How to change the bluetooth device address (BD_ADDR)

Cheap bluetooth adapters often share the same bluetooth address (BD_ADDR). That is especially a problem if you want to use both at the same time with the same device. Fortunately one can change the address of a bluetooth adapter with the bdaddr command (delivered with recent versions of bluez-utils). This is a quick howto for recent versions of bluez.


Python 2 vs Python 3: Bytes and Strings

Many Linux distributions will or have already switched over to Python 3 as default interpreter when running the python command. At the same time many people are still used to Python 2 and might not be aware of the changes that come with that switch. Especially string and byte handling is different from Python 2. This article is about some common pitfalls and how to prevent them with Python 3.


One-liner #2: Enabling and Disabling Synaptic Touchpads

If you have a notebook with one of these large touchpads you might have come across this problem: You type something on the keyboard and suddenly the cursor jumps to a different location messing up your text (because you accidently touched the touchpad with your palm). To avoid this syndaemon allows you to automatically lock the touchpad when you type something on the keyboard. Desktop environments like XFCE make use of it. The downside of that is, that it can result in a frozen mouse pointer (for some milliseconds or seconds). Therefore I prefer to disable the touchpad manually by using a shortcut whenever I need that feature.

This post shows a one liner which allows you to disable your Synaptics touchpad temporarily. The same command allows you to enable it later again. By binding the command to a shortcut, you can easily toggle between an enabled or disabled touchpad.


Ein Audio-Übertragungssystem mit Open Source Software auf WLAN Basis

Es ist rund zwei Jahre her, dass mich jemand fragte, ob ich nicht eine Idee für ein kostengünstiges Sprachkonferenzssystem hätte. Das System sollte als Simultanübersetzungssystem für Flüchtlinge verwendet werden. Die Übertragung sollte über Bluetooth oder WLAN stattfinden. Idealerweise sollten Smartphones als Empfänger verwendet werden.

Ich startete mit einem Raspberry Pi als Server und versuchte diverse Ansätze. Für den Datentransport wollte ich WLAN verwenden. Schnell stellte sich heraus, dass es primär zwei Probleme gab: Entweder war der Paketverlust gering (und damit keine oder kaum Abbrüche in der Audioübertragung), die Zeit zwischen Übersetzung und Empfang aber hoch (was schlecht für Simultanübersetzung ist) oder aber der Paketverlust war hoch (Abbrüche in der Audioübertragung) und die Latenz gering. Beides war nicht gewünscht.

Schließlich fand ich einen guten Kompromiss mit Mumble (einer Open Source Voice-over-IP Software). Dieser Blog Artikel ist als Howto zum Nachbauen gedacht.


Chinese looking characters in mails from MS Outlook users

Have you ever gotten mails from MS Outlook users which had chinese (or better asian) looking characters in the message body? Recently I got an email containing this sequence of UTF-8 characters in the message body next to the "normal" parts of the mail:


If you feed that string to the search engine of your choice, you will notice that they appear for many people and that this is wrongly encoded HTML. In this article I want to explain how you can examine such strings yourself and find their original meaning.