Third day at NRIDS Nepal

NRIDS Jos Groenewegen Daan Pijper

04-08-2009

Third day of training from Inveneo

Training:

Topics:

Wireless

Survey

Introduction:

After a fairly good night of sleep we went to the same place were we had breakfast the two days before. It was just as good as the days before and the place felt less hot than the day before. Training started with another game. The idea was that everybody stood in a circle, closed his eyes and grabbed another person's hand for each hand. Only two persons should hold each others hands. It took a wile until only two persons were holding each others hand. Then everybody opened his eyes and we had to unravel the knot of humans we had created without letting loose of each others hands. We got pretty far. We managed to get a neat circle expect for two persons. It was surprising how one person took the lead and managed the unraveling.

Wireless:

The first topic of today was wireless networking. It told us the basics of electromagnetic radiation. We are pretty familiar with that but it is crucial to know the basics considering we are working with wireless network. They covered basics like frequency, Gain etc. They spend some extra time dBi because it is a logarithmic scale rather than a linear scale and not everyone was familiar with logarithmic scales. And you can't make a proper judgment of the difference between Gain if you think 6 dBi is twice as good as 3 dBi. However, Gain affects range and the Gain required to span more distance also increases exponentially so the relation between Gain and distance is fairly linear.

After that they discussed antenna's and radios and briefly discussed the different types. This was interesting because we never heard about this before. One of the more important things mentioned for the situation in Nepal is that antenna's have both a vertical and horizontal beam-with. Most of the time the horizontal beam-with is bigger than the vertical beaming because vertical beam-with is only interesting when you are dealing with elevation differences. But in Nepal there are many elevation differences so vertical beam-with becomes important. It might be a good idea to look for antenna's designed in mountainous lands like Japan or Switzerland. They might make antenna's with bigger vertical beam-whits because this is also important in their country.

It was also interesting to see how different antenna's had fairly different shaped areas where there signal was broadcasted. The satellite dishes we see in the Netherlands are very directional but there are different types which broadcast in a much larger area. One type of antenna, the cantenna, was also interesting to see. A cantenna is an antenna made out of a can, preferably a full sized pringles can because this has the best dimensions. This is cheap but quite complicated to make. So if you have some money to spare a Cantenna is probably to much work to make.

After the theory we had a little bit of practice with using Visio modeler and modeling wireless networks. We already had extensive knowledge of using Visio but not with modeling wireless networks in Visio. However, quite some people had no previous experience with Visio so they made sure that each group had at least one person with experience with Visio. Unfortunately just when we needed it the most power started to fail. Though we didn't complete the full assignment we still managed to get some good hand on experience so it was still a productive assigment.

Survey:

The second topic of the day was surveying. They smoothly connected it with their previous topic by starting with things to look out for while placing antenna's. You need a clear area with a clean line of sight to the other antenna's it needs to communicate with. And you need to be able to get the antenna their and place it there. This affects both the location as well as the choice of antenna. And you need to keep security in mind. Find a place were the antenna can't be stolen or won't be vandalized. Also keep in mind forces of nature like wind or water.

But surveying doesn't stop at antenna's. It pretty much involves going to the location and looking at all the information you can get. The reason why you need to go to the location itself to get the information is because other sources might be unreliable. The client at the location is probably not a n expert on wireless connections. That is why he hired you. So he doesn't have the knowledge to answer you're questions. And information you get from the location itself is always going to be more extensive and accurate than what they tell you.

Apart from looking at the location you should also talk to the client and find out what he wants. And not just the client. There are more people than just the client who will use, benefit or will have a say in your wireless connection and telecenter. These people are called stakeholders because they are affected by the project and therefore should hold a stake in the decision making. Important stakeholders are the users and authorities. The users are important because they are going to use the system and if they don't feel comfortable with it and won't use it the project will have failed. Another important stakeholder are authorities. You will probably require to ask different authorities permission for different aspects of your system. If you don't ask them for permission you might get in big trouble. And just paying attention to the local authorities, while you don;t even need their permission might prevent getting in to trouble later.

Once you got the information you need you need to make a plan. Determine the locations where you are going to place the equipment and mark these on a map. GPS data plays an important role here but more about that later.

The trainers gave us an assignment to hold a small mini survey at the location where we stayed. We had the advantage that we already had a lot of details about the location and the people managing it. And I look forward to looking around at the location and mapping it.

GPS:

The last topic of the day was GPS. GPS allows for determining a location up to about 10m on basis of satellite data. It gives coordinates existing of Longitude and Latitude. Al you need is a GPS device and a somewhat clear contact between the device and the sky. You need at least 3 satellites to get a location and of course you want the most accurate location. Fortunately Jos and I were already familiar with GPS and GPS devices. But we still had a nice little practice were someone had to go to a location and mark it with the GPS device and then another group of people had to navigate their using the GPS device. Nobody went to far so it didn't take to long and everybody managed to do it.

Closing comments:

Again a productive day of training. We are learning a lot and I think many of the Nepali people, especially the telecenter operators are learning even more. Despite the small problems like power failures and rain we still managed and the problems could be a lot worse. I still think we have one of the best locations in Dharan.

Daan