Dear Rik van Riel,
There is currently no finite bandwidth limit
on HF data/text emission in USA ham bands,
except for the sub-band and band edges.
FCC data/text HF rules are still mainly based
on content of the digital emission, not bandwidth.
FCC rules allow hams to transmit a 149kHz bandwidth
data/text signal on the 20 meter band. It may
not be popular to do so, but it is legal :)
The amateur radio regulations of many other
countries of the world do not have bandwidth
limits on signals. Bandwidth regulation has
been recently adopted by some countries.
New SDR radios have the potential to transmit
and receive wider bandwidths. Perhaps we will
see more development in this area of technology
in the future. There are other HF services using
24kHz and 48kHz bandwidth fast data modems. Some
of these modems are capable of sending a page
of text in the time it would take you to call CQ
on one of the slow digital modes.
Perhaps there are good applications for 48kHz
modems in HF ham radio. For example, large portions
of the 24MHz, 21MHz, and 28MHz ham bands are
almost completely empty of amateur radio signals
for years. It would be easy to fit a 24kHz or
48kHz bandwidth signal in these bands.
Rik, you recently wrote that FCC part §97.307
places [bandwidth] limitation on any data
mode transmitted in the HF bands
Please check your copy of the FCC rules more closely,
because you overlooked what the rule actually says:
(f) The following standards and limitations
apply to transmissions on the frequencies
specified in §97.305(c) of this Part.
§97.305(c) is a chart of amateur radio bands
and sub-bands. Each sub-band has a note,
and the notes are listed in part §97.307.
The Note # (2) only applies a soft bandwidth
limit to non-phone emissions within the
Phone,image sub-bands.
Note # (2) does not apply to the CW/data/RTTY
sub-bands.
Several years ago, there was a proposal to FCC
to provide regulation by bandwidth rather than
content. However, it failed to be adopted.
Thus, USA hams still don't have a bandwidth limit
for HF data/text :)
Best Wishes,
Bonnie Crystal KQ6XA
Rik van Riel r...@... wrote:
Furthermore, from part 97.307 places this limitation on any
data mode transmitted in the HF bands:
(2)No non-phone emission shall exceed the bandwidth of a
communications quality phone emission of the same
modulation type. The total bandwidth of an independent
sideband emission (having B as the first symbol), or a
multiplexed image and phone emission, shall not exceed
that of a communications quality A3E emission.
