Ham Radio 2000/Ham Radio 2000.iso/ham2000/packet/aprs75c/uhf-freq.txt

Text File | 1995-10-22 | 6KB | 98 lines

UHF-FREQ.txt 6.2b    A NATIONWIDE UHF 9600 BAUD GPS TRACKING FREQUENCY

                         ??????  445.925  ??????


    With GPS ever decreasing in price, the time is approaching when EVERY
car in America, or at least every car with a two-way radio system will have
GPS in some form or another.  Amateurs will find that transmitting their
position while mobile, adds a new dimension to radio and facilitates amateur
response to emergencies as well as providing for just plain fun.

     Since GPS position reporting is a predominantly mobile operation, most
HAMs will eventually dedicate a single transceiver for single function
operation on a single tracking frequency.  Today (1994), 1 watt commercial,
single frequency UHF data transceivers capable of up to 9600 baud are
available for around $100.  This is approximately one-third the cost of a
typical mobile HAM transceiver or walkie-talkie.   Using these transceivers,
a nation wide GPS reporting and tracking frequency could develop very
quickly.

    Unfortunately, however, a nationwide tracking capabilty using single
frequency crystal controlled transceivers, cannot develop unless there is a
SINGLE NATIONWIDE UHF FREQUENCY dedicated to this application.  Since
mobiles by their very nature, wander everywhere, the evolution of different
GPS networks on different frequencies in different areas will permanently
encumber the growth of this fascinating new aspect of amateur radio.  The
success of GPS tracking on the two-meter band has been nothing short of
amazing, since everyone from the beginning seemed to cluster on the ARRL
established experimental frequency of 145.79.  Mobiles beaconing their
position on that frequency could be assured of tracking networks almost
anywhere they traveled.  But as more and more stations go GPS packet mobile,
there is the need to move to 9600 baud to avoid gridlock.

    Several 9600 baud single frequency data transceivers exist for the
UHF band.  See ad on page 18 Feb 94 QST for the TEKK radios:   T-NET MINI
$119.90 and T-NET MICRO $99.90 both are 2 watt UHF modules about the size
of a credit card that operate to 9600 baud! Call them at 1-800-521-8355.
PacComm builds these into some TNC enclosures for complete BLACK-BOX
TNC/RADIOS...

    Of course, a great buy for 2 meters is the MFJ 5 watt 2 meter 9600
baud radio for $119.  It comes on 145.01, but can be special ordered on
145.79 for only $14 more.


FINDING A UHF FREQUENCY!

    As anyone that has participated in a frequency coordinating organization
can attest, finding an available packet frequency in our already crowded
bands is a difficult and painful process.  Trying to find a single national
frequency will be virtually impossible!  As a weak-signal operator, and
ATV'er, I do not want to see any more encroachment on the 70 CM ATV
frequencies and certainly not on the the weak signal bands.  Also, as a
member of the local Mid-Atlantic Repeater council, I have avidly defended
the UHF FM voice frequencies from encroachment by packet operations.

    After a lot of thought, however, I do believe that a single frequency is
available and should be proposed for nationwide discussion.  Amateurs have
always been at the leading edge of new technology, and have usually been
able to accommodate new ideas when it seems to serve their general interest,
and their capabilities as a community communications resource.

     As stated before, GPS tracking is a SINGLE FUNCTION, SINGLE FREQUENCY
application.  Once a single frequency is identified, there is no reason and
little incentive for any further frequency spreading of this application.
BBS's and packet data networks, for example, are HUB or star based networks
which operate most effectively when each major NODE or BBS has its own
separate frequency.  Due to the community nature of these beasts, there is
always a crowding effect driving the users to find more and more
frequencies.  The GPS reporting and tracking network, however, gains its
advantage by having ALL mobile stations on one and only one frequency.  Just
as HAMS have 146.52 as a national calling frequency, and CB'ers have channel
19, the GPS application needs only a single frequency too.

     Maybe it is time to allocate a single FM simplex channel to high speed
GPS position reporting and tracking.  Just as 446.00 is recognized as the
UHF calling frequency, there should be a comparable 445.xxx GPS status and
tracking frequency for mobiles nationwide.  I anguished long and hard over
this proposal, and I suspect that it will meet with a lot of emotional and
idealogic controversy.   But I think that anyone that is watching the
trends in communications technology will certainly conclude that GPS
position reporting of mobile radio operations WILL BE FUNDAMENTAL IN EVERY
MOBILE NETWORK within 10 years.  We either bite-the-bullet now and plan for
the orderly development of GPS applications on the 70 cm band, or we will be
fighting this same battle for the next ten years.

     If you have any comments on this idea, or can see a better way, please
contact your local frequency coordinating council.  If there is any
precedence anywhere for a single DATA channel in the FM simplex band, please
let me know ASAP!  Otherwise, HOW ABOUT the lowest simplex FM channel on
445.925 MHz ?

     I just can't get over the excitement, of someday, being able to glance
at your dash-board mounted full color map display and seeing the location of
every mobile HAM within 30 miles!  Setting aside a single GPS status and
position reporting frequency NOW, will make this happen!