Category Archives: Technology

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Purchase of 4K Display (Dell P2715Q)

I bought Dell 4K Display P2715Q. I’m using with New Macbook (12 inch) and Vaio Z Canvas.



It is difficult to set up. Many problems had happen. It might be because of large bandwidth usage.

Screen flickering with Included cable

This problem had happened when connected with Vaio Z Canvas. The cable connecting was the cable which converts mini DisplayPort into DisplayPort.
Sometimes screen flickering happend, sometimes it became blank screen. Sometimes becomes stable. They happened in any resolution mode.

I noticed that it became stable when putting up the cable little bit. I think connectors or cable around connecter had broken, so I purchased new cable. I bought Cable Matter’s mini DP to mini DP cable from Amazon.
My display became very stable when using this cable. This flickering problem was caused my the included cable.

Some people said the included cable was wrong at some review sites (Reviews for P2715Q at Yodobashi Camera, thread of this display at 2ch and so on.)

Unstable when 4K

This problem was also happend when using with Vaio Z. Sometimes I could not select 4K resolution mode. Or sometimes become unstable when select 4K.

This problem caused by combination of Vaio Z Canvas and Windows 10. I updated my BIOS Firmware at Vaio’s site (BIOS R1090VE Windows 8.1/Windows 10アップグレード用) then this problem had dissapeared.

Few flickering when using with New Macbook 12 and HDMI 4K30p

This problem was rarely happened. This combination was almost stable. But sometimes white screen flickering happened repeatedly (about 30 seconds period).
This was because of 7m long HDMI cable which I used. I had shorter (2m) cable, so I switched cable to it, then this problem had dissapeared.

I bought 4K monitor, but no machine can play 4K60p contents

I cannot see any 4K60p contents smoothly.
I had not any PC’s which could play 4K60p movies. My Vaio Z Canvas could not too. Dissapointed.

No problem with Linux

I’m using this display with Linux on Vaio Z Canvas, no problem happens after installing BIOS update firmware. I could use as 4K 60Hz with Gnome3 normally.


I had used 2K Dell monitor. New 4K display is lighter than my old display. My display arm became able to move up and keep. Light thing is good.

Also USB 3.0 Hub functionality is a little bit useful. Good.

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My WordPress site has improved performance (In particularly Admin pages)

WordPress is too heavy for my small instance. In particularly Admin pages is heavy. Pages viewers is not really because of page caches. (These pages are heavy too when not on caches.)

However, I found a web page about WordPress running time. I installed a plugin “001 Prime Strategy Translate Accelerator” which introduces in the page then my WordPress web site improved a little bit. This plugin improve performance with MO files (translation files) caches.

I am using W3 total cache for overall performance. Some blogs say it is good for admin pages performance to disable Object Cache of W3 total cache. ( ((Japanese) WordPressの管理画面が重い場合の対処法) ) I did it. But I don’t know how good it is.

Some people might say anyone would not care about performance of admin pages. But I do. Because it makes me very frustrating. I gave up writing posts many times because of it.

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India Impressions And The SIM Card


  • Many Indians.
  • I went to India Gate. No impression particularly.
  • Walk around delhi. Dirty. Bad smell. Danger. Violent people.
  • I went to Nehri Place which said indian “Akihabara”. They recommended me laptops many times. I don’t neet.
  • Breakfast was curry with something. Launch is McDonalds. Dinner is Domino pizza. I love america.
  • This hotel is a little noisy. Someone played music in midnight with large volume. It is hard to me. I’ll use earplugs.

Seriously India is best place ever visited. Very tired.

How to configure Airtel SIM

I had believed that it could use immediately after an activation without any configuration, but it is not.
We probably need to configure APN (Access Point Name) .

I configured it with my Xperia Z2, but other machines might be able to configure almost same way.

(1) Let’s activate as I wrote yesterday. (Insert SIM. Turn off roaming and Wifi. Call 59059 and answer the questions)

(2) Open [Setting] > [More…] -> [Mobile networks]

(3) Make sure that airtel is selected, It could from [Service providers] at (2)

(4) Open [Access Point Names] at (2)

(5) Tap add button, and enter below (Any other options than below should be keep in initial state. Maybe.)

  • Name: Airtel Internet
  • APN:
  • Proxy:
  • Port: 8080
  • MCC: 404 (Entered initially in my case)
  • MNC: 10 (Entered initially in my case)
  • Authentication type: Not set
  • APN type: default

(6) Save. I could use network with them. If you cannot, try rebooting.

Below is my screenshots of setting screens. (But it is in Japanese)




Probably there is information about this configuration in airtel homepage or elsewhere, but could not find them. I found this config way with googling and try many partial information.

Some informaion says they send about configuration via SMS. But I could not receive them.

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I bought GPS Logger (i-gotU GT-900Pro) & wrote reader program

i-gotU GT-900Pro

i-gotU GT-900Pro

Accuracy of my tablet’s GPS is bad. And app for recording is also too bad. So I decided to buy dedicated GPS Logger. I bought i-gotU GT-900Pro. It is watch type GPS logger.

Pros I think:

Cons I think:

  • A little bit large (It’s okay for me)
  • No way to erase GPS logs? (I don’t know. There is a hard reset but it maybe erases configure.)
  • Accessory software is for Windows-only. gpsbabel cannot read data from this device. (It means hard to use in Linux)

I hope to contribute OpenStreetMaps. There is not enough data of some isolated islands. Google Maps is not enough too.
(Currently, OpenStreetMap is better than Google Maps in some islands. But not enough for some islands.)

By the way, it cannot used with gpsbabel. There is some software for i-gotU series supporting Linux.

Former is GUI program written in Java. Latter is too old and maybe not working with GT-900Pro which is newer model. (And it could not build in my environment)
Probably there is no CLI program working with GT-900Pro.

So I wrote a small CLI program in Python. It can be downloaded in my Mercurial repository:

It can read data from GT-900Pro. Purge is not working now. I have been implementing it now. (It’s difficult…)