Tuesday, January 17, 2017

APRS Symbol Look Up Table

Click to Enlarge
In APRS, symbols on the map are encoded as two ASCII characters. The first character selects the table (primary or secondary) and the second character selects the symbol from that table. (The table selector can also be used as a alphanumberic overlay on top of the secondary table)

The symbol list is available online here, but I've always wanted an easy-to-use graphic with the symbol codes and the icons right next to each other. I finally broke down this week and created the image you see above based on Hessu's great APRS vector symbol set. Click on the table to see it in full resolution.

To use this table, simply find the icon you want to use, read off the symbol code above it, and use "/[symbol code]" if it's in the middle square and "\[symbol code]" if it's in the bottom square.

Sunday, January 1, 2017

2016 Retrospective

It's the end of the year, so I figured I'd do a general life recap and wax on what I'm looking at in 2017.

First and foremost, I changed jobs this year. I'm now an electrical engineer at Lam Research in the etch engineering group, where I'm working on their wafer plasma etchers used in semiconductor fabrication. This is particularly fun because I got this job through one of my Cal Poly Amateur Radio Club cohorts, so I get to see him nearly every day (thanks Sean!). It's an interesting group to work in since wafer processing spans a wide breath of fields including power systems, vacuum tech, RF power, embedded controls, etc. Most of my workload is related to my experience in RF systems, so designing RF filters, but the Lam Etch Engineering group is organized in such a way that I enjoy a high level of diversity in the problems I get assigned to, so I'm not concerned about ever getting pigeon-holed into just working on RF.

My group at Lam has been growing very quickly this year. Even just since I started we've hired three more EEs and looking for a few more. If you're in the bay area and looking for a job feel free to shoot me an email if you're interested.

My personal hobbies have continued to be involved and time consuming. My previous new year's resolution was to get back into public speaking and give four talks to radio clubs. I only ended up developing two new talks this year, but there was enough interest in them to take them on tour and give the same talks several times so I think it mostly counts as a success:
I've been having fun building and deploying radio repeaters. On the bench side, I've been putting together a collection of videos on repeater building [1][2][3][4]. Online information on repeaters is tough to come by, and I don't feel like I've even made a dent yet, so plenty more repeater videos are yet to come. On the repeater deployment side, I got to spin up several of my personal repeaters at events like the Wildflower Triathlon under my commercial radio license and at the Bay Area Maker Faire on the amateur repeater test pair.

In addition to working communications for the Wildflower Triathlon for TriCalifornia, I got talked into volunteering for several other of TriCal's events. A dedicated communications team isn't needed for their other events, so I instead got to work on the course team placing cones and traffic control around the race courses for the Pacific Grove Triathlon, the SF Triathlon at Alcatraz, and the Giant Race. Getting to drop traffic cones off the back of a moving box truck is a kick.

Sadly, TriCalifornia recently announced that they're not hosting any of their own events in 2017, so my event support in 2017 is going to need to be more diverse.

I've been having fun climbing towers for the Salinas Valley Repeater Group this year. They're a good group of guys with an impressive repeater network set up covering the bay area down to Fresno. I love tower climbing since it's a good day of exercise on top of a great excuse to get tours of radio sites.

In the category of "crazy adventures I never got around to writing about," one of my friends this year called me up at the last minute in the end of June:
"Hey Kenneth, I know you like to go on crazy adventures. You want to help one of my friends put on a commercial fireworks in Ft Bragg?"
Yes. Yes I do.

It ended up being a full day experience of get up at 5am, drive up to Ft Bragg, spend the afternoon unloading 650lb of fireworks and the corresponding gun racks out of a box truck, and then firing the show before crashing in a motel. The fun part about these "hand-fired" shows is that we don't use a mile and a half of electronic matches to light off the shells but I get handed a 20 min road flare at the beginning of the show and get to run around using the road flare to light off the fireworks.


So now for the question on what I want to try and do in 2017. My tradition of trying to pick up a new hobby every year started getting more difficult recently mainly because my hobbies (repeaters, beer brewing, tower climbing, etc) all tend to be so equipment intensive that my apartment is starting to get ridiculous with all my stuff.

I think I was on to something good with the 2016 "public speaking" objective, so I think I'm going to go on a similar vein this year and try and get four magazine articles out the door. I've been complaining about how disappointing the amateur radio magazines have been long enough that I just need to put up and start delivering the content I want to read. The ARRL also pays pretty decent money for accepted content too, so that's a nice perk that this year's hobby might actually be cash positive for once. We'll see at the end of the year as to how I do.

Here's to another year, and I hope all of your objectives and achievements find you in good health as well!

Tuesday, December 27, 2016

Experienced my First Escape Room

As my Christmas gift from my sister, she booked the two of us a session in an escape room today. Escape rooms are a live-action puzzle experience where you get locked in a room and have one hour to solve the series of puzzles provided to try and find the final key which unlocks the exit so you can escape from the puzzle.

Extra Credits has also made a video on escape rooms:

The room that we did was "Secrets in the Attic" from Beat the Lock. The room's story is that your grandmother has died and you have an hour to find your inheritance before the greedy relatives arrive. Beat the Lock also has a "Spy Room" scene which my sister has done before. Since we only made our appointment as the two of us, there was an additional eight participants grouped with us who we didn't meet until we checked in. They turned out to be a very cheerful extended family, so we were able to integrate with the rest of the team relatively quickly and they certainly had a big bearing on the overall experience since these rooms are primarily built around teamwork.

The Good

When we first arrived in the lobby, our moderator greeted us and made a point during the room briefing to make sure we all got to know each other and got a good grasp of the scope of the puzzles we were getting ourselves into.

Once we all understood the rules about being able to ignore the scenery tagged with the "no clues here" stickers and how we as a team can wave at the surveilance cameras at any time to spend one of our hints if we all get stuck, we were lead into the room and "locked" in. I say locked in quotations since they didn't actually lock the door like is traditional but simply closed it and we simply treated it as locked until we found the winning key. I very much appreciate their motivations for moving to this format, and I did find the experience a bit less stressful knowing that we weren't really locked in.

Once we got started, we had one hour to assemble associated clues and solve the presented puzzles to open locks and activate mechanisms which all got us closer to finally finding the victory key. Since this was my first escape room experience, I can't speak to how these puzzles ranked against other escape rooms, but it was pretty clear that Beat the Lock has an in-house puzzle development team and isn't buying an off-the-shelf escape room kit. The puzzles has a good variety of formats, and they were good about not expecting you to bring any outside trivia to the table.

Between the ten of us (my sister, the random extended family of eight, and myself) the puzzles were big and multi-faceted enough that we all got to contribute to the final solution. There wasn't much time during the hour when not everyone was busy working on something.

One thing that I did really appreciate about our moderator was that she did get on the room intercom a few times in excess of us spending our hints to keep us from veering wildly off-course. At one point during the experience we had the dialog:
Me: "Ok, well try the combination XXXX"
Other participant: "Nope, that didn't work..."
[About a minute of us brainstorming and trying other combinations]
Moderator on the intercom: "Someone has said the right combination; try them again"

Turns out we were right on our first combination, but the padlock just hadn't opened. Per the rules, she didn't have to have gotten on the intercom and told us we had already gotten it, but it saved us several minutes of fumbling around on a few of the puzzles during the hour. Which brings us to...

The Bad

On most days these escape rooms are booked for six to eight sessions across the day. That's possibly 80 people a day coming into a very physical experience and having an hour to tear apart the room to find their way out. The room certainly did show some wear and tear; everything was a little broken and a bit ajar.

The room had a slightly cheap feel to it. Many of the props felt like they had been bought from a thrift store or put together from plywood and 2x4s. The padlocks were all very cheap and sloppy combination locks bought from the local hardware store. (Remember how we dialed in the right combination and it didn't open?) There was certainly a level of effort put into the ambiance of the room, but you could still tell that this was an office in an office suite with some wood paneling screwed into the walls. The experience was enjoyable and I had a good time, but it wasn't what I'd call immersive.

I don't know how the $30/person price here ranks with other escape rooms, but I will admit I ultimately found the pine instead of hardwoods and overhead office lighting instead of mood lighting forgivable at this price point for the experience.

I feel like if they brought in a good woodworker to tighten up their boxes and panels, a painter to make their artistic elements a little less "hand-drawn", and an engineer to tie together their interactive elements a little better with some sort of programmable logic controller, it would have taken away my only real disappointment with the room in that it felt a little cobbled together.

Final Thoughts

I carried a lot of anxiety into the room, but between the moderator and everyone else on the team the experience ended up being very low pressure and enjoyable. Compared to what I've read about other escape room experiences online, Beat the Lock is clearly a much more comfortable and laid-back environment to get introduced to the medium than others, and for that I am very grateful. The experience wasn't entirely immersive and had some loose threads around the edges, but coming for the hour of frantic puzzle solving and not the roll playing, I still very much had a good time. I'd say the room's strengths were where it mattered.

I had fun! We solved the room in 55 minutes, albeit needing to cash in all three of our hints. I would do a puzzle room again. I will likely come back and try Beat the Lock's other current room or their future rooms as well.

Disclaimer: This was a Christmas gift from my sister. I have no business relationship with Beat the Lock, but simply enjoyed their service.

UHF Amateur Repeater Test Pair

Repeaters are expensive and time-consuming systems to build and deploy. Because of this, the frequencies that repeaters operate on are actually afforded a special level of protection in title 47 part 97 that normal amateur radio operations are not. When two groups come up on a simplex channel, everyone is obligated to sort it out among themselves as to how to resolve the issue, but when it comes to repeaters, they're allowed to defer to centralized regional coordination bodies to mediate which repeater gets to stay on a frequency and which one has to close up shop and move to a different frequency pair or go off the air.

In California, the relevant organization is NARCC. Any time that you set up a new repeater, you should ideally go to them and follow their policies to get your repeater into a state of "coordinated" so you can fall under their protection from future interference. Unfortunately, when it comes to high density urban areas like the bay area, we are essentially out of free repeater pairs, so unsurprisingly the politics involved in getting a new repeater on the air is eye-watering for "just" a hobby.

While I do work on a few permanent repeater systems coordinated under NARCC, I'm not the formal trustee for any of them, so I have relatively little interaction with the coordination committee. Where I do often end up being the trustee is for temporary repeaters which are deployed for only a matter of days for special events such as the Wildflower Triathlon or the Bay Area Maker Faire. Getting coordination for these events wouldn't work out, since the coordination process is so slow and labor intensive, so I often get challenged by other amateurs for "how dare I set up a repeater without NARCC coordination."

When it comes to UHF repeaters, I actually kind of do technically have NARCC coordination. At least in the 440 band, NARCC was kind enough to set aside one of the repeater pairs to be designated as a "test" pair. This pair is designated as a free-for-all, and presumably meant primarily for use at new repeater sites for evaluating range to assist in getting a new repeater coordinated. I've been having great success using it for these small weekend deployments in much the same way that you would select a simplex frequency for an event and just pray that no one else needs the frequency.

At least in California, the best pair to use for temporary or portable repeaters is:

I didn't know about this pair until last year when I stumbled upon it in a band plan graphic on the NARCC and the Santa Clara County websites.

Unfortunately, it doesn't seem that there is a likewise allocation on any of the other repeater bands, which is understandable since 2m repeater pairs are in such greater demand than UHF pairs (at least a longer waiting list beyond there being none left?). I know of some groups who will just pick a repeater pair that's not locally used much and try and fly it in under the radar, but if I were to ever need a 2m pair for a temporary deployment, I plan to follow essentially the same protocol I use for utilizing an existing repeater, only for just their frequency pair instead of their actual machine:

  • Identify a repeater within the area where I need communications resources.
  • Reach out to them before the event to seek permission to use their repeater pair.
  • Set up a repeater on their pair with a different PL tone. Possibly have them disable their box for the hours of operation.
  • Thank them profusely after the event
  • Nudge the hosting organization to donate $100-$750 to the repeater trustee for the use of their repeater pair and dealing with us for the weekend.
Many repeater trustees take the coordination process very seriously, and it's a relatively tight-knit community of repeater operators across California, so you will make a bad impression on a lot of people very quickly if you get known for setting up random repeaters on other people's repeater pairs, even if just for a special event.

Sunday, December 25, 2016

Mastr III Repeater Teardown Video


I recently purchased a pallet (!) of Mastr III repeaters for some parts. These are really unique radio systems since they're so modular, so I thought you'd enjoy a video where I tear one apart and talk through its basic theory of operation.

I mention the video I've previously done on phase locked loops.

Repeater Builder has a prohibitive amount of information on the Mastr line of radio, including a giant list of datasheets on each module which I really enjoy.