Showing posts from June, 2020

Packet Radio on a Raspberry Pi the cheap way!

Packet radio is, in essence, the transmission of data over radio using a protocol called AX.25. It is the mechanism of transmission under the hood for APRS. However, APRS is unconnected packet, while Packet Radio is connected. This implies that Packet can be used for a number of other applications, such as keyboard-to-keyboard chat or connecting to a mail server or a BBS -- not just "blast away" the message. In this post, I'll cover how to install and setup packet radio from a Raspberry Pi, without any additional hardware, and for a fraction of the cost. A terminal showing the output of the HELP command in a TNC I was recently introduced to the wonders packet radio. It has both a post-apocalyptic and 80's nerd feelings to it that I'm enjoying a lot. The fact that my background is in computer science might have something to do with it, too. Packet Radio is a marketing term to refer to AFSK-modulated FM using AX.25 at 1200 baud (or 300 baud on most HF bands). Tradit

Radio adventures in an apartment complex

Radio is the greatest hobby if you live in the countryside. But you live in an apartment complex in the center of a 9 million people city, and you cannot install that 60-meter-long doublet that you've seen on YouTube anywhere. Now what? Hire rise buildings are not really RF friendly Let's all acknowledge that amateur radio is a great hobby. Specially if you live in an area where you are not physically limited by the space you have. In this case, you can set up your 10m tall vertical antenna, and lay down all that copper wire that you need to create your 120 radials ground plane. But this is not your reality. You live in a 60m^2 unit on the 4th floor of a eight-storey high apartment block, surrounded by even taller buildings in every direction. And you still want to play radio. Now what? Background When I first move to London, I used to live in a tiny ground flat in a Victorian house in the South West. I had access to small back garden, where I installed a co-linear white stick