Thursday, November 27, 2008

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.

Wednesday, September 03, 2008

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.

Monday, August 25, 2008

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.

Wednesday, August 13, 2008

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.

Tuesday, August 12, 2008

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.

Saturday, August 09, 2008

Some of My Favorite Free Music Streams...

I am a music addict. I always have to have something going on in the background or at full blast. I love getting turned onto new music or just toe-tap to a golden oldie. Although I have a decent size library of music, it gets a little old some times and I want to tune into something new. This is where I launch iTunes and bring up some of my favorite streams.

I have to start off with the one that tune into the most and have a lot of respect for; Radio Paradise. Bill Goldsmith is a pioneer in many ways on the net. He built out KPIG's web site and streaming. Just before he left KPIG, he started up his own streaming station and moved to Paradise California. Hence the name. To use an over-used word, the music is eclectic. Rock, Blues, Folk, World, etc. The way I like it.

Bill has a zillion different streams to pick, from 31 to 192 Kb/s and WinMedia to MP3, depending on what you are using to listen to it on.

Speaking of KPIG, there are a number of Americana streams to pick up out there. Another old friend, Felton Pruitt has a site called FAT Music Radio. The music hearkens back to the station that was the predecessor to KPIG and where Felton worked, KFAT. KFAT defined Americana radio and the music.

Roger Coryell (another good friend from my broadcast days) has a site called Twang City that falls into the Americana camp but with a bit more "Twang" to it. You just have to tune in to see what that means.

I mentioned earlier that I love getting turned on to new music and tapping my toes to the oldies. At Beyond the Beat Generation I get to do both. They have the more arcane selection of underground and pop of the later half of the sixties.

Aural Moon picks up were Beyond the Beat Generation leaves off. Dedicated to progressive music from the sixties on toward the current day. You can bump into Brand X, Genesis, Gentile Giant, King Crimson, Yes and the more arcane artists of the progressive movement.

Then there is the point I just need to chill and the best place to do that is at SomaFM. Over the years Rusty Hodge has been putting extraordinary effort into developing the streams that makes this place the reference for trance, ambient, electronica and lounge streaming. Perfect for those late nights when you want something to listen to as you head off to join Little Nemo in Slumberland.

All of the streams I mentioned above are only available on the web. They are "listener sponsored" so they don't get the big bucks from commercial institutions. Streaming uses bandwidth and power, that they need to pay for. Throw them a buck if you can. Some of the sites get some kick back from places like Amazon if you follow the links to buy a CD. This is also a good way to help them out.

Later, I will write about terrestrial stations (AM/FM) streams that you should check out.

Friday, August 08, 2008

Why you should never use zip (wire) ties...

Lets get geeky...

A good argument against zip ties was very well documented by a friend of mine, Steve Lampen at Belden[1]. It gets down to the fact that, as with any wire, you have a transmission medium. Much like coax and open line, you need to have a constant impedance through out the length of the line, else your signal will not arrive on the other end the way you may want due to mis-matches in the impedance of the wire causing standing waves.

What determines the impedance of a transmission line is the dielectric (the material between the conductors, the diameter of the conductors and the distance from each other. Zip ties typically will change that with the amount of pressure that is used for installation of the ties.

Additionally, you have to be careful in how you tie your cables together. Everyone wants a neat looking installation and will likely have a nice even spacing between ties. With the change in the characteristic impedance of the ties and spacing them out evenly, you get a really big notch in the frequency response of the line that is based on the distance of the ties. It is actually better to randomly space the ties.

Cable lacing with flat waxed string is one of the better ways to tie down cable. It provides for less pressure on the cable and is also less of an obstruction when you have to work with adding more or moving cable around the area that you have previously tied down. Many colos and Central Offices (CO) I have worked with have banned wire ties for these reasons.

A great alternative to lacing is VELCRO[2] or hook and loop fabric straps. Velcro has the advantage that it can be quickly moved around and doesn't bind or change the cable specification. Typically it is used to bind a bunch of cables together. You may still need to use lacing to tie that bundle down to a wire tray. RIPTIE was one of the first companies to sell VELCRO for cable bundling. They have nice individual ties but they are expensive. If you don't mind not having a fancy tag on your ties, then just get a roll of VELCO from pretty much any dealer. Wrap the cable and cut as needed. You can even get different colors to identify different bundles. Such as using the resistor color code to indicated bundle numbers. At my last company, we would use one color for core cables and another color for customer facing cabling.

And again, check out Steve's report.

[2] VELCRO is the registered trademark for the Velcro Industries' product

More on Fiber for SF...

I got a very nice email from Christopher Mitchell who is with the Institute for Local Self-Reliance (ILSR) which is a non-profit that "provides technical assistance and information to city and state governments, citizen organizations and industry". The report give a great overview of the different technologies that are available for municipal broadband deployment and can be seen at:

I sent Mr. Mitchell back the comments below on this report:

Much like other reports in this area, it sees WiFi as a solution that I have always had grave doubts about. You can see my "report" concerning this at:

It really comes down to the issue that these deployments on unlicensed bands (i.e. ISM bands) can't guarantee an uptime for the service due to interference from other users on the bands. There is also the fact that 802.11 really has very poor interference handling.

The ILSR report says that wireless is needed for mobility. I really don't think there is as much of a need for a municipality to address this. There area a number of other companies that are already addressing this and, as I see it, the real need for broadband is in the home and business. With that, mobility can be address a couple of different ways. First off cell phone providers do this pretty well for outdoor use. For indoor deployments, that really has be handled by the building owners or tenets. Penetrating walls at any frequency and especially at 2.4 and 5.8 GHz is very difficult.

I do strongly support fiber deployment and it being owned by the local government. The last mile is where 90% of the cost in broadband deployment is. Most of this is artificially high as there is only one or two carriers for the last mile in an area. If we can have a municipal deployment then any Mom-and-Pop through existing incumbent can be on equal footing for providing services to an area. We will see competition at that point.

As no one company can the justification of a city wide fiber deployment, it is up to the city to make this happen.

I have been involved in actively supporting this idea for some time with the city of San Francisco. As such I have provided comments and have worked with the city of SF that outlines a basic working and financial model for the city to deploy fiber.

At this point, I think most cities have a much better and more realistic view of how the technology works, we just need to bring more material to them to justify how municipal broadband will financially work for a city.

Thursday, August 07, 2008

Fiber for SF...

It isn't like there hasn't been any screaming in the past about putting fiber in when San Francisco digs up the streets for the new sewer system, but Tim Redmond makes it seem so in this recent editorial in the SF Bay Guardian. San Francisco Board of Supervisor Tom Ammiano proposed this nearly 4 years ago. His proposal to study deploying fiber was stalled for more than three years by the Mayor's initiative to deploy WiFi with Google and Earthlink. Once that deal died, when Earthlink couldn't figure out how to make a buck off of this plan, then San Francisco started to study this again. I have to throw some of the blame at Mr. Amiano's office as they didn't try to push this study through during the three years it was stalled.

Mr Redmond does make a point. San Francisco will miss this opportunity to significantly reduce the cost of installing fiber for the city and the city residents if they have to go back and dig up the roads again. Just like they missed the opportunity to do this 10 years ago when there were nearly a dozen different fiber providers installing fiber in the ground and they city could have demanded that a portion of those strands be handed over to the city. Or the city could have pulled city owned fiber when other companies were pulling theirs.

The City did eventually come out with a fiber study that raves about the opportunities with city-wide fiber deployment. Lets hope that it has an impact with the city's direction on municipal broadband.

More on Duplicate Email Messages

My other "fav-o-rite" mail user agent (MUA) is Mutt. Seems that Mutt has a nice duplicate mail detection scheme already built in. You can see details of it at:

Wednesday, August 06, 2008

Metro Traffic adds tens of millions of virtual traffic reporters via cell deal.

From "Inside Radio" for August 5th....

    Metro Traffic adds tens of millions of virtual traffic reporters
    via cell deal. Westwood One’s Metro Traffic and AirSage partner
    to use cell phone signals to provide faster alerts, more
    reliable travel times and better alternate route suggestions.
    AirSage compiles anonymous data from signals sent from 53
    million Sprint Nextel mobile phones on traffic flow and speed.
    AirSage’s network covers 150,000 miles of roadway, compared to
    fixed-traffic data sensors, which monitor real-time traffic for
    about 7,000 miles of interstates. The new reporting technique
    will begin rolling out next month.

What a great idea. Typically folks have been dependent on getting traffic info from the sensors that folks like CalTrans puts in the road bed.

I would expect that the technology wouldn't be too complex to do this. You just need to track when a particular cell phone gets handed off between cell sites. Since the tower locations (Lat/Lon) are known, you can determine speed. You can even use the Inverse Square Law and smooth out the signal strength the cell site is getting to see how fast someone is going towards or away from a cell site.

The Trouble with Imap and Thunderbird...

One annoying thing about Imap clients like Thunderbird is you can end up getting a bunch of duplicate messages in various folders from copying messages from your Inbox. For instance, I have one folder with about 17,000 messages in it and a bunch of duplicates that are just taking up space, bandwidth and CPU cycles when I open that folder.

This is where a really nifty Thunderbird plugin comes in handy with the amazing name of "Remove Duplicate Messages". With a simple download, install and a restart of Thunderbird and I found I had about 1,000 messages that were duplicates in that folder, or almost 6% of the folder. In another folder that has my NANOG mailing list, I found about 10% of the messages were duplicates.

The defaults are pretty sane, where it will keep the first message it finds and delete all duplicates after that message. Just right click on the folder (control-click for Mac OSX) and you will see in the menu "Remove Duplicate Messages...". It will start to scan your folder and then give you a list of duplicate mail it found. You can scan through what it though where dups to verify and then click "Delete Selected" to have it move to the trash the duplicate messages. Quick and easy.


Here we go again.

I have recently "retired" from a 9 to 5 life and hence I have a couple of spare minutes to rant about things in the forum. It may be to a "null" audience or someone may stumble across it and find it useful. Heh, that is what the Internet is all about, a way for anyone to publish ideas and thoughts. "Once more unto the breach"...