[RTTY] K3 reduced-bandwidth RTTY analysis

[aflowers at frontiernet.net]

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