2013. december 1., vasárnap

Castleton-Edale túra

Múlt héten voltam egy konferencián Manchesterben, és egy napot túráztam. Itt van pár kép egy fish and chips-szel egyetemben.

2013. október 21., hétfő

Sqlite vs. portable Boost serialization storage

I have been using sqlite storage in my hobby robotics research project to storage some basic information about the transfered data from AIBO via network. It was really lightweight, some tables and I was committed to use this solution because it is easy to browse a standard Sqlite database and analyze the content. However, I have switched to serialized archives from Boost today, especially a portable archive implementation (http://epa.codeplex.com/). I had some performance testing earlier and the portable archive is 2-3x slower compared to ordinary Boost binary archives, but it is portable. I have simulated a longer session with AIBO on my laptop, restricted to the lowest CPU frequency.

The sqlite performance:
Writing database: ~25000 msec
Reading database: ~2400 msec

The exactly same portable binary archive:
Writing archive: ~200 msec
Reading archive: ~300 msec

Reading is ~8 times faster and writing ~125 times faster with portable boost archives (boost) than sqlite. I have to emphasize that the database is very simple with a few tables and relations are not used in the queries.

2013. augusztus 10., szombat

Nyári nyaralás

Nyáron voltam Tatabányán egy kedves barátomnál és felmentünk a Szelim barlanghoz.

2013. május 1., szerda



A sűrített tej-mentes marlenkám is egy kész kínszenvedés volt végigcsinálni az éjszakában, de a végeredmény baba lett. Ez volt az eredeti recept:


Amit másképp csináltam:
- Nem raktam bele tojást, hogy ne romoljon meg hamar.
- Nekem nem volt itthon dió, csak vmi más mag (vmilyen mandula vagy mi a halál), aztán azt raktam bele dió helyett (de 10 dekát 8 helyett)
- A krém az istennek se akart besűrűsödni, pedig kb. 6 deka liszt (3)+polenta (3) combót raktam bele meg a ledarált levágott tésztaszéleket. Úgyhogy beletoltam még egy tonna krumplikeményítőt, illetve egy tasak vanília pudingport.
- Ja és a tészta egy napot időzött a hűtőben, a kész süti meg vagy másfél napot pihent. Szal jól összeállt a cucc.

2013. április 25., csütörtök

Szokásos tavaszi hóvirágaim

Újra kivirágoztak a hóvirágaim az idén.

És a sóskák is kibújtak:

2013. március 24., vasárnap

Tegnapi kaja

Polenta (gombás, fetás, olivabogyós) és petrezselymes csirkepörkölt ecetes jégsalátával.

2013. március 6., szerda

Tojásos-spenótos pite

Tojásos-spenótos pite készült, aztán gyorsan el is fogyott...

2013. február 25., hétfő

Strange Bluetooth pairing problem

I use Ubuntu Precise at home/my workplace and I could pair a Nokia BH-214 without problem in work, but the pairing kept asking "PIN code is needed for pairing..." at home and it failed every time. The workaround was to use install the blueman and use its applet to pair the headset...



2013. február 21., csütörtök

Slow wireless performance

I had slow wireless performance with Atheros AR928X card in my 2510p notebook with Ubuntu Precise and A-Link RR24AP-N station. I tried all sorts of tweaks with the atk9k kernel driver, but nothing seemed to fix my issues, the wireless speed was dropped to 10-13 Mb/s after a successful connection to the WEP protected wireless network. The solution was to disable the "Aggregation" in the Advanced settings of my router.

2013. február 14., csütörtök

A possible fix for choppy Bluetooth headset connection under KUbuntu

I tried some different Bluetooth headsets and transmitters with my laptops these weeks to have a low-cost, but satisfactory wireless audio experience. The initial trials were disappointing.

I use Koss Porta Pro for listening music and other contents, so it was a starting point to compare the quality. I bought a Sony DR-BT22A headset which was praised by several reviews and customers on Amazon, but it is quite bad quality compared to the Koss. I also bought a Rapoo H3010 wireless headset, which has almost the same quality like the Sony, but the headset+the transmitter are rechargable via USB, it lasts for several hours. The Rapoo's transmitter is connected to a sound source via a standard audio jack, so it is very handy to my home theater system where I don't expect high sound quality for movies; without losing a USB port.

What was a surprise that I tested a Nokia BH-214 transmitter and it is amazing. It is a Bluetooth headset/transmitter with some buttons and you can connect your favorite headphones to the transmitter. At this point, I did not have to deal with any compromise: I get exactly the same sound quality from this transmitter with the Koss Porta Pro instead of directly connecting the headphones to my laptops.

Ok, sound quality is fine, but my Ubuntu Oneiric did not work quite well with the Nokia transmitter. I could pair and connect the transmitter to my machine, but the connection becomes choppy/dropping audio packets after getting disconnected/reconnected because of distance or if I don't listen to something on the connection for a while. After disconnecting/reconnecting the transmitter manually, the connection is good again (except the volume is always dropped to maximum level :( ). The quick fix was to sketch a script to disconnect/reconnect the transmitter, fix the volume level and specify a shortcut in KDE to execute the script.

Note1: First time when you pair/connect your Nokia BH-214, you should change the Master channel in the KMix settings to the headset to control the transmitters sound level (later on KMix switches automatically on reconnection).
Note2: Something was wrong with the KMix by default and it tend to crash when the Bluetooth was used and the Amarok changed tracks. The fix was for me to install a newer version of KMix from a later Ubuntu version.

The script:

# Mute the master volume with KMix
qdbus org.kde.kmix /kmix/KMixWindow/actions/mute com.trolltech.Qt.QAction.trigger
# Disconnect the headset
sudo hcitool dc xx:xx:xx:xx:xx:xx
# Reconnect the headset with kdebluetooth
bluedevil-audio bluetooth://xx-xx-xx-xx-xx-xx
# Wait for a while to get the connection again
sleep 2
# Decrease the volume to reset the master volume from muted to the last level
qdbus org.kde.kmix /kmix/KMixWindow/actions/decrease_volume com.trolltech.Qt.QAction.trigger
# Increase back to the original level
qdbus org.kde.kmix /kmix/KMixWindow/actions/increase_volume com.trolltech.Qt.QAction.trigger

2013. január 27., vasárnap

New AiBO+ demo

I forget to write that I reached an other milestone in my AiBO+ project. I have been implemented a brand new PC application with Qt/Qwt to connect to the dog and transfer the robot states to the computer. This new tool was really needed for me to speed up the debugging and the analysis of the sensor and other data. For fun, I implemented custom gestures and ported the application to Windows and Android.

The usual demo is here:

How to clone a hard drive over the network

1. Download the Clonezilla and burn to CD or USB stick.
2. Boot two computers with the needed hard drives with the Clonezilla image.
3. On the source computer follow the steps and select the copy over network from this source computer.
4. During the final steps, the Clonezilla will write on the console what commands should be executed on the target machine.
5. Go to the console on the target machine and execute the needed commands. After a few questions, the cloning will start. Yuppee!

2013. január 10., csütörtök

Rfkill hard blocking problem under Ubuntu natty

I experienced hard blocked wlan devices on my HP 2510p laptop with Ubuntu. Like this:

$ rfkill list all

0: hci0: Bluetooth
    Soft blocked: no
    Hard blocked: no

4: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: yes

The solution was on an Ubuntu forum topic: go to BIOS and restore the defaults.