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[Ham-80211] HSMM: 420-430 MHz

Brian Webster bwebster at wirelessmapping.com
Sat Mar 5 03:07:25 UTC 2011


Don't get me wrong I am all for the idea of running these OFDM radios. That
spectrum is underutilized without a doubt. If it has been determined that it
is legal then let's build some networks.

Brian N2KGC

-----Original Message-----
From: ham-80211-bounces at tapr.org [mailto:ham-80211-bounces at tapr.org] On
Behalf Of kb9mwr at gmail.com
Sent: Friday, March 04, 2011 3:34 PM
To: ham-80211 at tapr.org
Subject: Re: [Ham-80211] HSMM: 420-430 MHz

Here is some explanation from the QEX article, for those concerned:

In 47 CFR 97.315 the emission type "image" is defined as including
"emissions having B as the first symbol; 7, 8 or 9 as the second symbol; W
as the third symbol".

In 47 CFR 2.201 (c) (2) a first symbol of B defines the type of modulation
of the main carrier as an "emission in which the main carrier is
amplitude-modulated (including cases where sub-carriers are
angle-modulated) with independent sidebands". The OFDM modem fits this
description as it has a central carrier with multiple subcarriers in the
upper and lower sidebands that are angle (phase) modulated. In 47 CFR 2.201
(d) (5) a second symbol of 7 indicates that the nature of the signals
modulating the main carrier are "two or more channels containing quantitized
or digital information". 47 CFR 2.201 (d)(2) and (3) indicate that
time-division multiplex is excluded for a single channel so the time
division multiplex inherent in HSMM communications creates two or more
channels.  In 47 CFR 2.201 (e) (8) a third symbol of W indicates that the
type of information to be transmitted is "a combination of the above" and
that includes (4) "facsimile", (5) "data transmission, telemetry and
telecommand", (6) "telephony" and (7) "television". HSMM fits this
definition as it includes data, speech and image components.

I am more concerned by underutilized spectrum, and red flags that people
throw that deter experimentation in the hobby.

That said I have a few extra picture frames and would be fine framing my
first "pink slip" over silly rules in the name of experimentation.

I firmly believe that the rules will change as we do.

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