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Ecowitt WH51 at 915MHz decoded by Classic but not Minmax #2235
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I got 2 of these (same part number) in late September, and they worked fine with rtl_433, the same as one that I got in probably June 2020. They report every minute and the values make sense. (I will not say they are calibrated.) Beware that the frequency offset of lesser dongles is significant. I found that to get reliable decodes (of this or something else from ecowitt, perhaps outdoor PM2.5?), I had to adjust the frequency offset, as in My advice is look at output of everything else, and see what the freq or freq1/freq2 is, compared to nominal, even if it's at 433.92. Then figure out the -p to make it right, and then listen at 915. Also get closer if you can. My other advice is, if you can, get a Blog v3 with the dipole kit. The Blog v3 and Smart v5 are pretty much equal but the dipole kit vs the mini mag mount is way better. I don't remember where the edges were, but this process took me from missing a lot of decodes to reliable. |
also your rtl_433 version is strange; I can't find the SHA1 in the commit history, but it looks like 9 commits before current master. This worked in 2020, so you shouldn't need super recent, but always better to be up to date. |
@gdt thanks for the suggestions. I am getting good SN ratios with lots of devices at ~ 914MHz and scanned up and down with Maybe there is a good external calibration standard? |
Proper calibratiion is hard; you'd need real test equipment and need to know how to use it. No, I didn't pay attention to SNR when doing frequency. What I did was write a python program that would graph the freq1/freq2 or just freq vs time and plot it in xplot, and then capture a bunch of sources. I found that with high-quality dongles (SmarTEE v2, Smart v5, Blog v3), that most sources were very close to nominal frequencies. And the good dongles were 1-2 ppm different from each other. I then looked at the same sources with two older NooElec dongles, and they were -73 and -51 for the -p argument to move the frequency output to match. Doing this right requires a calibrated signal generator to make something at 915 MHz exactly and then measure that. But things like that are expensive, and no I don't have one either. It should be possible with ham-type equipment to figure out a cal scheme, but I don't think it's easy, even for someone with a formal background in RF. SNR and frequency are separate. If you are getting one tone and not the other, the one you are getting could be poor SNR but no decodes. And -8 is ok, but I tend to see signals at -0.5 and noise at -28. Hard to tell until you figure it out. |
See the mailinglist archives. I sent a long note on October 2, 2022. |
Thanks for the reply! I might need to upgrade my dongle... Mine is a "TerraTec Cinergy T Stick+" that I picked up ~10 years ago. It works amazingly well for picking up most things, so could also be a problem with the transmitting device. I'll take a look at your Oct 22 post. |
Link to calibration post: https://groups.google.com/g/rtl_433/c/xg7f7haSE8I |
I tried following the decoding in the fineoffset.c using: According to the source file it should look like:
|
Can you bring the sensor and the dongle to be only 2m apart? I still think you may be having weak signals and It's good to exclude that. Nobody else has reported that ecowitt has a new format -- but they could. Also calibrate first before proceeding. |
They are about <2m apart.
I tried doing calibration with kalibrate-rtl and rtl_test -p
but didn’t get a sensible result.
…On Sun, Nov 13, 2022 at 10:09 AM Greg Troxel ***@***.***> wrote:
Can you bring the sensor and the dongle to be only 2m apart? I still think
you may be having weak signals and It's good to exclude that. Nobody else
has reported that ecowitt has a new format -- but they could. Also
calibrate first before proceeding.
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Ah, well then I don't really know what to say. You might try to calibrate with other sources that work. |
Of the 10 different devices I am decoding properly, all of them are ASK. This will be my first FSK device. Perhaps FSK requires a more stable frequency in the receiver? |
Can you grab sample and post as zip here? Noise, errors and position in the band will be visible there. |
I have discovered that the decoding does work when I do analysis on the .cu8 files. i.e. :
But when running
See zip file with two samples: |
For some reason the |
Awesome, Thanks! That did it. Get reasonable decoding with
and wet:
Is there an easy way to incorporate this into the decoder? Or just run w |
The demod (technically a discriminator -- decides 0/1 state in the signal) is global. There are ideas to run both parallel and use the "better" output or let decoders choose, but that won't happen soon. |
Thanks for helping figure this out. Made a pull: #2236 |
I looked at my invocations, and found
but, I am getting extremely clean signals. |
@gdt thanks! I tried your invocations and found many more decoded signals than I usually do, however, without the |
I wouldn't necessarily say that |
Please let me know if there is any more distorted data I can provide :) |
Tested with a new Blog V3 receiver and can confirm that the WH51 is decoded without the As a side note, I was disappointed that the SNR and reception was not better @433.92MHz with the new Blog V3 device: Antennae are same length and right next to each other (~20cm apart). |
My opinion is that the noise measurements and AGC behavior are complicated, and I don't at the moment really believe them. The real test is decodes. I would suggest that you run with each for a while and look at decode rates of distant, near-the-edge emitters. For me, the Blog v3 and Smart v5 were about the same, vastly better than the mini/mini2. Your older one might be great - I have no idea of course. But super high SNR values for strong signals does not mean that much IMHO. I will try to clean up my analysis code enough to check it in. It takes a json output stream and turns it into xplot format, and that made the differences among receivers and antennas really clear. |
I think this PR has run its course and can be closed. |
Anyone have any suggestions about getting this device (labelled "ecowitt wireless multi-channel soil moisture sensor model no: WH51" to decode? I saw that the device might decode with the following https://github.com/merbanan/rtl_433/blob/master/src/devices/fineoffset.c
But, the one I have does not. I have sampled what I believe are the "unknown" signals (6) as attached here:
wh51decode.out.txt
If you have any suggestions for how to decode, please let me know.
Thanks!
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