Upgrade your CB - add a Ham Radio

Submitted by tsm1 on Wed, 11/18/2009 - 16:57
Body

During our last Delegates meeting we discussed Divide Ride 2010 in the Boulder area, and Don Apker and I spoke a bit more and I happened to mention that we would have good "2 meter radio coverage" for the area thanks to a repeater on Boulder Hill and other resources. As many of you know, I picked up a new hobby a year ago by becoming a licensed ham radio operator. Don expressed some interest in what advantages ham licenses could be for all of us, and what steps are involved. So, here's my attempt.

An Amateur Radio operator, or ham, is a licensed, non-commercial radio operator. There are various frequency "bands" or ranges set aside exclusively for use by amateur radio operators. These include short-range as well as worldwide capable frequencies. There are three tiers of licenses, but only the first two are of concern - Technician, and General. Tech privileges are mostly short-distance, while General opens up the worldwide frequencies. Tech is the license class most 4x4 enthusiasts are interested in.

Getting a license is pretty easy. You no longer need to know Morse Code. You just need to get 29 of 35 multiple choice questions correct on a test. The test costs $14-$15 to take, you can take it as many times as you'd like, and once you pass, your license is good for life. Well, the license is good for 10 years, and you can then renew, free of charge, for another 10 years and so on. If you just remember to renew every 10 years, the license is free for life.

The test consists of 35 4-choice questions of basic electronics theory, basic radio theory, and some "policies and procedures" that are specific to how the FCC wants you to behave. Those with electronics backgrounds can probably pass the test "cold" on the first try. If your electronics are a bit rusty, a little study wouldn't hurt.

There are various study guides available from www.arrl.org and elsewhere. If you sit down and read the Technician book from cover to cover, you will have everything you need to pass the test. It might take a month of evenings, or a week of good reading.

Once you've studied, or just to find out your weak spots, you can take an online test. http://www.eham.net/exams/ (select the Technician option). You can take these tests over and over again, and they will show you the correct answers and whether you ultimately would've passed or not. Once you manage a passing grade on the online tests with regularity, it's time to contact your local "VE" (Volunteer Examiner) at your local radio club, and find when they'll be doing their next test session. Walk in with a #2 pencil and $15 and some ID. Mark the cirlces on the test, and if you pass, expect a unique call sign to be assigned to you by the FCC within a week. At that point, you're a licensed ham radio operator.

What does that get us?

I'll start with the mostly boring and mundane bits.

Everyone has a CB in their 4x4, right? CBs operate around 27Mhz. A high performance CB installation involves an 8.5' whip antenna mounted in the center of your vehicle, ideally with 8.5' of metal in all directions (you *might* get that front to back, but never side to side). Your 8.5' whip is driven by a 4 watt AM signal, or maybe if you're fancy a 12 watt Single Side Band (SSB) signal. This is good for a few miles, and when conditions are right (skip) good for a thousand miles or more.

The most common Ham band we would use while 4-wheeling is the "2 meter" or 144Mhz band. This band is near the "land mobile" business band some of you may be familiar with - also used by fire and police services. A comparable installation to the CB would use a 19" long steel whip, with 19" of roof in front, behind and - now we can get on either side too - and driven by a "low power" hand-held ("HT") radio making a mere 5 watt of FM power. FM means nicer audio (less "scratchy"). You won't have much chance of "skip" for long-haul communications (which means a lot less noise), but with 5w and that 19" long antenna you can talk farther than the CB on a line-of-sight "short" distance contact (short meaning

5w is what a battery powered hand held outputs. Most "mobile" radios (akin to your CB) for ham use are 25w to 50w output radios, with 75w and even 110w units available. With a CB, you are limited to 4w AM or 12w SSB maximum. With a ham license and a 2 Meter radio, you're limited to 1,500 watts - or the safe exposure limit. (1500watts into a hood mounted antenna 3' from your head is not within the safe exposure limits).

So right off the bat, we can get more reliable communications, clearer communications, smaller antennas (less twanging of tree branches) without compromising on signal, and we have the option of running more power to make it even better. Oh, and no "skip" noise booming in.

The downside is everyone needs a ham license ($15 and a test).

Better rig to rig communication (called "simplex") is nice, but there's another big upside. Hams have gone through the trouble of installing mountain-top repeater sites. 2 meters is line-of-sight, so they install repeaters on top of towers on top of mountains, giving the repeater a hundred miles or more of "line of sight" coverage to hand held or mobile operators. Repeaters also have good antennas, and powerful transmitters. 100 milli-watts into a hand held radio with a very poor antenna is sufficient to go from downtown Helena to the Belmont repeater located near Marysville (Great Divide Ski Resort) 25 miles away. The repeater then retransmits your signal, reaching all the way to Three Forks. To hear a response from a friend in Three Forks would require more than 100mw hand a hand-held because of the distance involved, but 50w and a mobile station would probably do the trick.

Repeaters mean we have the ability to "get out" to someone else. Many times we're out of cell coverage, but we are within repeater coverage. You come upon a forest fire, or an injured ATVer, or something else. You now have the ability to call for help through the repeater - someone else with phone coverage will hear you and relay your emergency. In other situations, a fellow wheeler, or concerned spouse, can monitor the repeater from home (or wherever they happen to be) and you can use the repeater to relay home that you'll be late for dinner, or that someone is broken and needs a part delivered, or to bring the truck and trailer. All from areas where cell coverage is unavailable.

The third hot item to explore is a little more technical, but also pretty slick. Hams have a service they call APRS, for Automatic Packet Reporting System. Sometimes also called the Automatic Position Reporting System, which sells the whole thing a little short. This is the marriage of your ham radio with your GPS. A small device called a "Tracker" is installed between the radio and the GPS. There are one-way and two-way trackers. A one-way tracker receives info from the GPS (your position, heading, etc) and then keys up the radio and operates like a modem, encoding your position and transmitting it out. It does this on a regular basis, or when a preset condition occurs (you make a turn).

Two-way trackers do the same as the one-ways and report their position, but also receive position reports from the other radios in the area, and then either shows a screen of the other stations, or plots them on the GPS as waypoints. Want to know if your tailgunner made the correct turn at the fork in the road a few miles back? Just look at your GPS and you'll see a (periodically moving) waypoint for the tailgunner.

Taking this another step, the hams also have a network of APRS "digipeaters" and iGates. The digipeaters just repeat what they've heard and are often co-located with voice repeaters, so the same coverage areas apply. Once a packet (transmission) reachs an iGate, it gets put onto the Internet as part of APRS-IS. You can then use tools like http://map.findu.com or http://www.aprs.fi to plot a position onto Googlemaps. In this manner, someone back home can monitor your progress and knows your exact location should something go awry.

There are a number of other more advanced topics to touch upon, like using your truck's mobile radio as a repeater allowing you to use a small hand held to relay through the powerful mobile radio, or high gain antennas to make more out of your available power, sending messages (email) via APRS, and others.

Back to Divide Ride. There are repeaters on top of Boulder Hill. There are other repeaters in the area as well if the Boulder repeater is hidden by a mountain from a particular spot, but with the repeaters available coverage of most of the DR 2010 area is possible using ham radios. APRS coverage is also available. This means we could set up a laptop and radio at camp and someone could just look at the display and know immediately where all of the trail groups are, if they are on schedule, and estimate when they'll be home. We can also use FM voice to contact the trail leaders for a status update - or in reverse, to radio back for help, supplies, or a trailer.

Beyond Divide Ride, there are areas we wheel where cell coverage doesn't exist, but the risk of injury does. The Rubicon Trail, in particular, has good repeater coverage, but poor cell service. As you get to eastern Montana, or northern Montana, tall repeater installations can cover a hundred miles. I am able to access a repeater located in Great Falls from car in Helena (~90 miles) using 50 watts. I'm also able to access that same repeater from Havre with the same setup.

My CB has never provided 100 mile coverage with any reliability. I've been able to talk to Tennessee, but not Great Falls.

Discussion