airwaves-digest V2004 #283
 

Doug Smith replied:
Don't really see much demand for spectrum for data on shortwave.
(VHF & especially microwave are a different story!) It's not easy to
reliably transfer significant amounts of data over shortwave; SW
transmission will be very much a last resort.

This is pure speculation on my part, but I can foresee a time when the
VHF/UHF bands become so clogged with highspeed data that less glamorous
operations such as regional/citywide paging, low-rate text messaging,
product ID tagging, water meter transponders, etc., go looking for the
lower frequencies. Without broadcast QRM, a relatively modest paging
transmitter on, say, 6.1 mHz could blanket a 10 mile radius 24 hours with
little of the line-of-sight problems of VHF.

I could even see a point where the FCC concludes a segment could
be opened for "amateur broadcasting", where "pirates" could operate
legally as long as they keep their power down to a reasonable level.

This would be great, then I could ignore all of them in one spin of the
dial. :)

Al Q.
NY

On Thu, 2004-11-25 at 08:27, Al Quaglieri wrote:
Doug Smith replied:
Don't really see much demand for spectrum for data on shortwave.
(VHF & especially microwave are a different story!) It's not easy to
reliably transfer significant amounts of data over shortwave; SW
transmission will be very much a last resort.

This is pure speculation on my part, but I can foresee a time when the
VHF/UHF bands become so clogged with highspeed data that less glamorous
operations such as regional/citywide paging, low-rate text messaging,
product ID tagging, water meter transponders, etc., go looking for the
lower frequencies. Without broadcast QRM, a relatively modest paging
transmitter on, say, 6.1 mHz could blanket a 10 mile radius 24 hours with
little of the line-of-sight problems of VHF.

I can see RFID tagging and water-meter transponders operating on SW
frequencies. Maybe with a modest spread-spectrum (over a few hundred
KHz) scheme.

I don't see portable messaging schemes working on SW. The problem is
noise from digital equipment. (computers, mostly) I think you're going
to have a hard time pushing enough RF through modern metal-framed
buildings to overcome computer hash.

--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

Al Quaglieri wrote:

This is pure speculation on my part, but I can foresee a time when the
VHF/UHF bands become so clogged with highspeed data that less
glamorous operations such as regional/citywide paging, low-rate text
messaging, product ID tagging, water meter transponders, etc., go
looking for the lower frequencies. Without broadcast QRM, a relatively
modest paging transmitter on, say, 6.1 mHz could blanket a 10 mile
radius 24 hours with little of the line-of-sight problems of VHF.

Only problem with your scheme and frequency choice is that even very low
power signals can propagate at odd times. There are lots of hams
running 1 or 2 milliwatts and getting contacts on HF frequencies, and
signals from miles away would be just as receivable as those close by.
Instant interference. One of the reasons that VHF and up are so
desired for data is that they propagate less than HF and below.

On 26 Nov 2004 03:22:25 GMT, Doug Smith W9WI wrote:

I can see RFID tagging and water-meter transponders operating on SW
frequencies. Maybe with a modest spread-spectrum (over a few hundred
KHz) scheme.

I guess if consolidation in all industries continues there might be a
reason to control a water heater in Tonga from Con Edison in New York.

Rich