SFWEM.NET is the San Francisco Wireless Emergency Net, which is a mesh network that’s being built out by amateur radio operators with the intention of being a communications backup in time of emergency — when phone and data networks may be locally overwhelmed or not functional. Beside that, however, it’s an interesting experiment for amateur radio operators seeking to understand the benefits and limitations of “wi-fi” as a long-distance tool.The wi-fi that most people know is range-limited and often flakey.  SFWEM works with directional antennas that have far greater range, and with higher radio power (permitted to amateur radio operators) on a band of radio frequencies not available for public use. So rather than being stuck with a 50-foot maximum range, we can get good connections over distances of 20+ miles. The connections are still line-of-sight, meaning that one antenna must be able to literally “see” the antenna on the other end that it’s connecting to. Any buildings, trees or hills in between the two will reduce or eliminate the signals.

So the idea is to create a mesh or network of interconnected stations to cover the space — in this case the northern end of San Francisco Bay, and soon the southern end of Marin County — with stations that automatically relay communications from one node of the mesh to the next. And as long as even one mesh node has a connection to the Internet, all of the other interconnected mesh nodes can reach the Internet (and each other).

My “interconnection” consists of the packet radio station, which is linked to the amateur packet radio network in the area (in my case to KE6JJJ in Bernal Heights, and to NøARY in the South Bay). And two nodes on the SFWEM mesh. The link between the two is software. A JNOS software system running on a Raspberry Pi4 computer. JNOS can send and receive messages on the packet side, and can send, forward and receive messages using regular Internet-based email.

The whole setup is currently solar powered. Summer in San Francisco is cold, and sometimes foggy, but there are enough sunny days that the batteries can make it. (Winter, with different sun angles, is a bit more challenging.) Currently (May 2021) I’m testing to determine how long the solar powered system can supply both the packet and the SFWEM systems, as well as solving some issues with how many different voltages are required for all of this equipment, and how efficient the whole power supply thing can be.

Lots more to say; enough for now.

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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.

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.

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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.

Read more about this packet radio setup in the PDF file.

(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.

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Of course, they are called amateur because they are not professionals, in that they are not paid for their work and it is a sideline and not their primary work in life.

And calling it “ham” has always been tough for me. To get ham, you have to do something bad to a cute little piggie, and “ham it up” has always been a distasteful phrase to me because of the connotation—bad (or embarrassing) acting.

So enough complaining—what should we call it? Maybe base it on experimentation. “Radio experimenters” Nah. “Radio hobbyists?” Nope. “Radio people?” Nyet.

 Then what could it be called?

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Using amateur radio repeaters — there were lots of folks watching for the aircraft all along its route — I tracked the flight’s progress from Southern California up past Stockton, where it flew around the capitol building in Sacramento twice, then down the Sacramento River to the Bay Area. The craft made a pass by the Golden Gate Bridge, one around the Bay in a big loop, and then back out straight between the bridge towers. I joined hundreds of enthusiastic fans viewing from Twin Peaks (elev. 800+ ft) in the geographical center of San Francisco. We were nearly the same elevation as the aircraft, which flew between 1,200 and 1,500 feet during the entire maneuver.The shuttle rode piggyback, held to the roof of a specially-configured 747 by struts. This is the same arrangement that was used to ferry the shuttles from landings in southern California out to Florida for later takeoff on subsequent missions.

The aircraft entered SF airspace in the East Bay, flew down past San Ramon, then came back up the east side of the actual bay and over to Marin County where it made a tight left turn back toward the Golden Gate.Three big engineering feats from different times, all visible at the same time (shuttle, huge 747, and GG Bridge…).

The piggyback pair was easily visible from major peaks around the Bay during the entire circuit. There was a big viewing party at the Chabot Space & Science Center in the Oakland hills.

Here’s a shot of the dual craft passing between the towers of the Golden Gate (only one tower in the photo) with just a bit of fog in the air, and (above, top) a closeup of the craft as they swept past Twin Peaks nearly at our eye level. A fighter jet escorts them in the bridge photo.

The viewing area was packed with natives and tourists. Parking areas overflowed. This is one of the big benefits of living in a beautiful tourist city…we get to participate in events like this several times a year. Last month it was the America’s Cup World Series (catamaran sailboat racing), with another round beginning October 2nd. And right after that the Blue Angels’ next airshow  coincides with Fleet Week October 4th to 8th, 2012. Exciting stuff!

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As the craft was descending into the Martian atmosphere, one of the engineers reported it was drawing 300mA of current. That’s the same current my FT-817 radio draws when receiving (let alone transmitting, as Curiosity was). Hardly anything at all. And later they reported just over 2000mA while transmitting and landing (at 32V). About the same power as a 60W bulb. The signals that were going out from the spacecraft were a bit stronger than those I put out when I’m on the air (but not much), and yet they were traversing 156 million miles (if my math is right – based on 14 seconds and the speed of light) before being received here on Earth, and the data was coming through just fine. Of course, we’re also talking extremely high-gain antennas here on earth (Canberra and Goldstone—the deep space network).

Also, the idea that these signals could bring telemetry data with them — those first 64×64 photos, then 256×256 photos of the craft’s wheel on the Martian surface, was quite striking. The bit rates were way low, and yet data was coming through on those weak signals. Then the first photo, of one wheel of the most recent object from Earth to reach Mars. What’s more, the signals were being relayed through another satellite, so the whole process was even sketchier. Xeni Jardin’s question about what data-compression method was used to transmit the photo was fun, but probably irrelevant for a 64 x 64 photo (probably 32k bits altogether).

So why do I say this affected my radio operations? It’s because I’m now motivated to dive even more into data transmission and automated operations. And especially radio communications that can function well under adverse conditions.

In the words of White House Science and Technology Advisor John Holdren, “Long live American curiosity.” And I would add, all curiosity.

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Jeff Goldsmith, who has made many of these trips with me and the group, was the only one with a full week to spare this summer, so he and I made this journey, which we called “27.1” because it’s the first hike of the 27th year that I’ve been doing this.

The photo gallery shows some photos taken along the way. My Yosemite page contains most of the trips taken in the last 10 years.

This year’s trip was highlighted by the following events and observations:

• We attempted to cover 10+ miles per day. We could actually only cover  8 miles on average due to the excess weight (“hobbies”) we were carrying. It is important to recognize these limitations early on and adapt the schedule!
• The amateur radio hobby was a bust this time for two reasons. Although I had a five-watt transceiver and a nice antenna, I wasn’t able to make a single contact on any band because conditions were pretty bad. I’ll have to check further into whether it was an antenna issue or an output-power issue. The second problem was that this hobby accounted for over eight lbs in my pack, which really slowed me down.
• The photography hobby needs to be scaled back. My Nikon D7000 camera works great, but it’s a heavy beast, weighing in at something over two lbs, and it’s hard to carry on the trail, since it really has to be fastened to the chest strap on the pack and it still bounces around significantly. A camera weighing a few ounces would be much better. In all I was probably carrying upwards of 10 lbs of such hobby gear that was not necessary for this trip. My pack weight was 44 lbs and could have been 34 if I hadn’t carried the extra gear. (This included 11 lbs of food, which was also excessive.)
• The Pacific Crest Trail hikers were friendly and are in general an outgoing group. Ran into more than a half dozen every day, and most were hiking from the Mexico border to the Canadian border. Many had been on the trail since April or May this year, with a few down-days (they say “zero days”) along the way. Most of them were covering 20 miles or more each day. We were on the PCT every day except for the time in Matterhorn Canyon.
• Matterhorn itself is a long ways in. I figured about 35 miles from Tuolumne Meadow. That’s just too much for slow and heavy-pack hikers to cover in three days, especially given the 3000+ to 4000+ ft elevation change on the last day going toward Matterhorn. So we just relaxed once we realized we wouldn’t make it either to Matterhorn or around the loop I had charted out in advance. We adapted and enjoyed the area.
• There are great lakes along the trail. Miller Lake, where we spent the 2nd and the 4th nights (see top photo), is a wonderful little lake and is warm enough to comfortably swim in with few mosquitoes. McCabe Lake, which I’ve visited before, is more than two miles off the PCT and thus not on the itinerary for most PCT’ers, but we spent a night there and it was a great place.
• After accounting for limitations and changing the plans, it was a memorable week-long trek.

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Summits On The Air [SOTA] is an organization that operates mostly in Europe and the US, which encourages amateur radio operation from mountain peaks. In many areas these are really just large hills, but here the western mountains of the US, we have many hundreds of peaks that are truly mountains and not just high spots.

The SOTA organization awards points for those who climb peaks and “activate” them by making a minimum number of radio contacts. It also awards points to chasers who listen for the climbers and contact them. This encourages more people to pursue the hobby, be on the air at the right time (when someone is on a peak!), and to actually make the contacts.

Backpack mobile operation, which is really what this is, requires either 1) carrying a honking big battery (several pounds); or 2) carrying smaller batteries and perhaps going solar-powered. Since my trail forays are generally 4 to 8 days in the wilderness, I go for the lightweight solution, which includes small batteries and solar-panels to charge them up.

SOTA: (UK)
SOTA Watch (current activity): who’s on top right now
SOTA enthusiasts online: KDØBIK // KØMOS

This summer as I make week-long treks in the Yosemite wilderness, I’ll be operating low power (2.5w) and attempting to activate a couple of SOTA-rated peaks. I’ll do a sneeze page of links later as I build up more of an inventory of sites.

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I remembered that 73 was a “message number” as used by amateur operators in the 1950s when I got my license, so I looked further.

I got the lead I needed from SignalHarbor who says that in the April, 1935 issue of QST magazine, on page 60, there is an article “On the Origin of 73” — and that is correct! I looked it up (ARRL members can read old QST issues online). They quote from “Telegraph and Telephone Age” 1 June, 1934 (which I could not find), and list the following message numbers:

• 1- Wait a minute
• 4- Where shall I start in message?
• 5- Have you anything for me?
• 9- Attention, or clear the wire
• 13- I do not understand
• 22- Love and kisses
• 25- Busy on another circuit
• 30- Finished, the end
• 73- My compliments or Best regards
• 92- Deliver

“It appears … that in 1859 the telegraph people held a convention, and one of its features was a discussion as to the saving of ‘line time.’ A committee was appointed to devise a code to reduce standard expressions to symbols or figures. The committee worked out a figure code, from figure 1 to 92. … ”

And, of course, “30” is used by lots of people, including newspaper writers at the ends of their stories. Since stories were originally wired or telegraphed, this usage of “30” makes a lot of sense.

So where does “86” come from then? One of my favorites, but it’s not a telegrapher’s message. Google it and see which theory you believe. It clearly means “removed from circulation” or “ended” but the theories of its origin are interesting and inconclusive in my opinion.

The post 73 and 86 appeared first on Sky's Blog.

Inquiries or QSL “cards”  »  QSL@aa6ax.us

I’ve had an amateur radio license since 1958 when I was in sixth grade—back in Illinois. A bunch of old WWII veterans got me involved as a favor to my father (who was one of the “country doctors” for the area). I started studying the electronics theory and the Morse code when I was 10. Their club meetings were held in a smoky room over one of the downtown stores, and I routinely got sick due to the smoky air. Code practice was on the radio once a week, and I could borrow a perforated paper tape “code practice” machine to fine-tune my skills. It wasn’t easy to get the license!

As a geeky little introverted kid, amateur radio was not really my thing, though morse code (CW) was kind of neat and a fun challenge. It also meant I didn’t have to think of much to say. I never was much for small talk.

The image of ham radio operators is that they are the geekiest of the radio geeks – carrying around little hand-held radios, long whip antennas on cars, and the obligatory plastic pocket protector that all nerds use. Kinda true, but honestly you’ll find most of them are just the friendliest people in the world! And a lot of this friendly activity takes place “off the air” at various meetings. And getting involved in civilian emergency preparedness is really a kick. The NERT program, sponsored by the San Francisco Fire Department, has a whole group of amateur radio operators who participate in weekly drills and activities. And the Department of Emergency Management of the city also has a program that involves amateur operators as a secondary channel for the Fire Department in case of emergency (ACS).

What I found after getting more active again here in San Francisco is that it’s an interesting way to meet a real cross-section of folks from many ways of life, professions, interests, and actually it’s kind of neat to see whether a little 5 watt radio can really allow me to be in a mountain peak in the High Sierras (in the summer) and talk to a friend back in the San Francisco Bay Area.

One of my friends here in the East Bay is a true aficionado, and a great “found-items” artists as well. KY6R

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Now that Apple has announced that the reception measurement on the iPhone is incorrect (reading too high by about 2 bars in some cases), I no longer have an excuse. AT&T claims to have 10 towers within a 2-mile radius of my home office, but most of the time 2 or 3 of them are ”down” and besides, in San Francisco, over half of them are “behind a hill” from me so they do me no good. There are probably only 2 or 3 towers that actually give me any coverage in the office here.

But, Apple knew about the +2 bars problem a long time ago. It was reported in 2009. We were all seeing 2 or 3 bars, and then our software was upgraded and we were seeing 5 bars routinely (except when there were none). We customers knew that the iPhone was giving us more bars than it should have. So why did Apple not know this, or not see the change when this happened in the first place?

And Apple was surprised about this?

Any mobile phone is a mobile radio. And amateur radio operators, which we all are these days, know that if you touch (and thus “ground”) the antenna, you cause a change in signal strength.

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See his photos directly on Flickr for even more.

Here is the second of his photo sets that I promised I’d feature:

The post KY6R Art Gallery (2) appeared first on Sky's Blog.

I particularly like Rich’s approach of using found objects, which trigger nostalgia, and positioning and lighting them creatively. Some might describe his work as spooky or weird as well as completely intriguing.

I’m going to feature two sets of KY6R photos, one set today and one set tomorrow – here is the first:

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