[TangerineSDR] SAQ scheduled to air on World Radio Day Feb 13th, 2023

Sun Feb 19 13:38:53 EST 2023

Hi Joe,

Thanks for the reception report! You can look at the listener's report
interactive map here
<https://alexander.n.se/en/listeners-reports-interactive-map/>.

Jonathan
KC3EEY

On Sun, Feb 19, 2023 at 1:29 PM Jonathan <emuman100 at gmail.com> wrote:

> Hi All,
>
> I wanted to share my 02/13/2023 SAQ transmission report.
>
> Using vtsid, I set it up to record the amplitude of SAQ just to see if I
> could see any possible signal from the 1500UT transmission. This looks
> promising:
> [image: Screen Shot 2023-02-13 at 9.21.18 PM.png]
>
> While a lot of it looks pretty noisy, it looks like there was some signal
> around the time of the transmission at 1500UT. Zooming in looks even more
> promising:
> [image: Screen Shot 2023-02-13 at 9.21.48 PM.png]
>
> It could just be noise peaks, but their duration seemed too long for
> noise, so I was hopeful! To be sure, I wanted to look at the non-coherent
> spectrum. Using vlfrx-tools, I used this signal pipeline from the raw data
> I pulled from the signal store and ran it through vtnspec, integrating over
> the transmission duration:
>
> vtcat -T2023-02-13_14:49,+12m 2023-02-13_14-00p1.5h_SAQ_test_and_main.vt |
> vtnspec -f17200 -w200 -r1 -av > SAQ220213.dat
>
> I used vtcat to send only the transmission duration to the input of
> vtnspec with a center frequency of 17200 Hz, 200 Hz wide, at a resolution
> of 1 Hz. Using gnuplot, I plotted SAQ220213.dat using the following script:
>
> echo "set terminal png small
>          set style data lines
>          set xlabel 'Frequency, Hz'
>          set ylabel 'Relative amplitude'
>          set nokey
>          set title '2021-12-24_07:46:00,+16m in 1Hz'
>          plot 'SAQ122421.dat' using 1:2
>      " | gnuplot > SAQ122421.png
>
> This produced the following plot:
> [image: SAQ230213.png]
>
> Peaking only a little bit above the noise a very promising peak of SAQ's
> signal! Compared to Christmas Eve of 2021, this is much more centered at
> 17.2 kHz. Well done getting such an old transmitter as spot on as this
> transmission is! Here is vtnspec's output:
>
> vtnspec: amplitudes 0 m/p/r: 4.557e-06 6.411e-06 1.407 p-m 5.01 sigma
>
> Now, the real test is the listening test. Using the following pipeline, I
> produced a wav file from the data, running it through some filtering:
>
> vtcat -T2023-02-13_14:49,+12m 2023-02-13_14-00p1.5h_SAQ_test_and_main.vt |
> vtfilter -h bp,f=17200,w=1000 -g100 | vtmult -f 16700 | vtmix -c 1,-j |
> vtraw -ow > SAQ230213.wav
>
> Again, vtcat pulls the duration of the transmission and runs it through
> vtfilter at the 17200 Hz center frequency, 1000 Hz wide, adding a gain of
> 100. It's then sent to vtmult and vtmix to downmix down to 500 Hz, then
> converted to wav. I used lame to convert it to mp3:
>
> lame -b64 -m m SAQ230213.wav SAQ230213.mp3
>
> You can listen to it here
> <https://drive.google.com/file/d/13voNd4aXxw9kWNZ4vHlwOoXceTzeN9V5/view?usp=share_link>
> .
>
> Since the signal was pretty close to the noise floor, it blends in with
> the noise pretty well, but if you listen very carefully, you can hear the
> message!! Using smaller bandwidths didn't give me the desired tone due to
> the fact the filter is a brick wall filter, so I decided to use the
> Butterworth bandpass filter in sox, 20 Hz wide center at 500 Hz, also
> adding a gain of 20 to make it even more audible:
>
> sox -v 20 SAQ230213.wav SAQ230213_20Hz_g20.wav bandpass 500 20
>
> Encoding to mp3 again using lame:
>
> lame -b64 -m m SAQ230213_20Hz_g20.wav SAQ230213_20Hz_g20.mp3
>
> You can listen to it here
> <https://drive.google.com/file/d/1dDOM6GrHj79ggzeyuyHkIAR7qlWh82i-/view?usp=share_link>.
> It's much easier on the ears this time and makes copying the message much
> easier. There was much less fading this time, but possibly due to the fact
> that the transmission occurred during local daytime. It's really cool that
> signal processing can bring this transmission out of the noise! A huge
> thanks to Paul for helping me with this last year and for his vlfrx-tools
> software.
>
> Can anyone copy the message from my audio file and decode it? If you can,
> please post it to this thread.
>
> Thanks.
>
> Jonathan
> KC3EEY
>
> On Mon, Feb 13, 2023 at 12:21 PM Joe Hobart <nova at npgcable.com> wrote:
>
>> Hi Jonathan,
>>
>> Nothing heard here or seen on WF at or around 17.2 kHz from 1200 to 1530
>> UTC.
>> Plenty of other signals present.  Due to distance and time of day, the
>> non-detection of SAQ was considered likely.
>>
>> Good copy from youtube.
>>
>> Here is a screen grab typical of the listening period showing at least 4
>> Navy
>> transmitters and other signals.  The carrier at 15 kHz is a locally
>> generated
>> weak signal.  The intermittent carrier at 18 kHz is unknown.
>>
>> 73,
>> Joe, W7LUX
>> Flagstaff, AZ
>>
>>
>> On 2/13/2023 8:11 AM, Jonathan via TangerineSDR wrote:
>> > Hi All,
>> >
>> > Reminder, the SAQ transmission is currently going on. (15:00UT)
>> >
>> > Jonathan
>> > KC3EEY
>> >
>>
>>
>> ---
>> This email has been checked for viruses by Avast antivirus software.
>> https://www.avast.com/antivirus
>>
>
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