daughter cards and log skidding
Sunday, February 9 2014
During the weekly ritual of Sunday morning coffee in front of the woodstove, Gretchen solved her crossword puzzles, Ramona gnawed on a deer antler, and I researched 433 MHz reception and digital data decoding, a subject I have pursued largely without satisfaction in the past. I want to improve the reception of my main Meade weather station by swapping out its 433 MHz daughter card with something more powerful but compatible. And I also want to be able to capture the signals transmitted by the sensors on some sort of Arduino-type microcontroller. In researching this matter, though, I was unable to find anyone who had successfully pulled Meade sensor data out of the air and decoded it. As for the daughter card that does this in the Meade weather station, it's a surprisingly simple device of tiny discrete surface-mount components, the largest of which is a LMV358L dual operational amplifier. That daughter card connects to the rest of the weather station through only three wires: 3 volts, ground, and data, though I don't know if the signal is digital or analog. (I haven't looked at it with my oscilloscope, which doesn't work very well.)
I also have a little eight-pin digital receiver board that I got from Sparkfun that is tuned to the 433 MHz band. I hooked it up and found that it gathered some sort of data every time one of the sensors broadcasted a signal (indicated by a blinking light on the sensor and a nice robotic three-beat noise from the receiver board). I tried reading this data using an Arduino running both the Virtual Wire and the RCSwitch libraries, but neither produced any data for me to attempt to decode. I also tried using the Sparkfun receiver board in place of the one that came with the Meade Weather Station (to do so, I had to use a board to translate the five volt logic signals to three volts), but Meade station never successfully read any sensor data through that board, even when I used its newly-discovered "analog out" (though that would have been immediately digitized by the voltage translator). Clearly I'm going to need other 433 MHz receiver boards to experiment with, including simpler ones like the one the Meade actually uses. I'd also like to look at the data received from the sensors by the Sparkfun board either through an oscilloscope or a logic analyzer.
This afternoon I decided to do some much-needed firewood gathering. So I took the small GreenWorks battery-powered chainsaw across the farm road and used it to fell a couple of smallish long-dead oaks. Though small, one of them was at the limits of what I could cut through with the saw's ten inch bar. Though convenient, the GreenWorks is slow and underpowered for most firewood work, after felling the trees, I cut them into roughly ten-foot lengths and then skidded those home using a rope, taking advantage of the lubricating layer of snow. This is a technique I learned as a kid; my father often had me and my brother skid logs like this down Pileated Peak so he could pick them up with the pickup truck down at the bottom. Back then, though, as I worked I had to be content with the thoughts that spontaneously appeared within my head. These days, I do all such work while listening to podcasts. I recently discovered Snap Judgment, and it has a vast archive lasting hundreds of hours. The episode that struck me today was one that featured a tale told by the host, Glynn Washington. He told of what it was like growing up in a "cult" that didn't believe in medical care. He told of losing most of his hearing due to an ear infection and then of the generalized loss of faith in the congregation after the father of one of his friends died of treatable liver cancer. I won't spoil it for you, but suffice it to say that Glynn Washington went on to become a radio guy with an evidently-keen interest in sound design.
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