Terry
Under current FCC rules, the 300 baud limit does NOT limit bandwidth except for
two-tone
RTTY signals. Note for example that PACTOR-3 occupies 2.2 kHz and uses a baud
rate
of 100. There is no BW limit for non-FSK signaling (like PACTOR-3). The 300
baud limit
does not stop 2.2 kHz wide PACTOR-3.
PACTOR-3 does not use "two-tones" so the 1 kHz FSK limit does not apply. It
occupies
2.2 kHz. That is the TRUE situation today, which RM-11708 leverages to argue
for a
bandwidth limit, as in "we don't understand". It is OK to remove the baud rate
limit since
it doesn't limit BW of non-FSK modulations. But what is NOT OK is the 2800 Hz
limit,
like "the ARRL do not understand this."
For two-tone RTTY, the limits are 300 baud AND 1 kHz maximum tone separation,
so the maximum permitted band width is 300+1.2*1000 = 1500 Hz. Amateur RTTY,
what we we all use today occupies 45.45+1.2*170 = 250 Hz.
Watch out for the deceptive part of RM-11708. Today there is indeed NO bandwidth
limit
in the CW/digital band segments, and yes, RM-11708 would impose a limit of 2800
Hz.
Now the deceptive part: The effect will be to enable PACTOR-4 which also
has a 2.2-2.4 BW (depending on what you use for your source material), but
operates at a much
higher baud rate. The ARRL are right but deceptive. There is no BW limit now,
but the deception
is that a BW limit as high as 2800 Hz will devastate the incumbent fragile
narrow band digital modes
such as PSK31, JT65, J9. and amateur-RTTY.
The correct arguments to make are:
(1) Remove the archaic 300 baud language AND
(2) take ALL that occupy more than (for example) 500 Hz (digital and
analog)ABOVE the CW/digital
boundary.
That is, put them in the "phone sections" of the bands where there are already
wide band digital and
analog signals like ATV, HF-D-STAR, and AM.
It becomes regulation by bandwidth, but that is the right thing to do. We's
still have to contend with
PACTOR-1 and others that occupy less than 500 Hz, but in my opinion, that is
manageable.
Wide and narrow band digital mode just do not mix well in the same spectrum.
73
Kai, KE4PT
On 4/15/2014 10:40 AM, Terry wrote:
Folks,
It's still not too late to file comments regarding RM-11708. Also please
copy your directors on your comments. If anyone needs help in the filing,
please let me know as I have helped a couple of folks with their filings.
The current 300 baud limit is a very real protection mechanism designed
specifically to limit the power spectral density of all users in the CW-only
bands. The 300 baud law practically limits useable signals to about 500 Hz
in the low portion of the band. Wider band signals that are currently
required by law to remain below 300 baud are simply too inefficient and not
commercially viable to find use, hence the FCC was very wise to naturally
protect narrowband RTTY and CW users through the 300 baud limit. Wider-band
signals, when operated below 300 baud, do not appreciably interfere with
today's CW and RTTY users due to lower power spectral density. The baud
rate is the key protector for narrowband operations.
ARRL leadership is ignoring, misstating, and misrepresenting the facts in
this issue, both on its website, and now in its board minutes, as is clearly
shown in section 4.2.4 of its recent board minutes of late March.
Below is more information from Ted, K9NB expressing his concerns.
Terry
----------------------------------------------------
At the risk of stirring up some uneasiness, but in the sincere interest of
our beloved hobby, I ask for all CW and RTTY operators, and anyone else
reading this message, to please consider an immediate grass roots e-letter
writing campaign to any and all of the ARRL Board of Directors, the
president of ARRL, and to Dave Sumner. Please feel free to forward this note
to anyone, as we need DX and contesting clubs around the country to get
involved.
Urgently.
Perhaps even more importantly, I urge everyone to file ex parte public
"comments" at the FCC website regarding RM-11708. The chief engineer told us
late comments are welcome and considered as "comments".
CW and narrowband modes are under attack by the ARRL in RM 11708. And the
ability to openly observe ham radio communications is also under attack.
The ARRL is failing to represent the interests of CW and narrowband users in
RM-11708, and even at it's March 31 board meeting, is on record saying that
"opponents of RM-11708 simply do not understand the rulemaking.
The facts are clear: the ARRL is proposing through RM-11708 to remove the
300 baud limit in all of the HF CW subbands, and is urging the FCC to
replace the 300 baud limit with no baud limit, and a 2.8 kHz bandwidth
limit.
The facts of communications engineering are that the removal of the 300 baud
limit will allow much greater baud rates, which in turn will make the power
spectral density, and thus the interference energy of these new wideband
data signals as great or even greater than SSB signals.
By removing the 300 baud rate, the ARRL is requesting to allow SSB-like
signals (on an interference bandwidth basis) in the CW-only bands.
The FCC created the CW-only subbands expressly for the purpose of protecting
these narrowband modes from wider band interference. That's why there is a
separate SSB subband.
The 300 baud rate has protected narrowband CW and RTTY users for decades,
since the 300 baud spec naturally limits the power spectral density
(watts/Hz) of transmitted signals, and thus discourages the use of wideband
data in the CW-only subbands due to the fundamental laws of Communications
and signal to noise ratio (see Leon Couch- Digital and Analog
Communications, or my textbook on Wireless Communications).
Thus, wider band data signals limited to 300 baud perform much poorer than
300 baud narrow band signals, and are not practically viable and pose no
current threat. The current law protects CW and RTTY users
> From interference
by the 300
Baud Limit.
Now, though, the ARRL through RM-11708 is trying to allow much stronger data
interferers that have both much greater baud rate AND much wider bandwidth,
into the CW only bands.
This is a huge attack on the narrowband CW and RTTY users! The resulting
interfernce will be enormous, and is like allowing SSB into the CW bands.
Also, many have recently pointed out that some of the existing or proposed
uses of these new wideband signals will use encryption, so that Official
Observers and FCC officials will have difficulty intercepting
communications, thus making the CW and RTTY Bands of our hobby more like
private radio or for-profit networks.
I have filed public comments at the FCC, so has Terry.
The Last ARRL board of director meeting minutes of 3/31/14 are quite
disturbing, and show wanton disregard for Narrowband cw/rtty users, and
complete neglect of the above facts. The ARRL is hiding these fundamental
facts, and does not properly present these obvious technical facts on it's
FAQ at the ARRL home page. In numerous email conversations I had with K1ZZ
over the course of a week, he never wanted to recognize these technical
facts.
I ask that all of us who want to maintain the ability to operate CW, RTTY
and PSK31, and to preserve the narrowband (300 baud) protections that allow
us to enjoy RTTY, PSK31, and CW... We must become vocal.
Now we must speak up immediately, and clearly, and we must spread the word
for a massive letter writing campaign to ARRL leadership, and with public
comments at the FCC.
If you care about the CW and RTTY sub bands, and want to keep out voice-like
interference, I hope you will get Involved! Your hobby needs you!
Our hobby needs your public activism to protect CW and narrowband data! The
ARRL has forsaken its CW, RTTY, and PSK31 members, and now we must do this
ourselves at the grass roots level. Please file your public comments at the
FCC RM-11708 website.
73
Ted
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