Thursday, September 29, 2011

Wireless antenna technology: SISO, SIMO, MISO and MIMO

The wireless data transmission system consists of 2 parties: the transmitter and the receiver, whereby data is transmitted into the air from the antenna of the transmitter and received by the antenna of the receiver.

In a Single Input Single Output (SISO) system, both the transmitter and the receiver have one antenna, and data transmission over the air is through a single radio frequency (RF) signal chain.

An example of SISO type of wireless is Bluetooth.

Multiple antenna technique has been developed to improve wireless performance.

In a Single Input Multiple Output (SIMO) system, there is one antenna at the transmitter side and multiple antennas (each with an RF chain respectively) at the receiver side.

In a switched diversity or selection diversity implementation, the receiver chooses the best antenna to receive a stronger signal from the transmitter. In a maximal ratio combining (MRC) implementation, the receiver combines signals from all its antennas so that to maximize the Signal to Noise Ratio (SNR).

The Multiple Input Single Output (MISO) system is the other way round, with multiple antennas (each with an RF chain respectively) at the transmitter and a single antenna at the receiver.

A technique known as Alamouti Space Time Coding (STC) is employed at the transmitter with 2 antennas, allowing the transmitter to transmit signals both in time and space. This means data is transmitted by the 2 antennas at 2 different times consecutively.

Multiple Input Multiple Output (MIMO) system is commonly used in today's wireless technology, including 802.11n WiFi, WiMAX, LTE, etc. Multiple antennas (and therefore multiple RF chains) are put at both the transmitter and the receiver.

A MIMO system with same amount of antennas at both the transmitter and the receiver in a point-to-point (PTP) link is able to multiply the system throughput linearly with every additional antenna. For example, a 2x2 MIMO will double up the throughput.

Spatial Multiplexing (SM) technique is used in MIMO to enable signal  to be transmitted across different spatial domains. This is used  to provide additional data capacity.

Therefore, when buying a Wireless-N access point or router, to get a stabler WiFi with higher bandwidth, look for those that support MIMO and with more antennas.

Acknowledgement: the above diagrams are taken from the website.

Thursday, September 22, 2011

Using NetSetMan to change Windows network settings with a single mouse click

If you are using a laptop, you must have faced the problem of having to manually adjust the network settings to connect to the network (either LAN or WiFi) in different places. This is really a tedious thing, isn't it?

Although many places make use of DHCP to automate the IP address assignment (so that you are free from the hassle to manually set the IP address, subnet mask, gateway IP, etc.), you might probably still need to do some adjustment to some other settings, such as the SMTP email server, the DNS server, the default WiFi AP you want to connect with, the default printer, etc. Worse still, there are places that don't make use of DHCP server, and you have to manually change the network settings, especially the IP address, subnet mask and gateway IP, in order to connect and use the network there.

For example, the DHCP server might assign you with the ISP's DNS servers, and you prefer to use Google's DNS servers instead. In some other places, you cannot use Google's DNS servers because the firewall might have blocked DNS request to WAN, and you have to use their internal DNS server.

I found NetSetMan to be a very handy tool allowing you to quickly change your Windows network setting with just a mouse click to connect to the network in different places. It lets you pre-configure the network settings and save them in different profiles. By switching the profile, all the pre-configured settings will be switched over accordingly.

NetSetMan is free for personal non-commercial use. The free version lets you set up to 6 network profiles, while the Pro version lets you set unlimited profiles.

You can customize the settings in each profile for:
  • IP address (to use DHCP or manual setting)
  • DNS servers
  • DNS domain
  • WINS servers
  • Default WiFi AP
  • Default printer
  • Network adapter status (activate, deactivate or restart)
  • Your PC name
  • The workgroup / domain to join
  • SMTP server for email sending
  • Network drive mapping
  • Browser homepage and proxy setting
  • Local "host" file setting for mapping domain names with IP addresses. Normally the setting in this "host" file will supersede the DNS result
  • IPv6 settings
NetSetMan also allows you to run Windows script before and/or after a profile is changed.

It also has feature to allow you to copy-and-paste profile settings from one to another. This is handy to create a new profile where most of the settings are the same with the existing. You just need to make a copy, and modify those settings that need to adjust with.

Sunday, September 18, 2011

The relationship between multi-storey building floor number and the 5 elements of Feng Shui

Nowadays, multi-storey or high rise building is everywhere in urban areas.

You might live in multi-storey building, and you might also work in multi-storey building.

Do you want to know the relationship between multi-storey building floor number and the 5 elements of Feng Shui? With that, you can find out how compatible is the floor you are staying with your own element.

Note that in Chinese floor naming convention, the 1st Floor is the floor that is same level with the ground, which might be known as Ground Floor in certain places. The 2nd Floor is the floor above 1st Floor, which might be known as 1st Floor in buildings that start with Ground Floor.

Before we proceed, please keep in mind that we are using the Chinese floor naming convention here, so do your own adjustment if your building's naming convention is different.

To determine the element of the floor, we look at its last digit. Therefore, 1st Floor, 11th Floor, 21st Floor, 31st Floor, 41st Floor, ... all have the same element. The same concept applies to 2nd Floor, 12th Floor, 32nd Floor, ... and so on. (Remember: use the Chinese floor naming convention!)

And here is the associated elements:

  • Water: 1, 6
  • Fire: 2, 7
  • Wood: 3, 8
  • Metal: 4, 9
  • Earth: 5, 10

There is also a mapping between the 5 elements and your Chinese Zodiac animal. Your Chinese Zodiac animal is determined based on your year of birth. The mapping is as follow:
  • Water: Rat, Boar
  • Fire: Snake, Horse
  • Wood: Tiger, Rabbit
  • Metal: Monkey, Roaster
  • Earth: Cow, Dragon, Goat, Dog

It is a basic Feng Shui concept that:
  • Water produces Wood
  • Wood produces Fire
  • Fire produces Earth
  • Earth produces Metal
  • Metal produces Water
and that:
  • Water destroys Fire
  • Fire destroys Metal
  • Metal destroys Wood
  • Wood destroys Earth
  • Earth destroys Water
Now, you have enough information to evaluate whether the floor your are staying in has positive or negative impact to you.

For example, if you are born in the year of Rabbit (Wood element), and you are staying/working in 5th Floor (in Chinese convention) (Earth element), Wood destroys Earth and therefore Earth suppresses Wood, it seems to be not a good matching. In Feng Shui, this situation is considered Neutral and not as Bad. However, if the floor is Metal (destroys Wood) or Fire (burns up the Wood), that is considered as Bad. If the floor is Water (produces Wood) or Wood (enriches Wood), that is considered as Good.

Sunday, September 11, 2011

A family vacation trip to Koh Lipe, Thailand

My family has just spent a breakaway vacation to a small island called Koh Lipe in Thailand. The island is also known as "Maldives Of Thailand" for its beautiful coasts and beaches, clean and wonderful sea, and very relaxing simplicity lifestyle. It is located at the northern-west of Pulau Langkawi.

We first drove our car to Bukit Kayu Hitam, parked our car at the carpark near the border. Then, we hired motobikes to escort us to the Malaysia custom, and then cross the border to Thailand custom. After that, we took a minibus to Hat Yai, stayed a night there, and then transported by taxi to a jetty at Pak Barra. From Pak Barra jetty, we took a speedboat to Koh Lipe. There is only one boat from Pak Barra to Koh Lipe per day during this low session, departed at around 11.30am.

We landed at the Sunrise Beach, and walked to Castaway Beach Resort which we've booked for 2 night stay at the cost of 2500 bahts.

We settled down at our double-storey wooden hut of Castaway Beach Resort.

Downstair is an open shower place and toilet with no shelter. So, this kind of hut is only suitable to stay with close family members, and could be embarassing to live together with ordinary friends.

Upstair is the sleeping room with a balcony. There is no aircond but there is a ceiling fan on top. Mosquito net is provided as there will be insects at night.

Castaway Beach Resort has a nice restaurant with delicious food, just nearby the huts.

As in our travel plan, after 2 days, we moved to the more "civilized" Sita Beach Resort & SPA at another end of the island. Sita Beach Resort provided motorbikes transportation to bring us there.

We stay in bungalow villa there, at higher cost than Castaway of course. See the difference between them.

Koh Lipe is about castaway and relaxing, a nice getaway for urban people to enjoy the nature. There is a small street at the center of the island, and the rest is about scenery and nature. The island is so small that you can walk on your legs from one end to another.

We also spent a day visiting to Koh Adang, Koh Ravi and some nearby islands with long tail boat. There is a small island with lots of rocks called Koh Hin-ngam nearby, which is a nice place for swimming, snorkeling and even diving.

Here are some of the photos taken there with my Canon PowerShot S95 digital camera.



Saturday, September 10, 2011

Citibank finally got their Online website fixed for IE 9

If you are a Citibank Malaysia customer and have been using their Citibank Online website for online banking, you might be aware that there is a major revamp to Citibank Online 1 month ago.

If you are using Internet Explorer 9 (IE 9) to access that website, you would find the webpages after login all got screwed up. This problem would not happen if you access it with  other browsers such as Firefox.

Well, it is a long known issue that Microsoft's IE browser does not follow the general standard in rendering webpages, especially in later versions of IE 7, 8, and 9 in handling Web 2.0 components. Web developers always find they need special treatments in their codes to make the webpage in IE to be appeared as the same looks-and-feels in Firefox, Chrome, Safari, Opera, etc.

However, it is the QA issue with Citibank and their web vendor for failing to test and assure the accessibility of their new website in all major browsers, which should include IE 9 (as it is pre-installed in all Windows 7 computers).

I am among the users who had provided feedback to Citibank regarding their web accessibility problem. After waited for about 1 month, finally they fixed this issue by today. Citibank and their web vendor should be more careful in handling the QA of their website, and should not simply roll out something without thorough QC. Luckily, this is just an accessibility issue. If this is a security issue, happened to a bank website, you imagine what would be the impact and lost incurred.

Friday, September 9, 2011

Garmin releases MalSingMaps Malaysia/Singapore/Brunei NT 2011.30 for free update

Garmin has made available MalSingMaps (MSM) Malaysia/Singapore/Brunei NT 2011.30 (2011-Q3) for free update now.

You can click here to download the installation file of MalSingMaps Malaysia/Singapore/Brunei NT 2011.30 from Garmin server. The download file is split into 4, and you just need to download the file relevant to your Garmin GPS navigator:

  • nuvi 3790V or 3790
  • nuvi 1250
  • nuvi 2575R, 2565, 2465, 1460, 1350, 765 or 255w
  • nuvi 205 or 205w
The installation file for nuvi 255w is 234MB (245,858KB), about the same size with its previous version released in 2011 Q1.

For nuvi 255w, the installation program requires you to have an SD Card slotted in your GPS before it can proceed. Just like the previous version of MSM NT 2011.10, it will install gmapprom1.img (44,484KB) and SGMYMAL.JCV (215,715KB) into your SD Card instead of the flash memory of your GPS. If you prefer them to be in the GPS internal flash memory, you can manually move them from your SD Card to the flash memory, and I've done that without any issue. Anyhow, the gmapprom1.unl file is still updated in the flash memory of the GPS.

During the installation process, you'll be asked for the unlock key. The key is stored in the existing gmapprom1.unl file in your Garmin GPS navigator, which you can open with Notepad or any text editor. Just copy and paste the key to the installer when asked.

I couldn't find any description about what has been changed in this new version of MSM.

Thursday, September 8, 2011

The end of Papago! GPS support for X3 / X5 / X6 / Reality 7 / OEM and final MalFreeMaps for those versions

Maction has forced an end support to all earlier version of their X-Series Papago! GPS by end of August 2011, which include the hardware and software (Android, iPhone, Win CE, ...) version of X3, X5, X6,  Reality 7, and OEM versions. Those will be replaced by the new X8 version using a new map format with no backward compatibility.

They have also officially requested MalFreeMaps (MFM) to cease providing map updates to all earlier versions of Papago! by end of August 2011, and only provide future map updates for Papago! X8.

As such, MFM-PPG-110823 is the final MalFreeMaps map release for those earlier versions of Papago!.

I can understand their move, which I believe is a bold business decision to fight against piracy to their software. The pirated Papago! GPS software had been used in some China-made GPS gadgets and also embeded GPS in car audio-visual devices, selling at cheap price. Beside that, cracked versions of Papago! for Android, iPhone, Win CE, Symbian, etc. are not difficult to be found, downloaded and installed from the Internet.

In fact, Garmin GPS also faced the same software piracy problem before, until they ceased the production of software version of Garmin Mobile XT GPS navigator.

Anyhow, this is a very risky move of Maction. Regardless whether it is legal and/or ethical to do so, for sure they have lost in customer satisfaction, loyalty, and brand reputation. But this will also kill off some of their competitors who pirated their software and produce cheap GPS gadgets.

Existing users of genuine Papago! are told to bring their devices to Papago! service centres for upgrade to version X8, either free or at cost, based on the terms and conditions.

Are you a Papago! user? What do you feel about this drastic action?

Hint: Click on the "Older Posts" link to continue reading, or click here for a listing of all my past 3 months articles.