[RTTY] Hints and tips on how to file comments on RM-11708

[Kai]

Joe
Let's be careful about associating PACTOR with "inefficient modes".
My VERY PRELIMIARY assessment is that PACTOR-III  in its lowest
data rate of about 76 user bps  may outperform "Steam-RTTY" by as
much as 7 dB, while the highest data rate may be 6 dB worse than
Steam-RTTY,  but delivers 2722 bps compared with roughly 30 user
bps for RTTY.

I don't think we'll win by making "inefficient mode" arguments.
I also think we'll eventually lose with no BW cap.

Our best hope is to cap BW at 2200 Hz.

73
Kai, KE4PT


On 11/24/2013 9:28 PM, Joe Subich, W4TV wrote:
>
> If it is 2.4 KHz wide, it can not be legal ... how can one square
> 2.4 KHz occupied bandwidth with a rule that states a combined
> criteria of 1000 Hz and 300 baud which works our to 1500 Hz?
>
> This is *exactly* the reason that comments need to stress a 500 Hz
> bandwidth limit for all "RTTY, data" emissions in the spectrum
> covered by 97.307(f)(3) and 97.307(f)(4) to be consistent with
> "traditional radiotelepinter bandwidths" as the Commission held
> in "Further Notice of Proposed Rule Making, 43 Fed. Reg 36984".
>
> The Commission believed that a 1000 Hz shift and 300 baud symbol
> rate would assure emissions consistent with "traditional radio-
> teleprinter bandwidths" would provide for bandwidths consistent
> with then standard operating practice.  Unfortunately, there was
> at that time no use of composite FSK/PSK systems, multi-tone
> systems, etc. and their use has exploited a regulatory loophole
> *that needs to be closed* lest these wide bandwidth and inefficient
> modes cause irreparable harm to traditional narrow bandwidth modes
> which are limited to frequencies where F1 emissions are authorized.
>
>
> 73,
>
>    ... Joe, W4TV
>
>
> On 11/24/2013 9:01 PM, Kok Chen wrote:
>>
>> On Nov 24, 2013, at 5:02 PM, Joe Subich, W4TV wrote:
>>
>>> PACTOR III is *NOT* currently permitted under the rules.  Its use has
>>> been *overlooked* by enforcement organizations as it *absolutely* can
>>> not be justified under the *dual standard* in 97.307(f)(3) which has
>>> both 300 baud and 1000 Hz shift limits.
>>
>> That is not true Joe... please don't make that mistake in your FCC filing.
>>
>> At all SL levels, Pactor III's symbol rate is fixed at 100 baud (yes, not 
>> even close to 300 baud).  (Don't confuse Symbol Rate (baud rate) with data 
>> rate (bit rate)).
>>
>> Pactor III is not 2 tone FSK, so the FSK shift rule does not even apply 
>> (makes no technical sense since there is no frequency shift happening).
>>
>> Pactor 3 SL1 (the slowest rate) consists of two synchronous PSK signals (not 
>> FSK), that are separated by 840 Hz.  840 Hz is the maximum tone separation 
>> for Pactor 3 (if you want to apply the term "shift" to the signal).  As more 
>> tones are added (SL2, SL3, etc), the tone separations become narrow, and at 
>> the narrowest, there are 18 tones, separated by 120 Hz from one another.
>>
>> Pactor 3 SL1, 2 and 3 uses binary PSK, and Pactor 3 SL4, 5, 6 uses Quadrature 
>> PSK.
>>
>> It is much clearer if you go take a look with a panadapter or a waterfall, or 
>> if you can, in I/Q phase space.
>>
>> Pactor 3 SL1 looks like two broad indistinct tones that are 840 Hz from one 
>> another, with a distinctive gap in between them.  It is quite unmistakable 
>> once you see it on the waterfall.
>>
>> 73
>> Chen, W7AY
>>
>>
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