![]() With that range of speeds, our calibration errors are commonly 0.5% or less.Ĭapturing a range of grain flow rates during calibration can be a nuisance because it typically requires harvesting individual full header-width "loads" at different speeds or partial header-width "loads" at a constant speed. When we harvest our field-scale corn research trials around the state, we typically aim to harvest calibration loads at speeds ranging from about half of normal to slightly faster than normal. The goal with multi-load calibration procedures is to "capture" the full range of grain flow rates (aka yield levels) you expect to encounter when harvesting a field. This recommendation suggests that the calibration response curve for these yield monitors is not a straight-line, but is rather some sort of non-linear response curve that requires a number of calibration points to best "train" the yield monitor how to interpret the flow sensor signals (see "Non-linear calibration curve" graphic below). ![]() Other manufacturers recommend between 3 and 6 grain loads are required to perform a satisfactory calibration of the yield monitor. While the standard recommendation is for only one grain load, the "fine print" in the owners' manual suggests that additional calibration loads may be added to fine-tune the accuracy when necessary. That recommendation implies the calibration response curve is a straight-line or near-linear relationship between grain flow rates and flow sensor signals (see "Near-linear calibration curve" graphic below). Some manufacturers suggest that only one grain load is necessary to perform an accurate calibration. The nature of the calibration curve appears to differ among some makes of yield monitors. Conceptually, the calibration process involves fitting a response curve between grain flow rate and flow sensor signal strength in order to estimate low, medium, and high yields. The actual weight for each load is then entered into the yield monitor console and the yield monitor firmware makes mathematical adjustments to the calibration response curve. The grain for each specific "load" is then offloaded from the combine grain tank and weighed on calibrated or "known to be accurate" weigh wagon or commercial scales. The grain weight of each "load" is estimated "on the go" by the yield monitor as the grain is harvested. The amount of grain required for each calibration "load" ranges from 3,000 to 6,000 lbs (50 to 100 bu grain) depending on the manufacturer's recommendations for the specific model/make of yield monitor. One of those steps involves the harvesting of calibration "loads" of grain that are used to "teach" the yield monitor's "black box" how to accurately convert the electrical signals from the sensors into ESTIMATES of grain flow rates.Ĭalibrating a yield monitor typically requires the harvest of individual "loads" of grain that represent the range of grain flow rates (i.e., a range of yield levels) you expect to encounter throughout the field. Yield monitor calibration involves a series of steps taken to ensure that the ESTIMATION of each of these factors is accurate. the yield monitor's firmware / software then ESTIMATES "dry" grain yield per acre, at a moisture content of your choice, and records those yield estimates, and their geographic location in the field, every second or two in the display's memory or uploaded by cellular data connection to a Cloud-based Web server. Along with ESTIMATES of distance traveled (usually based on differentially corrected GPS signals), header width, and ESTIMATES of grain moisture content. What I want you to understand is that yield monitors ESTIMATE yield by converting electrical signals received from a mass impact or optical sensor, located somewhere in the clean grain elevator of the combine, into ESTIMATES of grain flow (lbs) per second or two of travel time. Understand this one simple fact about grain yield monitors: They do not measure grain yield.
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