information on the switch-over is
there, as well.
When the analog to digital
switch-over occurs, your local stations
will move to different channels, most
likely from VHF to UHF. If you don’t
know how to find the new channel,
you can go to the FCC’s website
chanplan.html) and get details there.
One quick comment on antennas.
If your rabbit ears get both VHF
channels (2-13) and UHF channels
( 14-59), you will be okay. Same with
an outdoor or attic combo VHF/
UHF antenna. Remember, higher
frequencies travel shorter distances
than lower frequencies for the same
power. So, your stations new UHF
signals could be lower in level with
the new digital TV. A higher gain
antenna will make up the difference.
With digital signals, there is no
gradual weakening as indicated
by “snow.” What you will get is a
pixilated screen and then nothing if
you are out of range.
■ FIGURE 1. This
cell phone modules
by Telit Wireless
Solutions is only
1.7 x 1.7 inches
square and operates
in the standard
MHz cell phone
bands. It can send
short text messages
or audio. This model
has a built-in GPS
receiver so it can
report its location
to the caller.
M2M ON THE RISE
What the devil is M2M, you ask?
It stands for machine-to-machine. It is
a growing technology that extends
the use of a cell phone system to
other than personal human to human
voice and text communications.
Instead, it implements communications between machines — machines
talking to other machines or humans
talking to machines. Sounds a bit
eery at first but as it turns out, it is an
amazing additional use of the large
and very expensive cell phone infrastructure made up of over 260,000
base stations in the US alone. Here’s
how M2M works. It is a form of
wireless telemetry and control.
Telemetry is the old term that means
measurement at a distance — usually
by wireless. Suppose you want to
watch the temperature of a pipeline
miles away from you or even across
the country. You install a temperature
sensor on the pipe and send the
electrical signal to a cell phone. The
cell phone is basically just the radio
without the keyboard, display, speaker,
and microphone. It
sends the digital
version of the
temperature over the cellular network
to your phone or computer.
Suppose you want to control the
liquid level in a remote tank. You
could monitor the level with a sensor,
then use that indication to turn a
pump on or off to refill the tank
when necessary. Could all be miles
or a continent away.
M2M is the ultimate long range
remote control. As long as you can
get through a cellular network, you
can monitor or control anything from
any place at anytime. M2M has been
around a few years and growing
silently. Tiny cellular radios in
modular form are cheap and widely
available to enable almost any conceivable remote monitor or control
function at a very reasonable price.
Vending machine companies use
M2M to alert them that a machine
needs refilling or maintenance.
Trucking companies routinely use it
to track their trucks and payloads.
Companies attach an M2M transceiver
on a high value asset like a bulldozer
or large crane and monitor its
presence or condition by a simple
phone call. You can even put a video
camera on one of the transceivers
and keep an eye on your home while
you are on vacation. Just call in and
take a look at the current video
conditions. Figure 1 shows a typical
M2M cell phone module.
M2M is an impressive extension
of the cellular system. With cell
phone saturation nearing 50% of the
world population of just over 6. 5
billion folks, where does one go for
growth? The answer is M2M. Some
companies have estimated that there
could be between 50 or 60 billion
devices, machines, or things that
ought to be monitored, tracked, or
controlled. M2M is cheap and easy,
so look for more of this “invisible”
WHITE SPACES IN
Another hot topic these days in
wireless is “white space.” This is the
term for those TV channels that will
become vacant during the switch-over from analog to digital or those
TV channels essentially unused or
unassigned. With spectrum so limited
and expensive, many are wondering
why all that precious TV spectrum
will go unused. Why not put it to
work in cellular or other forms of
wireless like high speed Internet
connections or wireless networks?
Most of it is in the highly valued VHF
spectrum where signals travel far,
penetrate walls, and allow many new
useful services to be implemented.
By using smart technology, a
radio will be able to monitor the
spectrum for potential interference
before transmitting and then
decide not to transmit or to change
The FCC recently issued a
December 2008 83