Here are some posts by Mark Forbes to the CBCC email list. Mark cross-posted from another list. The posts talk about using Business Band radios to access the USHPA frequencies. Business Band is above the two-meter HAM band that we use. But, the use of Tone Squelch is exactly the same for any radio freqency band. The only difference is that in Business Band you have the potential to step on Police, Fire, Ambulance, etc. traffic since that's where they operate. In HAM, you only step on your friends - and the HAM 'police'.
Posted by: "Mark G. Forbes"
Mon May 10, 2010 9:59 pm (PDT)
(Re-posting a comment I made on the Alaska list last week...)
Folks, I saw the comments on tone squelch. I must emphatically state that I do NOT
think this is a good idea, and here's why.
I'm sure that every one of you is using a type-accepted, business band radio. Not
one of you is using a ham radio which is modified to transmit and receive out of
band. None of you would even consider doing such a thing. With that in mind, I'll
point out what could happen to people who might not be as ethical and careful as
you all are.
The ONLY radios which you may legally use on the business band are those radios
which are type-accepted, business band radios. These radios are not ones which
you can select a particular frequency on, nor can you change their settings. Only
a licensed radio technician can make those changes. Operation of any other type
of radio on that band is illegal, and may subject you to a fine of up to $10,000
and confiscation of your equipment. These radios have a simple user interface;
a knob to select channel 1-2-3-etc, and a volume knob. My Icom IC-F11 is a
canonical example of such.
The FCC has limited resources for investigation and enforcement, and so they
rely heavily on reports of interference to target their efforts. The most common
cause of interference reports is operators on a shared band stepping on each
Tone squelch makes it so that you don't hear traffic on the band unless it has
a particular sub-audible background tone overlaid onto the voice traffic. These
tones can be set for different frequencies, and so you can distinguish different
radios by setting different tones. There's also digital squelch, where each radio
has a particular number and each transmission has a little data blast attached
that tells the radios which ones it's for.
The five business-band frequencies are NOT solely owned by USHPA. They're what
are known as "transient", meaning that they're shared among many users, and all
users are expected to listen first for a quiet opening, then make their transmission
and ID with their callsign. These frequencies are licensed nationwide, unlike
most others in this band which are allocated to specific fixed services like
taxi companies, buses, contractors, truckers and so on.
Near this band, and interspersed in it, are police, fire, ambulance, public
works and other government allocations, all with their own dedicated assignments.
All of these users have sole use of their frequencies, and interference is
dealt with very assertively.
A person running tone squelch cannot hear other traffic on the band, and will
therefore tend to transmit over the top of other legitimate users without
regard to them. This quickly results in complaints. Some radios have a feature
called "busy channel lock-out" which prevents transmission when there is
activity, and if tone squelch is used then that feature is absolutely a
necessity. A business band radio should have this feature enabled by the
technician whenever coded squelch is turned on. Generally speaking, if the
tone squelch system is used, then the owner of the frequency has organized
some sort of operating plan for the radios allocated to that frequency,
and has trained the operators of those radios in its use.
The real answer is that if there's substantial traffic from other users, it's
time to go find a different frequency. You can select one of the other
business band channels which are authorized, or you can get your ham license
and operate a ham radio on any of the simplex frequencies between 144.5 and
148MHz. As a ham, you'll be aware that there's a band plan which defines
how that space is used, and only certain areas are to be used for simplex
(non-repeater) operations. And there are a few other dedicated frequencies,
like 144.39 for the national APRS network, and weak signal/satellite
operations down near 144.0. I personally use 145.555 as my local 'talk-around'
frequency with friends who are hams. "Meet me on fives."
Having a ham license also means you can use repeaters, which may greatly
extend the range of your handheld radio. Don't do this if you're able to
connect locally, but if you're out in the boonies it can be a big help.
Ham operators are fairly vigilant about people mis-using their band, so
don't go operating a radio on the ham bands unless you have your license.
That's not very hard to do; there are on-line practice tests, and you
can find a local exam every few weeks. Study the book and/or take the
practice tests until you're passing reliably, then go do it for real.
Tone squelch is a useful tool in the hands of someone who fully understands
the implications, is operating legally with proper equipment, and usually
is licensed for sole operation on a particular frequency. It's NOT
appropriate for a shared transient channel.
Mark G. Forbes
(and now USHPA radio-guy too, since JZ retired)
Posted by: "Mark G. Forbes"
Mon May 10, 2010 11:06 pm (PDT)
Steve Pieniak wrote:
> The Yaesu VX-7R has digital tone/squelch capability. I don't know of
> any pilots who have tried to use this function- the radio is relatively
> expensive so not ubiquitously owned by pilots. Would the use of this
> function be an acceptable/ethical/
The essential fact to remember is this:
Those frequencies which are authorized for use by USHPA pilots are SHARED. They
are not allocated solely for use by pilots. Instead, they are part of a pool
of 'transient' frequencies used by many different people. Operators of radios
on these frequencies are REQUIRED to coordinate their usage, by listening for
a quiet period and then making their transmission.
The whole point of tone squelch, digital squelch and so on is to allow you
to not hear other traffic on the frequency. That's fine, only so long as
you are the sole licensee. When you own it, you can sort out conflicts
within your own group of radio users. But USHPA does not "own" those
frequencies, and pilots using them MUST NOT assume they're the sole
users. That means you MUST LISTEN TO ALL TRAFFIC, all the time. I hope that's
clear enough for everyone. If you're doing something that makes it so you
don't have to hear everyone else, then you shouldn't be using the radio
to transmit. Period.
I'm ignoring the fact that the VX-7R is not a type-accepted business band
radio. It's not legal to transmit on any of the business band frequencies,
absolutely and without question, regardless of tone squelch or anything
else. You may *listen* legally, but you may not transmit legally. If you
want to transmit, you need to use a legal radio to do that. I pointed to
mine as one example, and there are others. I can offer a list of them if
folks are interested.
One way to mitigate the "listen all the time" problem is to set up the
radio with "Busy Channel Lock-Out", which blocks you from transmitting
when there's a carrier present from someone else talking. The down side
of this is that you may not realize you're not transmitting, though many
radios will give you an error beep indicating the channel is busy. And
even that won't help you if you set the squelch too high, because traffic
from distant radios won't trip the BCLO circuit. When you're flying high
in the air, your radio "footprint" can extend out to a fifty mile radius
or more. That's much bigger than a radio on the ground, and you therefore
have a much greater chance of causing harmful interference to other
legitimate users of the band. On the ham band, I've succesfully talked to
pilots 35 miles away, clear and readable, using a radio that puts out 3/8
of a watt. I was standing on a mountaintop, and so were they, and we were
at 5000 feet over Tiger. Everybody in Seattle can hear you, and probably
some folks in Chelan too.
Get your ham license, move over to an unused simplex frequency in the ham
band, and you're golden. Your VX-7R is now legal, you can use tone
squelch and BCLO, digital squelch and whatnot, and everything's fine. I
strongly recommend that pilots do just that, particularly because it's
easy to pass the test and there's no good reason not to. If you can learn
to fly a glider, you should have no trouble passing the ham exam. You
don't need to learn Morse code or anything complicated. It's just a few
basic rules of operation, a smattering of simple electronics that you
can just memorize, and a dose of common-sense for the most part. Take the
on-line test and see how well you do. You just might pass without even
studying for it.