Unto the pure, all things are pure

It's very easy to plan a do-it-yourself tour of the Great Wall of China at BaDaLing (八达岭). And it costs only RMB12x2 (total USD4) for the journey there and back. The Internet is full of postings on how people signed up to tours only to be held at ransom to cough up more money after the bus has moved off. Do not be another victim. By the way, most of the victims are Chinese nationals from out of town or people who speak some Chinese. The swindlers, or enterprising businessmen depending on how you view them, tend to leave the non-Chinese speakers alone as sign language is harder, I guess. Follow these steps carefully for a low-cost and enjoyable tour. We just did it last week. 1. Make your way to DeShengMen (德胜门) . This is once a city gate of which only the archer's tower is now left standing. The archer's tower is a huge structure that cannot be missed once you are in the vicinity. There are a few bus terminals there. The one you must go to is north of the tower. Fro...

Remember CT2 or the initial incarnation of PCN?  They have gone the way of the dodo.  The technology is now used in DECT phones. Efforts to expand wifi to provide wide area coverage will meet the same fate. CT2 was marketed as a poor man's alternative to cell phones.  It is a neat engineering idea.  You get to use a wireless phone when you are in range of a base station.  But it is just that, a neat engineering idea. Using wi-fi as a poor man's wide area data network is in a similar situation.  The reason is not un-obvious. If only, say, 20% of the time that you need to use the Internet you find yourself outside wi-fi coverage, you would need to pay for a data subscription from your cell-phone company.  And, if you already have paid for wide-area data why would you still pay or need wi-fi? Wi-fi has its uses, just like DECT phones.  You use it at home or in the office, when you are pretty stationary and there is no point expending power...

One of the fundamental principles of communications is that the amount of planning is inversely proportional to the efficiency of communications available.  The better communications you have the less planning you have to do.  The more planning you do, you are less dependent on the need to communicate. To illustrate: a family hits the shopping mall.  In the old days, a detailed plan would have to be worked out, something like: "Everybody, it's free and easy for the next 30 minutes.  Then we meet at this water fountain.  If by 35 minutes, Johnny doesn't show up, this is what we will do,......"  Lots and lots of if's then else's to cover all conceivable contingencies.  Today, when a family reaches the mall, everyone takes out his or her cell phone, does a battery check, and everyone do whatever he or she likes.  When someone feels it's time to go, the phones start ringing. This similar scenario occurs everywhere.  When an army wants to conduc...