Archive for the 'Ham radio' Category

The joys of 2 meter simplex

Monday, March 2nd, 2009

I’m up in Parsippany, New Jersey at the moment on business travel. That in itself wouldn’t be anything special, except that the eastern seaboard was just rocked by a huge snowstorm. I had to leave a day early to ensure that I made it here for an important meeting Monday morning, only for that meeting to be canceled while I was en route and incommunicado. To add insult to injury, none of the client employees I work with even showed up for work today, and my car died at the hotel this morning so I walked to the client site in the falling snow. And just for some added excitement, I had to run to escape the torrent from an oncoming snowplow at one point.

The drive up here was no picnic either. About an hour in it started raining, then quickly turned to snow. Thankfully none of it started sticking to the road until I arrived at the hotel four hours and many wrong turns later (not the best time to try a new route). I saw a surprising number of other vehicles driving in the snowstorm without lights on, including one semi-trailer which kept on disappearing and re-emerging from the mist of snow in a terrifying fashion. Even my high beams didn’t provide nearly enough illumination to see the road ahead of me. This was made worse by the constant glow of headlights shining over the jersey barrier from vehicles in the opposite direction, like some dividing line across the horizon, which lit up the entire sky from about six feet above the road on up. The road was thus made darker and less see-able by contrast.

The only thing that hasn’t sucked about this trip so far is ham radio. Sunday night is an excellent time to work the ham bands, which is what I spent my whole commute doing. Repeater contacts have become passé for me these days because they are so easy; at any random point along the I-95 corridor, you can hear at least a couple simultaneous conversations on various nearby repeaters. As such, I focus mostly on making simplex (direct) contacts, which at least provides somewhat of a challenge, especially while operating mobile. I was mostly using the national calling frequency on 2 meters, which is 146.520 MHz, though I did talk to one man on another simplex frequency while idly scanning the band.

I made more simplex contacts during this trip than I ever have before. At one point I was talking with two to three people simultaneously, a feat I’ve never experienced outside of pre-arranged simplex nets while operating stationary. I had some pretty long conversations with stationary operators, as well as some shorter conversations with other mobile operators (as mobiles tend to be a lot more limited in terms of antenna size, elevation, and to a lesser extent, transmitting power).

But the neatest point in the trip was when I briefly became the best ham radio station in the whole area.

I had been talking with a stationary operator for around fifteen minutes. The signal went from bad to good to bad as I-95 took me closer and then farther from his position. His signal was never stronger than S-5 (S-meters give a measure of signal strength from 1 to 9, on a logarithmic scale). About ten minutes after we said our good-byes and he faded into the radio-frequency mist, I arrived at the foot of the Delaware Memorial Bridge.

All of a sudden, the stationary operator I had been talking to earlier came in again. And his signal strength just kept getting better and better. We excitedly traded signal reports in a rapid-fire series of transmissions, remarking on how much the signal quality of the other was improving by the second. My S-meter kept on climbing until it pegged at S-9, still 50 feet shy from the apex of the bridge. The other operator’s signal was full-quieting, meaning that his signal was so strong that not only could I hear him perfectly, even the lulls between the words of his transmission were perfectly silent (because his carrier was so strong that it overwhelmed the ambient radio-frequency noise).

Then as I reached the apex of the bridge, some 200 feet in elevation above the ground and quite the enviable radio location, something really cool happened.

I was able to make contact with my previous contact, much further distant than even the current contact that had just gotten back in range. And in between the gaps in our conversation, I heard a multitude of other voices rising above the static, a chorus of conversations on the calling frequency many miles distant in all directions on the compass rose. So many things were being said at once that I couldn’t make sense of any individual transmission. I could only hear it all as a collective murmur. All of these people out there, each holding separate conversations — and unlike any of them, I could hear it all at once.

As I crested the apex of the bridge, the signal strength from my primary contact rapidly faded back down the S-meter, and with one last hurried transmission, we said good-bye. Then he, along with everyone else, was lost to the static, and I was alone again.

Field Day 2008, wherein even a near-miss with a collapsing antenna can’t spoil the fun

Tuesday, July 1st, 2008

On Saturday this past weekend I did so many ham radio activities I had to split them across two blog posts. Yesterday I wrote about the 17 foot antenna I installed on top of my house. Today, I’ll regale you with tales from Field Day 2008.

Field Day is an annual 24-hour North American amateur radio event running from 2pm on Saturday to 2pm on Sunday. Amateur radio clubs and operators all across the nation set up stations off the grid as an emergency preparedness exercise and public outreach event. Contesting is a large part of it, with the goal being to make confirmed contacts with as many other Field Day stations as possible. So after finishing setting up our own antenna, and after grabbing a quick bite for dinner, my dad and I headed over to Montgomery Amateur Radio Club’s (W3EXP) Field Day location at the Montgomery College campus in Germantown, Maryland.

The Field Day setup was quite impressive. Antennas were everywhere. Many temporary masts, some guyed, some not, filled two different parking lots, a gravel area, and a field. Longwire antennas were strung between trees and in giant inverted-Vs off masts. Altogether the setup had eight separate antenna systems and at least fifteen towers/masts. Two gasoline generators provided electricity for all of the equipment. Three separate rental vans were set up as operating stations, with the radio stations inside of them shielded from the weather (they had a bad experience last year with the weather).

When we arrived, W3TDH was still working on setting up a 20m Yagi on a 50′ crank-up military mast made of aircraft-grade aluminum left over from the Korean War. Unfortunately, we never got that antenna up, because about an hour before dark a vicious thunderstorm blew in. Luckily, being at a ham radio station is about the best place to be when inclement weather is coming in, because everyone was kept apprised with up-to-the-minute weather information using the club’s repeater (it seemed like everyone there had a handheld VHF radio). I was also getting weather reports off the National Weather Service’s channels and the Blumont, Virginia ham radio repeater (147.300), which runs a SkyWarn net during inclement weather. As the storm came in, we shut off the transceivers and most of us headed into the nearest building on Montgomery College’s campus.

However, before I started to go inside, I had the immense “pleasure” of watching two guyed masts come down in the gale-force winds just forty feet away from me. Apparently they had been put up with only two guyed tiers (against W3TDH’s recommendation to use all three), and they came down quite quickly in the high-speed winds. It was a sight to see. The bottom sections of the masts, which were not secured to the ground, blew sideways, either coming undone from their locking joints or snapping right off. Then the entire masts toppled over sideways, straining against their guy anchors, many of which came ripping right out of the ground. Guy wires flew menacingly across the darkening sky. I was very fortunate not to be downwind of the masts when they blew over, because I was closer to them than they were tall. After this, I dithered no further outside.

After weathering out the storm inside the Science Building at Montgomery College until it was merely raining, we emerged to survey the extent of the damage. Those two masts were the only things that were damaged by the storm. Everything else survived just fine. Unfortunately in the meantime darkness had descended, and making progress on putting up that 20m Yagi became nearly impossible.

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Taking amateur radio to the next level

Monday, June 30th, 2008

This weekend was pretty awesome. Saturday was jam-packed with ham radio activities, from morning until midnight (and beyond). That’s right, an entire day of ham radio! I started off by installing the 17-foot antenna I bought awhile back on top of our house. That took a good four to five hours, many of them spent on top of a burning-hot roof forty feet in the air. But it was worth it! Here’s a close-up look at the antenna.

Don’t be fooled by the upwards-looking perspective; this antenna is a full 17′ tall. The mount also adds about two feet to the overall height. Altogether, the antenna is about 30′ in the air. That’s not bad considering we didn’t have to put up a tower or anything. The three spokes sticking out of the bottom of the antenna are the radials, which create the ground plane for the radio signals. And I should point out that this antenna is a marked improvement over my previous antenna, which was a 44-incher at ground level.

The two flanges of the mount are located off-center on the pressure-treated wood blocks. This was not intentional, but rather, a consequence of bad measurement and trying to get the darn thing straight up in the air. But don’t let its looks fool you: the mount itself is rock-solid. You could throw a grappling hook through the mount and ascend to the roof from the ground. Each wooden block is secured with four 4.5″ bolts to blocks of wood on the interior of the house that are screwed directly into the house’s frame.

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How to learn Morse code in GNU/Linux

Monday, June 23rd, 2008

I know what you’re thinking — as if GNU/Linux and ham radio couldn’t possibly be nerdy enough when separate, let’s put them together! But let’s take a step back …

I started getting involved with ham radio just three months ago with VHF/UHF voice FM, and already I’m hungering for more. I don’t have an HF rig yet, and might actually not have one for awhile, but since I know it’s something I’ll want to do eventually, I figure I should just start learning Morse code now. As for why I want to learn Morse code, I couldn’t exactly tell you — there’s just a certain romance to it, and pounding away on a key is such a delightfully different method of communicating than just speaking into a microphone. But ignoring why I want to learn it, here’s how I’m going about doing it, in GNU/Linux no less.

Learning Morse code on the computer is actually harder than it should be. I couldn’t find any Flash or Java applets that do something as simple as generate Morse code. Seriously. I found some really old Java applets that no longer function in current JDKs, but they don’t count. I found lots of DOS programs, many of which are pushing two decades old, but I wasn’t having much luck with them even under Windows. And since I’m running GNU/Linux as my primary desktop now, these programs weren’t helpful at all. Luckily, there’s a simple up-to-date command-line utility for GNU/Linux that does all the basics with a minimum of fuss.

First, you’ll want the morse program. In Ubuntu or Debian GNU/Linux, you can do the following:

sudo apt-get install morse

If you’re not using Ubuntu or Debian, you should be able to find it using the package manager in your distro of choice.

Now, learning Morse is as simple as passing in the right command-line parameters to morse. Here’s what I’ve started with:

morse -rC 'ETAOINSHRDLU' -w 5 -Ts

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Antenna preparations for ARRL Field Day

Friday, June 20th, 2008

It’s been awhile since I’ve discussed non-computer-related construction projects on this blog, so to break the drought, here are some details on a shortly upcoming antenna project.

The Amateur Radio Relay League’s annual Field Day is coming up next weekend. Field Day is the largest weekend of the year for amateur radio operators. It includes of all sorts of outreach activities, as well as heavy contesting (racing to see who can make the most radio contacts over the weekend). Since I only became involved with amateur radio recently, it’ll be my first Field Day. Unfortunately, the only antenna I’m operational on right now is a 44″ magnetic mount 70cm/2m dual-band whip antenna. It’s decent for operating mobile, but its performance isn’t anything to write home about.

Luckily, I bought a 17-foot 70m/2m dual-band base station antenna at a hamfest in March. A 201.5″ antenna is a bit more impressive than a 44″ antenna, don’t you think? I haven’t actually gotten around to installing the antenna yet, but Field Day is as good a reason as any to finally get it done. I’ve already done all the prep work and assembled the mount, which you can see in the picture. The domestic house cat is for scale.

I bought all the parts from Home Depot at not-too-ridiculous prices. All of it is galvanized steel (and thus rustproof), except for the tee-junction, which this particular Home Depot seemed to be out of in galvi. I do have a can of clear gloss waterproofing spray paint laying around though — hopefully a couple layers should be enough to keep the tee-junction safe from the weather. Most of the piping is 1″ interior diameter.

As for how the mount works, it will be installed vertically just below the peak of the roof on the side of the house. The two flanges will be secured to the side of the house using four-inch-long bolt screws. The screws will, of course, be going into studs accessible from inside the attic. The aluminum tube you see attached to the top of the mounting assembly is the base of the antenna; the antenna itself simply drops right into it once the mount is attached to the house. As for the decision of the overall placement, I’m putting the mount on the side of the house instead of on top of it so I don’t have to drill any holes through the roof, which could potentially cause some leaking.

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An amazing 4X Yagi array

Monday, April 7th, 2008

This right here is the definition of want:

Yes, that’s right, it’s a 4X Yagi antenna array on an electronically controlled alt-azimuth mount. Oh man, what I wouldn’t do to have one of those. It’s amazing. It has four times the antennae of a simple Yagi beam, thus four times the gain (an increase of 6 dB). And the alt-azimuth mount gives you two full degrees of freedom, allowing you to track satellites. The one problem I see is that it looks like the Yagis are horizontally polarized (although it’s hard to tell from the YouTube video), whereas for space contact you’d want them to be cross-polarized to account for spinning satellites. It’s still an impressive show all around though.

Plus, you can’t deny how cool it is. It reminds me of a Death Star laser turret, only it’s used for peace, not war. You can’t claim to be a nerd if, after seeing a video of a 4X Yagi array on an electronically controlled alt-azimuth mouth, you have any thought other than “I want one of those”.

How to run a power cable through a 1996 Ford Taurus firewall

Monday, March 31st, 2008

I bought a fused power cable at the hamfest in Maryland this weekend so I could install my mobile ham radio in my 1996 Ford Taurus. There was just one problem: getting the cable from the battery in the engine compartment to the passenger compartment. In between these two sections is the firewall, and the firewall on the Ford Taurus is notoriously hard to get through. Many other vehicles have unused or underused grommets that a cable can be passed through, but preliminary investigations on the web revealed only one unused grommet in the Ford Taurus, but I couldn’t even locate it. I’m writing this blog post so that anyone else who finds themselves in a similar situation will know what to do, whether they’re powering a ham radio, subwoofer, amp, whatever.

Since I couldn’t find a grommet to pass the cable through, I ended up drilling a hole through the firewall near where the gas pedal wire goes through the firewall. I chose this location to drill because it was one of the few spots that was relatively unobstructed on both sides of the firewall. I was worried about the wires potentially interfering with the movement of the gas pedal in the passenger compartment, but I came up with a solution (more on that later).

The place you want to drill through is directly to the left of the circular metal pad surrounding where the throttle wire passes through the firewall. Drill from the inside of the vehicle; the engine compartment is way too cramped. The foot well is cramped too, but doable. You’ll have to lie with your back on the lip of the doorway and your feet on the ground. I recommend using a power drill plugged into 120VAC from an extension cord. Battery-powered drills are more bulky and might not fit in the cramped space inside the foot well, and you’re going to need a lot of power to get through that firewall (you are drilling through fireproof metal, after all).

Power cable going through hole in firewall
Fig. 1: The hole in the firewall where the cable passes through. The two black cylinders contain the fuses. The hole in the insulation is a bit bigger than the hole in the metal firewall underneath, which is just big enough to fit the cable.

My power cable consisted of a red and a black wire joined together, so it was significantly larger in one dimension. Thus, I had to cut out a tall hole that would allow the wire to pass through. A neat trick is to drill two separate close-by holes with a smaller drill bit, then keep drilling with larger drill bits until the two holes merge. Then you’ll be able to fit your non-circular wire through. Also, I definitely recommend wearing a heavy duty leather glove on the hand that’s holding the drill. I wasn’t, and I left a good bit of skin on the sharp steel vent when I scraped my finger against it after the drill abruptly pierced through to the other side of the firewall.

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Attending my first hamfest

Sunday, March 30th, 2008

Earlier today I attended my first hamfest (amateur radio convention), the Greater Baltimore Hamboree and Computerfest in Timonium, Maryland. Having just started with ham radio less than a month ago, I’m definitely getting into it pretty quickly. The rate at which I’m blowing through money will attest to that.

Overall, I give the hamfest mixed reviews. I’ll start with the negatives first so we can end on a positive note. Most of the negatives stem from my misconceptions of what this hamfest was. I was expecting a convention where the main activity is chatting up fellow hams and checking out cool rigs, but this hamfest turned out to be basically a large flea market, with a good mix of professional and not-so-professional vendors. It had a $10 per head admission charge.

The computer part of the show was just outright crap. Most of the computers on sale looked like they were acquired by the pallet-load from public auction, and simply weren’t worth buying even at the low asking price of $100-$200. I swear, some of those computers were pushing ten years old. If you wanted cheap and/or used peripherals though, this was your place (yay for $5 three generation old non-scroll-wheel optical mice). And if you want to risk all of the rest of your expensive computer components on shady unmarked power supplies, this was your opportunity! In the end, I just couldn’t justify spending any money on the computer stuff, so I didn’t. I’ll take NewEgg any day of the year. The tailgating part was especially depressing; a bunch of people (some of them hucksters) were selling miscellaneous computer and electronics junk set up on cheap tables out in the parking lot. I saw electronics equipment that was decades old. Who wants this stuff?!

There were lots of vendors selling vacuum tubes of all shapes and sizes, tens of thousands of them. The average price was about $1.00 per tube, which my dad says is less than they used to cost decades ago when they were still widely used (and that’s not taking inflation into account). None of the tubes were manufactured in the past few decades either. It’s like the transistor exploded onto the electronics scene so quickly and so completely that the inventory of tubes the manufacturers happened to have on-hand at the time was more than enough to satisfy the entire lingering tube market in perpetuity.

A lot of the vendors were, and there’s no other way to put it, shady. I wouldn’t go so far as to accuse them of having outright stolen what they were selling, but a lot of it wasn’t on the level, starting with the fact that most people weren’t charging sales tax and probably weren’t even reporting their sales to the IRS. There was no way to verify if a lot of things that were on sale were actually working, and presumably no way to return them if they weren’t. I’m also not intimately familiar with most of the kinds of things that were on sale, and I would have no idea if I was getting a good deal or a bad deal.

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This is Major Tom to ground control

Monday, March 24th, 2008

GeneSat-1
My friend Greg and I spent several nights this past week attempting to listen to amateur radio signals from the International Space Station (he’s been using Gpredict to find time windows of orbits close to us). Not only is one of the crew members on the station a ham, but they also have a fully functioning repeater on the station as well. The uplink frequency is 437.800 MHz and the downlink frequency is 145.800 MHz. I had my squelch turned to minimum and my volume set high, but I never heard anything but white noise. Oh sure, I fleetingly thought that I had a variety of contacts, but that was just my brain playing tricks on me. It’s a well-known psychological quirk that people can fool themselves into hearing meaningful noises in pure static, or seeing patterns in random shapes.

I spent twenty minutes on each of several different nights listening to white noise, straining with all my mental might to hear something amidst the cacophony. But we never heard anything. None of the orbits brought the ISS closer than 800 miles. It was simply too far for our receiving equipment. We both have 44-inch magnetic mount dual-band whip antennae, the kind that can be affixed to the top of a vehicle. They’re good for ground-based mobile operations, but not for trying to receive signals from space! For that, you really want a cross-polarized Yagi antenna on an altitude-azimuth mount (imagine how large ground-based telescopes are pointed and you’ve got it). And that represented a far larger investment in the hobby than either of us has made so far. Are receiving transmissions from space limited only to the upper echelons of the hobby? Is attempting it with entry-level equipment as foolish as someone with a cheap telescope from Wal-Mart searching for a new planet? I would soon find out.

After another annoyingly silent ISS pass last night, gpredict showed that the biological research satellite GeneSat-1 (see picture above) was passing almost directly overhead in another twenty minutes. It also happens to be equipped with a beacon operating in the 70cm amateur radio band. I was skeptical, and it was getting late, but I couldn’t miss the opportunity. This would be four times closer than any pass of the ISS so far (and thus sixteen times the signal strength, thank you inverse-square law), so I was hopeful. The frequency of GeneSat-1′s beacon is 437.067 MHz. I can only tune my radio in 5 KHz increments, but the Doppler shift of the orbit spreads the signal out enough that it would be heard on the frequency I tuned my radio to, 437.065 MHz, if indeed the signal was strong enough to be heard at all.

So again I turn the squelch all the way down and the volume up to almost painful levels (if you’re a fan of overblown metaphors, imagine a fighter pilot setting his afterburners to maximum, his plane roaring and rumbling around him). I listened intently as the minutes slowly ticked away. GeneSat-1 crested the horizon; nothing. It began rising higher and higher in the sky; still nothing, though my mind was now alerting on fake signals at an alarming rate, only for each to be rejected after a moment’s consideration.

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We get signal. Main transceiver turn on

Saturday, March 22nd, 2008

First of all, accept my apology for the groan-inducing title of this post. It popped into my head and I couldn’t not run with it.

Last night I was idly chatting away on a 2 meter band repeater in Rockville, MD (frequency 146.955 MHz) when someone by the name of Fred (callsign K3CSX) broke in at the end of the conversation and said he had a radiogram for KB3QNZ, aka me. He proceeded to read off a message, which I copied. Here it is:

Greetings via amateur radio. Congratulations on your new callsign, a most worthy and deserved achievement. Welcome to the amateur radio world. We are glad to have you with us and hope you will enjoy the fun and fellowship of the organization.

The message came from Gil (callsign W1GMF) out of Massachusetts. Of course, I immediately had some questions, such as: What is a radiogram? Who is Gil? How did this message get to me from Massachusetts? Luckily, Fred stuck around long enough to answer my questions.

My radiogram was transmitted using the National Traffic System, a nationwide, hierarchical message-passing system relying solely on amateur radio links, and thus not dependent on the phone system, the Internet, or any other communications infrastructure. The nodes in the traffic net have backup generators for use in emergencies, so the National Traffic System isn’t even dependent on the power grid. If everything else goes down, it will still be there. Think of it as a safety net for society, silently chugging away unnoticed in the background of everyday life, ready and waiting for a mega-disaster to spring into action at full speed and save many lives when all other means of transmitting emergency communications go down.

However, the NTS just isn’t used all that much in non-emergency situations (it used to be, but then email came along), so people like Gil routinely put messages into the system just to keep everyone in practice. And what better messages to send than greetings to new hams? He tracks down the new hams to send messages to by looking for recently published callsigns in the FCC’s database of licensed ham radio operators.

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