Cynics Soapbox

Random thoughts...

SDR Pt.6

SDR Pt.6

It's been a while since I was able to devote much time to this and as the Weather Underground service is still not accepting submissions it hasn't been a high priority. However, with the festive season upon us and some time available I sat down to look at things again. The code I had written worked on my laptop but failed on the RaspberryPi :-( thinking about the differences between them an obvious line of investigation was the relative processing...

SDR Pt.5

SDR Pt.5

After the highs and low of the last coding session, it was heartwarming when after a few minor tweaks I saw this... Reading direct from the ISS :-)Now I had readings the next step was to start collecting them and then uploading to Weather Underground via their Personal Weather Station (PWS) network. My initial aim was to get a simple uploader working and then refine the data to slowly add the more complex items as time permits, but this...

SDR Pt.4

SDR Pt.4

I've managed to spend more time looking at it and have made some progress, though have once again run into issues. After much investigation I've created a processing flow that takes the raw samples and can extract valid weather packets -  but only from recorded files. When trying with live data it always returns invalid packets :-( The flow is this parse the samples into complex numbersdown mix these initial complex numbers using an appropriate frequency offsetpass the downmixed data...

SDR Pt.3

SDR Pt.3

Having found what appeared to be signals from the weather station in the data I captured (read here for more) the next logical step was to try and decode it. Inspectrum has some useful tools and following an example of analysing data I watched on YouTube, I started by adding a frequency plot (right click, Add derived plot > Add frequency plot). The center of the plot and the spectrum covered can be easily adjusted. Frequency plot centre and spread...

SDR Pt.2

SDR Pt.2

Continuing to try and figure out how to grab the data from the SDR it struck me I had  a few pieces of the puzzle to complete. Can I actually capture the data using the SDR? Until I know for sure that the data is available then doing anything else seems a little premature.If I can see the data, can I decode it and does it look as the information I have found on the web implies it should?...

Blog

I've finally got round to moving my blog to Ghost though the change has not been simple and I think images may not be fully working yet. I'm still using the default theme though I do plan to change at some point. Hopefully it will make things easier to read for people on mobile devices. Let me know :-)...

SDR

SDR

For the last few years I’ve had a Davis Vantage Vue weather station. It’s been great though getting the data in a useful format is far from easy. Following our recent move the weather station needs to be relocated. It’s new home will be more exposed and as we’re still building the house there isn’t anywhere convenient to locate the large weather station base unit or associated pieces to upload the data. This has led...

Flirting with the dark side...

Last month our 2010 27″ iMac stopped working. There was no drama, just a black screen where previously had been the High Sierra backdrop. A quick bit of investigation showed that it wasn’t as simple as a dead machine. The fans still blew and when turned off and on it made all the expected noises. There was just no picture. Plugging in an external monitor soon showed that the machine was usable and still functioning normally. After 7 years...

Simple ZFS Usage

For years all I heard from various people I know was “ZFS“. It was the answer to almost every question and given how few OS’s supported it always appeared to be the promised land over the rainbow. That was then, but in recent years the availability of ZFS has grown quickly and I can now fully appreciate what they were saying was true. I’ve used ZFS on Ubuntu and now am using it on FreeBSD without too many...

Fail2ban Logging

Over the last few days I’ve been trying to help one of my users who had an odd connectivity issue for my server. After looking at the obvious issues it started to look more and more like he had triggered one of the fail2ban rules and was being blocked by iptables. This has been the case a few times and normally checking the rules shows the problem, but this time it didn’t show anything obvious. $ sudo iptables -L...

Multiple Postfix Instances

I’ve been using Postfix for around 5 years now and it’s been a great solution for mail. Initially I used a single instance, but as the mail volume grew it started to cause bottlenecks and frustrations. The solution was to move from one instance to 3! Basic Flow The theory is to have each instance of postfix performing a specific role and using the standard communication mechanism between them. Each instance operates independently and using it’s own...

PostgreSQL & FreeBSD 10.3

I’ve recently started moving back to FreeBSD from Ubuntu. As it’s a large move and I’ve not touched FreeBSD for quite a few years, baby steps are required. With that in mind I’ve started small with my home server and once I’m comfortable with that and how things work I’ll look at moving my online server. The reasons for the move will have to wait for another post 🙂 Previous the home server had both...