ons: buggy, can cause lots of frustration until you’d learned some hand – on experiences with it, image quality is not really good under sub – optimal lighting conditions, short battery life… Pros: simple handling, great protections for outdoor uses (the case is water – proof up to 60m), have tons of accessories for all your needs: diving, racing, skiing… lots of software options and settings to try out… A demo video below, you may recognise the background music: Deep Purple’s Highway Star 🙂 , once one of my favourite songs! It’s only when reviewing this clip did I realise that traffic is very dangerous nowadays in Saigon (or never has it been safe!?). Should we ban motorcycle completely, I would be happy with my bicycle then!


Beau le bateau, dansant sur les vagues,
Ivre de vie, d’amour et de vent.
Belle la chanson naissante des vagues,
Abandonnée au sable blanc!

ros: ruggedised, water – proof (to IPX – 7 standard only), good battery life (uses 2 AA batteries, I can usually make 4, 5 paddling “sorties” before having to recharge), good display (clearly visible under sunlight with low – LCD – backlight setting), doesn’t depend on cellular network to function like a cellphone, could use both GPS (US) and GLONASS[1] (Russia) satellites’ signal, good 3D – stabilized digital compass to show directions (very useful for navigating even on rivers.

Sometimes, the river is so wide that I can hardly find correct heading based solely on its 2 banks’ landmarks), large internal storage space plus the ability to add an external memory card to store more maps. Cons: the Garmin’s default map is very vague on Vietnam’s territories, next to unusable, GUI responsiveness is slow compared to a smartphone’s standard. Most importantly, correct and content – rich maps are very much demanded:

General map

I’ve replaced my Garmin’s default map by Open Street Map, which is much better. However, Open Street Map, and even Google Map, are somewhat outdated for many parts of Vietnam. I’ve found out some places which are not right, even in the very vicinity of Saigon.

Topographic map

Thanks to NASA’s satellite image projects, the topographical information is now available publicly for most part of the globe, in high resolution. I’ve found these data built – in into Open Street Map already, so “the contours” are available on my Garmin.

Hydrographic map

I’ve long been collecting hydrography data, but there’s very few of them for Vietnamese water, and most are for blue – water regions, not the brown – water. Also, I’m still seeking a way to convert those data into Garmin map format to make them usable.

Tidal charts

Garmin supports displaying tidal information (given it is in the map), but unfortunately, those information for Vietnamese water is virtually zero. For me, this is currently the most important issue. Southern VN belongs to an area with complex mix of diurnal and semi – diurnal tides (Vietnamese: nhật triều & bán nhật triều). The highs and lows of tide within a single day can differ by 2 ~ 4 meters or more, which could make paddling very difficult, or even impractical at times (e.g: spring tide at new moon phase). For now, I consult this website to do the planning prior to going to the fields.

[1] From iPhone – 4S onward, Apple includes a GLONASS receiver into its hardwares, this explains the exceptional positioning performance of the devices. In term of precision, GLONASS is better than GPS at higher latitudes, but slightly behind GPS elsewhere. The use of both systems greatly extend signal coverage: GPS alone has 31 satellites, a receiver working with both GPS and GLONASS will have support from a total number of 55 (31 + 24) satellites, which improves signal fixing time, improves tracking performance and even precision would also receive a boost.


ìm khắp Sài gòn bói không ra được một cái, dù vẫn biết là nó chưa phát hành đại trà mà chỉ mới bán cho những ai đặt hàng trước. Trông chờ từ hơn nửa năm nay: ..::Lytro::.., tật xấu của mình là một khi đã thích cái gì thì phải có cái ấy cho bằng được (và một khi đã ghét cái gì thì…) ấy thế mà suốt một tháng nay vẫn: cám treo heo nhịn đói! 🙁 Được quảng cáo là cuộc cách mạng trong nhiếp ảnh, là máy ảnh thế hệ thứ 3 (thế hệ 1: máy cơ, thế hệ 2: máy kỹ thuật số)… và đủ thứ ngôn từ tốt đẹp khác! Tôi chẳng tin gì vào quảng cáo, nhưng đã theo dõi dòng công nghệ này từ hơn một năm nay, “trực giác kỹ thuật” báo cho mình biết đây sẽ là một thay đổi lớn trong nhiếp ảnh.

Chính thức thì nó được đặt cái tên: máy ảnh trường sáng, light – field – camera, một kỹ thuật thu ảnh không cần focus, chỉ bấm một nút, không hiệu chỉnh gì cả, việc lấy nét được thực hiện lúc… xem ảnh! Chiếc camera này có khả năng ghi nhận 11 triệu tia sáng (chứ không phải là 11 triệu điểm ảnh “đẳng hướng”), và tính lại thông tin focus sau khi chụp dựa trên những dữ liệu không gian đã ghi nhận. Khung hình dưới đây minh hoạ cho kỹ thuật này: click chuột vào vị trí bất kỳ, ảnh sẽ được lấy nét ngay tại vị trí đó. Điểm rất hay với kỹ thuật này là không ai phải phân bì sao mặt của mình không được nét bằng người khác! Tự hẹn với lòng: em yêu, mình sẽ sớm gặp nhau!

Cupid’s shadow

Him and her

the new ipad

ust got the new iPad (or we called it: the iPad 3) in hand today and I’m stunned by it’s new retina display. There’s not such a fever like when the iPad 2 was released, I guess since the new iPad is almost identical to iPad 2 in appearance, people will consider about the fact that they won’t be able to show it off. In term of general performance, iPad 3 does not stand out to the previous iPad, or it could be worse in term of 3D – OpenGL performance according to some reviews. From a programmer’s point of view, this could easily be understood since doubling the resolution means 4 times the memory and processing power for each graphics API, which also means Apple has been pushing things over the Moore law’s limit!

Personally I’m not really a passionate fan of these Mắc – Xinh – Tốt [1] (Macintosh) assets, but professionally as a computer – graphics coder, I’ve always admired the prestigous 2D graphics tradition come with Apple’s products. Back to the retina display, on the left is a reduced – size screenshot of this blog taken on the iPad 3 (see full version here, it would take some times to load).

2048 x 1536 is a huge resolution that does magic to the vector things, e.g: displaying fonts! Not only the screen is much sharper, even at first look, its color tone appears to be truer, and the new iPad gamut covers 44% more into the sRGB color space compared to the previous iPad. The second picture: funny capture of Walter Isaacson’s Steve Jobs autobiography put on – top the God of Wealth’s altar in our office 🙂 !

[1]Mắc – Xinh – Tốt: a phonetical transcription of the name: Macintosh, which is a play–on–words, Mắc means: expensive, Xinh means: cute and Tốt means: good in Vietnamese 🙂 .

byzero stylus

uch an interesting device I’ve used recently, a stylus for iPad. While stylus like Wacom’s Bamboo is fine for general sketching, it’s not really suitable for fine – grained drawing. This Byzero takes a different approach as it does not use iPad’s touches, but provides its own mechanism. Image on the left: you can see that the pen is actually an ultra sound source, two microphones (and an infrared receiver) in a single piece plugged into the iPad connector port. Pen position detection is done by triangulation on the acoustic signals. This kind of setup can be found on many other things like this 3D laser scanner.

If you use the iPad seriously for taking notes and drawing, a stylus like this is a must, sometimes your thoughts, ideas can only be expressed with a pen: text, drawing and all kinds of presentations on a page. The stylus is sensitive, it can captures any glyphs you draw. However, it’s very irritating that the calibration process is not really exact: pen position is offset – ed by a small varying distance, and with a noticeable delay… This reduces the usability of the stylus much since it’s important to have immediate and correct responses on the screen for user to make micro – adjustments in his hand to produce good writing, drawing.

kindle touch

ell, having played with this “irresistible” Kindle Touch for almost two weeks. The good thing is that I can now continue with my favorite readings on e – ink display like before. The even better thing is that there’s no more clumsy buttons, only “touches”. I’m trying to keep my habit of reserving 4 ~ 6 hours a week for reading, and reading only, no email, no web surf meanwhile, just to be a little bit calm, slow and undistracted. The device now is smaller and fits into my jacket’s pocket so that I can carry it anywhere, just like a small notebook. Image on the left: Kindle Touch, next to an iPad 2 to compare the form – factors.

Updated, Jan 8th

A perfect complement for Kindle touch would be this SolarKindle, a cover and solar charger which would be available on the market next January to eliminate your need for charging a Kindle ever again!

neo – analog

t has been in my mind for quite a long time, the coined term of neo analog, just like neo classical, neo colonial, neo nazi… Starting from Kindle, I love the idea of an e – book reader with e – ink display which mimics traditional reading material (no more developing on Kindle, gave it to my sister already). Then came the interesting concept of Livescribe, the smart pen that records your hand writing & drawing, then this latest “toy”, a vinyl disc player.

I’ve been making a small collection of Vietnamese oldies on vinyl discs, which are really hard to find at the moment. This is an entry – level turntable that can be connected to PC via USB cable. The sound can be captured into digital format as the analog device is being played. Images on the left: the turntable connected to PC, and recording with Audacity on my Ubuntu laptop. I’m digitalizing the lovely songs from the 2 discs brought back from my last trip to Dalat.

Every motivation that makes a man do something can be classified under: survival, social life and entertainment. Progress is defined as reaching a higher category: not doing a thing merely for survival, but for social reasons, and then, even better, just for fun. (Linus Torvalds’ law)

For the time being, I still can not refine the sound quality recorded via USB on this Ubuntu laptop, though the really aging discs still produce good sound with speakers :-(. Would post the music samples once they are done, the very early recordings of outstanding Vietnamese masterpieces!

Updated Oct, 27th

Let listen to the beautiful music on the margin. What’s next on neo analog!? Something would be mentioned in one of my next blog post!

Trường ca Hội Trùng Dương
(Thái Thanh & hợp ca Thăng Long)

kindle – the verb

Xa cách – Tuấn Ngọc

indle, I’m using it extensively for the time being, my reading list is growing huge with so much books, documents to be read. Kindle suits my needs very well, you can make side notes along the lines, like writing on the margins (similar to the layout of this website with notes putting on the left). These notes can later be synchronised to your laptop so that you can re – organise your random thoughts into systematic thinking and schedule. You can also use dictionaries without having to leave your reading. I’m still getting surprises on Kindle’s audio quality and its battery time, you can read, listen to music for weeks before having to recharge.

While I’m trying to develop some home – brew softwares for Kindle (including an email client), I’m also getting sympathised to Amazon’s designs. You would only got a special – purpose machine by removing odd features, confiding yourself to very specific needs, anything rather than reading is strictly restricted. Reading, taking notes, making investigations and drawing out plans are real pleasures, at least for the time being. Just want to discover what I wanna want to do until the time of vanishing out of this earthy world!

I used to criticise reading a lot, and I still do. We’d had generations of parrot – repeating readers already. You don’t have to read (at all), but whatever you read, do it thoroughly. I have to speak straight out, as many of our fellows pretend to read something other reads, listen to music other likes. But the cassock doesn’t make the priest, literature, music… are of personal values. Whatever you read or listen does not matter, it does only matter if you can discover new things out of the contents. I apologise the true readers and listeners, this is specific to my environment only, I get disgusted with all those “fashionable things” going on around down town!

home servers

The C-Media usb board adds a cheap (~ $5) sound solution to the Debian box, sound quality is fair enough for “ad-hoc” listening (comparable to that of AC97 on-board chip, and for serious music, there’s already the home media player).

uite a long time it takes me to finish and “stabilize” all these “home servers”… and finally here it is… On the left, you can see: #1: the 650 Watt UPS that provides about 3 hours of un – interrupted electricity for the whole system, #2: the WAP54G Access Point (hacked with OpenWRT), #3: the Comtrend ADSL router, #4: the LinkStation CHL (Debian Lenny: print server, 1T disk space for samba share, bittorrent server), #5: the LinkStation Duo (Debian Lenny: 1T of RAID-1 disk space for important data, SVN, Web, VPN servers (for remote access) and MPD music servers), #6: speakers.

All these miniature machines help streaming lossless music and HD video to the media player (LT-H90LAN – another Linux box resides in the living room). Except for the router (which is specialized hardware & firmware OEM-ed by Comtrend to FPT – the local ISP), all others devices runs Debian or another Linux variant. The total power consumption of the whole system is less than 50 Watt. Future computers would consume less than 1/10th of power compared to today’s ones… Power is the key, less power means less heat, less noise, more stable and more durable… the factors that make successful home services!

buffalo duo

My Buffalo, a 400 MHz, power-efficient ARM system (it consumes about 17W on average). The duo: two SATA disks (1TB each) running in RAID-1 configuration. The system can also act as a print server: most cheap home laser printer are not stand-alone device (lacking PostScript capability) and need to be attached to a PC in order to print, instead we can connect printer to this Buffalo box via usb and serve printing over network.

y newest toy: a Buffalo LinkStation Duo Network Attached Storage (NAS – or a poor man’s home server). Had thought about this long ago but don’t have time till now to dig a little bit low-level to get the thing to work! Basically what I want to have is a miniature general-purpose home server, which would run continuously 24/7. But you know with the temperature and electricity conditions here in HCMC, most PC would surely break down if let running continuously for a few months. The idea is to hack this NAS device to run Debian and turn it into a hybrid system: NAS (file server, torrent, UPnP…) and a home server which would handle a little more extra tasks. I took me a whole night to figure out how to do it.

1.   Boot the device via tftp, using u-boot, the universal bootloader. We need to to erase the HDD’s partition table (with something like: dd if=/dev/zero of=/dev/sd[a/b] count=1) to force the device into tftp boot.

2.   Telnet to the device and prepare the disks: using fdisk to apply a same partition structure to both two disks (/dev/sda and /dev/sdb) with the usual Linux FS: /boot, /swap, /(root), and /data). The disk structure would appear like this:

Device Boot Start End Blocks Id System
/dev/sda1 1 6 48163 fd Linux raid
/dev/sda2 7 1200 9590805 fd Linux raid
/dev/sda4 1201 60801 478745032 85 Linux extended
/dev/sda5 1201 1329 1036161 82 Linux swap
/dev/sda6 1330 60801 477708808 fd Linux raid

3.   Setup the RAID-1 (one-to-one mirror) structure, you can see that we mirror /boot (sda1, sdb1), /(root) (sda2, sdb2), and /data (sda6, sdb6), there’s no need to mirror /swap:

mdadm –create /dev/md0 –level=1 –raid-devices=2 /dev/sda1 /dev/sdb1
mdadm –create /dev/md1 –level=1 –raid-devices=2 /dev/sda2 /dev/sdb2
mdadm –create /dev/md2 –level=1 –raid-devices=2 /dev/sda6 /dev/sdb6

4.   Install Debian (Lenny) using debootstrap, a very handy tool to install Debian directly from a repository. DeBootStrap pulls the packages over network, build a new rootfs, after chroot-ing to the newly build system, pull and build the kernel from source. After that, we can use regular Debian commands to update, configure network, add softwares, etc… After rebooting, we’d got a brand new Debian with 1TB of RAID-1 disk space, which runs flawlessly and which is ready to serve my various automation tasks!

Notes: installing Debian would void the warranty and could easily brick your device, use the information at your own risk. The steps here are just summary, there’s been various try and fail to get the thing done, e.g: we need priorly to have binutils, wget, zlib and libssl binaries for debootstrap to work (download the deb files from Lenny’s repository, extract and copy over the Buffalo), after debootstrap-ing, I forgot to set the root password, and unable to login when the machine reboot, thus having to start the whole process over again 🙁 . For further details, please consult the Buffalo NAS community.

UPDATE, Nov 18th, 2010

For a NAS which runs 24/7, it’s critical to monitor system status (temperature and the moving parts). I wrote this little fand script, a daemon to monitor hard disk temperature and adjust the fan’s speed accordingly. HDD’s temperature can be retrieved using smartmontools (most hard disk nowadays has S.M.A.R.T capabilities). And fan control on Buffalo LS Duo is done via the gpio module (thanks to talent hackers on the Buffalo NAS forum), something like this:

# values can be ‘off’, ‘slow’, ‘fast’ and ‘full’
$ echo ‘slow’ > /proc/linkstation/gpio/fan

I’ve defined some thresholds, in a tropical country like VN, room temperature around 30° ~ 35° (Celsius) is a common thing, so if the HDD’s temperature is below 35°, we would turn off the fan. If it is between 35° ~ 40°, the fan speed would be ‘slow’, from 40° to 45°, the fan will be turned to ‘fast’, and if temperature excesses 45°, fan speed is set to ‘full’. Well, and even if 50° is reached, we would send a notification email (via sendmail) and shutdown the system. If you find it interesting, here is the fand scripts.

UPDATE, Nov 20th, 2010 (THE REAL DUO)

To pair with the Link-Station NAS is its cousin also from Buffalo, the Link-Theater LT-H90LAN. The LT-H90LAN reads media from Samba shares or DLNA server via LAN and is a 720p and 1080i HD-ready device. Although not Full-HD (1080p), that’s enough for my need (I don’t have a Full-HD TV in my house anyhow, maybe I’m waiting for 3D home video). It’s quite pleasing to enjoy good video quality and excellent audio in your living room, all streaming from a central NAS. The box also runs a variant of Linux (though hacking can be a pain, I would only left the device untouched for safe). This is one further step toward an all-Linux-devices home (thought I should buy an OpenMoko phone then).