Great tool for checking Line of Sight…

Google Maps has opened up access to resources that would take considerable work and expense to access. Just purchasing software that can do ray tracing over a geographic area 10 years ago would have cost tens of thousands of dollars. Now “HeyWhatsThat” has leveraged Google Maps to do just this and it is free.

Now, why would I be so interested in this site? Being a bit of a wireless geek, it is a great starter tool to understand how much coverage area a mountain top has. In the example shown in the right you can see the coverage area from the Twin Peaks communications site in San Francisco. The orange/red overlay indicates area that this site can see. You can see the shadowing of some of the hills of San Francisco affecting the coverage area.

At the top of the frame, shows a panorama of the skyline seen from that site. The list on the right shows what mountain tops can been seen and distance to them.

HeyWhatsThat is a great starting point in checking out coverage area. I wouldn’t throw away your $50,000 coverage software just yet as that will be a bit more accurate using better algorithms to calculate coverage such as Longley Rice and TIREM as well as their own tweaks.

Major Rant – Title 24

In its every intention, Title 24 tries to reduce power consumption for new and remodeled buildings. In its current structure, it can make it worse.

I really have been trying to be aware in my design and purchase of lighting in our new kitchen remodel. I have been looking at every different lighting option and in particular, LED in the assumption that anything that doesn’t have a “heater” in it and creates waste heat, is good (BTW, this is a whole other blog regarding LED lighting). One of the first things I ran into in my design is California’s Title 24 requirements. At least up to August of this year, California has standards that have a rather strange way of promoting and calculating effective power usage for kitchens.

  1. There is no limit on the power you can put into the lighting of a kitchen. (a bad thing)
  2. The wattage allocated for high efficacy lighting must be 50 percent or more of total lighting wattage. (a bad thing)
  3. Any fixture that can take non-high efficacy lighting devices like incandescent will be counted at the maximum wattage of the fixture. (a bad thing)
  4. High efficacy lighting is based on the number of lumen per watt (a good thing)

What this means is if you have 200 watts of low efficient lighting, you must have 200 watts of high efficacy lighting which makes no sense at all. In fact it could force you into putting more high efficacy lighting in that you need. In addition to this, the old screw-type Edison base for light bulbs is a standard. There are many more compact florescent bulbs out there designed for this base than for a proprietary pin-type base for recessed lighting. Guess which one is cheaper? In order to “comply” with title 24, you need to use non-standard fixtures.

If they really want to “fix” this, they could just limit the number of watts per square foot and strike out this silliness with standard lighting fixtures.

The Farallon Islands’ Web Cam

For some time now, as someone has had an objective to get broadband in remote areas of the world, I have been looking at some lonely islands 50Km off the coast of San Francisco known as the Farallon Islands. Back in 2001 or so, at a past Bay Area Wireless Users Group meeting, Simon Barber, suggested that we hook the island up as the main island is staffed and they just had basic two-way radios for communication to the main land. For various reasons it never quite happened until this year when a number of different interests and funding fell into place.

I was introduced to folks at AirJaldi who were looking for locations in the Bay Area to test their radio deployments. I have access to a number of hill tops around the Bay Area and suggest to them that we put a link into the Farallons. I called US Fish and Wildlife and was pointed to the Point Reyes Bird Observatory as they do the day-to-day operations and science on the islands. At the same time I reach out to them, the California Academy of Science was looking to put a high-definition web cam out on the island to stream back to the public. Bingo, we have funding and very interested parties that want fast bandwidth to the island.

After much work in planning, purchasing and deployment, the Farallon Cam was turned up a couple of weeks ago.

It hasn’t been smooth. Some of the problems encountered have been links failing due to interference or hardware failure. This has caused the stream to be down more than we wanted to, but it did show for a small budget, that consumer grade unlicensed radios can provide decent bandwidth tens of km to provide the infrastructure for applications like streaming video, voice, data, etc.

Startbucks Gold Card..

Months fly by and I get back into the mode of throwing out pointers and thoughts again.

I came across a nice little deal in the last couple of weeks; the Starbucks Gold Card. For $25 a year you get 10% off of over-priced purchases but what hooked me was the fact you also get 2 hours a day of free WiFi at a Starbucks ATT Hotspot. Nice little deal when ATT wants to ding you for $6 to $10 for some part or whole of a day. Just 4 or 5 two-hour visits pays this thing off. The pricing works well if you are a light user of these spots. If I was more of a road warrior then I would look more at Boingo. As someone that is looking for a place to do some work between meetings, it fits the bill.

Uncovering history through National Coast and Geodetic Survey benchmarks

Gads it has been a while. Between conferences, work and play, I let this site languish a bit. Well, here is a cool thing to do and not a rant.

In walking around, do you ever look down and see a small circular brass marker that are embedded into rock, concrete or even buildings. They were placed by the National Coast and Geodetic Survey and are survey benchmarks.

A good description of these benchmarks can be found at:

Many of these were surveyed and planted there at the turn of the last century. As there has been some time elapse since most of these were established, there is some interesting history that can be gotten by looking up these sites and reviewing the data sheets for each marker. Fortunately, the National Geodetic Survey (NGS) has this data on line. By going to:

and entering your longitude and latitude and a radius of the area you want, you can get nearly all of the markers. I say “nearly” as I have found markers that are not in the database. Once you get the listing of markers in your area, tell the page to get the data sheets for the markers. Each data sheet is a bit messy to ready and you can get some guidance on how to go through them from the “” URL above.

Once you have the data sheets, try to find the markers. It is much like geocaching in tracking it down, ‘cept you don’t leave or take anything once you find the spot.

What has been interesting to me when I have gone looking for the markers, is the history of the site during the time the markers have been established. Looking at the data sheets you can see the descriptions of the site at the time it was established and when they revisited the site every 30 years or so. You will find the changes in the area documented in these sheets. For instance, living in San Francisco, I was interested in seeing markers in my area. What I found was a establishment of a long forgotten overseas radio station near my house on Ocean Beach or be able to review how South of Market had changed from a massive Southern Pacific rail yard to a trendy geek enclave.

Homebrew GSM with OpenBTS

Unlike most of San Francisco who was at Burning Man, I was out this last week at the Strawberry Music Festival so there was another gap between postings. There are a couple of interesting stories from Strawberry I will get into later. But for now…

I was having lunch with John Gilmore who was freshly back from Burning Man. Stories abound the festival but one that I zeroed into was the experiment of one of the camps at Burning Man to build a GSM celluar service on a Software Defined Radio (SDR). John was certainly tracking this as he help start gnuradio which is an open-source SDR package that is currently lead by Eric Blossom. Matt Ettus is a another notable as he had created the default hardware platform that Gnuradio runs on.

SDRs are radios where the hardware is designed to be very general purpose so as to receive and/or transmit many different types of modulation and frequencies. The software for SDRs do all the work of setting the frequencies and what to do with the received signals. Hence the name of Software Defined Radio where the software models a hardware design that would create a building block such as single-sideband modulation or a quadrature FM detector. As such, a critical component in an SDR is an Analog to Digital (ADC) or a Digital to Analog Converter (DAC) where the software will do all the math in the digital domain of the analog wireless signal.

What was interesting to me with this deployment was the fact that OpenBTS project built an SDR radio that would transmit and receive on cellular GSM frequencies and become a base station for GSM cell phones. Not only that, they took an open source phone switch called Asterisk and, using VoIP and the Internet connection at Black Rock City, provide cell service to the public switched telephone network PSTN.

Providing service at Burning Man was a stroke of genius as the OpenBTS folks had a great test bench of almost no existing cell coverage there and thousands of attendees that have their cell phones turned on. In fact, this test site was a bit too successful as every GSM phone tried to associate with their setup in almost an inadvertent denial of service attack. Their rig, had a hard time keeping up with the cell phone requests. After they resolved this issue, they were experimentally passing phone calls from Black Rock City off to real telephone numbers around the world.

Now, this is all fun playing with Asterisk and OpenBTS in the middle of North America where wireless phone service is taken for granted. For instance, in the United States we usually have at least two or three base wireless phone carriers providing service to an area. Although these deployments are ubiquitous in first world countries, the current cell phone tower installation is expensive and financially prohibited in deploying in third world nations or even many lightly populated areas in the US. Using Asterisk that easily replaces a 10s or 100s of thousand dollar phone switch help reduce the cost of deploying wireless cell service. In the case of the Burning Man deployment, OpenBTS was able to put a rather effective Cell site for under $5,000. With this low cost of deployment and the combination of OpenBTS and Asterisk vast areas of the earth that are not covered by phone service now could be covered by open source cell phone deployments.

Musicina Blender


I just came away from a week and a half contract gig that had me working from 7am to 11pm many of the nights. Hence the period of radio silence from me. So, I need to get my Blog legs going again.

In the mean time, I just reconnected with a friend and ex-coworker of mine from back when I was the Chief Engineer for KKSF. Nick Francis is now at KPLU in Tacoma Washington and has always been a creative guy. He has started up a new blog called Musicina Blender. It is a list of mash-up that Nick creates. It is pretty interesting how Peggy Lee’s “Fever” can have a reggae beat in what Nick calls “Reggae Fever“. Or Dylan goes Pop with “Positively Fifth Beatle“.

Check it out.

Ancient Audio Streams

Cory Doctorow, posted “Old time record enthusiast rips and posts thousands of 78RPM tracks” on BoingBoing today that points to a collection of 78s on the net. One of the commenter’s of the post pointed to the “Cylinder Preservation and Digitization Pilot Project” (CPDPP) that UCSB runs since 2002. The CPDPP has about 8,000 archived and available for download.

One feature on the site that I have been checking out is the various streams of recordings. For instance, you can get “Historical Speeches on Cylinder“, “Pioneers of Audio Theater” or “Popular Songs of World War I“. I have been glued to listening to “Operatic Cylinders from the William R. Moran Collection“.

I doubt that these streams will give SomaFM a run for the money, but it is certainly worth checking out.

50-in-1 Electronic Kits…

Once upon a time, back in the days of “stone knives and bearskins“, Radio Shack made a series of kits for the budding electronic engineer known as 50-in-1 kits. (You could get bigger sets that promised up to 200 different things you could make.) The kit would be a box with a nice wood frame and a cardboard top that had bunch of different electronic components on it like resistors, capacitors, diodes and one or two transistors. Each of the components would be tied to a little spring that you would bend back to insert hook-up wire into. No soldering and it was a breeze to take apart. The kit would start off with something simple showing how circuits are made using a switch, a light bulb and a battery. It would end up showing you how to make a tunable AM radio or oscillator.

I had one of these kits when I was a kid. My sister and I split the cost of buying one and I ended up monopolizing the use of it. It was at this point when I was a kid, I knew I was going into some line of electronics. I loved following the directions and learning the art and also trying to design my own buy taking there design and “bending” it so the oscillator would run a little faster or slower or pick up a different spectrum of radio to listen to.

Radio Shack has long since stooped producing these kits. I think Radio Shack is missing an opportunity here as they are very visibly sponsoring things like the Maker Faire and other MAKE Magazine Projects efforts. So where Radio Shack, dropped the ball on this a company called Elenco has put out a similar 50-in-1 kit. Amazon sells them for less than $25 each. Cheap! Having a 9 year old son that has a technical bent, meant we had to have one. It was a great time bonding with him on how to build a simple circuit and creating something more complex like an AM radio. It is well worth the $20 investment. (Actually, I have to credit David Diaz for buying it for my son at Fry’s.)

Elenco has a number of pretty cool electronics kits that you can buy and put together with your kids. Their model “FUN-875” is a radio controlled race car that took my son and I a couple of evenings to put together. Once we did, we had a pretty nice little car that ends up being pretty sturdy too.

So, three cheers to Elenco for making electronics a little more accessible to kids again.

Fiber for SF – Part III

Christopher Mitchell wrote back with these comments:

      I don’t think WiFi is a good way for a city to encourage broadband. You note many of the problems, but I also just view it as uneconomical in the long term.
      However, I think there is value in WiFi in certain circumstances. The value of WiFi for a city that has substantial fiber assets is to provide coverage for muni functions and perhaps those who know what they will be getting. Building inspectors, social workers, many city employees can be more productive in the field with wireless broadband access but they need greater capacity than the cell networks currently offer and they can save substantial money when they can put nodes anywhere due to abundant backhaul afforded by the fiber network.
      I agree that indoor access should be handled by the building owner or occupant. WiFi doesn’t penetrate much and offers poor speeds anyway when multiple users are on it.

Christopher is being an activist for St. Paul, Minnesota. I hope he can get further in getting St. Paul to think about deploying broadband over fiber than we have gotten with San Francisco.