Archive for the ‘Science’ Category
Published by
Nicky Ang under
Science on
January 7, 2009
What would be your BIGGEST joke of the year for 2008? Let me tell you mine.
On Friday (19-Dec), I noticed my Streamyx connection was down. I didn’t took a lot of notice on it, because Streamyx customers got an email on Thursday that says maintenance upgrade was done in Kuala Lumpur and will last till Friday morning. Coincidentally, the international link to Europe was also having problems.
On Saturday (20-Dec) and the connection is still down. The modem DSL Sync light is ON but it wasn’t possible to dial-in and their PPPoE server seems dead. Getting annoyed, I decided to dig a little deeper to see what’s the issue.
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Published by
Nicky Ang under
Science on
May 22, 2008
All Internet Service Providers (ISP) have limited international capacity they purchased. In other words, bandwidth is traded like a commodity nowadays and it’s getting more expensive. What does this mean for end users like us? This article attempts to answer the most common question we always ask: Why are overseas web sites so slow?
International backbone 101
To become an ISP, you need to have two major infrastructure in place: local backbone (LB) and international backbone (IB). The LB consist of the local network that connects the ISP and subscribers. IB connects the ISP to major Internet traffic exchanges (IX) around the world.
When you connect to an overseas web site, your request goes through the LB to the ISP and head towards multiple IX before it reaches the intended web site. The web site’s content then travels the same path back to you.
I define “major ISP” as an ISP that can provide bulk bandwidth to other minor ISPs and has the capability to join worldwide consortiums to lay submarine cables. Purchasing IB capacity is very expensive and sometimes beyond the purchasing capability of minor ISPs. Therefore major ISPs for a particular country (ie. TMnet in Malaysia), play a major role in IB capacity planning.
Other smaller ISPs purchase bandwidth from major ISPs. Hence, the so called “international bandwidth” for smaller ISPs is the bandwidth they purchase from major ISP.
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Published by
Nicky Ang under
Science on
April 20, 2008
Streamyx technology relies on ADSL. To provide high speed connection, ADSL relies on unused frequency bands of your telephone cable. A twisted pair copper cable can carry analog voice as well as digital signals simultaneously. The diagram below shows the bandwidth available for a typical telephone cable.
Red block: Analog voice signals. Your normal voice calls are allocated to a maximum of 4kHz.
Green block: Digital Upstream signals. For uploading data to your ISP.
Blue block: Digital Downstream signals. For downloading data from your ISP.
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Published by
Nicky Ang under
Science on
April 20, 2008
Here are five most important tips on how to get really stable Streamyx connections. Everything else is secondary! What I meant by "stable connections" is the physical connection between your modem and Telekom exchange. In other words, the "hardware" part of it must be properly checked and adjusted to reduce possibilities of connection problems later.
- Use high quality internal wiring - Always ensure you install your internal telephone wiring with high quality twisted pair cables. Run your cables away from noisy sources like fluorescence lamps, heavy machines like fridge or washers. Use high quality splitters and connectors. I also recommend the phone cables from your wall jack to the modem be changed every one or two years. This is to reduce chances of copper oxidation that happens with really old wires.
- Rusty phone jacks – My friend’s Streamyx connection is horrible. Despite numerous complains to TMnet, nothing much can be done to improve the connection. One day I went to check the phone jacks used and it’s all covered in greenish rusts. Rust is produced due to oxidation. A small item like phone jack is the whole culprit. After changing the entire phone cable with new jacks, the connection is sustained for 24 hours a day without problems.
- Separate router and modem unit- I’ve used this configuration ever since I started with Streamyx. The idea is to have separate router and modem units. Such setup somewhat lowers the CPU load of the modem and allows more CPU time to process incoming high speed data (light NAT translation) and pass it directly to the router. The router will then sort out the traffic (heavier NAT translation) to various computers. Also check whether your modem and router is overheating. As you’ve known with computers, overheated ambient temperature inside the modem will cause "crashes" and modem needs to reboot.
- Check for noisy phone lines – Noise and attenuation in the phone line are the top issues that most customers are facing. Pick up your phone, press a single digit and listen quietly for few seconds. If you hear hums, hisses or crackling sounds, no matter how soft, then you have a noisy phone line. You will need to take this up to Telekom so that they can check for the noisy segment in your cable. Also avoid installing too many phones as this will cause overall signal loss.
- Use high quality modems - Some modems is just not suitable for your phone line, especially if you live too far away from Telekom exchange. Low quality modem will not be able to cope with bad attenuation and signal loss. Modems that overheat easily are also prone to give problems and fire hazard. Invest in good modems. I personally have used Alcatel ST510 and Aztech 600ER. These are quite stable and always-on for months between reboots. Also their mainboard and power adapter do not overheat.
Published by
Nicky Ang under
Science on
March 23, 2008
Black Brush Algae (BBA) are notoriously difficult to remove. Unless you have a bunch of Siamese Algae Eaters (SAE) ready, the only way is to cut the infested leaves off.
Alternatively, you can burn BBA using high powered laser as shown here. Because I’m using a green laser, the green Anubias leaves will not absorb the green light. Therefore minimum damage is done to the leaves.
On the other hand, BBA is black and will absorb almost all laser light causing it to heat up. The BBA vaporizes instantly when laser hits it. You will also hear crackling sounds and smoke that smells like burnt hair. This laser is fitted with a "burning capset" (magnifying glass that narrows the beam further).
Results after one week
Here are the results of the laser treatment after one week. Suprisingly, entire leaves did not die out, but only the part that received the burning laser dries out and whiter away.
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Intense laser treatment. The tip of the leave did not survive.
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Mild laser treatment. BBA completely gone.
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Mild laser treatment. Only little bit of BBA left.
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Looking for a cheap treatment to BBA? Nope, this is not the cheapest and safest method. The laser used here is a 125 mW laser and safety goggles are mandatory when working with lasers at close range.
Tank update – 30 days after set up
I’ve done some minor adjustment to the big rocks, by placing them at 45 degrees angle. Also added some new Java moss on stone and it’s growing well. Glossostigma and Riccia starts to bubble due to intense lighting and high CO2. I can see streams of O2 bubbles being released everywhere in the tank.
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30 days after set up
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New Java moss on stone
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Riccia bubbling
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