Sunday, December 2, 2012

Disturbing GMRS Trend

Went it Frys to buy some walkie-talkies for the neighborhood kids. My girls often loan theirs out, and since I went high-end for them I wanted something less painful should they get damaged.

Problem is that it seems like most of the radios now don't come with CTCSS/DCS support. You have to go up into the > $50 range to get tone squelch. Midland seems to have more models at the lower range; from what I saw Uniden had almost none. The premium price seems like a lot, given that the code squelch support is likely already in the radio's ASIC. (It would make zero sense for the radio vendors to design more than one radio ASIC.)

I should probably note that I can understand the business motivation behind this. Most people who don't work with radio as amateurs or professionals are likely confused by CTCSS/DCS. The vendors made this problem worse by marketing it as a "privacy code" - customers likely call tech support all the time complaining that people can monitor their "private" transmissions. Eliminate the code, support call rates will go down. That doesn't mean it's a good idea.

Wednesday, November 28, 2012

Are Church Steeples the Answer to Cellular's Prayers?

CBS5 in San Francisco recently ran a story about how churches are allowing cellular carriers to locate cell sites in their buildings and steeples.  It's a seemingly win-win solution - churches are usually in need of supplemental funding, and carriers are faced with the dilemma of adding coverage while also dealing with community rejection of towers/poles due to aesthetics and/or concerns about RF radiation safety.  Win-win?  Maybe not...

Over the past few years there have been a lot of new stories about problems with police radio systems.  Complaints about noise, drop-outs, and sometimes a complete failure of the system are often cited in these articles.  In some cases, the issues are caused by substandard equipment, poor planning, and poor installation.  But other times all of these are ruled out, and yet the system remains problematic.

What then is the cause?  A while back the City of Oakland, which has been plagued for years by failures of their police radio system, pointed the finger at cellular carriers as the culprit.  Oakland PD's radios are very close in frequency to some of the cellular bands, so it makes sense to investigate this.  And in fact, when the cell sites were turned off the problem went away.  So is the problem with the cell site, the police radios, or both?  Certainly there are some radios on the market which have poor receivers and are likely to pull in radio signals from cellular bands.  But lately I've been working with a team of consultants on analysis of these cases which shows that over-crowded cell sites may in fact be contributing to the problem.

Securing the permits, regulatory approvals, and community support for cell site construction is a huge problem for the cellular carriers.  So when they find a site, they tend to load it up with as many systems as they can.  The problem is that the signals can mix with each other and create very fast transient high noise floors near the sites, even outside the cellular bands.  The more systems sited close together, the more likely it is that this will occur.  So while cellular may seem like a God-send to churches, they should be careful to avoid overcrowding - or there might be hell to pay in the long run.

Sunday, October 14, 2012

Pacificon 2012 : Club is a Four Letter Word

Had a great time at Pacificon 2012 today.  This was the first year I brought the kids.  It may have been a bit over Tara's head, but Nora enjoyed hearing from NASA Astronaut Lee Morin about life aboard the International Space Station, and soldering her own Morse Code Sounder at the ARRL's Youth Program area. 

My presentation this year was on organizing in the 21st century, and how to reorganize existing organizations to attract and retain people born after 1980 (termed "Millennials").  I think it was well received, and in fact the audience started asking so many questions that I didn't get through all my slides.  For anyone interested here's the presentation.