pig-monkey.com - radio

APRS becomes a more useful expedition messaging service with the addition of SMS and email gateways.

2023-05-01T00:00:00-07:00

These gateways bypass the traditional APRS messaging requirement that both parties be online at the same time. With the SMS Gateway and Email Gateway, I can send a message to someone back in the world, and the message will arrive on their computing device as normal SMS or email. Critically, both gateways store messages for 24 hours and allow receivers to request unacknowledged messages be resent. This means that someone can reply to my SMS or email at any time, even when my radio is off. I just have to turn on my radio at least once per day and instruct both gateways to send me any new messages.

I’m interacting with both gateways directly from my Yaesu VX-8DR but this thread on the Expedition Portal forums provides a good introduction of using them via APRSdroid.

APRS gateways also exist for weather reports, WhatsApp messaging, and requesting the nearest repeaters.

A Better Clipboard

2019-12-21T00:00:00-08:00

One of the things I learned over the years at 2 Meter Critical Mass and other radio events is the value of a good clipboard. The Field Message Pad or Field Memo Pad or even the Field Notebook are great for my own notes, but when responding with a radio on behalf of an agency, said agency will probably have official log and message forms, and those forms will probably be on 8.5” x 11” paper. A clipboard is an important tool for making those forms usable in the field.

Many people end up with a Gibson approved Saunders Storage Clipboard. They’re nice, but too bulky for my tastes. I use a WhiteCoat Clipboard.

These clipboards are hinged, allowing them to fold in half. They are intended to be folded so that they fit in the pocket of a lab coat and protect patient information from shoulder surfing. But when folded they also fit well into a decent sized cargo pocket, or larger jacket pockets. Folding the clipboard also provides some protection to the paper itself. Even if you’re just putting it in a pack, it’s nice to be able to fold the board and not worry about the paper becoming wrinkled.

The WhiteCoat Clipboard is available with different quick reference medical stickers. None of these are extremely useful to me. I went with the EMT Edition because it has a scale for estimating pupil size, which is something I have struggled with in the past. I’ve considered printing my own stickers to put on the board – perhaps with some kind of radio reference material – but I haven’t decided what information would be useful to include.

A simple rubber band is available to secure the bottom edge of the paper. This is critical to one’s sanity in windy conditions. A pen clip to keep your Fisher Space Pen M4B close to hand completes the package.

The system is overpriced, but I am very happy with its functionality.

2 Meter Critical Mass

2019-12-18T00:00:00-08:00

2 Meter Critical Mass is a monthly radio practice event at Spreckels Lake in Golden Gate Park. The practice grew out of the NERT community and sought to help people keep current with their handheld radios. I started attending on a fairly regular basis a couple years ago. We’d jump around to different frequencies on the 2 meter band and practice sending and receiving traffic.

Changing frequencies was sometimes the most difficult part of the practice. Most people, myself included, program their radios with software like CHIRP. When it comes time to do something like change to a frequency that is normally used for repeaters, and then remove the offset because you need to use it for simplex, it can be a struggle to remember the correct sequence of steps. But simple skills like that are critical in the field during an emergency.

After the struggle of getting everyone onto the correct frequency, some people would start sending traffic while others would copy it down onto standardized message forms. This is the primary role of radio operators during an emergency, but is not often practiced. The messages were often lists of medicines, the Latin names of plants, or some other gibberish that would require use of the phonetic alphabet to transmit. Somebody in the group would be picked to be the net control operator, which brought with it an entirely different set of skills to practice. Somehow I always got “volunteered” for that – rain or shine (often offering an example of why you fill your field message pad with waterproof paper).

2 Meter Crical Mass was the child of Peter McElmury, AA6SF. In November there was no practice, which I thought was odd. I had never known Peter to miss a month. But he was a Marine and it was his birthday that weekend, so I figured he was just busy celebrating. The December practice was four days ago. It turns out Peter was absent in November due to a medical emergency. At this month’s event he was walking with a cane and having trouble with motor skills, like writing, but he was in a good mood and happy to be radioing, as always. Yesterday he died.

A Brief Survey in Marin

2019-10-29T00:00:00-07:00

This past Sunday I rode to Mount Tam.

The electrical grid was down throughout Marin county, and for some reason that meant the state had closed some of the roads in the park to motorized traffic. Fortunately my vehicle runs on man-power and works just fine when the power is out. I figured the closure would make the ride more pleasant and I would just slip around any gates.

As I was riding in the general direction of fire I decided it would be prudent to throw a radio in my handlebar bag. From past experience I know that my cell phone reception can be spotty at the best of times in the hills and valleys up there. I assumed that the power outages and strong winds wouldn’t do me any favors. (It turns out I was right.)

After much climbing and much wind I reached Ground Equipment Facility J-33. This abandoned Nike missile site on the West Peak of Tamalpais is a reliable site for radioing. It has been host to a couple Field Days and was the destination of last year’s SOTA trip. And it’s a nice spot to bicycle to.

The Marin Amateur Radio Society maintains an excellent network of linked repeaters that I was able to hit immediately upon turning on my radio. Despite the distance, I was also able to reach back into San Francisco. Line of site to Sutro Tower meant I had a clear, strong signal on the San Francisco Radio Club repeater W6PW. I talked to a guy on there who told me that the Marin Radio Amateur Civil Emergency Service had been activated due to the fires. I keep some of the Marin RACES simplex frequencies programmed into my radio, just in case Godzilla walks through the bridge and we have to coordinate across the bay, so I jumped over to those channels to listen for any action. After that I was able to reach out to the East Bay, and listen to the effects of the fires that had just started that day in Contra Costa County.

After completing my survey of the airwaves I flew back down to sea level at approximately Mach 3, though I had to stop once for a California Highway Patrol helicopter that decided to use the gated off road as a landing pad.

It’s impressive what you can get done on a little handheld radio with 5 watts and a small antenna, assuming you can get to a good position. A bicycle is a good way to get there.

Avian carriers achieved a message delivery rate of 95% in the first World War, and were reported to reach 99% success in an Army study published in 1944.

2019-02-28T00:00:00-08:00

In an article at At War on the Rocks, Dr. Frank Blazich provides a brief overview of the military use of homing pigeons and argues for their reintroduction as a response to electronic warfare.

Considering the storage capacity of microSD memory cards, a pigeon’s organic characteristics provide front line forces a relatively clandestine mean to transport gigabytes of video, voice, or still imagery and documentation over considerable distance with zero electromagnetic emissions or obvious detectability to radar. These decidedly low-technology options prove difficult to detect and track. Pigeons cannot talk under interrogation, although they are not entirely immune to being held under suspicion of espionage. Within an urban environment, a pigeon has even greater potential to blend into the local avian population, further compounding detection. The latter presumably factored into the use of pigeons to clandestinely smuggle drugs, defeating even the most sophisticated of walls.

Furthermore, pigeons provide an asymmetric tool available for hybrid warfare purposes. The low-cost, low-technology use of pigeons to transport information or potentially small amounts of chemical agents — or even coded cyber weapons — makes them a quick and easy asset to distribute among a civilian population for wider military purposes. During World War II, the British Confidential Pigeon Service of MI14(d) dropped baskets of homing pigeons behind enemy lines for espionage purposes, gathering invaluable military intelligence in the process from a wide array of French, Dutch, and Belgian civilians. Even as a one-way means of communication, the pigeon proved an invaluable military asset.

Via Schneier, who reminds that we have an RFC.

I don't know anything about, or have much interest in, high-frequency trading.

2019-01-06T00:00:00-08:00

But some of the technology behind it is fascinating. This past summer the Sniper in Mahwah blog published a four part series investigating the use of shortwave radio as a low latency link in high-frequency trading. I’d call it the best piece of hacker-tourism since Mother Earth Mother Board, but I think it’s probably the only piece of hacker-tourism since Mother Earth Mother Board. It doesn’t have much competition.

I was reminded recently of John Michael Greer's comments on distributed communications.

2018-12-24T00:00:00-08:00

To wit:

What would a viable long-distance communications network in the age of peak oil look like? To begin with, it would use the airwaves rather than land lines, to minimize infrastructure, and its energy needs would be modest enough to be met by local renewable sources. It would take the form of a decentralized network of self-supporting and self-managing stations sharing common standards and operating procedures. It would use a diverse mix of communications modalities, so that operators could climb down the technological ladder as needed, from computerized data transfer all the way to equipment that could be built locally with hand tools. It would have its own subculture, of course, in which technical knowledge and practical expertise would be rewarded, encouraged, and fostered in newcomers. Finally, it would take a particular interest in emergency communications, so that operators could respond to disruptions and disasters with effective workarounds at times when having even the most basic communications net in place could save many lives.

The interesting thing, of course, is that a network that fills exactly these specifications already exists, in the form of amateur radio.

This weekend I tagged along with the SFRC on their first SOTA activation.

2018-05-13T00:00:00-07:00

We took a short hike up to Ground Equipment Facility J-33 on the West Peak of Mt. Tam. This was the first time I’d been back up there since Field Day 2017. I was able to get two contacts on 2 meters with my VX-8DR, and another two on 20 meters with one of the other operator’s KX3. The club has more photos.

Bicycle Mobile

2018-04-22T00:00:00-07:00

Bicycles are fun. So are radios. Why not combine them.

For overnight trips I run my Yaesu VX-8DR in the handlebar bag, with the MH-74A7A hand mic and FGPS-2 module, and a Diamond SRH320A. This let’s me broadcast APRS, letting people know where I am, and is everything I need to hit area repeaters to see if there’s anything interesting going on. Calling in as “bicycle mobile” usually generates interest, and it’s fun to check into a net without having to stop pedaling.

After pitching camp I can kill time by making more contacts. Also on this trip was a Nelson Antennas Slim Jim, but I didn’t bother putting it up.

I’m not quite up to Steve Roberts’ level, but I’m also only pushing a fraction of the weight.

Resilient Communications with Continuous Wave Radio

2012-11-18T00:00:00-08:00

Codegroup is a program written by John Walker that encodes and decodes any file into groups of five letters. For example, take an image, run it through codegroup, and this is what you get:

$ cat avatar.jpg | codegroup | head -n 4
ZZZZZ YPPNI PPOAA ABAEK EGEJE GAAAB ABAAA AABAA ABAAA APPPO
AADLE DFCEF EBFEE PFCDK YCAGH GECNG KHAGF GHCAH GDBCO DACAC
IHFHD GJGOG HCAEJ EKEHC AEKFA EFEHC AHGDG YDCCJ CMCAH BHFGB
GMGJH EHJCA DNCAD JDAAK PPNLA AEDAA ADACA CADAC ACADA DADAD

The resulting code groups lend themselves to being transmitted via low-tech, resilient means, such as continuous wave radio. The ability to do this with any file is a simple but amazingly powerful concept.

I discovered codegroup around the same time that I was learning Morse code. I decided to take advantage of codegroup and put what I was learning into practice. This led to the development of morse.py.

With codegroup, I end up with a series of ASCII characters. I wanted to be able to feed those characters into a program which would convert them to Morse. The program should display the dits and dahs, but more importantly: it should beep them out.

morse.py is a simple script which does just that. It accepts ASCII input and encodes it to International Morse Code. The Morse is printed to the screen, in case you want to key it out yourself. Johnathan Nightingale’s beep.c is used to play the beeps with the terminal bell. The length of dits, dahs, and the pauses in between are configurable, but the defaults conform to International Morse. The input can be a file, but if no file is specified the script simply reads from standard input, which allows it to be piped together with codegroup.

$ morse.py --help
usage: morse.py [-h] [-b BEEP] [-s SPEED] [-f FILE] [-q]

Convert an ASCII file to International Morse Code and play it with system
beeps.

optional arguments:
  -h, --help            show this help message and exit
  -b BEEP, --beep BEEP  The location of the program that plays the beeps. This
                        script is intended to be used with Johnathan
                        Nightingale's beep: http://www.johnath.com/beep/
  -s SPEED, --speed SPEED
                        Reduce the pauses between message characters by the
                        given amount.
  -f FILE, --file FILE  The location of the ASCII file to convert.
  -q, --quiet           Do not print the dots and dashes.

What is the application? Suppose your government has shut down your internet access. You want to send a map to an acquaintance. With these tools, you can encode the map with codegroup, pass the result to morse.py, hold your radio up to your speakers and key the mic. That’s it. Censorship bypassed.

$ cat map.pdf | codegroup | morse.py -b ~/src/beep/beep

On the receiving end, the Morse needs to be translated back to ASCII characters, which can then be decoded with codegroup. It’s a slow process, but resilient. To speed things up, the file being transmitted can be compressed before being passed to codegroup. (And if privacy is a concern, the file can also be encrypted, but that would be illegal unless you are doing so to protect life or property.)

Learning Morse Code

2011-09-16T00:00:00-07:00

Although it’s no longer required for the amateur radio Technician license, I have decided to learn Morse code. Despite it’s age, Morse remains one of the most effective ways to transmit information over long distances using minimal infrastructure and power.

To begin, I have printed and laminated the code chart from learnmorsecode.com. This makes encoded and decoding Morse a simple (although not fast) task. I’ve also put a variety of audio files consisting of slow Morse transmission on my media player. With a notebook and pen, I can practice decoding the messages wherever I am.

I’m aiming for 10 minutes of practice per day.

Studying for the Amateur Radio Technician Exam

2010-10-15T00:00:00-07:00

I’ve been vaguely interested in amateur radio for a few years. The idea of decentralized, low-infrastructure communications appeals to me, but knowing nothing about radios, I was somewhat overwhelmed by it all and didn’t know where to start. I didn’t pursue the interest until now. In case anyone else is in the same position, I thought I would outline what worked for me.

A couple weeks ago I saw that the local library had a copy of the ARRL Ham Radio License Manual. The Manual is meant to teach beginners the basics of radio and help them to pass the Technician license exam: a 35-question multiple choice test. The entire question and answer pool is publicly available.

My method for using the book was to read one chapter every morning. Immediately afterwards I would quiz myself on all the relevant questions for that chapter (included in the back of the book). For the rest of the day, I wouldn’t think at all about radios, until the evening, when I would once again quiz myself on all the questions from that day’s chapter. The book consists of nine chapters. I combined chapters seven and eight into one day, and so finished the book in 8 days. Over the course of the ninth day I took a dozen or so practice tests on QRZ.com. The following day I took the real exam.

Thanks to the book, in little more than a week I went from knowing absolutely nothing about radios (and near to nothing about electronics) to being confidently able to ace the Technician exam and earn my amateur radio license.

One could just memorize the question pool and probably easily pass the test the same way. I’m not much interested in licenses. I didn’t start this venture just to be awarded a slip of paper by the FCC. I’m after the knowledge. Using a resource like the book to help me in comprehending all of the relevant topics appealed to me much more than rote memorization of the exam’s answers.

Of course all I possess now is book knowledge. That needs to be supplemented with experience. But once I buy a radio, I feel that I have a solid base from which to leap.