On Tue, 19 Aug 2008 06:01:35 -0700, Mike Scott wrote: >Could someone explain a method of measuring roofing filter offset? >I have spectrum analysis software.
Once you've studied the manual thoroughly and learned to use the radio, it will become obvious. First, the FFT system must be set for high resolution scan rates. I use a professional audio FFT (EASERA SysTun) with band noise as the signal source and lots of averaging. I measured and stored plots of the DSP filters, then measured and stored again with the K3 set so that the roofing filter kicks in with the DSP filters set to be very broad band. Then I overlaid those plots. It's important to measure at the headphones output -- the Line Out can overload at relatively modest signal levels, as noted in the manual. These offsets are nothing more or less than manufacturing tolerances in the filters. Ain't no big thing, since the K3 can easily be adjusted to compensate. But it's wrong to deny that they exist. 73, Jim Brown K9YC _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
