[RTTY] K3 reduced-bandwidth RTTY analysis

[Jeff Blaine]

Very nice work, Andy...

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

-----Original Message----- 
From: aflowers at frontiernet.net
Sent: Thursday, March 21, 2013 8:16 PM
To: RTTY Mailing List
Subject: [RTTY] K3 reduced-bandwidth RTTY analysis

Hello again,

I have finally gotten around to finishing up a short analysis of the 
reduced-bandwidth FSK keying in the K3.  As many of you are aware, Elecraft 
made some beta firmware available several weeks ago that attempts to reduce 
the clicks that result for unshaped keying.  They analysis involves a before 
and after pictures comparing the FSK spectra from the general release 
firmware (representative of most radios, to the best of my limited 
knowledge) and the bandwidth-reduced firmware.  I've also included some 
analysis using a 300 Hz "roofing filter" to measure the noise floor at 
different dial offsets from the transmitter to give and idea of what it 
"feels" like when it is QRM.  There are a few people who operated WPX and 
and other contests with this firmware, and I am sure they could tell of 
their experiences on the transmitter side.

http://www.frontiernet.net/~aflowers/k3beta/

While on the subject of clicks, spurs, and other nasty things, I also would 
encourage people to have a look at N2QT's question on p. 55 in the April QST 
and WB1GCM's (at ARRL Lab) response, which also address this and some other 
issues around RTTY keying.  He distinguishes "clicks" that result from the 
waveform from the other bad things that can happen with broken audio signal 
chains.  This is an important distinction to keep in mind.

Enjoy!

Andy K0SM/2
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