jbd

The GPS has arrived and I verified its operation on the beaglebone. Also, Ben Smith (from CCOM at UNH, and an old sailing buddy) has joined the project and briefed me on the PPS (Pulse Per Second) signal provided by most GPS's. Since, to keep cost of the "roving radios" down, we won't have much computational ability on the rovers (if any); rovers == cattle ear tags. I've noted that the chronodot has something similar to the PPS, but I don't know if it is tied to the "start of the second" like it is on most GPS devices. Iif it is, and if it gives us sufficient accuracy, then we can use it for sub-meter accuracy. (I'd really like to have 1-inch accuracy, but I'm willing to give up on that somewhat.) The chronodot is low power and relatively temperature insensitive, and we can probably get it to shut down every few seconds to improve the power consumption. I think the next steps are: 1. Prototype an "ear tag" rover with an XBee, battery, and chronodot. 2. Verify the rover can talk, over the XBee, to an anchor (Beaglebone with GPS and XBee).

I purchased two XBee's, a beaglebone and their various accessories for development. Two XBee's are required to check the timing algorithm between a "cow" and one of the anchor points, one of the XBee's will be on the beaglebone (acting as an anchor point with a GPS), and another will be on my laptop/workstation (acting as a cow). At this stage of development, we're only concerned with getting the various components checked out and writing any low-end software required to interact with the hardware components. I've looked at the XBee specs, and although the power requirements for the Series 2 are in line with our needs, I suspect we'll need to add a high-resolution clock to the XBee to get sufficient accuracy in distance measurement. And I'm really concerned about weight and power draw - don't forget, these things have to be small enough to fit on an ear tag or (at most) a collar. I've got the GPS on backorder.

This appears to be http://www.farmshow.com/

Something that has been used with some success in the Open Source world is bounties... One would offer a bounty for a solution to a problem. I know its not much different from an "X Prize", but tends to attract those with the knowledge and time to perform "one off" projects. But things like explanation and documentation could be a problem. Of course, in all cases, patent/royalty-free would be required. And this brings up an ugly potential issue that would need a lawyer. Groan.

We can always transmit the data we get from the radios on the mobile units, upload it to the anchor points, and let a server do the computations. Supposedly the anchors are fixed positions (and may be GPS enabled). However, as I remember my radio theory, we will need a number of samples to get a reasonable approximation to use in differential distance computation to the anchor points. Each radio will have to be calibrated to determine what its "reasonable sample rate" would be. Or does the Zigbee already do this? (does it provide a signal strength, or do we have to get the analog strengths in real-time)? Or am I thinking too deeply?