Interesting

In Kiswahili, the word “interesting” is apparently not used as in English- the diplomatic, malleable, all-purpose phrase that is so useful in everyday conversation. I really miss it during my feeble attempts to fumble through conversations in Kiswahili. Instead, I’m limited to words like “nzuri” (great/beautiful/lovely) and “sawa” (okay), which just doesn’t say the same thing!

Interesting is definitely what I would call the past two days of testing. Yesterday, J and I started taking measurements of the Laguna Beach House, the administrative building we want to get Internet access to first. We were considering several different places on the building where we might want to clamp the pole for mounting the antenna. Working under the assumption that providing Internet to any of the rooms in the building would be equally good, our first consideration was where reception would be the best. We suspected that the corner of the building closest to where we thought the 3G tower was would be where we got the best reception (right next to the wall on which we’d tested before), so we were planning to run a short coax cable from the antenna mounted there into the nearest room, which is currently an empty storage room but perfectly usable as an office or small classroom. We wanted to avoid having too long of a coax cable to avoid cable losses, and also wanted to avoid allowing the signal to travel over the corrugated metal roof, which could cause multipath (destructive interference caused by reflections).

With the help of Alex, Andy, Ming, and at one point Simon (a physics teacher), we moved a very tall and somewhat sketchy handcrafted ladder from its storage place by the kitchen up the hill to the cemented outdoor courtyard of the Laguna Beach House, and I used it to get onto the roof with my Macbook, a 3G modem, and the 3G ¼ wavelength monopole antenna. I got speeds of 0.9 Mbps download and 0.3 Mbps upload with 3 bars on the HSPA network on the roof next to the wall; further back on the roof right above the main administrative office, I got 0.5 Mbps download and 0.16 Mbps upload with 1-2 bars on HSPA. There was definitely better reception in the first location, although both seemed acceptable.

From left: Alex, Andy, me, J (and Ming took the picture)

Rather sketchy ladder

Edge of the roof next to the wall

Cleaned the solar panel while I was up there

Unfortunately, Alex told us afterward that it would be really inconvenient to use the Internet in that closest storage room as opposed to in the regular office/meeting room, because that room might be converted at some point into a temporary dormitory for students studying for the Form 4 Exams (scary tests that decide one’s future- more on that later). So we’d have to make sure our coax cables made it into the main administrative office; it’d be a trade-off between the accessibility and the quality of the Internet connection. We measured how many feet of cable we would need to connect the antenna mounted where we had originally planned to a USB modem in the office: around 65 feet. Our two longest cables were about 39 feet long, so we could connect two of them together and it would reach all the way back. But would cable/connector losses significantly slow down the Internet speed? I was inclined to think not, because of the high quality of the cable: LMR400, which has a loss rate of some .06-0.7 dB/ft. The total loss should only be about 5 dB- less than half the attenuation caused by a single average-sized tree in the line of sight of the antenna.

To verify the effect of the cable losses, today we tested the Internet connection again on the roof, with the monopole antenna on the end of the N male pin of two 39-ft coax cables connected end to end. On the other side of the cables, we had our modified N-male to stripped wire pigtail plugged into a USB modem in the office. Oddly enough, we had quite a bit of trouble getting on the HSPA network in the morning, and also seemed to be getting very variable WCDMA signal strength (at times fluctuating between 0 and 5 bars). I started out sitting on the apex of the roof (at 15 feet above the ground), but moved to mid-height on the roof because I wanted to see if mounting the antenna slightly below the apex level would still be okay. At Meena’s Hardware in Monduli where we were planning to get our mounting pole, we’d found out the previous day that we wouldn’t be able to get two sizes of pole that fit exactly into each other and assemble a two-piece 15+ foot mounting pole as we’d planned to do. So the shorter our pole could be, the easier (read: more possible) it would be to transport it to the school.

It turned out that as soon as I started sitting in the middle of the roof, the Internet in the office (where J was monitoring the results) slowed down drastically, becoming almost unusable. But even when I’d been sitting at the apex of the roof, the network had been flaky, switching between WCDMA and HSPA, and speeds had been comparable to those in Monduli: around 0.1 Mbps download and upload. After J and I regrouped with some granola bars, I went back onto the roof with the 24 dBi 2.4 GHz antenna, planning to put the monopole antenna in front of the dish as before. We tested the speed right above the office with only a single 39-ft cable, with the same results as before. At the point by the wall where we had originally wanted to mount the antenna, reception was slightly better (occasional HSPA of around 2 bars with mostly WCDMA at 0-3 bars) but speeds were not significantly faster.

As a sort of throwaway last check, I decided to try connecting the 2.4 GHz antenna directly to the N-male connector of the coax cable, even though I didn’t expect it to be able to pick up 2.1 GHz signal as well as the monopole antenna. Surprisingly, the WCDMA signal strength jumped to a consistent 4 bars, and within a few minutes the network switched to HSPA with 3 bars. I propped the antenna up on my head, and the HSPA signal strength jumped to 5 bars! Height really matters. But the Internet connection was somehow still as slow as before. What a mystery! Maybe traveling through the cable introduced errors in the signal that lowered the data rate drastically without decreasing the perceived signal strength? Maybe there were just too many users on the network at the time when we tested it; but we’d never observed that before at this time of day. The Internet with 5 bars on HSPA today was somehow worse than with 2 bars on the wall on the other days we’d tested it. I now realize that what I should have done is test the speed at the location I was receiving full bars on HSPA with just my laptop, 3G modem, and monopole antenna to eliminate the effect of the cable. We will be sure to do this on Thursday when we next go to school.

The trouble is that in order to keep the pole length acceptably short, it would be best for us to mount the pole on top of the courtyard wall, which adds about 5½ feet to the height of the antenna. If the cables are the problem, we’ll need to mount the antenna right above the office in order to shorten the length of cable we are using. Trade-offs are hard.

Other exciting business from this past week:

On Saturday, we went to the wedding of our host mama’s younger brother, held in the village of their boma (family home/traditional hut) around 2 hours outside of Monduli. A few notable pictures here:

J and our host mother (looking very beautiful in their handmade dresses)

The bride and groom taking first pieces of the wedding cake. (A whole roasted goat, actually referred to as the "cake!")

Today our host brother took us to see the Rift Valley, a very cool location on the outskirts of Monduli where continental plates are moving apart to reveal two sheer cliff faces and a huge, flat valley in between. According to J, this process is how new seafloor is created; in a few million years, the whole area will be in the ocean.

Our host brother

The Rift Valley

We saw a number of cool plants on the way:

This very unfriendly variety of acacia tree has very long spines (2 to 3 inches) on its branches and also its fruit. The fruit has a hard casing on the outside, and ants live inside eating the meat of the fruit. When I tried to pick the fruit, ants came crawling out through a little hole to protect it. When the fruit is picked clean on the inside, the ants bore more exit holes and move on.

This green fruit, called the ndulele, is slightly larger and a bright white-yellow color when ripe. The fruit is exceptionally bitter,  and both fruit and roots are used in traditional herbal medicine. According to Mama Lukumai, when Maasai are bitten by a poisonous snake, they eat that fruit as an antidote. After the fruit is eaten, apparently the blood at the wound begins to bubble as the compounds in the fruit take effect! The Maasai will then take a hot knife or other metal object and cauterize the wound after this treatment.

Driving was often very hard, because the roads were interrupted by deep cracks in the earth caused by the rains during the rainy season and afterward worsened by drying in the heat.