Monday, April 11, 2016

Wildflower Triathlon Lake Visit #3

Since it's now April, most of my free time is being dedicated to preparing for the Wildflower Triathlon. Of course, I'm nowhere near crazy enough to actually attempt to run a triathlon; I'm on the communications team, so my triathlon experience involves more radios inside a dispatch center than running or swimming out on the course.

This weekend was the last of several big work weekends before the event, where we worked to get all of the communications systems and plans ready, as well as cleaning up the whole park in general. When we weren't out setting stuff up or cleaning, we were sitting in meetings going over the event timelines or crisis plans for if anything happens (rain, heat, major injuries, etc).

My weekend started a day early; I took Friday off from work so I could beat the rush out of the bay area, and managed to get to Lake San Antonio around 1PM. First thing I did was stop by our radio site and turn on one of our UHF commercial repeaters, which is solar powered before the event and used to coordinate the pre-event logistics. Once that was sorted, I pulled into the committee campground and was immediately put to work unloading food and supplies to keep the committee fed and happy all weekend while working around the park. The majority of committee (~70 people across all the functional groups this weekend) showed up around 6PM, at which point we had dinner, a couple hours of presentations, and a scavenger hunt to familiarize the new volunteers with all the important locations around the course. The day concluded with some well-earned drinking, and it's off to bed at 2:30AM.

My Saturday started at 6:00AM, by which point the hospitality team had already made breakfast available, so a quick bagel and Greek yogurt for breakfast before it's off to work. Rumor had it there was a "tree issue" down at Beach City where all the Cal Poly volunteers camp event weekend, so I drove down there and showed up to this:
A tree had fallen over, and needed to be cut up into firewood/chipped before the event. Normally, the park rangers take care of issues like this, but since the San Antonio park was shuttered last year that work load has fallen on us to get the park ready for the event. A few hours of cutting wood, and it was time to go work on getting our dispatch center set up with the rest of the communications committee.
Normally, we run our dispatch center out of the park visitor center, but the building was recently condemned, so we've been getting creative with where we set up all of our radios.
Thankfully, the next building over happened to have an office available, so the rest of the morning was spent setting antennas up on this wooden frame we built last year, running coax, and reorganizing the inside of the office to how we'll need it event weekend. It's hard to see, but the unistrut has three commercial UHF antennas, two VHF commercial antennas, and an amateur X-50 dual band antenna. As you can imagine, needing six antennas means it can sometimes get a little fast and heavy in dispatch.
We also needed to set up a few lines of lathes for marking off the communications campground to afford our volunteers some separation from the event when we're off-duty. I left the communications committee with a pile of 50 lathes and a mallet, and later came back to discover their creative solutions on how to all pound lathes at the same time. Sticks and stones may drive our lathes, but something something something...

Having made it to lunch time, it was cold cuts for lunch, and then I reported to Race Command for a 90 minute meeting on planning EMS response event weekend. During the event, we're usually juggling several ambulances, a few fire response trucks, and a med-evac helicopter, so there's a lot of moving parts which we need to make sure all move in concert.
After the EMS meeting, it was back to Beach City to work on that fallen tree more, and have a meeting with the operations committee on how we were doing on the master to-do list. These are the great guys which you never see during the event, but who all make the entire event possible.
Chris and I caught the action item to go do more wood cleanup around the park. Various branches have fallen off trees, so we went out and Chris cut them up while I loaded them in my pickup to deliver to our firewood piles. My Ford Ranger may be the smallest truck of everyone on committee, but it pulls its weight.

After a few hours of branch cutting, it was time for dinner, and then more well-earned partying for the committee. Thankfully, I managed to get to bed sooner on Saturday: an opulent 1:30AM.

It's remarkable how well trained my body is after a few years of helping with this event; even after a day and a half of hard work and hard partying, Sunday I'm still up at 6:00AM sharp without an alarm.

Just as I'm sitting down to breakfast (again magnificently ready when I got up thanks to our wonderful hospitality volunteers), word comes in that one of the committee members is stranded a few miles outside the park where her car just died. A few of us load up in a truck and head out to see what we can do. We didn't manage to get the car re-started, so we hitched it to the truck and I got to steer the car back into the park while getting towed.

After grabbing a few bites of what was left of breakfast, it was back to dispatch to continue with some fit and finish there. Things were going smoothing, so Chris, Casey, and I loaded up to go attack another branch laying in the middle of one of the camp grounds.
This branch had clearly fallen a few years ago and been simply dragged off the road. We had need for the firewood, so the challenge was to see if we could again fit such a large branch in my pickup.
This was about when Chris looked over and saw a very young rattlesnake coming towards him in the grass. One point on the board to Casey for dealing with it.
Success! And working on it didn't even run over into lunch. We may have gone a little past my truck's load limit, but thankfully I only needed to limp it back to our volunteer campground. After dropping the wood, it was back to the committee campground for lunch.

After lunch, we started cutting volunteers loose as they finished up their final prep for before event week. Most of my afternoon was spent discussing our policies for using the computer aided dispatch system that I spin up for the event, and lots of cleanup around the committee campground. By 4:00PM, pretty much everything was cleaned up, so I dug deep and braced myself for the three hour drive home and rolled out.

At this point, the next three weeks for me will be spent in the bay area configuring and testing radios to be ready to drop in event weekend, which for me starts the Tuesday night (April 26th). Most of the rest of the volunteers show up Friday (April 29th), and work through Sunday afternoon (May 1st).

If you're interested in volunteering on the communications committee, we're still looking for more signups until this Friday (April 15th). It's best if you have your amateur radio license, but even if you don't we can still put you to good use in places where an amateur license isn't required.

Sunday, April 3, 2016

Speaking on Solar Powered Radios

One of my new years resolutions this year was to try and give four talks this year at conferences or club meetings, since I have recently fallen out of habit of doing that.  My first talk towards this goal will be next week, on April 13th for the West Valley Amateur Radio Association in San Jose.

Since my day job is as a solar test and applications engineer, I thought it would be fitting to be talking about how to build 12VDC solar systems to power radios. The talk will be including the basics of solar cells, how to wire them up to batteries using solar charge controllers, and some stories of how I've used them in the past.

So, if you're in the Silicon Valley, available next Wednesday night, and interested in using solar to power radios, I'd encourage you to come out.

Tuesday, March 22, 2016

Tower Climbing on Mt Toro

This Saturday was a nice change of pace; I got to climb a 180' radio tower.

Starting several months ago, my buddy Marcel and I decided to get serious about our amateur tower climbing and started putting out feelers for anyone in the bay area/northern California looking for volunteer tower climbers. This got us in touch with the WB6ECE repeater group and the Salinas Valley Repeater Group, which are both extensive repeater networks which inevitably have some tower work in their queues which we can get in on.

I had actually encountered the architect of the WB6ECE network before (Matthew Kaufman), when he gave a talk on simulcast repeaters at Pacificon in 2014. He had a project where he needed to move one and add another antenna to the Mt Toro radio site, which is south of Salinas.
The subjects for the day are the two black folded dipole arrays on the left of this picture. The four bay UHF set was already on the tower, but needed to be moved up to make room for the VHF pair which we added right below it. We also needed to run new 7/8" hardline for both antennas.

The UHF antenna feeds one of the several WB6ECE 441.300+100.0Hz nodes, which are all on a single frequency and use simulcast magic to allow you to wander up and down the whole coverage area while using the same frequency. The new VHF antenna was to bring up the 147.270MHz repeater, which will eventually be linked into the Salinas Valley network (which I often monitor from the bay area via KE6STH).
So the site details: The site is shared between MBARI and the department of education (for Santa Cruz county? Monterey county? I don't remember). The Monterey Bay Aquarium Research Institute had some really interesting radio systems on the site; particularly the two tracking microwave dishes (in the big white spheres) which point themselves at the MBARI research vessels out on the water so they can still have high speed Internet and HD video, etc.

The tower is 180 feet tall, and Matthew's mounting bracket was at the 110 foot mark. Moving one antenna, adding another, and hanging some coax may not sound like much, but that really is a full day's work on a tower like this. Marcel and I spent about five hours on the tower, and climbing 110' is tough enough that we opted to have our lunches delivered to us up on the tower. We were both rudely reminded that we don't do this on a regular basis, so hand cramping was a major concern (as was my ability to move at all on Sunday; my back is still complaining).
This was our view during lunch. This is why I'm willing to drive 1.5 hours to climb a tower for free.
When you're a radio nerd, Saturdays don't get much better than this.

Do you live in the bay area/Northern California and have a tower in need of climbing? Are you interested in tagging along and working on the ground crew for one of these visits? Drop me a line and we can talk.

Wednesday, March 2, 2016

Saturday, February 27, 2016

Lehigh ARKnet Site Install

Today was a big day. After nearly a year of searching for a radio site, we were finally able to move forward on the Cupertino ARKnet project, which I last blogged about last January.

The Cupertino ARKnet is a project that my friend Marcel and I decided to support with the city of Cupertino to build a point to multi-point microwave network across the city to provide resilient network connectivity between the city Emergency Operations Center (EOC) and various critical sites around the city. This network is designed to stay up in the event of a major disaster and still provide a suite of useful services, even if Internet connectivity is entirely cut off.

What has proven to be the largest challenge so far has been getting access to a site where we have line of sight for most of our sites of interest. This challenge was finally overcome when we signed a site agreement with Lehigh Southwest Cement to build a sector site on an abandoned water tower on the northern edge of their property, which is on the western edge of Cupertino.
The day started off bright and early at 8:30am. We all met up at Marcel's apartment and loaded up all the staged equipment and supplies between Marcel's car and my pickup. This radio site isn't the most difficult site to get to, but there are dirt roads involved, which are normally only used by heavy quarry equipment.
The site is an abandoned water tank on the side of the waste pile for the Permanente Quarry. Lehigh Cement wasn't able to provide us power this far from their plant, so it looks like we need to run the site off-grid.
The first order of business for the day was clearing and leveling a location for the solar panels. Lehigh was not able to provide us with power and our site agreement didn't include pouring concrete (the irony was not lost, considering that this is a cement plant), so the site is powered by a free-standing solar panel array on pavers.
Marcel did an amazing job designing and building the panel frame out of unistrut. You'll notice that we've got the panels angled unusually high. For angling solar panels, the rule of thumb is that for maximum power generation across the year you want to match your panel angle to your latitude. This is technically correct, but is only true for power generation averaged across the entire year. This is fine for grid-tied solar systems since any excess generation during the summer can be dumped onto the grid, and shortfalls in the winter can be covered by buying energy from the local utility company.
Since our system is off-grid and only has 100Ah of batteries, we're much more concerned with the minimum daily power generation (in the middle of winter) than the total available power across the whole year. During the summer, there's going to be so much power available that our battery bank is going to be fully charged half way through the morning, and then the rest of the power for the day is going to do nothing but keep the batteries topped up.  Instead of the 37 degrees elevation based on our latitude, we built the frame to hold the panels at 50 degrees elevation. Now our winter power is as high as possible, at the expense that we're leaving a bunch of power on the table during the summer, which wouldn't be put to any use anyways.
Once we got a good start on the solar panel install, I turned to the issue of mounting the access point on the top of the water tank. For our initial roll-out, we're only using a single 10MHz wide channel in the 5.8GHz unlicensed band. As our network grows and we find needs for greater bandwidth, we plan to add additional sector antennas here or at additional sector sites (the network routing has been designed with multiple sites/antennas per sector in mind).

As for the hardware up the tower, we're using a Mikrotik SXT SAr2. (Yes, it's really there; it's tiny!) This gives us a relatively wide 90 degree beam width, which for this site covers all of Cupertino with a single radio. All wisdom about deploying point-to-multi-point says that trying to cover this much of this area is going to be a bad time. Frankly, I'm going to be relatively shocked if we make it very far with just this one sector antenna, but getting to the site and adding more radios is so easy that I figured we would give this a wag and see how far it gets us. We're not looking for a huge amount of bandwidth (~5Mbps), so we can tolerate lower levels of quality than if we were trying to operate a consumer WISP.
While I was up the tower playing around with hose clamps and zip ties, the rest of the team installed the solar panels and electrical system.  The solar panels are four 80W CdTe thin film solar panels (BP Solar 980L). You might say 320W of solar panels for a single 5W router might be a little over-kill, and I wouldn't disagree with you. We are going to have a very comfortable power budget (which is going to keep our batteries really happy), and this leaves us plenty of room for growth as this site gains additional sectors, point-to-point links, etc over time without us needing to revisit the power system.

I deeply, deeply regret having gotten frameless thin film solar panels for this project. It's the timeless story: guy finds guy on Craigslist. Guy offers guy solar panels at $0.75/W. Guy gets great deal on solar panels before entirely appreciating what a pain it is sourcing 6mm frameless panel clamps.  Getting the edge clamps for these panels to mount them to the unistrut was a huge pain, and I'm never dealing with it again.
The electrical cabinet for this site was graciously donated to us by the Cupertino maintenance department (synergistically transferred, really?), and again is set up for growth. The bottom shelf holds two 100Ah 12V deep cycle lead-acid batteries, wired in series to make a 100Ah 24V bank for the solar charge controller.

The middle shelf holds an EPSolar Tracer 2215BN solar charge controller, a 24V-12V DC-DC regulator to provide some 12V power for the network switch and fan, and an unmanaged workgroup switch with a PoE injector for the access point on the tower.  The solar controller warrants some particular attention: this is by far the least expensive solar controller I've seen which actually uses Maximum Power Point Tracking (MPPT), which is a big deal. Lots of $20 charge controllers on eBay will claim that they are MPPT, but they simply aren't. MPPT means that the controller is going to make an effort to hold the panel array at the correct voltage/current to extract the maximum amount of power available from it given the current solar conditions, which isn't a trivial task since this magic point moves throughout the day based on the amount of sunlight and temperature, and the fact that the panels are wired as an 80V array while trying to charge a 24V battery bank. This takes a serious DC-DC buck converter, which is why MPPT controllers need such a beefy heat sink compared to the cheaper PWM controllers.

The top shelf is currently mostly empty, waiting for more equipment or a second battery bank. The only thing there now is an MT-50 control head for the solar controller. This is another feature of the EPSolar Tracer series controllers that I absolutely love: their user interface is over RS-485 MODBUS, so you can mount your controller as close as possible to your batteriy bank and load, and all you need to do is run CAT-5e to wherever you want your nice user interface to the controller. The control head lets you set the battery charge mode, etc, as well as review all the collected statistics like current panel/battery/load voltage/current and cumulative power generated/consumed in kWh.

SHAMELESS PLUG: I'm giving a talk on solar panels and designing these sorts of solar power systems next month in San Jose on April 13th, 2016 at the West Valley Amateur Radio Association. If you're in the Silicon Valley and interested, I encourage you to come see.
Last points of order for the day were fit and finish on the cabling and adding weights to the array frame.
I will freely admit that it is possible that two T-posts, three cinder blocks, and 20 sandbags are maybe overkill for keeping this panel array from blowing away, but we really don't want it to blow away, and the sandbags were free (thanks city of Cupertino!). In an ideal world, we'd have poured concrete and/or had a much better idea what our worst case weather conditions would be on this hill. Barring both of those, we decided to just make a good wag at "really heavy."
As for the question of how well the site is working, that's a question I can't answer yet. The next step in the project now that we have the first access point up is deploying client sites to connect to this one. The first 90% of the work is done, so now we just need to get the next 90% done and see where it takes us.

Of course, a huge thanks again to our great team of volunteers, the city of Cupertino for supporting us on this project, and a HUGE thanks to Lehigh Southwest Cement for entertaining some random group of volunteers setting up some equipment on their property. The Cupertino ARKnet wouldn't be possible without everyone's help.

(Thanks to Marcel AI6MS and Jim KN6PE for letting me use their photos in this blog post)