Impressive, Luc. I admire your persistence! -tk
On Sun, Mar 3, 2019 at 11:33 AM Luc Heijst <[email protected]> wrote: > Recently my attention was brought to a SDR tool for receiving wireless > sensor data (TFA IT+ KlimaLogg Pro, LaCrosse, WeatherHub). See: > https://github.com/baycom/tfrec. > > I wrote a weewx driver which parsed and stored the tfrec data of my 9 > KlimaLogg sensors. The weewx driver can be found here: > https://github.com/matthewwall/weewx-tfrc > > After this success I searched for a package that reads the radio data of > Vantage Pro weather stations with a (cheap) RTL-SDR dongle and found: the > rtldavis package on: https://github.com/bemasher/rtldavis. > > With this package were a few problems: > 1. The development of the package stopped three years ago. > 2. The set of European frequencies appeared not to be useful. > 3. The package could only handle one transmitter (at a time). > 4. The package is written in GO. Not a big issue, but the GO language is > new for me. > > With two Vantage Pro2 systems, an anemometer station and a leaf-soil > station the challenge was to get this package concurrently working for more > than one transmitter (four in my case). > > With some modifications of main.go and protocol.go and trial and error I > could find a reasonable set of the European frequencies which are used in > the frequency hop sequence. > The next step was to get the data of more than one sensor wich each its > own hopping timing. > The last step will be to parse the data packets and store the data in > Weewx. This part is easy because this was already done by me via the > parsing of the raw meteostick data in the weewx-meteostick driver, see: > https://github.com/matthewwall/weewx-meteostick. > > The hopping mechanism has some prograss today. The principle is as follows. > 1. Wait long enough on a fixed frequency until you have seen at least one > message of each transmitter. For the five EU frequencies this process takes > 17 seconds or less. For the 51 US frequencies this will take about ten > times as much time. > 2, Calculate with help of the lastVisitedTimes of all transmitters what > the nextVisitTimes (in the near future) will be and how many hops would be > needed to get here. > 3. Detect the smallest nextVisitTime. This will be of the transmitter > which follows first. > 4. Calculate the hop channel for this transmitter. > 5. Calculate the loopPeriod for this transmitter. In case the signal of > this transmitter is missed we don't want to wait too long and miss packets > of other transmitters too. > 6. Start the hop process and wait for new data. > > I combined the weewx-sdr and weewx-meteostick drivers fr this weewx-rtld > driver. > The results so far: > > The first 1000 messages were read with the new driver. > Average percentage of received signals is 94,8 %, see table. > > ok missed tot pctGood > 341 19 360 94,7 > 335 16 351 95,4 > 324 20 344 94,2 > ---- -- ---- ---- > tot 1000 55 1055 94,8 > > The FreqError in general varies between -1000 and +1000. > When abs(FreqError) > 10000 the weewx-rtld driver will restart program > rtldavis. > > For a comparison between the Meteostick and rtld driver data see: > http://www.lucdesign.nl/_weewx/bootstrap_rtld/hour.html > > There is one challence left: how to get local barometer data in my > Raspberry PI? > I could use a BMP280 pressure/temp sensor... so, more to come. > > Cheers, Luc > > -- > You received this message because you are subscribed to the Google Groups > "weewx-user" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
