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Jul 292013
 
A radio repeater retransmits your radio signal, greatly increasing the range you can communicate over, and potentially getting it past obstacles and obstructions.

A radio repeater retransmits your radio signal, greatly increasing the range you can communicate over, and potentially getting it past obstacles and obstructions.

If you wish to establish emergency communications with other people in your immediate neighborhood, then you can probably do this successfully with portable VHF or UHF radios – ‘walkie talkies’ – ideally using higher powered longer range Ham radios analogous to but better than the popular FRS, GMRS and MURS radios anyone can use.  We have written about this topic regularly, most recently an article about optimizing the performance and range of short-range VHF/UHF radios.

But if your comm needs lie outside the admittedly very short-range within which convenient VHF/UHF direct communications will reliably work, even after optimizing your radio equipment and antennas, you have to consider either a different way of using your VHF/UHF radios, or switching to a different frequency band that allows for longer range (beyond line of sight) communications and which is less likely to be blocked by buildings, trees, hills, etc.

The simplest approach is to extend the range of your existing VHF/UHF radios by using a local repeater for your VHF/UHF communications.  Instead of communicating directly with the other people you need to communicate with, you send your signal to the repeater, and it then rebroadcasts it on to the ultimate recipient (and, of course, to everyone else listening at the same time!).

The wonderful benefit of this approach is that you use the same equipment you already have, and don’t need to invest in anything extra.

The Pluses and Minuses of Using a Repeater

We’re a bit ambivalent at suggesting you use public repeaters as a solution to your emergency communication needs, because we’re now saying ‘In the event there’s a massive disruption in society and its normal services, you need to rely on one such service still being available’ – that’s not a very sensible plan, is it!

But it costs you nothing at all to program some repeater frequencies into your radios.  Because the repeaters will be located some miles – maybe even twenty, thirty or more – away from you, maybe they will not be impacted by the same event that has caused the loss of cell and regular phone service and forces you to use your wireless capabilities.

The two big concerns with using repeaters in an emergency situation is whether they remain operational and whether they become very congested with lots of ham operators all excitedly chatting to each other about whatever event has occurred.

For the first issue – remaining operational – the big challenge probably relates to the continued availability of power at the repeater.

It would be helpful to find out if any of the local repeaters are solar-powered.  If they are, then clearly that is an enormously positive step towards being free of reliance on grid power.  Even if not solar-powered, maybe the repeater has a battery backup good for an hour or so of operation – that might be enough time for you to at least get in touch with your family members and agree on what, when, where and how you’ll meet up.

If your local repeater doesn’t have solar or battery power, why not suggest they add it.  Join the group/club that operates it (we’ll tell you, below, how to find out who the group is) and suggest you add this capability.  You’ll probably find the idea is warmly received – many ham enthusiasts are half-way to being ardent preppers already; and even those who aren’t love the thought of a ‘real’ emergency coming along where they can start to apply their ham skills and equipment in an important and essential manner.  Ham radio is a key part of our national emergency communication capability, and suggesting to your local repeater group that they should ‘harden’ the repeater and make it more disaster-proof is an issue that they’re probably going to be completely in favor of.

Having a repeater that will still work without grid power would be a very valuable enhancement to their ability to assist in a major emergency, and with the relatively low cost of solar systems these days, you might find it a concept that could be quickly implemented.  You might have to volunteer to coordinate a fund-raising appeal!

If all else fails, you could suggest applying to the local ARES or RACES coordinator for a subsidy to make the repeater self-powered, but there’s a danger that if you do that, ARES/RACES would claim it exclusively for their own use in an emergency, so perhaps it is better not to do that.

For the second issue, congestion, we can only guess as to what to expect.  In theory, ham operators are supposed to be very careful to avoid clogging up the air-waves, and should observe specific protocols and courtesies to enable the best use of the frequency at all times, including in an emergency.  In reality, though, what can we expect?  It is anyone’s guess as to what might happen.

You should also check if the repeater group has any arrangement to dedicate the repeater to ‘official’ emergency type services in an emergency, or if it will remain open, either to the entire general public, or to official members of the support group.  The best case scenario would be limiting the repeater to members of the support group, the worst case scenario would be restricting it to official emergency communications only.

Bottom line – we’re not saying that a repeater is something you should 100% totally rely on.  We acknowledge its limitations and instead are putting it forward as a possible alternate when all your more desirable options have failed.  It is something that might work and if it does, might be very helpful, and so, with no cost to you involved (because you already have your radios) why not at least include it as one level of your multiple levels of emergency communications.

Repeater Range

There’s nothing magical about how a repeater provides its extended range, although finding that your ability to communicate has suddenly grown from maybe being able to reach 5 square miles around you to now being able to reach over 1,000 sq miles sure can seem very close to magic.

The main benefit a repeater offers is that it is usually sited in an excellent location – on the top of a tall building, or on the top of a hill.  That simply gives it a much greater line of sight than you have on the ground, and because its signals are traveling down from a height, they are less troubled by buildings, trees, and other obstructions that otherwise cause you problems when trying to communicate, on the ground, to someone else on the ground.

A similar rule of thumb applies to repeaters as it does to direct communications.  If you can theoretically see the repeater (you might need binoculars or a telescope to actually see it), you can probably receive its signals and it can probably receive yours.    If you can’t see it, then it might still be within range depending on how much stuff there is blocking the signals – you’ll have to try it and see for yourself.

It is common for repeaters to be able to send and receive signals from 20 miles away, and often even further.  Just like the topography greatly impacts on non-repeater radio range, the same applies with repeaters too.  Some repeaters have a more than 50 mile range, and some reach out as far as 75 miles.

Remember that these distances are the repeater’s radius, which means you could be however many miles to the north and the repeater will receive your transmission and rebroadcast it, allowing it to be received however many miles to the south (as well as to the east, west, and everywhere else), giving you a best case range extension out maybe 150 or more miles.

This would be unusual, however, and normally you are better advised to consider most repeaters as having about a 20 mile radius of coverage.  If you can reach signals from further away repeaters, so much the better – the thing to do is experiment and create your own coverage map of where you can activate and receive repeater signals from which repeaters.  You need to become familiar with the repeaters in your area, their coverage ranges, their quirks of operation, and so on.

Short Range Benefits Too

So sometimes, maybe, you can get 100+ miles of range from using a repeater.  That’s great, but the chances are the people you most need to take to are much closer than that.  Indeed, sometimes the range extension you need is more like one or two city blocks, due to a block of tall buildings preventing any signals passing through them.  Or maybe you need a mile or two due to a small hill putting the person you wish to communicate with in your signal’s ‘shadow’ zone.

There’s every good chance a repeater can help in those cases too, and while it might seem ‘the long way around’ to communicate via a repeater 20 miles away to talk to a person one building over from you, the ability of the repeater, somewhere up high, to ‘see’ down to both your location and the other person’s location might enable some of the otherwise very difficult short-range special communication needs too.

Finding Nearby Repeaters

You might not realize it, but your local region probably has multiple VHF or UHF repeaters all within range of where you are and hopefully simultaneously within range of where the people you may need to communicate with will be, too.  The major challenge is knowing where the repeaters are, what frequencies they use, and what their CTCSS access control tones may be.

There are a number of sources you can turn to for this information.  This site shows, for example, 117 repeaters in ID (and the same number in MT too).  The ARRL Repeater Book lists 136 for Idaho.  Repeaterbook.com has 143 entries.  Radioreference.com has only about 60.

Note that a larger number of entries may or may not be better than a smaller number, because maybe the larger number of entries includes out of date listings for repeaters that no longer exist.

The best source of information – most complete and most up-to-date – is from the state or regional frequency coordinator group.  How do you find these groups?  You should get a copy of the annual ARRL Repeater Directory (we prefer the full size spiral bound edition, but there’s nothing wrong with the tiny pocket edition other than its small size print,, and its small size is a benefit when traveling) – this has a good listing of repeaters in it to start with, and has contact details for all the local frequency coordinators listed in the front.  Many of the coordinators publish their information on websites; if not, a courteous email from you to them (include your Ham callsign to confirm your bona fides) will usually get a fast and helpful reply.

Programming Your Radio to Work with Repeaters

Not all radios can work with transceivers.  You need a radio that can transmit on one frequency and listen on another frequency, and which can add control tones to its transmissions to ‘unlock’ the repeater.

Our favorite handheld radio – the Baofeng UV-5R– has all the capabilities you need, and so too does our favorite mobile radio – the AnyTone AT-5888UV.  Most other ham grade radios will too.

To work with a repeater, you need to know what frequency it listens on, and set that as your transmit frequency.  If the repeater requires a tone to activate it, you need to program that into your transmit side, too.  Then you simply add the repeater’s transmit frequency as your receiving frequency, and your radio is good to go.  Sometimes (rarely) a repeater might have a control tone on its transmit signal, but we usually ignore that when programming it in to our radios.

Most of the 2 meter repeaters transmit at a frequency 600 kHz higher than the frequency they receive on.  With the 70 cm band, the frequency change is usually 5 MHz, but some parts of the country have the transmit frequency higher than the receive, and other parts have the opposite.  So be careful to check which way around it is with the receivers you are hoping to work.

The information in the resources mentioned in the previous section give you all this data.

Which is Better?  VHF or UHF?

Should you search out VHF or UHF repeaters?  That question presupposes that you have the luxury of multiple choices of repeaters in the areas and locations you want to communicate within; that is usually true in most city areas, but much less true in rural areas.

Quite possibly, in a rural area there might be only one repeater, or – alas – maybe none at all (in such a case, don’t despair – we’ll be publishing a future article on how to set up your own repeater).

If you do have choices, our suggestion is to try them all and program them all into your radios.  At present, the ‘best’ repeater is of course the one which is most available and used the least, and which provides a good quality signal between you and the other people you need to communicate with.

But in a future event, WTSHTF, you’ve no real way of knowing which repeaters might remain functional, and for how long, and which repeaters may quickly become hopelessly overloaded with way too many people all excitedly and urgently trying to communicate each other.

The more different repeaters you have pre-programmed in to your radios, and the better you understand the coverage footprints of the repeaters in your area, the more likely it is you’ll end up finding one that works.  (Note that you and the other members of your group will need to have a pre-arranged methodology for which repeater signals you’ll listen to.)

If you are getting a single band mobile or portable radio, and plan to use it with repeaters, you should consider which band has the most repeaters available.  The two most common bands are the 2 meter and 70 centimeter bands, and (much less commonly) there are some 1.25 meter band repeaters too.  Some regions seem to be more focused on the 70 cm UHF band, others on the 2 m VHF band.

In terms of better range and signal, that is usually more dependent on the repeater location and equipment than on its frequency.

Who Can Use a Repeater?

Most ham repeaters can be used by any and all hams.  Some are restricted to members of the repeater association group only, but this is uncommon.

On the other hand, when you use a repeater, you need to realize that you are using someone else’s equipment.  Someone has spent considerable time and money creating and maintaining the repeater.  If you become a regular user of a particular repeater, it would be appropriate for you to join the group that manages and maintains the repeater, and contribute time, resource, or money to help in its upkeep.

Repeaters for GMRS Too

Although most of the ‘open to the public’ repeaters are for ham operators and are on ham frequencies, there are a number of GMRS repeaters out there too.  There are nowhere near as many GMRS repeaters as ham repeaters, though.

If you use a GMRS repeater, there is a slightly higher chance of you being required to have a current GMRS license, and if you’re going to get one of those, maybe you should get a Ham license instead (cheaper, albeit slightly more bother).

This website has a listing of some GMRS repeaters, some of which claim to have truly impressive coverages.

Note that very few GMRS radios on the market are capable of working repeaters, because they can’t send on one frequency and receive on a different one.  You would need to get a professional grade GMRS radio, or skirt the legal issues with using a dual purpose radio such as the lovely low-priced Baofeng UV-5R series (see our many articles on these radios, perhaps starting from here).

Summary

If there are repeaters in your area that provide coverage both in the locations you are likely to be in, and also in the locations other people in your group are likely to be in, then if you have problems establishing direct communication, working through the repeater might be a possible alternative approach.

Obviously direct communication is always better – less things to go wrong, and probably less congestion on the frequency you use as well, but this is not always possible.  In such cases, and assuming you’ve already done all you can to optimize your radios and antennas, it is logical to try repeater style communications.

It is unknown how available repeaters might be in a disaster situation.  Become a supportive member of the group that manages and maintains your local repeater(s) and encourage them to invest in standby power supplies such as batteries and solar.

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David Spero[suffusion-the-author display='description']

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