[RTTY] ARRL attack on current RTTY users

[Jeff Blaine]

Kok,

Yea, I also don't see the tie to "modern" in that none of the modern methods 
are wide banded.  Only the stuff for mail relay seems to be.  I actually 
don't understand how winlink mail makes sense - I can see and emcom 
justification but that's not the selling point.  Free email via HF seems to 
be the selling point.

I do find it pretty interesting that of the 5 ARRL signatures on the 
Document 28 petition, the chairman and second undersigned are promoters of 
the Winlink system.  And at the same time, none of these guys seem to be 
RTTY contesters - only K1ZZ sent a log in the 2012-2013 ARRL RTTY RU.

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message----- 
From: Kok Chen
Sent: Thursday, November 21, 2013 11:04 AM
To: RTTY Reflector
Cc: Jeff Blaine
Subject: Re: [RTTY] ARRL attack on current RTTY users


On Nov 21, 2013, at 8:26 AM, Jeff Blaine wrote:

> There is a lot of "modernization" and "flexibility" listed - but who, 
> beyond the PACTOR guys, would actually benefit from this change.  Figure 
> that out and we can likely connect the dots from that group to this 
> decision.

Unless the words "modernization" and "flexibility" are synonymous with the 
phrase "more data bandwidth," the ARRL proposal simply don't make any 
technical sense.

As I mentioned in an earlier private email to another reflector participant, 
take a look at all the advancements towards getting the most miles with the 
lowest power.  You need not look further than Joe Taylor's modes.

http://www.physics.princeton.edu/pulsar/K1JT/index.html

If you include the also widely used PSK31 (very good for folks with small 
antennas and low power when propagation is good) the focus on narrower 
bandwidths goes back for at least two and a half decades.

These folks had the freedom to use higher symbol rates and wider bandwidth, 
but choose not to.

Technically, you can use wider bandwidths to counter selective fades due to 
multipath in Rayleigh channels (best model for HF that has been used for 
decades now).  That is addressed in modern modes with good forward error 
correction (FEC) and longer data frames.  And even when you use simple two 
tone FSK, it has been known by amateurs since the 1960s that 170 Hz is 
already wide enough to derive information to apply a good automatic 
threshold correction to FSK.  As I mentioned in my "RTTY Demodulators" 
article,

"In a February 1964 article in the RTTY bulletin, Frank Gaudé reported that 
there is actually no significant difference anyway between the amount of 
selective fading between a wide shift and a narrow shift signal down to the 
170 Hz region."

So, the need for wider bandwidths has nothing to do with finding better 
modes for HF communications.  It does allow you to push more bits per second 
through the channel.

BTW, you can include references in your comments to the RM, and the 
references can include Web links, references to RTTY Bulletins from the 
1950s, or email to your kids, if those are pertinent.  Please feel free to 
do all the web research that you need and include references that you decide 
are pertinent to include in your own comments.

73
Chen, W7AY

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