Wednesday, April 25, 2018

Tuesday, April 17, 2018

Notes on compiling software lockin amplifier

Abbreviated notes from the software lock-in amplifier at https://github.com/hn-88/SoftwareLockin/

French lockin works on USB stick. Lubuntu 12.04

edited the pro files to add
QT += widgets

vumeter.h:40:25: fatal error: QtGui/QWidget: No such file or directory
on Mint 18.1

edit h files to make QtGui/QWidget QWidget

make clean
qmake multi.pro
make


error: ‘const class QString’ has no member named ‘toAscii’ - solved using

(was solved by install of package qttools5-dev-tools
more info here...) not used

QByteArray QString::toAscii() const
Returns an 8-bit representation of the string as a QByteArray.

This function does the same as toLatin1().

So, replaced in lockin.cpp and dockoutput.cpp

output has NaN

Edit: 20 Apr
ui_lockingui.h:13:29: fatal error: QtWidgets/QAction: No such file or directory
compilation terminated.
Makefile:406: recipe for target 'lockingui.o' failed
make: *** [lockingui.o] Error 1

probably have to find replace again?

Also QWidgets/QApplication

changed to QApplication etc - find replace QWidgets/ with nothing.

sudo apt-get --reinstall install libqt4-opengl-dev

Maybe if I upload the makefile?



Friday, April 13, 2018

USB to TTL link dump

A collection of links about communicating with serial control lines over USB - Arduino etc - 

Tuesday, April 10, 2018

bouncing emails in google groups

Maintaining google group by deleting bounced emails. And if needed, re-adding them. 

https://support.google.com/a/answer/7552660?hl=en

Edit: Users can reset their bounce status by going to https://groups.google.com/bounced?pli=1 or https://groups.google.com/a/example.com/groups/bounced?pli=1
next to Bounce Status, email status -> Reset bounce status. (which appears only if it is bouncing.)

Monday, April 09, 2018

Arduino IDE on Linux Mint

From https://playground.arduino.cc/Linux/Mint/
we should probably not use
sudo apt install arduino
because it is outdated or non-standard, and we should instead use the 64 bit binary from 
https://www.arduino.cc/en/Main/Software

Saturday, April 07, 2018

email slowdown and possible fixes

From March 24 or 25, our mailing list started having a lot of delays in email sending, especially to gmail.com. Found the following issues:

1. For some gmail emails, the server was trying the ipv6 address, and not able to reach it - like

Mar 25 09:34:15 krishna postfix/smtp[19788]: connect to gmail-smtp-in.l.google.com[2404:6800:4003:c03::1b]:25: Network is unreachable

Mar 25 09:34:28 krishna postfix/smtp[20163]: connect to ASPMX.L.GOOGLE.COM[2404:6800:4003:c02::1b]:25: Network is unreachable

This was probably due to a router change at the Studio.

Did this -
https://support.plesk.com/hc/en-us/articles/213398289-Specifying-Postfix-configuration-of-IPv4-IPv6-protocol-support
ie
adding the option:

inet_protocols=ipv4

to the /etc/postfix/main.cf Postfix configuration file. And then as root,

# postfix reload
# service postfix restart

That worked, the emails went out. But the email sending rate was only around 1000 emails per hour, as reported by
# qshape incoming active deferred

2. A lot of mails were being deferred instead of bounced by gmail, OverQuotaTemp.
cat  /var/log/mail.log | grep OverQuotaTemp | wc -l
5878
PB unconfirmed those emails using
cat /var/log/mail.log | grep OverQuotaTemp | grep 'to=' | grep -o '[[:alnum:]+\.\_\-]*@[[:alnum:]+\.\_\-]*' | sort | uniq -i

Then also for bouncing emails, like
cat  /var/log/mail.log | grep "does not exist"
cat  /var/log/mail.log.1 | grep "does not exist"
cat  /var/log/mail.log.1 | grep "553 Mail from 111.93.16.162 not allowed"
cat  /var/log/mail.log | grep "status=bounced"
cat  /var/log/mail.log.1 | grep "status=bounced"

3. Mails were still going out slowly, with the usage on the internet port being like

Next try was to speed up sending to gmail.com domain, since the other emails were going out OK. Then, added these two lines to /etc/postfix/main.cf - 

maximal_queue_lifetime = 2d
default_destination_concurrency_limit = 100

decreasing lifetime from 5d to 2d and increasing concurrency limit from 20 to 100. That seemed to improve things - the outgoing rate went up to almost the peak rate - 

and from the next day, the emails were going out like









Thursday, April 05, 2018

notes on startup / shutdown times

On a machine with dual boot,

Time taken for Windows 7 to boot, open firefox and open youtube.com - 3:30 minutes.
Time taken for Linux Mint 18.3 to boot, open firefox and open youtube.com - 1:15 minutes.
Similarly, Windows takes 40 seconds to shut down, while Linux shuts down in less than ten seconds.
Equivalent of Hotspot Shield, if you want to watch something which is blocked - have installed PureVPN extension for both Chrome and Firefox...

Linux vs Windows 7 brief speed test

N's Lenovo B640 laptop had become old and slow. Tried dual booting with Linux Mint, found quite an improvement. 

Time taken for Windows 7 to boot, open firefox and open youtube.com - 3:30 minutes.

Time taken for Linux to boot, open firefox and open youtube.com - 1:15 minutes.

Similarly, Windows takes 40 seconds to shut down, while Linux shuts down in less than ten seconds.