sky, Author at Sky's Blog

Visualizing packet traffic

26 April, 2020 by sky Leave a Comment

Very techie here… For a few months I’ve been operating a packet radio station on a 2-meter radio frequency here in the San Francisco Bay Area. I explored what it would take to make this a full “BBS” (like an online “forum”), and then backed off and let it just hang around n this frequency listening to the other (mostly BBS) stations. A few days ago, I got interested in graphing the data to better understand what stations were using the frequency and when.

Packet radio was very popular 20 to 30 years ago, and has mostly been displaced by other amateur radio digital technology and by the Internet. Yet, it’s still quite reliable and is a good way to pass messages from one place to another when Internet or voice communications are unavailable (i.e. in an emergency). I’ve always been interested in the presentation of data, and it was an interesting challenge to figure out how to chart the data in ways that support inquiry.The result of my experimentation is visible in a chart.

The chart is made by this process:

JNOS (the software that runs the packet radio station) logs all data it hears on the radio;
A Python script analyzes this log file, keeping track of what stations were heard in each hour;
The Python creates javascript data in a form acceptable to Google Charts;
The javascript is transferred to a web server;
PHP code reads the javascript and inserts it in an HTML page;
Google Charts javascript fashions the data into the interactive chart.

A “cron” job carries out this process once each hour to keep the chart data current. Because each data bucket spans a whole hour, there’s no need to update more than once an hour.

Tips for Recording Online Interviews and Conversations

31 March, 2020 by sky Leave a Comment

When you’re preparing for an online interview (Zoom, Skype), there are a few things you can do to really help it be a truly professional shoot. These tips are for both the interviewer and the interviewee. And they are the tips I suggest to interviewees on the Exploring Leadership podcast.

[Read more…]

Packet Radio Notes

25 February, 2020 by sky Leave a Comment

In amateur radio circles there’s much use of digital modes to exchange information. (In olden days it was almost exclusively limited to “chatting” on the air.) At least in the circles I’m running in these days this is true. “Packet radio” involves putting a computer on the front end, which then controls the radio, connecting to other packet radio stations and transferring messages digitally. At the lowest level the software has a command-line interface (accessed via radio), and at its highest level, it is basically supporting programs that exchange email (again, by radio, not thru the Internet).

Later articles:
° Packet and SFWEM Interconnects
° Visualizing Packet Traffic

My packet radio station operates on 145.07 or 145.09 mHz (also known as “2 meters” and mail is exchanged by “connecting to” AA6AX-1 via that radio. If you need to email me about this, please use the email address packet@aa6ax.us.

The station uses a Raspberry Pi 4 as the computer, and I use VNC to view the virtual “screen” of the RasPi and interact with the system. The radio is a cheap 2-meter transceiver, and a circuit board in a box called a “TNC” attaches to the computer and controls the radio. The photo shows the RasPi (about 4 inches wide) on top of the slightly-larger TNC. Plug it all into electrical power, add a radio with an antenna, and it’s on the air.

(More aa6ax info.)

This diagram shows the components of the packet station. Most notable are the Raspberry Pi computer (the “RasPi”), with the reddish TNC-Pi on the top, connecting it to the radio. The radio has an antenna, and is connected to a power source.

The computer itself is on the local network, and the VNC software lets me view its “screen” on my own computer, and use my mouse and keyboard as if they were directly connected to the RasPi computer. It’s kind of a virtual computer.

Music Video

19 May, 2019 by sky Leave a Comment

When I was an undergrad in college I helped start a few small companies. Some my own, and some other people’s. One of those other people was a guy who among his exploits used to buy up after-midnight time on cable TV (in Chicago) and then fill up that time with what he called “music video.” This was around 1968. (MTV wasn’t launched until 1981!) And I swear he actually called it music video, though Wikipedia disagrees with me. They played short video clips created by bands to promote their records. Remember that people made money by selling records and airplay on radio, so the goals wasn’t to play the video, but rather to drive the sales of records.

It has taken all those years for me to get around to not only making video but setting things to my own music. And here are the results. [Read more…]

A Sonic Indulgence

27 April, 2019 by sky Leave a Comment

Indulgence is a 20-minute indie film by producer Leo Maselli. It’s one of the segments of a compilation film CA Shorts, all of which are being shot in 2019, and it will be released in 2020.

The team completed the shooting of Indulgence early in 2019 (after postponement due to too much smoke in the air late in 2018). This week I saw the first rough cut of the film. I already wrote most of the music for Indulgence, and the next task is to cut-to-fit and add incidental music for this segment.

As part of the promotion and documentation of how we made the film, Erik Parker interviewed me about the creation of the music for Indulgence. Without comment, here’s that interview that he and cameraman Jason Fassler captured.

A Sonic Indulgence from Erik C. Parker on Vimeo.