> For two-tone RTTY, the limits are 300 baud AND 1 kHz maximum tone
> separation,
That is only true because neither the Commission or anyone else could
have foreseen multiple tone FSK or channel equalization methods when
the rules were written. That was still the case well into the late
1980s when the rules for automatically controlled digital operations
were written. Unfortunately, PACTOR II maintained the 500 Hz bandwidth
and when PACTOR III with its multiple channel modes was introduced
nobody thought to ask the Commission to apply the 1500 Hz limit. It
is likely, they would have done something if a timely complaint had
been made but once the mode became generally used they were reluctant
to order it withdrawn from use.
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.\
>
> It becomes regulation by bandwidth, but that is the right thing to
> do.
It is no different than the regulatory system that has been in place
for 80+ years. Regulations protecting narrow bandwidth modes from
the asymmetric interference caused by wide bandwidth modes have been
the norm since the FCC restricted phone to only part of each amateur
band.
If the Commission were to allow RTTY and data every where CW is now
authorized, apply a 500 Hz (or 300 Hz) limit in the current "CW bands"
and explicitly limit all modes except ISB and AM to 2.8 KHz instead of
the vague "bandwidth of a communications grade voice signal", the
regulations would become content agnostic. That is, it would not
matter if the source of the modulation was voice, image, keyboard
to keyboard or computer to computer communications. That environment
would allow innovation to flourish - particularly mixed data modes -
and would continue to protect traditional narrow bandwidth modes from
catastrophic interference levels while at the same time give the high
speed data transfer folks an opportunity.
The only other additions I would make would be:
1) all protocols, modulations, and encoding systems must be fully
disclosed. All encoding keys must be public, variable key
encoding would not be permitted.
2) proprietary protocols - those that require the purchase of a
software license or specific hardware in order to decode - would
not be permitted (e.g., AMBE or PACTOR III/IV).
3) all automatically controlled stations must include effective
channel busy detectors for both wideband and narrow band as well
as analog and digital signals.
4) any modulation/protocol not generally monitored "by ear" must
have a "waterfall" or spectrum display capable of showing any
other signal on the frequency so the operator can avoid causing
interference. Any mode/modulation/protocol that lacks visual
means for determining whether a frequency is busy must include
an effective software channel busy detector.
5) automatically controlled digital stations would not be permitted
in the narrow band segments of any band or 160 and 30 meters.
73,
... Joe, W4TV
On 4/16/2014 11:42 AM, Kai wrote:
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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