Wednesday, November 28, 2007

High Frequency RFmodule thoughts

I've been interested in radar for so long. How do you get it to work at short range where you have nanoseconds to determine range? Well, I've been looking into what an RF module would be required to build a modular phased array setup. This has let me to believe how freaking expensive GHz class MMICs are. I've looked at Hittite's phase shifters. Analog and 4 to 6 bit digital. Nice parts... but somewhat out of my parts price range at around $100 each.

While I'd love to work on a 10GHz range design, I'm realizing that a 5GHz range unit is far more plausible with the advent of 802.11A/N and Wimax. Heck, TI's WLAN chipset might build the whole system at 2.4 and 5.2GHz with two chips and a few passives.

Research research research!

Tuesday, November 27, 2007

The Wiimote IMU

I've always been interested in inertial measurement units. I recently looked at the Wii Zapper frame and thought that we now have a 5.5 axis IMU. The Wiimote has a 3 axis accelerometer. The nunchuck has another 3 axis accelerometer. Now, if you have six axes of accellerometers that are arranged right, you can get good rotational data from the accelerometers. Unfortunately, this isn't perfect in this setup. You get a good pitch and yaw, but no roll information. This can be estimated out when the unit is roughly at standstill by determining where gravity is. So, if you figure out your distance between the two accellerometers in the Zapper, you have a rigid 5 axis IMU with a wireless connection. No phystical hardware hacking required (other than maybe for measureing the actual center to center position of the accelerometers)

Pretty cool, no?