Saturday, February 28, 2009

Lunar repeater

Today's outlandish ham radio idea: plop a repeater on the surface of the moon.

This came up during a discussion on Twitter, of course.  The main challenge would, of course, be getting to the moon.  Also, the repeater would be have to significantly larger than a satellite repeater because it would have to have a significantly higher power budget.  Path loss from the earth to the moon (one way) is between 190 and 200 decibels, so a transmitter power of at least a couple hundred watts would be desired, more than can be handled in your typical cubesat. 

In order to power this device, a substantial solar array will be needed, and the lander will have be developed to self-deploy the array on landing.  The station's antennas will also need some way to track the earth, as we'd want to use relatively highly directional antennas for best results.  Presumably all the signals will be coming from the earth, and so an antenna whose beamwidth is only slightly wider than the earth's apparent size from the moon's surface (how big is that, anyway?) would make sense.  At the very least the deployment system has to find the earth initially; since the moon is tidally locked once you've found it it shouldn't move a whole lot, but I think libration movement probably exceeds one earth diameter when seen from the moon's surface and so active tracking would probably be a net gain.

This is, of course, completely impractical, but it would be fun.  And probably very expensive.  And the EME people would probably complain to high heaven if we ever did it.

Friday, February 20, 2009

South Carolina middle school cuts ham radio, astronomy clubs

I got word today that a middle school in South Carolina has cut its ham radio and astronomy clubs, apparently in the interest of cost-cutting, even though the ham radio club operated at no expense to the school.  These two clubs were the only non-sports clubs at the school.

No word on whether they cut any of the sports clubs; I'm still hoping to get more information on this.

Can someone explain to me, in the meantime, why we spend so much public money on sports for our kids, and so little on giving them opportunities to excel in science, math, and engineering?

Tuesday, February 17, 2009

Repeater maps!

Mainly out of curiosity, I decided to map the repeaters in my repeater database coded by CTCSS.  This was a bit of fun, because I had to clean the data (it's amazing how many repeaters are listed with silly CTCSS tone values like "961" or "Yes") and then figure out how to generate a map and put the data onto the map.  The last bit was aided immensely by the Generic Mapping Tools, a nice little set of tools very much in the UNIX spirit.  As K6HX put it to me, "it's quirky, but does a good job once you figure it out".

Click on the thumbnail to go to the full size image on my wiki.

I was kinda hoping that you could see the way some coordination councils use CTCSS tones regionally, but it's not very obvious except for a couple places, like Western Pennsyvlania, Michigan, and Wisconsin.  A different color code might help here; I'll have to explore that later.  I might also do another map, coloring by the majority CTCSS tone in each grid square, but first I'll have to figure out how to plot regions.

By the way, the most popular CTCSS tone is 100.0, with the next four (which trail by quite a lot) being 103.5, 123.0, 107.2, and 88.5.

I'm also really curious about the repeater out in the waters off the coast of North Carolina.

Sunday, February 15, 2009

Conspiring to control space weather

There's a pretty good discussion over on Watts Up With That? regarding the failure of Solar Cycle 24 to get up and go yet, something which has somewhat confounded stellar physicists so far.  Given the relatively high importance of the solar cycle to amateur radio operators, or at least those who operate in HF, we tend to be aware of the solar cycle, and talk about it quite a bit.

However, what got me was the discussion about vested interests lobbying scientists to predict higher solar activity levels than the data would otherwise support; in short, the allegation that elements (at NASA or elsewhere) are being influenced to predict relatively high solar activity levels.  Is there nothing that big business won't stick its big fat nose into and tamper with just to make a few extra bucks?

Friday, February 13, 2009

End of the rabbit ear era?

Image by via Flickr
I ran into this discussion on a blog the other day (thanks to Backtype, which I use to monitor for interesting discussions in places I might otherwise not see them).  It's interesting to me how ill-informed the general population is about the analog TV sunset (which is semi-delayed now, although many places will still go dark in just a few days).  The most interesting one to me is the apparently widespread belief that the converter box somehow replaces the antenna, rendering it obsolete, instead of acting in concert with the antenna.

I suspect a lot of people think that using a DTV converter box to receive TV is something akin to cable or satellite TV, probably because digital TV converter boxes resemble cable TV converter boxes in many ways.  There seems to be a lack of understanding that the DTV box is receiving signals transmitted over the air in the same manner as traditional analog TV, just in a different modulation that their old TVs aren't capable of understanding.  All the DTV box does is convert the signal to one that is comprehensible to an older TV that lacks the digital decoding hardware.  You still need the rabbit ears or rooftop antenna; the DTV box doesn't eliminate those at all.

Another comment in that discussion I found interesting was the notion that "I don't way to pay to watch TV".  Well, you presumably paid for your TV, right?

In my experience, the DTV box in conjunction with an existing antenna will actually work better than that same antenna did in analog.  Of course, my experience is limited to the relatively signal-rich Chicagoland area; your mileage may vary. 

Monday, February 09, 2009

Emergency preparedness doesn't just mean disaster-proofing

The recent ice storm in Kentucky left hundreds of thousands without power or telephone service, as nearly everyone reading the news is probably aware by now.  It also took out cell phone towers and wireless communication systems used by public safety agencies, by toppling their towers, taking out their power supplies, or taking down the landlines that connect the towers with the control points.  Several western counties had no effective communication within or without the county for several days.  This despite the expenditure of tens of millions of dollars to improve emergency communications across Kentucky, as reported by the Lexington Herald-Leader.

The problem is that we are taking the wrong approach to disaster preparedness.  Much of that money was spent on upgrading public safety communication systems to newer (often digital) technologies.  These technologies do not make those systems more disaster-resistant themselves, and in fact can make them less robust because they are often locked to use gear by a specific vendor, which means you can't grab some other brand of radio and just retune it to the right frequency.  More importantly, a fancy digital trunked radio doesn't come with a superstrength antenna that can't be blown down by wind or pulled down by ice, and it's just a pretty shiny box if it doesn't have power.

The Herald-Leader article notes that the state did make satellite phones available to its regional emergency managers, but those phones are expensive to buy and to operate, and are therefore not available in a dense enough distribution to be helpful in a disaster (like an ice storm) that makes travel difficult.  At least this is evidence of the recognition that having backup communications is important, but obviously enough wasn't done, both in material distribution and in training.

The problem, however, seems to be that there is no recognition that the best way to deal with disasters like ice storms, tornados, hurricanes, and earthquakes is not to build you primary infrastructure to resist destruction.  That's foolish.  No comm antenna is going to survive a direct strike by a Force 5 tornado; that mast is going to be either prezteled into uselessness, or else it'll be blown into the next county.  Either way, you won't be using it for communications.  Same deal if your mast is snapped in two by ice, or falls over because of an earthquake.  The way you prepare for disasters like this is to have "ready-reserve" equipment in bunkers that you can pull out and set up when the time comes.  And more importantly, people need to know where this equipment is and how to use it.

And because you want a lot of these bunkers (which by rights should also be stocked with food, water, medical supplies, blankets, fuel, and other such emergency-type things), the equipment should be cheap.  None of these insanely expensive fancy digital radios that only work with one another and cost a bundle.  What you want is a portable antenna mast with a simple antenna that connects to a VHF or UHF analog FM radio preloaded with designated emergency frequencies, and a nice book that explains how to set it up and some information on the designated emergency communication procedures to be used.  In many areas, especially those with rugged terrain or low population densities where VHF line-of-sight communications may not be adequate, an HF radio would be a good addition.  Even so, the portable tower is the most expensive part of this; you'd probably spend about $3000 per site for a basic configuration.

You simply cannot build your infrastructure up so that you won't have a loss-of-communication disaster; even if you had satellite phones at every location, there's the chance that the phones, or even the satellite itself, will fail.  The key here is in providing recovery resources, and in training people in how to use those resources to effect a recovery.  Too many counties in Kentucky had to make it up as they went, and that delayed relief efforts.

Personally, I'm hoping that the Kentucky experience leads to emergency management officials making more of an effort to reach out to amateur radio groups in their areas, and at the same time leads to amateur radio groups making a more concerted effort to organize themselves for preparedness and to communicate with emergency management officials what their capabilities are and how to call upon them.  It seems that both sides have been letting it slide a lot in recent years.

(Updated 2/13 to add link to Iridium satellite collision event.)

Sunday, February 08, 2009

Cell phone tower: NIMBY

It seems that a group of namby-pamby NIMBYs down in Florida (naturally) are objecting to the notion of a local school district installing a cell phone tower on its property in order to raise revenue, citing the fear that the antenna will bake the little heads of the poor unsuspecting students.  Depleted Cranium has a good article with some hard facts on how this is FUD, not that it'll matter that much.

While I remain open to the possibility that the 2 mW/cm² that one gets from using a cellphone next to one's head might be incrementally damaging in the long term, there is as of yet no convincing evidence that even exposure at that level is dangerous. The FCC's exposure studies (see FCC OET bulletins 56 and 65, required reading for any wireless licensee anyway) are based on whole-body models and may be inadequate for wavelengths shorter than 1 meter, but at this point we don't have any science that clearly indicates that the FCC's models are inadequate—just claims that they must be because "all the studies that say that cell phones are safe have been funded by cell phone companies".

I think in most cases the problem is that people think cell towers are ugly (and many of them are, although they are getting better at making them less so), but they think that argument won’t fly and so they rely on the FUD objection instead as that’s perceived as more likely to work. And besides, think of the children!