On our second Saturday morning, we met the Telecom technicians at Sekena. We were finally going to install the GSM equipment.
The first immediate glitch was that the u-bolts and pipe we had scavenged would not work. The pipe was too short and the u-bolts were too small. (It would really have been nice to have a mechanical drawing of that safety rail back in January...) The techs said they could probably bolt the antenna directly to the railing, with no pipe or u-bolts at all. At the very least, they could install the antenna cable and reposition the NS5 to shorten its CAT5 run.
(Toki spooling out the cable.)
(Sam hoisting the antenna.)
(Looking up the tower.)
While the Telecom guys worked the tower, we installed the BTS in the rack we had stripped a week earlier. By dumb luck, the 200' LMR-600 cable we brought was exactly the right length.
(Harvind and the newly-installed BTS unit.)
Once the techs cleared the tower, we engaged the power amp. A few handsets started beeping and buzzing as OpenBTS pushed the welcome message into them, but something was wrong. Even right under the tower, speech calls barely worked. Harvind started poking around in the radio layer and announced that we were getting hit with serious interference in the high-end of the downlink spectrum, probably from IUSN's 900 MHz gear. He made some gain and IF adjustments to get the best performance we could manage under the circumstances, but we were still loosing 6 dB of our noise floor. That's a factor of 2 in range and a factor of 4 in subscriber battery life. And the tower techs told us the antenna is at a funky angle because it didn't fit the hand rail very well without the pipe, so we might not even had coverage in Alofi. Arg!!
At this point we wondered: was the interference from IUSN equipment on the tower, or from remote sites beaming at the tower. There was a cabinet on the wall with two POE injectors in it. We had four good work days left on the island and not a lot of time for dodgy e-mails with IUSN's remote managers. Their service was completely unusable that morning, so it seemed unlikely that anyone would even notice a 5-minute link outage. I unplugged the IUSN equipment. The interference want away. I plugged it back in. The interference returned. It wasn't the most prudent thing I've ever done, but now we knew exactly where our problems were coming from.
Despite the interference, on the waterfront in Alofi, about 5 km away, we could get cellular coverage and LOS wifi to the tower site at the same time, so we set up an evening work session in a seaside park to play around with the first real timing advance we'd seen since Burning Man. It's not the worst place I've had to work.