Igor, You are missing the point. K8ZOA's measurements were for a continuous carrier. You can't measure speech intelligibility with the K3's dBV meter.
My recommendation for DSP bandwidth of 2.1 KHz and 1.8 crystal filter were based on what I consider the best compromise between bandwidth and intelligibility for SSB human speech. Look at it this way - My ears find SSB speech very intelligible with a DSP bandwidth of 2.1 KHz. You can put a 1.8 crystal filter in front of that DSP and SSB STILL is very intelligible, plus you have the advantage of a nice tight roofing filter to keep the hardware AGC from pumping. When you start reducing the DSP bandwidth below 2.1 KHz, intelligibility starts to become very dependent on the voice characteristics of the received signal, so you have to keep fiddling with the DSP controls. You don't want to be fiddling with the controls if you are running at 200 QSO's per hour. I'm saying that with DSP 2.1 and a 1.8 roofing filter, one can pretty much leave the controls alone for the duration of the contest. After the contest is over, you can go back to 2.7/2.7 filters for more natural-sounding audio. Dave Hachadorian, K6LL Yuma, Arizona -----Original Message----- From: [email protected] Sent: Wednesday, March 28, 2012 11:05 AM To: [email protected] Cc: [email protected] Subject: Re: [Elecraft] K3 Filter questions If it pleases you to use DSP set wider than roofing filter - by all means, go for it. I would not, however, clame objectivity based on my subjective experience or somebody's valuable opinion and simplistic explanation , I perefer measurements performed on good lab equipment. K8ZOA did some of the measurements on 500 Hz filter, but most of them probably applicable for the 1.8kHz filter. See report here: http://www.cliftonlaboratories.com/elecraft_k3_noise_blanker_and_crystal_dsp_filtering.htm In his measuremetns, setting DSP wider than the actual roofing filter actually degraded the total response in the stop band. 73, Igor, N1YX ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
