[RTTY] Wow - thanks Dr Flowers!
Robert Chudek - K0RC
k0rc at citlink.net
Thu Dec 26 15:45:08 EST 2013
/"...That is wrong, but that is the status quo, and RM-11708 has nothing
to do with it one way or the other."//
/
Neglecting the consequences of enacting one piece of legislation to the
detriment of existing legislation is both naive and dishonest. It's
equivalent to lying by the sin of omission.
I do expect the Commissioners will read past the "popularity contest"
going on and reject RM-11708.
73 de Bob - KØRC in MN
------------------------------------------------------------------------
On 12/26/2013 2:15 PM, Kai wrote:
> Hi Al,
> Baud rate does NOT limit BW, except for 2-tone FSK RTTY.
> Actually, two tone FSK RTTY is the ONLY digital modulation that
> currently has a defacto BW limit under FCC rules. Those limits are 300
> baud and 1000 Hz maximum spacing between tones, which would occupy
> 1500 Hz. No one uses that, but it is a limit.
>
> On the other hand, I can legally use, for example, 16 carriers (or 32
> or 64) spaced 1 kHz each, with each carrier containing QAM encoding,
> and as long as I strobe the ensemble of those carriers at less than
> 300 baud, I'm legal - and occupying more than 18 kHz (or 34kHz or 66
> kHz) BW. It's a crappy modulation but LEGAL today! The FSK shift
> limit doesn't apply because it's not FSK!
>
> The ONLY thing limiting modulations like the crappy ones I listed
> above is that VERY FEW receivers out there can handle a bandwidth of
> 18 kHz (or 34 kHz or more). Most radios can handle less than 2400 Hz
> of phase and amplitude-linear BW suitable for modern modulations.
>
> PACTOR-4 (which occupies about 2200 Hz BW, just like PACTOR 3 which is
> in use today) would indeed be permissible once the 300 baud symbol
> rate is removed.
>
> A sore point for me is that the PACTOR (3 and 4) encoding and decoding
> are not publicly available -unless you actually buy their modem. That
> is wrong, but that is the status quo, and RM-11708 has nothing to do
> with it one way or the other.
>
> Kai, KE4PT
>
>
>
> On 12/26/2013 12:44 PM, Al Kozakiewicz wrote:
>> As I said in my own comment, this is a straw-man argument. The
>> symbol rate has the effect (intended or not) of capping the
>> bandwidth. Although you are technically correct that the current
>> regulations stop no one from sending 45.45 baud RTTY using 120 kHz of
>> bandwidth, NOBODY does!
>>
>> Also, I thought that when the ARRL amended their filing to drop the
>> reference to "unspecified digital modes", that effectively removed
>> Pactor 4 as a permissible mode on amateur band HF if the proposed
>> rule was adopted. That's not true?
>>
>> Al
>> AB2ZY
>>
>> -----Original Message-----
>> From: RTTY [mailto:rtty-bounces at contesting.com] On Behalf Of Kai
>> Sent: Thursday, December 26, 2013 10:47 AM
>> To: rtty at contesting.com
>> Subject: Re: [RTTY] Wow - thanks Dr Flowers!
>>
>> Hi Chen
>> What a tortured argument he made!!
>>
>> BIG error here:
>> *"**So, before the FCC removes the symbol rate and allow higher
>> bandwidths ..."*
>>
>> Higher bandwidths ARE already permitted, or more precisely HIGHER
>> BANDWIDTHS ARE NOT PROHIBITED TODAY, with the exception of two tone
>> FSK ("RTTY"), which is limited at about 1.5 kHz BW. [My emphasis!].
>> Today, hams can use 2.8 kHz, 6 kHz, 12 kHz or 120 kHz or higher
>> bandwidths as long as the symbol rate is below
>> 300 baud, and the emission is confined to the ham band. The ARRL
>> proposal would limit the BW to 2.8 kHz where none exists today (well
>> below the 6 kHz permitted in Canada).
>>
>> 73
>> Kai, KE4PT
>>
>> On 12/26/2013 5:42 AM, Kok Chen wrote:
>>> On Dec 25, 2013, at 10:35 PM, Rex Maner wrote:
>>>
>>>> I'm glad I know how to press the ENTER key. I sure don't have any
>>>> idea what this person is talking about , but it sure sounds
>>>> informed.( I Think )
>>> I believe some of the points that Andy made are (I paraphrase, and
>>> also drill down a bit):
>>>
>>> 1) the Symbol Rate is not about the ARRL strawman of "spectral
>>> efficiency." The ARRL themselves have in the past said that spectrum
>>> efficiency is not a goal of amateur radio (and neither does
>>> §97.1(a-e)), and now the ARRL petition claims that it is, when
>>> arguing for wider bandwidths.
>>>
>>> 2) based on past FCC rulings, the Symbol Rate is never about
>>> bandwidth either, but about hams being able to self regulate.
>>> a) self regulation means that everyone else has to be able to
>>> "read the mail," (literally :-)
>>> b) this means that I should be able to copy a signal even when
>>> conditions are poor,
>>> c) well, if that is so, high symbol rates simply don't work
>>> anyway, since the symbol rate has to be kept low even though the
>>> path between the two parties is good, so that a third party (like an
>>> OO) can still monitor the conversation.
>>> d) by complaining that Pactor-3 is not efficient, the ARRL
>>> obviously don't even understand how the ionosphere works (Andy cites
>>> the Maslin book).
>>>
>>> 3) modern digital modes use what are called (by Harris, for example)
>>> "Serial Tone" modems.
>>> a) you cannot use low SYMBOL rates (like the 100 baud in Pactor
>>> 3) and keep adding subcarriers to get higher DATA rates,
>>> b) so, you use something like 64-QAM (QAM is a mix of PSK and
>>> amplitude modulation -- ASK), and you run at really high symbol rates,
>>> c) to get high symbol rates through HF propagation when
>>> conditions are poor, the Serial Tone modems equalizes the channel,
>>> d) to do equalization, they periodically send a long pseudo
>>> preamble (PN) sequence (example Andy gave is 176 bits long, used in
>>> STANAG 4285) .
>>> e) the receiver takes the PN preamble and performs an
>>> autocorrelation, and from that derives a real time equalization of
>>> ionospheric distortion.
>>> f) but here is the crux: unless the PN generator is openly
>>> published, it is equivalent to encryption, (which serves a dual
>>> purpose with the mil STANAG modems)
>>> g) so we are back to hams not being able to self regulate
>>> again, since we cannot read the effectively encrypted mail.
>>>
>>> So, before the FCC removes the symbol rate and allow higher
>>> bandwidths, they should make sure that Amateurs have the tools to
>>> read the mail. By citing Pactor-4 in the petition, the ARRL must
>>> think that Pactor-4 satisfy the "read the mail" condition, but Andy
>>> thinks that it does not. Pactor-4 does not satisfy the conditions
>>> needed to be used in the Amateur service.
>>>
>>> Andy also points to the fallacy with people who expect privacy when
>>> they use the Amateur service to forward email, since Amateur Radio
>>> principals have been that messages that are carried by the service
>>> must be transparent. By making encryption open, these email users
>>> will at least not be misled that they have any privacy when they use
>>> the Amateur service to forward their email. Since the principal is
>>> already embedded in §97.309(a), the FCC need not make a new ruling
>>> but just re-affirm it, since "it is obviously a point of confusion"
>>> to many parties.
>>>
>>> Andy also called the 2.8 kHz part of the petition "strange," and
>>> added that the ARRL has not specifically said why they think there
>>> is a "tangible need" for it. In my own comment, I had used
>>> "arbitrary and capricious" to describe the 2.8 kHz number -- in
>>> lawyerese, a rule is arbitrary if it is not supported by logic or
>>> the necessary facts; a rule is capricious if it is adopted without
>>> thought or reason or is irrational
>>> (http://definitions.uslegal.com/a/arbitrary-and-capricious/ ).
>>>
>>> 73
>>> Chen, W7AY
>>>
>>> _______________________________________________
>>> RTTY mailing list
>>> RTTY at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/rtty
>>>
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