This post describes how I setup a basic ADS-B receiver on a Raspberry PI Zero W using a USB RTL2832U based Software Defined Radio so that you can see any ADS-B equipped aircraft in your local area and present it on your own website.
Continue reading “Getting up an ADS-B receiver on a Raspberry PI”
Well done Oppy, you did way more than originally planned, but we knew this day would eventually come… RIP
This is a very hard post to write. It’s one I’ve been dreading, for years, literally years, but there’s no putting it off any longer.
Overnight last night the final, Final, FINAL ‘Wake up, please?’ commands were sent to Opportunity, the absolutely last throw of the last dice. Its been 8 months since we last heard anything from her, and even as those last commands were being beamed from Earth we all hoped against hope that Oppy would stir, and bleep back a last minute “Ha! Had you fooled! Surprise!!” reply –
But Opportunity didn’t answer.
So.
Barring some kind of miracle it looks like this evening’s (7pm) NASA press conference will be for the announcement that Opportunity’s mission is finally over. This day was always going to come, and it’s important for everyone to remember that Oppy – which we hoped would last for 90 days after landing –…
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One part of the rewrite of all of my sites is to make dynamic content more real-time, specifically using Websockets, so that content is as close as live as it’s possible. For this I’m using the current RabbitMQ release running within a docker container with the web_stomp plugin enabled. With this I can then have a webpage connect over websockets directly into the message broker and listen for messages.
Now the problem. Most events are defined as some change within a database so I now need a method to allow a database trigger to be able to send a message to RabbitMQ without hindering performance – more so when some tables are being updated 20-40 times a second.
Fortunately PostgreSQL provides us with asynchronous notifications via the LISTEN and NOTIFY commands, so we can add a notify command to the trigger to a named queue and then have a separate process listen to that queue. All I needed to implement was an application that did the listening. Continue reading “Publishing messages to RabbitMQ from PostgreSQL”
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