24 January 2007

I-TASC expedition 2006/2007

Yesterday Amanda and Tom went to Gronehogna to test the home-made antenna we made the day before. I was a bit nervous because I wasn’t sure if it would work or not. Making an antenna out of PVC pipe and old HF Radar elements, with extra bits of gaffer tape to hold it together seemed unlikely to really do the business. Also, we didn’t know they were going until about an hour before they left, so we had no time to make any adjustments. The antenna had to go as is (although we made a quick mounting bracket and mounted the antenna to an old broom handle). First then posed for a picture with the antenna and newly acquired broom handle and tried to look tough 😉

They left in the Challengers which takes a few hours, so in the meantime, First and I prepared the other modems and the equipment he would take to Lorenzo Piggen. The idea was to do the tests in the same order as we had done them 4 days earlier, which was this:
1. SANAE – Gronehogna (yagi-to-yagi)
2. Lorenzo Piggen – Gronehogna (omni-to-yagi)
3. SANAE – Lorenzo Piggen – Gronehogna (yagi-to-omni-to-yagi)
4. Lorenzo Piggen – Gronehogna (yagi-to-yagi)

The home made yagi antenna would be at Gronehogna the whole time and would be the only one used at that site. With the earlier test with the manufactured antenna, we got about 15% signal, yagi-to-yagi between Lorenzo Piggen and Gronehogna, and no signal to speak of using the omnidirectional antenna at Lorenzopiggen.

So, off they went. We decided to do the tests at 1500, and change every ten minutes. We had to decide on this beforehand as they had no radio equipment at Gronehogna that would go the distance, so we had to hope that Tom and Amanda would be there in enough time and we would then do the tests ‘deaf’ (so to speak). When 1500 spun around, we tried the connection. I could talk to First Born at Lorenzo Piggen but we could not talk to Gronehogna, so we had to go with our instincts a bit. I was pretty disappointed that we got no signal on all tests. First and I then agreed we would hold on a little longer, as the new antenna (if it worked at all) would be more directional than the ones we used earlier, so it might take them a little longer to ‘find target’. So we waited an extra few minutes, and bingo – we had 50% signal. Amazing! I was very excited. Just to be sure, I shut down the systems at SANAE so we could tell that this was actually signal coming from Gronehogna and not from the equipment I was using at SANAE. I shut down the modem and First reported the signal was still strong. He then opened a browser (we had a computer connected to each modem) and he could see the web pages we had setup on the machine they took to Gronehogna. First said it loaded instantly! Great!

The trick was, however, that this connection was yagi-to-yagi which is not what we would use in the final setup so we had to quickly switch to omni-to-yagi, the omnidirectional antenna being at Lorenzo Piggen. So First had to change the antenna very quickly as we were afraid that if we disconnected from the yagi for too long, Tom and Amanda would not see signal and would assume we had stopped the tests. To do this he would have to hold the omnidirectional antenna as he would not have time to mount it on the pole. So it was a bit hacky, but it wasn’t worth the risk of Tom and Amanda thinking we had stopped the tests and packing up before we could confirm the final set-up could work.

So First switched the antenna in the cold in record breaking time, with just a few tens of seconds downtime (he asked Luta, one of the crew that went with him, to hold the antenna). I turned on the modem here and ….. 30% signal! Great! First loaded their web page again to confirm the connection and it seems that our homebrew antenna was really doing a great job.

It wasn’t till Tom and Amanda returned that we learnt they had real difficulties setting up in the snow there (there was a storm) and that they didn’t have difficulties ‘finding target’. They couldn’t get the system working for some time, which was why we got no signal through the tests, but as soon as they were set up and turned on the modem they got 50% signal immediately. The fact that they had bad weather there was bad for them but in terms of the signal tests, it was a better situation for the tests than the earlier one as the first test was a perfect day. If we get 50% signal with some snow around, then it’s a very good sign. Tom apparently had also logged onto the IRC (chat) running on my computer at SANAE which is even better! Great.

So we know now the radio systems will work. Additionally, we can build a stronger antenna than this one,  one that is also more robust. It shouldn’t take more than about 4 hours to do. So now we await the discussions between Tom and the SANAE management about whether they can get us to Gronehogna before we leave in 9 days….

Leave a Reply

Your email address will not be published. Required fields are marked *