Posted by
alorona on
Jul 09, 2012; 6:15am
URL: http://elecraft.85.s1.nabble.com/K3-Spectrogram-and-the-K3-tp7558874.html
If you have nothing to do today, try this:
Install Spectrogram on your computer so that you can feed the audio output of
your K3 into your computer's line in (or your laptop's mic in).
Scan the input using the following parameters in Spectrogram (I am using version
5.1.7 here):
Sample Rate: 11 kHz
Resolution: 16 bit
Type: Stereo
Display Type: Line
Channels: Dual
Scale: 60 dB
Freq Scale: Linear
FFT Size: 1024
Spectrum Average: 32
Click on OK to start the measurement. Put the K3 into CW mode and vary the WIDTH
control. Look at that fine, flat frequency response that follows your WIDTH just
perfectly. I was using this today to help my son visualize what that control
does. (You may have to set the K3 volume control to about 12 o'clock to get a
good reading in Spectrogram, but this depends on your Windows volume control,
whether you have HI or LO audio gain selected on the K3, etc.)
Set the K3 WIDTH to 50 Hz and notice the response. Beautiful. Now, turn APF on
and watch very closely. Notice what APF does to the peak! Now you know why it
can be so effective under the right conditions.
I asked you to set the Type to STEREO in Spectrogram, but an interesting thing
happens when you set it to MONO instead.
After setting it to MONO, set your K3 WIDTH to a convenient width such as 1.0
kHz. Notice the nice, flat response as before. Now, turn on the K3's AFX and see
what happens. Change the AFX from Delay1 to Delay5 and see the results. For
extra credit, explain what is happening here. Here's a hint: set AFX to "Bin"
and notice that the signal goes away completely! My guess is because
Spectrogram's MONO mode is essentially L + R, and in Bin mode L and R are
out-of-phase and so their sum is zero. Assuming this, can you explain why Delay1
through Delay5 look like they do?
Al W6LX
______________________________________________________________
Elecraft mailing list
Home:
http://mailman.qth.net/mailman/listinfo/elecraftHelp:
http://mailman.qth.net/mmfaq.htmPost: mailto:
[hidden email]
This list hosted by:
http://www.qsl.netPlease help support this email list:
http://www.qsl.net/donate.html