Mike, Are you using the mic input or does your laptop have a line-in? You may be seeing the baseline noise of your soundcard input - some are noisier than others, and if you have an open input, that may be picking up noise - Spectrogram will display that open circuit noise pickup. Short the input and see if it changes.
In any case, I would not worry about it - it may just be some artifact of the soundcard that will not be relevant to what you are trying to accomplish. Put some kind of input into the soundcard and adjust the audio input level to place the display at some convenient point on the screen. You may have to adjust the sliders in your soundcard control panel, and adjust the audio level you are feeding to the soundcard. Try it - connect a cable between the K2 headphone jack and the soundcard, then play with it for a bit with both a single signal tuned on the K2 and with a wideband noise input to the K2 (even band noise will work). Once you see it, you will have a better feel for what is going on. A single tone signal will appear as a spike on the display at the audio frequency indicated on the horizontal scale - and the filter passband will be a wider "hump" on the display (at a lower amplitude than the signal). Adjust the levels and the slider on the right of the screen to place the display on the screen vertically anywhere you want to see it - then you can say that some signal is xx dB above the receiver noise floor, or if there are two signals, you can say that they are xx dB different from each other, or with only a wideband noise source into the K2, you can see the relative amplitude of the passband at various audio frequencies. A spectral line display is always relative on the vertical scale, it never shows any absolute value. The information that is conveyed is that one point is xx dB different than some other point. That is true with any spectrum analyzer type display. 73, Don W3FPR Mike wrote: > Hi all, > I am going to start setting up my K2 and will be using Spectrogram for > some of the steps. I downloaded ver 5.17 onto my laptop. Setup the > scan input page according to N0SS website. With no input the scan > input screen has the normal rise up to -20 then it dropes to -60. > Where it is suppose to stay but I have some ripples up around -40. Is > there an adjustment in the sound card I need to do? Or does one of the > scan input values need to be changed? > Mike > VE3WDM > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
