LITOPO
QRSS viewing using a browser by PA2OHH
(another hero of QRSS). All credit to PA2OHH.
-- Audio frequency (Hz): -- Tuned frequency (Hz):
Level (dB): - -
- - --
Audio band (Hz): --
--
LITOPO version: litopo1.htm (2021-12-15) -- QRSS
reception with a webbrowser
It is very simple!
Connect the audio input of your PC, Tablet PC or
Smartphone to your SSB receiver. Click a link in your webbrowser
(Chrome or Firefox etc.) to -litopo1.htm- and the QRSS signals will be
displayed on your screen! No extra software required, only the standard
functions of your webbrowser software are used. Modern webbrowsers have
audio processing software like a simple spectrum analyzer functionality
that is used here. Sensitivity levels, level ranges, smoothing are all
settings of this spectrum analyzer functionality of the webbrowser.
This simple program is intended as an easy way to get acquainted with
QRSS. It has less fuctionality and is much easier to use than the more
comlex and more sophisticated software programs. You cannot do an FTP
upload and it is not possible to save a picture. You have to make a
screenshot if you want to save a picture. Right click with your mouse
on the picture or use the Print Screen button of your keyboard. The FFT
sample length is limited to 32768 samples, so we have to downsample the
audio sample rate to 9600 samples for a good performance. It can only
connect to the default audio device of your computer.
Long wave notes
Thanks
to Mike N8OOU for the help with the Long wave settings! For QRSS on
Long waves, a dot time of 30-60 seconds is used instead of 3-6 seconds.
And a shift of only 0.5 Hz. So we have to downsample even more to the
lowest possible 3000 samples/sec. However, that is not supported by all
webbrowsers! It is by Chrome, Chromium. And we would like to have a
longer FFT array time length. However with the special Multi Smooth
function, the performance of LIPOTO for the Long wave bands is also
good! When 3000 samples/sec. is not supported, then the lowest always
supported 8000 samples/sec. is taken.
-Start-
Fill in the
-Audio frequency- and -Tuned frequency- labels and press -Start-. Wait
for the request for permission to use the audio. The button text
changes from -Start- to -Set-. Press it when you want to change the
frequencies later. If you want that the scan starts on exact multiples
of 20 minutes, press -Set- at that moment. For USB reception, the SSB
receiver has to be tuned to the LOWEST frequency of the QRSS band MINUS
the -Audio frequency-. For LSB reception, the SSB receiver had to be
tuned to the HIGHEST frequency of the QRSS band PLUS the -Audio
frequency-.
-Level-
The sensitivity level of the spectrum analysis. A lower value displays
a brighter background noise.
-Range-
The on the screen displayed range in dB. It acts like a kind of
contrast. A lower value gives a higher contrast.
-Audio band-
The Audio band is the displayed frequency band on the screen from
bottom to top. It can be set to 200, 300 or 600 Hz. For 300 and 600 Hz,
the screen is resized by 50%. Set the audio band before the start of
the reception. The 50 Hz and 100 Hz Audio bands are for QRSS Long wave
reception. Special settings for the QRSS long wave reception are also
applied.
-USB-
You can use it in Upper Side Band reception mode (normal) or Lower Side
Band mode (special cases like my simple 80 meter QRSS receiver).
For the normal USB reception, the BOTTOM line of the grid is the tuned
frequency PLUS the -Audio frequency-. For the special LSB reception,
the TOP line of the grid is the tuned frequency MINUS the -Audio
frequency-.
-Smoothing-
Smoothing reduces the noise a little but has the disadvantage that the
shift transitions of the QRSS signal are less sharp.
And...
Of course it is not convenient that you have to change the settings
every time you start the program. But you can download it to use it
locally and edit the first lines of the litopo1.htm script. I have a
few with different names: litopo1m80.htm, litopo1m30,htm and
litopo20.htm. Indeed, for 80 meters, 30 meters and 20 meters.