Not many people know that once upon a time, NASA built a Space Shuttle Launch Complex at Vandenberg Air Force Base in California, 1985. It was later dismantled, and no Shuttle was ever launched. Oh, how I wish they had kept it! I would've seen so many more launches, not having to travel across the country for each one.

Spaceflight Now has posted a series of articles with lots of photos from the era. Really great stuff.

Looks fake, doesn't it? It's not. It was built.

Each of these articles has a whole slew of images:

• Inside shuttle hangar
• Road trip to pad
• Arrival at SLC-6
• Shuttle stacked on pad
• Nighttime views
• Inside launch control room
• Final look at West Coast shuttle

In an effort to avoid cleaning for a bit, and because a friend inquired about this blog, I decided to write this short post.

In the last post, I hadn't yet received the barometric pressure sensor. It has since been installed and I wrote some code to talk to it. Unfortunately, while I'm pretty sure the SPI communications are correct, I'm getting bad data out of it. Pressures and temperatures after calibration are no good. Without the data sheet, these will be meaningless, but here's an example of what I'm seeing:

I sent an inquiry to Measurement Specialties, and they responded that they agreed the values didn't look right, but they didn't reply to my follow-up, and I got distracted with other things.

Well, that's enough procrastinating. Back to cleaning house!

I'm probably just procrastinating a bit before getting into writing firmware for this thing, but I though I'd post a picture of the Balloon Controller with nearly everything populated. I'm still waiting for the barometric pressure sensor and GPS connector to arrive, but everything else is installed.

I've verified that everything powers up, but beyond that, I have no idea if anything works. I was able to flash the MC with a blinky LED program, though, so that's a good start.

UPDATE (15:38): Got the DBGU serial port work. Note that this board has two USB ports. One for the MC proper, and one for an FTDI chip attached to the SAM7X's DBGU port. This was easier than writing a Mac OS X virtual serial port driver against the MC's USB port.

UPDATE (18:27): Got the battery voltage being measured, and also got the radio link working!

It's a little cumbersome to flash the MC when you have an external power source, because it needs to power cycle to re-enumerate the USB and set up for download. So I pulled the fuse that USB bus power goes through, which means that I only have to disconnect the main power supply to power cycle it, rather than disconnect that and unplug the USB cable.

Darren and I tried an 18 km range test today with the n920. Amazingly, we had success with just the rubber ducky antennas, and down to 250 mW transmit power on both ends! He was up near this winery, and I was on the fifth floor of Yahoo! building D.

At first we tried the new Yagi, but it didn't seem to work (at all). We were astonished to get a link with just the whip antennas. They didn't even have a proper ground plane, just being stuck out the side of the plastic boxes I had put the gear in (and pointing upward).

Using the ATS123? command to query the receive signal strength, Darren had -88 dBm, I had -105 dBm (measurements varied, but I think that was at 250 mW). I tried sending a file to myself via loopback, < 1 KB in length, which failed the first time and succeeded the second. A 131 KB file failed, and I didn't try it a second time. I could see it dropped stuff from within the file. We'll have to investigate exactly what went on. Are the radios full duplex? How big are their buffers? It seemed to send the entire file before receiving anything, but that could've been an artifact of PortTermX.

Interestingly, the Yagi didn't seem to offer much. It was also nearly impossible to hold while operating the computer. Next time, we need to put it on a stand of some kind.

Hopefully this weekend we'll try a much longer range test, from the winery to Coyote Hills.

Our balloon experiment is using a 920 MHz frequency-hopping radio link (we also have 2.4 GHz radios, but will probably stick to 920 MHz). The balloon will carry a dipole or vertical bazooka tuned for 920 MHz, but it will be rotating and squirrelly. It will also be 30 - 50 km away. So I decided a good Yagi on the ground will help ensure we maintain our fade margin.

I looked at a couple options from L-Com. The best 900 MHz Yagi they had offered 14 dBi in 109 cm, but was $120. The next best offered 13 dBi for $44, so I bought it. I didn't realize until it arrived that it was 145 cm long!

So, this will prove to be unwieldy, at best, especially from a moving car. We might decide to have a fixed ground tracking station, but that approach will need investigation.