There is unquestionably a bandwidth restriction on HF for frequency-shift
keying, though there could be debate about what "mark" and "space" mean for
FSK modes with more than 2 tones; the intent, however, seems clear enough.
Consuming 150 kHz of HF spectrum to convey 300 baud using something other
than FSK is not precluded by §97.307(f)(3), but would we be happy if
everyone started doing it?
73,
Dave, AA6YQ
-----Original Message-----
From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com]on
Behalf Of Trevor
Sent: Wednesday, March 25, 2009 5:30 PM
To: digitalradio@yahoogroups.com
Subject: RE: [digitalradio] Phone/Image Band FCC bandwidth limit on HF Re:
USA ham rules
FCC say "a RTTY or data emission using a digital code specified in
this paragraph may use any technique whose technical characteristics have
been documented publicly"
I can't see that you've got any bandwidth restriction on HF subject to
each individual carrier having a maximum symbol rate of 300 baud. That in
itself is a pointless restriction but it doesn't stop you having wide B/W
data transmission using multiple carriers.
In the UK there are no restrictions on modulation techniques or the
bandwidth subject to the transmission fitting within an Amateur band.
73 Trevor M5AKA
--- On Wed, 25/03/09, Dave AA6YQ <aa...@ambersoft.com> wrote:
From: Dave AA6YQ <aa...@ambersoft.com>
Subject: RE: [digitalradio] Phone/Image Band FCC bandwidth limit on
HF Re: USA ham rules
To: digitalradio@yahoogroups.com
Cc: "Dave Bernstein AA6YQ" <aa...@ambersoft.com>
Date: Wednesday, 25 March, 2009, 2:09 AM
The table in §97.305 (Authorized emission types) indicates that
§97.307(f)(3) applies to all use of RTTY or data emission types in the
amateur bands below 28 mhz.
§97.307(f)(3) says "Only a RTTY or data emission using a specified
digital code listed in §97.309(a) of this Part may be transmitted. The
symbol rate must not exceed 300 bauds, or for frequency-shift keying, the
frequency shift between mark and space must not exceed 1 kHz."
The table in §97.305 indicates that §97.307(f)(4) applies to all use
of RTTY or data emission types on the 10 meter band; it expands the upper
limit on symbol rate to 1200 baud, but retains the maximum FSK frequency
shift of 1 kHz.
See
<http://www.arrl.org/FandES/field/regulations/news/part97/d-305.html
#307>
73,
Dave, AA6YQ
-----Original Message-----
From: digitalradio@yahoogroups.com
[mailto:digitalra...@yahoogroups.com]on Behalf Of expeditionradio
Sent: Tuesday, March 24, 2009 6:44 PM
To: digitalradio@yahoogroups.com
Subject: [digitalradio] Phone/Image Band FCC bandwidth limit on HF
Re: USA ham rules
> Frank k2ncc wrote:
> I think the confusion I have with "quality phone
> transmission" comment is the part that says
> "...of the same modulation type."
Hi Frank,
The FCC rule about HF signal bandwidth limit
related to a "phone emission of the same
modulation type", applies mainly to Image signals
within the HF "Phone/Image sub-bands".
That limit DOES NOT APPLY to Data/RTTY signals
in the Data/RTTY sub-bands.
Beware, there are a few narrow-minded hams
continuing to spread disinformation about digital
bandwidth limits. What motivates them to do so?
Are they trying to scare us into self-inhibiting
our freedoms? Or a desire to retard the advancement
of radio technology? Whatever their reason is for
using the "Big Lie" technique, it won't work in
this case, because it is too easy now for USA hams
to go to the source of true facts about bandwidth
limits. That source is: the FCC rules on the web.
The best way to understand the FCC rules about
ham radio is to read the FCC rules, footnotes,
tables, orders, definitions, specifications, and
FCC opinions. I acknowledge that not everyone is
quite as enthusiastic about reading this exciting
material as I am. So, perhaps it will help to
point out the parts of the tome that are pertinent
to this discussion. Turn your hymnals to Part 97 :)
- The FCC rules contain a table of frequency bands
in paragraph (c) of "§97.305 Authorized emission types."
- In that §97.305 table, one can see "Standards" that
apply to each sub-band or segment of a ham band.
These little details are the key to understanding.
Some Notes apply to certain sub-bands but not others.
Here are the important things to look for:
- Observe that "Footnote (2)" can be found in
the "Phone/Image sub-bands" but Footnote(2)
cannot be found in the "Data/RTTY sub-bands"!
- The text of this important Standard (2) is
found in:
"§97.307 Emission standards" paragraph (f) .
Here is the full text of §97.307 (f) (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."
The main types of "non-phone emissions" this
bandwidth limit applies to, only in the
"phone/image subbands are:
1. Image content (such as video or photo)
2. FAX image (such as drawings or documents)
The FCC rules define what a "Phone" signal is.
It includes speech and some other things, such
as selective calling and controlling tones.
The FCC definition of the word "Phone" can be
found in §97.3(c)(5) Definitions of terms that
are used in Part 97 to indicate emission types.
So, everything in the Phone/Image sub-bands
that is not "Phone" is considered "Non-Phone".
On an interesting side note, did you notice...
there is no bandwidth limit for most common types
of AM and SSB "Phone" signals in the HF bands?
There is a non-specific limit for "angle modulated"
signals such as FM voice... but that is a topic
for another discussion.
See you on 20 meters FM simplex!
73 Bonnie KQ6XA
