This Post is Dedicated to Brandt

July 16, 2012

Three or four days ago, everything changed. We now have a reasonably reliable way of getting fast Internet at the school, sometimes at blistering speeds of around 0.3-1 Mbps (essentially the fastest we’ve seen outside of Arusha, and even faster than most Internet cafes there).

With the help of Brandt, a super awesome 3-week volunteer at the school who used to be a technical manager for Cirque du Soleil, we took apart two commonly used USB modems to see if we could attach an external antenna directly to the circuit board. On each board, we found a tiny female crc9 connector for an external antenna. Since we didn’t have a cable with that type of connector, we cut open an extra coax pigtail we had with one N male connector end (our antenna has an N type female end) and whittled down the wire to fit in the antenna port. Then we realized that the antenna we have was optimized to catch 2.4 GHz Internet signal, and not the 3G signal at 2.1 GHz. So we made a ¼ wavelength monopole antenna for the 3G band- basically a small piece of extra wire we had, cut to about 3.5 cm long (1/4 of the wavelength of the 2.1 GHz signal), and stuck it in the port. Like magic (except totally not), it boosted our signal at the school literally from no service to full bars on 2G, and sometimes with the Airtel SIM card, even 1 to 2 bars on 3G (which is still over 10 times faster than full bars on 2G). But the 3G service at first was flaky, and Brandt used an Airtel app on his iPhone to find out where the tower broadcasting the 3G network (HSPA/HSDPA) is. It’s a lot further away than the Monduli tower only 6 km away, which uses only 2G protocols (EDGE, GPRS, WCDMA).

We also tried using our largest antenna with the USB modem by cutting off the end of an extra RP-SMA to N-type coax pigtail that we had, whittling down the central wire and sticking it into the antenna port, and attaching the ¼ wave 3G antenna to the pin of the N-type connector with a piece of plastic insulation. Then we threaded the pigtail through the parabolic grid and wrapped it around the feed so that it was positioned at the focus of the antenna. Oddly enough, pointing this at the 3G tower only boosted the signal maybe one or two bars at most while we were on the 3G network- not as much as we expected for such a high-gain directional antenna. We are still not sure what is happening there.

But the main problem was that we had a very hard time connecting reliably to the 3G network in the first place. The monopole antenna, which was interestingly able to pick up both 2G (at 1.8 GHz) and 3G signal (possibly because 1.8 and 2.1 GHz are not that far apart), was already sensitive enough without the parabolic dish to receive very strong signal (-60s dBm) from the 2G tower. The parabolic dish only improved the 2G signal around 1 bar (bringing it up to -53 dBm). So we had to find a way to selectively join the 3G network; having the correct length of antenna is apparently not enough.

Luckily, the current Airtel USB modem interface for Macs has an option for choosing “3G-only,” wheras neither the Mobinil software interface on my unlocked Huawei E173 modem nor the Vodacom interface seems to have a “3G-only” or “HSPA/HSDPA-preferred” option. I might try to find new interface software that has the option and load it onto the modem if it’s compatible, but for now I won’t need to since the current Airtel interface seems to have it already.

All the first testing was done on the soccer pitch behind the school buildings, which we discovered was much higher up than we had originally thought- it actually has a line of sight to both the Vodacom and Airtel cell towers in Monduli. And it is a much more convenient place to have Internet access than the primary school. But while we were up there, we realized that the roof of the Laguna Beach House (the main administrative building at Orkeeswa) is at almost the same level as that soccer pitch.

Today’s testing was done sitting on the wall around the Laguna Beach House inner courtyard, facing out towards the 3G Airtel tower. The first major goal was to try to select the 3G network, which we did successfully using the Airtel USB modem interface. The second goal was to determine if soldering would work as an attachment mechanism for keeping the coax cable mated to the connector. Soldering into such a tiny connector is really hard! Ultimately we ended up soldering a thinner 2.1 GHz monopole antenna into the connector just because it was easier to deal with than the coax cable; the weight of the coax cable pulls against the solder in varying directions as it is moved. We were able to get a 3G connection with that antenna sitting on the wall outside, but not indoors. So we tried using the monopole antenna as a wire by twisting it around the coax cable inner wire, soldering the connection, and wrapping electrical tape around it. That connection was secure, so the other one broke off. In summary, we have to find a better way. 

Tomorrow in Arusha, I’m hoping to order a cable with the correct mate (crc9 male) for that tiny antenna port on the USB modem. As a kind of experiment/test of the Tanzanian postal service, we’ll probably order two, having one sent to the States and mailed to us via FedEx, and the other shipped to TZ straight from the retailer. 

A note past all the technical details that I’m trying to record scrupulously for future reference:

While J and I were sitting on the wall trying to get a 3G connection, a pair of curious students stopped by to ask us about what we were doing. When we told them that we were trying to get Internet access to the school, they first asked whether they (the students) would really be able to use the Internet, and we said yes. Then one of them asked, “When we have Internet access, what does that mean?” J explained that the Internet connects everyone in the world who has Internet access, and makes available huge stores of information that people have put there. The student asked, “Does that mean that if there’s a person in Australia, we can mail them there?” J replied, “Yes, through email!” Both boys seemed fairly impressed, and I think they would have continued to question us if they hadn’t been called away by what they’d been doing before. 

Sometimes I get so focused on trying to solve technical problems that I miss opportunities to notice other areas of need and expand the scope of the project; I might not have thought twice about the incident. Fortunately, J was struck by the fact that they seemed to have no conception of what the Internet was and how to use it. We came to the conclusion that we should try to hold some seminars on basic Internet research skills like how to search for information online, and how to evaluate the validity of your sources. Maybe this would solve a common problem with teaching computer skills in developing countries that Andy and Ming once told us about: as interested and earnest the students are when they enter the classroom, the minute you give them free reign with Internet access, they will usually go straight to Facebook or download pictures of their favorite celebrities instead of being able to use it effectively for gathering information. But maybe that’s just the nature of high schoolers. We’ll see when we get there.

Another note: We went back to Mama Lea's house for dinner one night, with Alex. From left: J, Fausta, Lea, Alex, Mama Lea. We had a great time, and Alex made tasty chapatti!

-E