KA7U

Dave,
I think you have the most efficient way of routing the audio to the decoder software, using a Windows PC. If you chose to use Pulse Audio it would give you somewhat different setup options, but the results would be the same.
Ron

Dave,
The program suite is called Kiwiclient.
https://github.com/jks-prv/kiwiclient/tree/jks-v0.1

I use it to record when I'm not there, or to obtain an audio file for further uses. I was interested in DRM and would not stay up late or get up early to seek a DRM station. So I setup cron jobs to do the recordings and then listened to them later. Below is an example:

Now for a cron job to start and stop the recorder. I think I might manage that... Is there a way to specify the recording length time on this recorder?

So how to start and stop the kiwirecorder.py using crontab (ie. cron job)
add these commands in crontab:
ron@linux-4cdz:~> crontab -e

# DO NOT EDIT THIS FILE - edit the master and reinstall.


# (/tmp/crontab.JBGmN4 installed on Thu Nov 23 10:37:32 2017)
# (Cronie version 4.2)
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# | | | | |
# * * * * * command to be executed
# * * * * * command --arg1 --arg2 file1 file2 2>&1
00 12 * * * python ~/kiwiclient-jks-v0.1/kiwirecorder.py -s southwest.ddns.net -p 8073 -f 5955.00 -m iq -L -5000 -H 5000
30 12 * * * for pid in $(ps -ef | awk '/python/ {print $2}'); do kill -9 $pid; done


I haven't used it for a while and have not checked for updates. So there may be new options or features not described in this limited example.

Ron - KA7U

Suppose you want to notch 800KHz >10dBm. You could place a series LC circuit consisting of a 68pF capacitor and a 575uH inductor from the signal input lead to ground. A calculator to help with this determination is here: http://www.deephaven.co.uk/lc.html

You can buy parts at mouser.com and many other places. For example check out the part #143-10J12L on the data sheet located here:
https://www.mouser.com/datasheet/2/597/uni10-463412.pdf and the capacitor could be a ceramic disk like this one:
https://www.mouser.com/datasheet/2/427/dseries-371291.pdf

It is good to either use a variable inductor or a variable capacitor to help center the notch on the strong signal. You do this by adjusting the variable while observing the amplitude of the signal on the KiwiSDR and stop when it is at the lowest point.

You can change the values of inductance and capacitance to select parts that fit into your enclosure better. for example a 2000pF capacitor and a 20uH inductor. In this case you would probably wind the inductor on ferrite toroid and adjust the winding spacing or number of turns to find the inductance value. The capacitors will be +/- if they are fixed capacitors and it helps to have a LC meter to see what they are to get close to the resonant frequency.
Ron
KA7U

I found it tough to find 3 stations that could plot WWVB on the map. I don't know if it is because of the type of signal transmitted or what.
Ron - KA7U

Just a note to compliment on the wonderful FAX decoder. This image was taken at 17149.3KHz @ 02:15 UTC.
Ron
KA7U