features at all. I just saw it on the Flytron site one day and made a mental note to revisit...

G

Quote from: Devonian on July 18, 2011, 11:07:45 PM
Hi Shikra,

It'll be good to have a UK programmer around as it's not my specialist subject!
I have a basic grasp of what's going on, but couldn't actually write code from scratch.

The product has some inovative benefits, not just to get it onto UK legal UHF airborne control.
I guess you've had a look at the features and maybe downloaded the code to give it a once over?

You can already add i2C devices directly to the Rx and the Rx can also Tx data back to the ground station.

OpenLRS + Wii Motion Plus

Nigel.

Devonian · July 21, 2011, 09:03:05 PM

Small update:
Melih from Flytron has also been in touch with HopeRF technical team and below is their response to my findings for 459MHz when using the 430 module.

"...the sensitivity we tested at 459mhz has been reduced about 1-2dBm.
The output power you tested is 90-92mW（19.5dbm~19.6dbm,which is similar with our test result.
This little difference of sensitivity doesn't affect much on RF range..."

For reference, the module can only deliver 20dBm (100 mW) maximum anyway.

Nigel.

thundead · July 22, 2011, 10:26:16 AM

That doesn't sound too bad :)

My LRS shipped yesterday so 5 days and we can start developing :D

Talked to Bora Acar and apparently the new batch of openlrs systems are also based on the 430 module. Apparently it's a lot easier for them to get the 430.

Oh well, at least we can go 7W if we really get angry lol.

I had a quick look at the code and think we could squeeze a lot of nice features from this system.

First thing i'm going to do when I get the lrs is do a proper range test on 459 on Devonian's changes and report the findings and if that goes well I was thinking of implementing a nice LCD telemetry thing starting with RSSI readings back to the tx. Here's a project I did for uni:
http://www.youtube.com/thundead#p/u/6/kphz8NxG_Jk
Soo, should be fun :D

Anyway, any ideas are welcome

Cheers,
Mihai.

sheep600fx · July 22, 2011, 10:38:48 AM

Very tempted with this, Looking forward to the range test as that all thats holding me back

Devonian · July 22, 2011, 11:19:10 AM

Mihai,
Excellent!
As I said before, good to have a UK programmer on board.
I think that we are going to have to live with the 430 module running at 459.
David of RCexplorer.se has flown to 4km on the standard 100 mW and got 100km+ with the 7W module!
For me, 100 mW is no problem and it's better to maximise the antennas rather than slapping on a booster (plus it's illegal in the UK).

Get registered on the Flytron forum and have a look around the code and the ideas floating around in there.
Tons of potential and with both the Tx and Rx able to transmit/receive (transceive) Telemetry is entirely viable.

Sean,
Range is very subjective, 3-4km in wide open moorland should be no problem but maybe only 300 metres in an RF poluted city?

Nigel.

thundead · July 22, 2011, 11:25:14 AM

Well that's why we need to get channel hopping on 459 working good :D.

if I get at least 3km out of the stock setup I'm more than happy considering I usually fly battery hungry planes haha. Anyway I'll let you guys know when I have the lrs :)

By the way, I'll probably have to trim the antennas down to better match them for 459 i think.

Cheers,
Mihai.

Devonian · July 22, 2011, 12:09:39 PM

Yep, I have frequency hopping working on 459MHz.
I also made 'proper' length antennas for the Tx and Rx and don't use the supplied 433 'rubber duck' ones.
I have linked to info on both in the first couple of posts.

Nigel.

thundead · July 22, 2011, 12:13:56 PM

Saw the post but didn't have time to properly look over it :)

I'll have a look today and maybe start doing my antennas untill the modules arrive.

You did great work on the code. donno yet if we need to change anything. I'm still going through the data sheets though.

Mihai.

simondale · July 24, 2011, 01:39:39 PM

Excellent! I'm back from holidays and this has moved on loads since I went away - brilliant!

I'll order a set of OpenLRS, and the programmer jobby, up today and join in the fun. I'm not much of a programmer but I'm certainly good at testing!

Nice one Nigel and I can't wait to see what you come up with too Mihai

All the best

Simon