MathJax

MathJax allows you to include mathematics in your web pages, either using LaTeX, MathML, or AsciiMath notation, and the mathematics will be processed using JavaScript to produce HTML, SVG, or MathML equations for viewing in any modern browser.

<head>
...
<script src='https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.4/latest.js?config=TeX-MML-AM_CHTML' async></script>
...
</head>

\begin{equation}
\begin{pmatrix}
M&m_1&m_2&0 \\
0&m_{1}&-m_2&0 \\
2&-1&-1&0
\end{pmatrix}
\begin{pmatrix}
A \\ a\\ b\\ T
\end{pmatrix}
=
\begin{pmatrix}
F-Mg-(m_1+m_2)g \\ (m_2-m_{1})g \\ 0
\end{pmatrix}
\end{equation}

\begin{equation}
H_c=\frac{1}{2n} \sum^n_{l=0}(-1)^{l}(n-l)^{p-2}
\end{equation}

\begin{equation}
\left.\begin{aligned}
B’&=-\partial\times E, \\
E’&=\partial \times B – 4\pi j,
\end{aligned}
\right\}
\qquad \text{Maxwell’s equations}
\end{equation}

PDS5022SとOwondump(2)

オリジナルのプログラム、owondump.c 0.3を、ほんの少しだけ改変しています。

Display Set Menuで、Carryを手動で選択することにより、”owondata.bmp”もしくは”owondata.txt”を得ることができます。

% gcc -o owondump owondump.c -lusb
% sudo ./owondump
% gnuplot
gnuplot> plot 'owondata.txt' using 1 with line, 'owondata.txt' using 2 with line

PDS5022SとOwondump

% gcc -o owondump owondump.c -lusb
% sudo ./owondump
% gnuplot
gnuplot> plot 'output.bin.txt' using 1 with line, 'output.bin.txt' using 2 with line

SDR用のアンテナスイッチ(5)

Airspy HF+の仕様は;
+10 dBm Maximum RF input.
となっています。

IC-7410の最大出力は100Wなので、40dB以上の減衰量がアンテナスイッチには求められます。

非常に雑な実験をしてみると、送信RFパワーが7MHzで35dBmの場合、受信機ポートには-6dBm (=S9+67dB)程度の漏れがあるので、41dBの減衰があることになります。

Airspy HF+とIC-7410をRaspberry Pi 3で

WSJT-Xを2つ同時に起動します:

% wsjtx --rig-name=IC7410 &
% wsjtx --rig-name=AirspyHF &

pi@raspberrypi:~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
  Subdevices: 7/7
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
card 0: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 1: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 2: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
pi@raspberrypi:~ $ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 1: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 2: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

WSJT-XとGridTracker

GridTrackerは、WSJT-Xに随伴するプログラムです。

あなたは、このプログラムがPSKreporterでは提供されない情報を与えてくれることに気がつくかも知れません。

このケースでは、2つのプログラム、WSJT-XとGridTrackerは、同じマシン上で動作しています。

そして、このケースでは異なるマシン上で。

Raspbian Stretchとsystemd-timesyncd

pi@raspberrypi:~ $ lsb_release -a
No LSB modules are available.
Distributor ID:	Raspbian
Description:	Raspbian GNU/Linux 9.4 (stretch)
Release:	9.4
Codename:	stretch

pi@raspberrypi:~ $ uname -a
Linux raspberrypi 4.14.34-v7+ #1110 SMP Mon Apr 16 15:18:51 BST 2018 armv7l GNU/Linux

pi@raspberrypi:~ $ ps aux | grep time
systemd+   276  0.0  0.4  17276  4012 ?        Ssl  Jun18   0:00 /lib/systemd/systemd-timesyncd

pi@raspberrypi:~ $ timedatectl status
      Local time: Tue 2018-06-19 01:55:55 UTC
  Universal time: Tue 2018-06-19 01:55:55 UTC
        RTC time: n/a
       Time zone: Etc/UTC (UTC, +0000)
 Network time on: yes
NTP synchronized: yes
 RTC in local TZ: no

pi@raspberrypi:~ $ cat /etc/systemd/timesyncd.conf
# Entries in this file show the compile time defaults.
# You can change settings by editing this file.
# Defaults can be restored by simply deleting this file.
#
# See timesyncd.conf(5) for details.

[Time]
#NTP=
#FallbackNTP=0.debian.pool.ntp.org 1.debian.pool.ntp.org 2.debian.pool.ntp.org 3.debian.pool.ntp.org

pi@raspberrypi:~ $ ls -l /var/lib/systemd/clock
-rw-r--r-- 1 systemd-timesync systemd-timesync 0 Jun 19 01:59 /var/lib/systemd/clock

Airspy HF+とRaspberry Pi 3でFT8

FT8信号をデコードする非常に小さなシステムです。

pi@raspberrypi:~ $ uname -a
Linux raspberrypi 4.14.34-v7+ #1110 SMP Mon Apr 16 15:18:51 BST 2018 armv7l GNU/Linux

pi@raspberrypi:~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
  Subdevices: 7/7
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
card 0: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 1: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 7/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7

pi@raspberrypi:~ $ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  Subdevices: 7/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
card 1: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7

pi@raspberrypi:~ $ lsmod
Module                  Size  Used by
snd_aloop              24576  4