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Re: [RTTY] RTTY Now trashy signals

To: Al Kozakiewicz <akozak@hourglass.com>, "rtty@contesting.com" <rtty@contesting.com>
Subject: Re: [RTTY] RTTY Now trashy signals
From: "aflowers@frontiernet.net" <aflowers@frontiernet.net>
Reply-to: "aflowers@frontiernet.net" <aflowers@frontiernet.net>
Date: Wed, 9 Jan 2013 09:03:08 -0800 (PST)
List-post: <rtty@contesting.com">mailto:rtty@contesting.com>
>Don't underestimate the importance of the words "in the sense that"!

Fair enough, Al!  I've had my coffee now...
 
Here's a very simple way that might get at the crux of the issue.  Let's say 
that signal number #3 was your signal (yes, this was recorded off the air this 
weekend, and no, I'm not going to identify him or her publicly):   
 
http://www.frontiernet.net/~aflowers/rtty_examples/
 
Would knowing that was was being heard up and down the East (and probably West) 
coast bother your conscience enough to look for ways to change something?  Does 
anyone want to say 'no'?  
 
We all (well, most of the big contesters) managed to modify our early model MPs 
to reduce the nasty CW  key clicks without some objective standard from on 
high.  The problem was identified and people came up with solutions pretty 
quickly.  Hams have historically been able to make many changes for the better 
without big brother drawing a line in the sand.
 
Andy K0SM/2
 

________________________________
 From: Al Kozakiewicz <akozak@hourglass.com>
To: "aflowers@frontiernet.net" <aflowers@frontiernet.net>; 
"rtty@contesting.com" <rtty@contesting.com> 
Sent: Wednesday, January 9, 2013 11:08 AM
Subject: RE: [RTTY] RTTY Now trashy signals
  
Don't underestimate the importance of the words "in the sense that"!

While we are all ultimately responsible for operating to a set of acceptable 
standards, the FSK operator has no choice to make in the matter short of 
ceasing operation if their transmitter is performing poorly*.  The AFSK 
operator, on the other hand, makes all kinds of choices in software, soundcard, 
interface, computer output levels, transmitter gain, compression, ALC, etc. 
etc.  All have a direct impact on signal quality.

I too would be interested in knowing both how to define and measure the quality 
of FSK transmissions and how products perform with respect to those metrics.

*-Anyone can plot quality (however you'd like to define that term) of 
transmitted signals along a line from bad to good.  What I'd like to know is 
where you draw a line distinguishing acceptable from unacceptable?  If width is 
king, queen and everything in between with respect to RTTY signals, how many db 
down do the modulation byproducts have to be how far from the mark/space 
frequency?  And who gets to decide that?

Al
AB2ZY


________________________________________
From: RTTY [rtty-bounces@contesting.com] On Behalf Of aflowers@frontiernet.net 
[aflowers@frontiernet.net]
Sent: Wednesday, January 09, 2013 10:28 AM
To: rtty@contesting.com
Subject: Re: [RTTY] RTTY Now trashy signals

Al,

I respectfully disagree in small detail (and please forgive me if I 
misunderstood).  I think everyone owns equal responsibility for his or her 
signal *regardless of the process creating it*.  We make the decision to either 
trust that the manufacturer has implemented the feature properly and we choose 
use it, or we choose to do it by other means.  Contesters are always making 
decisions like this.  Really capable people will measure the things that matter 
to them, if they can, and the magazines try to publish product reviews to help 
us out.  In the final analysis we make a good choice or we make a bad choice 
based on available information, but either way we make the choice and we are 
responsible for the signal we put out.  Sometimes getting a new radio may be 
the only viable option, and that is expensive, and yes, we will be upset at the 
manufacturer for giving us a raw deal.

I think your main point is that "the transmitter made me do it" isn't a 
justification for keeping on doing it.  Spot on, in my opinion.

I think that begs a really important question though: is there any meaningful 
difference among the FSK signals generated by different radios' internal FSK 
generators.  Forget whether it's done by switching the LO frequency, by magical 
DSP fairies, or by black and white mice spinning the mark and space wheels next 
to the flux capacitor:  *among the internal FSK generators in the K3, IC-7800, 
FT-1000MP, and IC-706, or any radio made in the last 15 years, is there any 
meaningful difference when it comes to the RF coming out?*

If so, what are the differences?  Anyone have pictures of radios side by side 
when keyed in their "FSK" mode?

Andy K0SM/2


----------------------------------------------------------------------


Which was basically my point.  Discounting analog FSK implementations from 30 
years ago, there is nothing you, Joe Ham,  can do should it be proved that, yes 
indeed, your 2 year old DSP transceiver is splattering when modulated using 
FSK.  There are no user accessible adjustments and with the few DSP designs 
I've looked at there are no internal hardware adjustments either so you can 
probably safely attribute the problem in that case to bad design.  Which has no 
cure except to buy a different model radio.

A ham running AFSK owns a lot more responsibility for the cleanliness of his 
signal than one running FSK in the sense that AFSK performance is more 
dependent on user configuration.

Al
AB2ZY

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