Decoding the Fine Offset station RF transmissions ?

[mr.sneezy]

Has that been done by anyone ?

By that I mean receiving the RF signal on 433Mhz receiver module or similar, and running the demodulated data into an MCU and decoding it to usable values. Many uses are possible once that's done...

Anybody know of somebody that's done that or doing it ?

Cheers,
Martin

[timfy]

I did once consider this as a project and the it dawned on me that there was very little to gain... all the usable data is output by cumulus in the logs in a much friendlier format and without having to attach anything to the outputs of my radios.

I'm interested to see if I've missed anything... what uses would you have for the raw data that the cumulus logs could not provide?

[Gina]

I thought that too. Plenty of more useful things to do

[mr.sneezy]

I see.
I had multiple small displays in mind though, with only a few key sensors shown at once. To augment the main station in other locations around the house and workshop.

For instance I was thinking that I'd like to build my own small bedside display, using a small 16x2 LCD, for those time I wake up from a 'WTF was that' sort of weather event...
Like the times you hear very heavy rain during the night, or a big wind gust shakes the house. I'd like to know what just happened, but couldn't be bothered getting out of a warm bed to find out what on the main station.

My display station is wall mounted permanently, and not near a PC. I don't have a PC running night and day for Cumulus anyway, and I worry somewhat about security of my relatively large home network if I did do that (uploading data to a website constantly).

Sure, it seems I could buy a second unit and just use the display station, but it's too large for a bedside table (mine anyway). I had small in mind, and maybe one in my workshop as well.

Oh well, I guess I'm on my own with the idea, but I'm still interested even as just an interesting RF and telemetry project.

On that note, I already verified my transmitter is also on 433.900Mhz, and transmits either one or sometimes two 100mS data chirps at a 48 second rate. It looks like the bandwidth is quite large, maybe 50-100khz. My gut feel from the sound of the data chirp is that it's 9600baud or higher. Not new info most of that.

If I can find a receiver from an otherwise dead FO weather station I could learn a lot fast (anyone?).
Or next step is to find out the brand and model of the TX/RX pair used in the late Fine Offset units and see if they can be bought without silly amounts of trouble.
Martin

[Orion]

There is one on Ebay at the moment
http://cgi.ebay.co.uk/Weather-Station-R ... 3f07052634

[mr.sneezy]

There is one on Ebay at the moment
http://cgi.ebay.co.uk/Weather-Station-R ... 3f07052634

Thanks. Temping if it was in Australia. Post to AU plus the currency conversion will sink that one I reckon.
Martin
PS. Can the WH1081 display work with a WH2081 transmitter ? Do they send the same data string ?
At least the RX modules should be the same you'd think.

[jim-easterbrook]

There is one on Ebay at the moment
http://cgi.ebay.co.uk/Weather-Station-R ... 3f07052634

Oooh, thanks for that. I'm thinking of getting a second console to help with my software development. If no one else bids for it that's an attractive price.

[mr.sneezy]

There is one on Ebay at the moment
http://cgi.ebay.co.uk/Weather-Station-R ... 3f07052634

Oooh, thanks for that. I'm thinking of getting a second console to help with my software development. If no one else bids for it that's an attractive price.

Go for it then, I'll wait for something more local.
Actually a dead one from a forum member would get me going with the idea. Even if it's not practical thing to do for anyone else it will at least fill in a knowledge gap about what the TX sends (as opposed to what the RX stations regurgitates).

[6719jason]

I am intending to put my soon to be replaced (As in tomorrow), Watson W8681 Console, Transmitter & Rain Gauge up for offers!

[Synewave]

I am intending to put my soon to be replaced (As in tomorrow), Watson W8681 Console, Transmitter & Rain Gauge up for offers!

Just to let everyone know, if anyone interested is wanting to use it for spares, even though it is a Fine Offset the frequency is different to that of a N96GY (so is incompatible between the transmitter and console).

[6719jason]

Just to let everyone know, if anyone interested is wanting to use it for spares, even though it is a Fine Offset the frequency is different to that of a N96GY (so is incompatible between the transmitter and console).

Thanks Paul! I meant to say that! All is in working order! Photo's upon request - Being replaced with a La-Crosse WS2300

[mr.sneezy]

Following up nearly two years later than my OP

I gathered data from around the WWW over the next year when time permitted (which was not often) and also bought a 433Mhz Hope RF RFM12 TX/RX module off Ebay as well.
About six months ago I started to put information and hardware together, and put a 16x2 LCD, a PIC16F819 MCU and the Hope RF module on a Proto-board to get started.

Bit by bit I've got it all working. First issue being the not very friendly Hope RF module. With some hard Googling I found the info needed to make it work with the Fine Offset WH2081 weather station outdoor transmitter. Mainly it involved an undocumented configuration setting that allows the normally FSK receiver to work with Fine Offsets OOK transmissions (On Off Keying). Once I had that I was getting good pulses out (not data) that could be measured for length. Turns out short pulse around 550uS is a '1' and a long pulse around 1500uS is a '0'.

Moving on to the decoding of the WH2081 frame I initially had some puzzles to solve. Turns out the transmitter sends data bytes MSb bit first, and my software was decoding LSb first, so each of the frame bytes was reversed bit wise end for end. The WH2081 sends an 11 byte frame 48 seconds apart BTW, with every second transmission a double identical frame.

Finally moving on to decoding the frame, most of the sensor data fell out as expected. As a few other people had already worked out the scaling and/or offset of most sensors it was not too hard.

I've now got the four main outdoor sensor values displayed, with only rain to add. I'll do that sometime soon or maybe opportunistically when it rains next (probably about April here).
The PIC MCU also outputs the received data in Hex via a pin in RS232 inverted 8N1 format. I use this for debugging, but it could directly feed a PC comm port with raw sensor data as well.

I'm thinking of using a Nokia cell phone display instead of a standard 16x2 LCD, but I'm thinking the text might be too small to be useful on a bedside table display.

I'll see if I can post some pictures...

[mcrossley]

Glad to see you are making some progress. Unlike me with an 868MHz transmitter

A phone display may well be too small, larger displays (touch screen even) can now be bought quite cheaply, would one of those be possible to hook up?

The 433 units seem to be fairly easy to pick up and decode by several people using the Hope receivers and Raspberry Pi's, but I have yet to find anyone being successful with the 868 units. I cannot even get mine to detect the signal never mind move on to decoding the data stream. I think something is fundamentally wrong with how the Hope receivers are being configured.

[philcdav]

Hi guys.

just for info, I treated myself to a Funcube Dongle at Christmas.

A really neat radio solution that covers all areas I need including the 868 MHz frequencies.

Running the free SDR software gives a panoramic display that shows the FO data in fine detail.

I have heard that someone is trying to unpick the data using a Raspberry Pi but I am not really bothered about that.

Call if you need more info.

[mr.sneezy]

Hi guys.

just for info, I treated myself to a Funcube Dongle at Christmas.

A really neat radio solution that covers all areas I need including the 868 MHz frequencies.

Ah, me too, but I'm using the $10 RTL-SDR dongle method with a R820T based USB digital TV tuner stick. I did use it to confirm the frequency of transmission of the WH2081.
I can post a link to the dongle if anyone's interested.

Mark, I can understand the frustration with getting the Hope RFM module running....
If it's any help I can post the SPI configuration settings I used, or you can post yours too and I can see if it looks OK.

Martin