Miscellaneous Monitors and Controllers

Grain Loss Monitors - Gleanings (Gleanings Report - PDF File - 0.14 MB)

General Description
Grain loss monitors are electronic instruments designed to indicate combine grain loss. Sensors, sensitive to seed impacts, are mounted behind the straw walkers and the cleaning shoe. The signal from these sensors is displayed on a meter at the operator’s station (Figure 1).

Figure 1.

Most loss monitors are not designed to measure the actual amount of grain loss but will only warn the operator of increases or decreases in combine lossrate.

Commonly available models can be installed on conventional pull-type or self-propelled combines in about five hours using common tools. They range in price from $325 to $650.

Functional Performance
Loss monitors require calibration to suit field conditions and combine loss characteristics to provide meaningful information.

Sensitivity must first be adjusted to discriminate between the particular variety of grain and bits of straw, chaff or weed seeds. This is done by adjusting the sensitivity control to suit the type of grain being harvested. A common method is to drop several grain kernels on the sensors and set the sensitivity control so that the indicator meter responds.

The combine should then be set to field conditions in the normal manner. Once the operator is satisfied with the combine setting, the loss monitor gain control should be set to indicate a reading of about one-third scale, which will represent satisfactory operation.

When this calibration has been accomplished the loss monitor will indicate relative changes in lossrate to the operator. A significant increase in the meter reading is a signal to reduce the feedrate by slowing down. A reduction in the meter reading is a signal that feedrate may be increased to optimize efficiency.

Changes in crop conditions often occur during the day. As a result, occasional loss checks should be made and the loss monitor readjusted, if necessary.

Loss monitors are not designed for use on the new axial threshing combines. Straw and grain, propelled from the back of the combine, strike the sensors at high velocity. When impacted in this way. most loss monitors cannot distinguish grain from straw and they read in error.

The shoe of an axial threshing combine could be fitted with sensors, however, a properly adjusted shoe normally has very low losses even at high feedrates. The use of a loss monitor on the shoe would only be to warn the operator of plugging or of loss increases on sidehills.

It is also suggested that, since the losses from an axial type combine are quite low at normal feedrates, the need of a loss monitor is questionable.

While loss monitors can warn the operator of changes in the lossrate, they do not accurately measure the amount of loss. Figure 2 shows a typical grain loss monitor reading compared to the actual grain loss of a combine. At higher feedrates, combine losses increase rapidly in proportion to the loss monitor reading.

Factors which affect monitor performance are the adjustment of the sensitivity control, sensor size and location, and the responsiveness of the meter.

The sensitivity controls of most loss monitors perform well in heavy grains such as wheat and barley, but only a few perform well in light seeds such as flax or rapeseed.

Sensor location is very important to the performance of a loss monitor. Several sensor locations are usually suggested in the operator’s manual, however, it is advisable to observe the path of grain loss from the shoe and the straw walkers to determine the best locations.

Sidehill combining can cause significant increases in lossrate at the lower side of the shoe. Full width sensors, or two smaller sensors, appropriately placed, are necessary to monitor these losses.

Figure 2.

The lossrate from a combine may fluctuate significantly over shorter periods of time. However, these fluctuations are usually too rapid for the operator to control. A responsive meter will fluctuate with these losses and be difficult to read. A dampened meter showing average lossrate is more desirable.

Dependability
Loss monitors can give reliable service if installed correctly and handled carefully. Some loss monitors are affected by electrical interference from other components on the combine. This problem is usually identified by erratic meter readings and can be controlled by attaching an electrical noise suppressor to the instrument, or by using a dry cell battery to power the monitor.

Summary of Senstek DCM-2 Depth Control Monitor (Evaluation Report - PDF File - 0.42 MB)

Overall Performance: Functional performance of the Senstek DCM-2 depth control system was good. Performance was reduced by inadequate system response in very soft, lumpy or heavy trash field conditions.

Installation: The Senstek DCM-2 was easily installed by one man in about three hours. No modifications to the tractor or implement were required.

Seed Placement Accuracy: Seed placement accuracy depended on soil conditions. A more uniform depth of seed placement resulted when using the depth control system in varying soil conditions. No difference in seed placement was obtained with and without the depth control in firm soil conditions.

Response: The depth control system response was adequate for most field conditions. In very soft, lumpy or heavy trash field conditions the system would over compensate and result in erratic depth control.

Field Variables: Some error in average depth could result when travelling along field ridges. Depth control system performance was improved when travelling at an angle to field ridges. Similar error in average depths occurred when one cultivator section (one depth sensor) encountered an extended hard area in the field that it could not properly penetrate. Due to cultivator frame geometry, the depth control system could not effectively maintain a uniform depth of tillage through gullies and over sharp hill crests.

Ease of Operation and Adjustment: Control system operation and adjustment were easily performed. An experienced operator could adjust the depth control system to suit most field conditions in less than five minutes. Implement depth adjustments were easily made from the tractor cab. Approximate depth of tillage could be read from the digital display.

Operator Safety: The Senstek DCM-2 was safe for field and transport use. Implement safety lock-ups should be used to ensure safe transport.

Operator's Manual: The operator's manual was well written and contained useful installation, operation, set-up, maintenance and trouble shooting information.

Durability: One failure occurred during the evaluation. Two control console integrated circuits required replacement.

Summary of Jeannotte Depth Control Controller (Evaluation Report - PDF File - 0.51 MB)

Quality of Work: The ability of the Jeannotte Depth Controllers to maintain a uniform seeding depth was good. Disk gangs with the controllers maintained a more uniform seeding depth in fields with varying soil hardness, than disk gangs without controllers. Additional weight or spring force could be added to the disk gangs to penetrate hard soils without excessive penetration occurring in soft soils.

The seeding depth with or without the controllers was not affected by changes in ground speed. In sharply rolling land, the disk gangs with the controllers followed the surface contours better than the disk gangs without controllers.

Disker stability was not affected by the controllers. Soil surface ridging did not occur. Mud did not build up excessively on the tires. The tires rode over trash and castored around stones and other obstacles.

Ease of Installation: Ease of installing the controllers was good. It took one man about 2 hours to install each controller.

Ease of Operation and Adjustment: Ease of operating and adjusting the controllers was very good. Disker gang and frame levelling and on-the-go adjustment of the depth control cylinders were less critical and seldom required when the Jeannotte controllers were used.

The seeding depth was easily adjusted and the wheels easily positioned behind the gangs. Clearance for transporting was adequate, however, the controllers interfered with the packer hitch when fully raised. A good, accurate low pressure gauge was required to measure tire pressure. Tire pressures were checked daily. No other servicing was required.

Operator Safety: No safety problems were apparent.

Operator Manual: Installation instructions were adequate. An operator manual was not available, but several operating hints were included with the installation instructions.

Mechanical History: No mechanical problems occurred during the test.

Summary of Microtek Automatic Depth Controller (Evaluation Report - PDF File - 0.39 MB)

Performance: Functional performance of the Microtek automatic depth control unit was good. Performance was reduced when working in moist conditions due to soil build-up on gauge wheels.

Installation: The Microtek was easily installed by one man in about four hours. No modifications to the tractor or implement were required.

Seed Placement Accuracy: Seed placement accuracy depended on soil conditions. More uniform depth of seed placement resulted when using the depth control unit in varying soil conditions. No difference in seed placement was obtained with and without the depth control in firm soil conditions.

Response: The depth control unit response was acceptable for all types of conditions encountered.

Field Variables: Error in average depth could result when travelling along field ridges. The automatic depth control unit performance was improved when travelling at an angle to field ridges. Similar error in average depths occurred when one cultivator section (one gauge wheel) encountered an extended hard area in the field that it could not properly penetrate. Due to cultivator frame geometry, the depth control system could not effectively maintain a uniform depth through gullies and over sharp hilI crests.

Ease of Operation and Adjustment: Control system operation and adjustment were easily performed. An experienced operator could adjust the depth control unit to suit most field conditions in less than fifteen minutes. Implement depth adjustments were easily made from the tractor cab. Approximate depth of tillage could be read from the digital display.

Operator Safety: The Microtek was safe for field and transport use. Implement safety lock-ups should be used to ensure safe transport.

Operator's Manual: The operator's manual was well written and contained useful installation, operation, setup, maintenance and troubleshooting information.

Mechanical Problems: Two failures occurred during the evaluation. Three O-rings failed and a depth control cable was damaged. Both O-rings and cable required replacing.

Summary of Depth Master Automatic Depth Control System (Evaluation Report - PDF File - 0.39 MB)

Performance: Functional performance of the Depth Master automatic depth control system was good. Performance was reduced when working in moist conditions due to soil build-up on gauge wheels.

Installation: The Depth Master was easily installed by one man in about four hours. No modifications to the tractor or implement were required.

Seed Placement Accuracy: Seed placement accuracy depended on soil conditions. More uniform depth of seed placement resulted when using the depth control unit in varying soil conditions. No difference in seed placement was obtained with and without the depth control in firm soil conditions.

Response: The depth control unit response was acceptable for all types of conditions encountered.

Field Variables: Error in average depth could result when travelling along field ridges. The automatic depth control unit performance was improved when travelling at an angle to field ridges. Similar error in average depths occurred when one cultivator section (one gauge wheel) encountered an extended hard area in the field that it could not properly penetrate. Due to cultivator frame geometry, the depth control system could not effectively maintain a uniform depth through gullies and over sharp hill crests.

Ease of Operation and Adjustment: Control system operation and adjustment were easily performed. An experienced operator could adjust the depth control unit to suit most field conditions in less than five minutes. Implement depth adjustments were easily made from the tractor cab. Approximate depth of tillage could be read from the digital display.

Operator Safety: The Depth Master was safe for field and transport use. Implement safety lock-ups should be used to ensure safe transport.

Operator's Manual: The operator's manual was well written and contained useful installation, operation, setup, maintenance and trouble shooting information.

Mechanical Problems: The threads on the bolts, used to tighten the shock mounting plates in position, stripped. Holes were drilled through the gauge wheel arms so bolts could be used to ensure proper tightening of the shock mounting plates.

Summary of FG Auger Alert (Evaluation Report - PDF File - 0.33 MB)

Quality of Work: The performance of the F.G. Auger Alert was very good. The Auger Alert was effective in alerting an auger operator of a full bin.

The Auger Alert did not diminish the capacity of the auger to which it was attached and did not alter or interfere with flowing grain.

Ease of Installation: Ease of installation was very good. The auger alert was easily installed on a 50 ft (15.2 m), 10 in (255 mm) diameter grain auger and took one person about 30 minutes to install.

Ease of Operation and Adjustment: Ease of field operation was very good. The Auger Alert was easy to operate and required little operator experience. The Auger Alert did not require lubrication or daily service.

Ease of adjusting the Auger Alert was very good and took one person minimal time. The switch can was lowered into the bin or truck to the desired level and secured in that position.

Power Requirements: The Auger Alert required an independent 12 volt electrical power source. The device was supplied with power cables and suitable clips for attaching the cables to a battery.

Operator Safety: Safety was excellent. The Auger Alert was safe to operate, and when used as intended, helped prevent accidents at the auger site. In addition, use of the auger alert diminished the need to climb to the top of a bin to determine grain height.

Operator's Manual: The operator's manual was poor. Operational instructions consisted of a product literature sheet and a typewritten page with installation instruction.

Mechanical History: The pendulum switch within the sensor can failed at 15 hours.

Summary of Kee Ultrasonic Depth Control System (Evaluation Report - PDF File - 0.48 MB)

Quality of Work: Tillage depth accuracy of the KEE Ultrasonic depth control was very good. The depth control was effective in maintaining the desired tillage depth in both normal and deep tilled fields. In primary soil conditions there was no difference in tillage depth between the depth controller and using no depth control.

The depth control response to field surface variations was very good. The depth control was effective in maintaining a constant working depth.

Performance of the KEE depth control was good in variable field conditions. The number of measurements taken and the filtering process of the controller enabled the tillage unit to maintain uniform depth in varying field conditions. The depth controller had difficulty properly adjusting to hard soil conditions and in fields with heavy residue coverage. A temperature sensor allowed the depth controller to correct sensor depth measurements due to changes in the temperature.

Ease of Operation and Adjustment: Ease of calibrating the KEE depth controller was very good. Five minutes was required to calibrate the zero position. The system required rezeroing after cleaning a plugged sensor, changing to a different tillage tool or replacing worn tillage tools.

Ease of setting the depth adjustment was very good. The vertical bar graph on the control box displayed the depth operating range. Implement depth was manually or automatically controlled. In manual operation the tractor's hydraulics were isolated from the control box. The hydraulics then could not be activated automatically.

The hydraulic solenoid valve could be installed on tractors equipped with either open or closed centred hydraulic systems or a load sensing hydraulic system.

Ease of Installation: Ease of installing the KEE depth control system was good. For proper operation of the sensors the distance between the sensor's backing plate and the tillage tool point was 27.5 in (70 cm). The hydraulic lines were difficult to connect to the tractor remote hydraulic couplers. Installation of the control box, hydraulic controller, four sensors, junction box and hydraulic solenoid valve took two people five hours.

Operator Safety: The KEE depth control was safe to operate if normal safety precautions were observed. A throttle interlock switch disabled the automatic operation of the controller at low tractor throttle speeds.

Operator's Manual: The operator's manual was good. The manual contained useful information on operation, installation and troubleshooting.

Mechanical History: Two hydraulic coupler fittings were replaced during the test.

Summary of DICKEY-john DjCCS100 and DjCMS100 NH₃ Control and Monitor System (Evaluation Report - PDF File - 1.95 MB)

Quality of Work:The metering accuracy of the DICKEY-john DjCCS100 automatic controller was good for nitrogen rates between 40 and 180 lb/ac (45 and 202 kg/ha) and fair for rates below 40 lb/ac (45 kg/ha) or above 180 lb/ac (202 kg/ha). Entering the desired rate into the control console set the nitrogen application rate.

The thermal transfer unit's ability to maintain NH₃ in a liquid form was good. The vapour detector monitored the vapour (ammonia gas) in the flow of liquid from the thermal unit. A "check mark" displayed on the control console warned the operator when the acceptable level of vapour was exceeded.

The motorized control valve's response time in the automatic mode was very good. The valve responded quickly to adjust and stabilize the nitrogen flow due to changes in ground speed or application rates. Manual operation of the motorized control valve was not possible with the DICKEY-john DjCCS100 control console.

Ease of Operation and Adjustment: Ease of performing maintenance was good. A pressure relief valve to drain the control system and a strainer assembly to prevent foreign material from entering the thermal units was not provided.

Ease of programming and operating the control console was very good. The console was calibrated for Imperial (acres) and a radar ground speed sensor. Programming the console required entering and storing calibration numbers into memory. Disconnecting the battery power did not affect console memory. Changing the nitrogen application rate was easy. A new rate was programmed into the control console or changed by the "Application Rate ±" adjustment constant.

Ease of programming and operating the monitor console was very good. The console was calibrated for Imperial (acres) units and a radar ground speed sensor. Programming the console required entering and storing calibration numbers into memory. Disconnecting the battery power did not affect console memory.

Ease of Installation: Ease of installing the DICKEY-john DjCCS100 and DjCMS100 NH3 control system was good. Installation of the control system took 2 people, 7 hours. A mounting bracket was fabricated to support the 2 thermal units.

Operator Safety: Safe operation of the DICKEY-john DjCCS100 and DjCMS100 control system was directly related to the operator's knowledge of handling NH₃. Classified as a dangerous good, extreme caution and care must always be used when around NH₃. Safety features supplied with the DICKEY-john DjCCS100 and DjCMS100 control system were the procedure for entering the set-up mode and message area on the control console, operation of the off/auto/flush switch and the preset pressure relief valve on the thermal transfer units.

The DICKEY-john DjCCS100 and DjCMS100 control system relied on a continuous power source for safe operation. Unsafe operation of the control system could occur with a loss of power to 1 or more of the electrically controlled components.

Operator's Manual: The operator's manuals were good. The manufacturer supplied manuals for the control and monitor consoles. The manuals contained useful information on calibration and operation of consoles when applying anhydrous ammonia. Safety precautions when using anhydrous ammonia were included in the control console manual.

Separate installation manuals were provided for the thermal unit, flowmeter, control valve, vapour detector, ground speed sensor and consoles. A detailed parts list was not included.

Mechanical History: No mechanical problems were encountered during 102 hours of field operation.

Summary of Micro-Trak MT3000 Control System (Evaluation Report - PDF File - 1.95 MB)

Quality of Work: The metering accuracy of the Micro-Trak MT3000 automatic controller was good for nitrogen rates between 40 and 140 lb/ac (45 and 157 kg/ha) and fair for rates below 40 lb/ac (45 kg/ha) or above 140 lb/ac (157 kg/ha). Entering the desired rate into the controller set the nitrogen application rate. Field tests showed as the NH3 temperature increased above 59°F (15°C) the minimum controlled application rate also increased. Adjusting the butterfly valve did not reduce the application rate as the system pressure prevented the butterfly valve from closing. Plugging 1 hole on the butterfly valve reduced the pressure, allowing for lower application rates.

The heat exchanger's ability to maintain NH₃ in a liquid form was good. The vapour produced from the heat exchanger was discharged through vapour lines. The amount of vapour discharged was related to the metering accuracy of the controller and the percentage of nitrogen loss corresponded to the actual application rate.

The motorized control valve's response time in the automatic mode was very good. The valve responded quickly to adjust and stabilize the flow of nitrogen due to changes in ground speed or application rates. Manual operation of the control system reduced the efficiency of the motorized control valve, therefore manual operation was limited to initial field use or when the controller was not used for a period of time.

Ease of Operation and Adjustment: Ease of performing maintenance was very good. Maintenance included checking and fixing all NH₃ leaks and cleaning the strainer assembly and flow meter.

Ease of programming and operating the console was very good. The console was programmed for American English (US) units and a radar ground speed sensor. Programming the console required 8 calibration numbers be entered and stored in memory. Changing the nitrogen application rate was very easy. A new rate was programmed into the control console or changed by the Delta Rate function.

Ease of Installation: Ease of installing the Micro-Trak MT3000 control system was good. The manufacturer assembled the components of the NH3500 control system. Installation of the MT3000 control system took 2 people, 5 hours. The main harness cable supplied was too short to connect the console to the hold cutout module so a 10 ft (3 m) extension cable was ordered.

Operator Safety: Safe operation of the Micro-Trak MT3000 controller was directly related to the operator's knowledge of handling NH₃. Classified as dangerous goods, extreme caution always was necessary when around the NH₃. Safety features supplied with the Micro-Trak MT3000 controller were the on/off valve placed before the control system and the procedure for entering the calibration mode.

The Micro-Trak MT3000 control system relied on a continuous power source for safe operation. Unsafe operation occurred with a loss of power to 1 or more of the electrically controlled components.

Operator's Manual: The operator's manuals were fair. The manufacturer supplied a manual for both the control console and the NH₃ control system. The manual supplied for the control console was written mainly for spraying operations. The NH3500 installation/operator's manual supplied useful information on the installation, operation and maintenance of the control system. The manual was similar to the 1 supplied with the control console. A detailed parts list was not included. A detailed section on the mandatory safety precautions to be followed when using NH₃ was not included.

Mechanical History: The in-line power fuse was replaced and 1 hole on the butterfly valve was plugged.

Summary of Nitro-Trak NH₃ Automatic Control System (Evaluation Report - PDF File - 1.95 MB)

Quality of Work:The metering accuracy of the Nitro-Trak TNc9541 automatic control system was good for nitrogen application rates between 40 and 120 lb/ac (45 and 135 kg/ha) and fair for rates below 40 lb/ac (45 kg/ha) or above 120 lb/ac (135 kg/ha).

Nitrogen application rates below 40 lb/ac (45 kg/ha) required operating the Continental meter near its low limit application range. Field tests showed how variations in ground speed allowed the actuator arm to turn the meter dial beyond the operating range of the meter. The clamp securing the actuator arm to the meter dial turned changing the calibration settings on the Nitro-Trak TNc9541 controller. Improper application rates resulted, which required recalibration of the system to ensure the dial reading on the display monitor and Continental meter was similar.

The actuator arm assembly's response time in the automatic mode was very good. The actuator arm assembly of the meter control kit controlled the movement of the Continental meter dial position to adjust and stabilize the flow of nitrogen due to a change in ground speed or application rates.

Ease of Operation and Adjustment: Ease of performing maintenance was very good. Maintenance included checking and fixing all NH3 leaks and cleaning the Continental meter screen assembly.

Ease of programming and operating the console was very good. The console was programmed for either American English (US) or metric (SI) units. Radar or wheel drive sensors recorded ground speed. Programming the console required 13 calibration numbers be entered and stored in memory. Changing the nitrogen application rate was very easy. A new rate was programmed into the display console or changed by the Delta Rate function.

Ease of Installation: Ease of installing the Nitro-Trak TNc9541 control system was good. The manufacturer assembled the components of the meter control kit. Installation of the Nitro-Trak system took 1 experienced person, 5 hours. The main harness cable supplied was too short to connect the console to the servo control module. A 10 ft (3 m) extension cable was ordered to connect the display console to the module.

Operator Safety: Safe operation of the Nitro-Trak TNc9541 controller was directly related to the operator's knowledge of handling NH₃. Classified as dangerous goods, extreme caution and had to be always used around NH₃. Safety features supplied with the Nitro-Trak control system were the condensed calibration mode and security function.

The Nitro-Trak control system relied on a continuous power source for safe operation of the system. The console displayed an "ERR" message when a power loss was detected from any of the electrically-controlled components of the system. Unsafe application of NH₃ occurred with power loss to 1 or more of the electrically controlled components. However, the control system could not stop the flow of NH₃ through the meter. The shut-off valve hydraulically controlled the flow of NH₃ on the meter.

Operator's Manual: The operator's manual was good. The manufacturer supplied a manual for the display console. The manual contained useful information on the calibration and operation of the display console when applying NH₃ with a Continental meter. A detailed safety section on the mandatory safety precautions to be followed when using NH₃ was not included.

Mechanical History: The Nitro-Trak TNc9541 was operated in the field for 86 hours. The intent of the test was evaluation of functional performance. An extended durability evaluation was not conducted.

Summary of Raven SCS440 NH₃ Control System (Evaluation Report - PDF File - 1.95 MB)

Quality of Work: The metering accuracy of the Raven SCS440 automatic controller was good for nitrogen rates below 140 lb/ac (157 kg/ha) and fair for rates above 140 lb/ac (157 kg/ha). The nitrogen application rate was set by entering the desired rate into the control console.

The heat exchanger's ability to maintain NH₃ in a liquid form was good, The vapour produced from the heat exchanger was discharged through vapour lines. The amount of vapour discharged was related to the metering accuracy of the controller and the percentage of loss corresponded to the actual application rate.

The motorized control valve's response time in the automatic mode was very good. The valve responded quickly to adjust and stabilize the flow of nitrogen due to changes in ground speed or application rate. Manual operation of the control system reduced the efficiency of the motorized control valve, therefore manual operation was limited to initial field use or when the controller was not used for a period of time,

Ease of Operation and Adjustment: Ease of performing maintenance was very good. A pressure relief valve was used to drain the anhydrous ammonia before working on the system.

Ease of programming and operating the console was very good. The console was calibrated for American English (US) and radar (SP2) ground speed sensor. Programming the console required 8 calibration numbers to be entered and stored into memory. Changing the nitrogen application rate was very easy. The flow control rate switch was moved to the second programmed application rate or a new rate programmed into the control console.

Ease of Installation: Ease of installing the Raven SCS440 NH₃ control system was good. Installation took 2 people, 7 hours. To read the temperature and pressure gauges from the tractor cab required the control system be mounted toward the front of the tillage unit. The control cables supplied were too short to connect the console to the flow meter and valves and a 24 ft (17.3 m) extension cable was ordered.

Operator Safety: Safe operation of the Raven SCS440 controller was directly related to the operator's knowledge of handling NH₃. Classified as dangerous goods, extreme caution and care had to be used at all times around NH₃. Safety features supplied with the Raven SCS440 NH₃ controller were an emergency shut-off valve, a pressure relief valve, and the "DATA-LOCK" and "SELF TEST" functions on the control console.

The Raven SCS440 control system relied on a continuous power source for safe operation of the system. Unsafe operation of the control system occurred with a loss of power to 1 or more of the electrically-controlled components.

Operator's Manual: The operator's manuals were fair. The manufacturer supplied a manual for the control console and the NH₃ control system. The control console manual was written for spraying operations. The manual contained no information on the operation of the console with NH₃. The NH₃ control system manual supplied useful information on the assembly, installation, operation and maintenance of the control system. A detailed parts list was also included. A detailed safety section on the mandatory safety precautions when using NH₃ was not included.

Mechanical History: No mechanical problems were encountered during 56 hours of field operation.

A Comparison of three popular Yield Monitors and G.P.S. Recievers (Research Update - PDF File - 1.00 MB)

A yield monitor used in conjunction with a Global Positioning System (GPS) receiver records field and crop information during harvest that can help producers make sophisticated farm management decisions.

The system performs three functions:

• The yield monitor measures the amount of grain in the hopper by using a flow measuring device and other devices such as a grain moisture sensor.
• The Global Positioning System (GPS) determines the combine’s location from a satellite radio signal.
• Together, data from the monitor and the GPS system is used to create a yield map for every location in the field. This map can then be used, along with other data, to make crop input and other decisions as a part of a Precision Farming system.

What is the Global Positioning System (GPS)?
The GPS is a network of 24 U.S. Department of Defense satellites orbiting the globe, transmitting signals that can be received anywhere on the planet. A GPS receiver uses these signals to calculate its location on Earth.

However, the signals from these GPS satellites alone do not provide an accurate enough location for Precision Farming. To obtain an accurate location, a second signal, called a differential correction signal, is needed. This signal can be received from either another satellite or from a ground-based beacon. Most combine yield monitor/GPS receivers used in Western Canada use a satellite-generated differential correction signal. Standard GPS signals are free of charge to everyone, but the differential correction signals can only be obtained through a paid subscription service. This service can cost several hundred dollars per year.

The satellite that provides the differential correction signal is located over the equator. If the combine is in a location where the antenna’s view to the south is blocked, the differential correction signal may be temporarily lost. In the tests conducted by PAMI, the antenna was mounted on the highest point of the combine to minimize this problem.

Are all yield monitors created equal?
While this technology has a lot of potential benefits for agriculture, it is an emerging technology. The accuracy of results provided by yield monitors is sometimes difficult to assess. The intent of this research project was to:

• operate three yield monitor/GPS receivers in the field,
• measure their performance, and
• report the results to producers to help them make informed decisions about the use of this technology.

• How well did the yield monitor indicate the amount of grain in the hopper?
• How well did the GPS receiver indicate the combine’s location?
• How well did the entire unit function to indicate the yield at any given location in the field?

To test the accuracy of the GPS receivers, each was removed from the combine and the antenna was mounted on a mast in the box of a ½ ton truck. The truck was driven over a track at different speeds and directions, and the path the receiver recorded was compared to the actual track location. The actual location and shape of the track was determined using conventional land surveying methods.

Three methods were used to assess the system’s ability to report the yield at a location in the field.

The first method involved marking and harvesting 10, 20, 30, and 40-foot sections of swath with the yield monitor turned off. This created "holes" in the swath of varying lengths. The swath, "holes" and all, was then harvested with the yield monitor turned on. Ideally, the resulting map was expected to record the "holes" in the swath as a section of "zero" yield in the correct location. The actual map produced was compared to this ideal.

In the second test, 20-foot sections of swath were removed by hand and placed on top of the existing swath either before or after the resulting "hole". The ideal map should then have shown a section of normal yield, a section of twice the normal yield, and then a section of "zero" yield (or vice versa, depending on which side of the hole the removed section of swath was placed). The actual map produced by the monitor was compared to this ideal.

For the third test, a known quantity of grain was placed in a dump bucket and mounted at the combine feeder house intake. A stake was placed in the ground next to the swath to mark the start of the test. When the combine passed this stake, a mechanism was tripped that dumped the grain from the bucket onto the swath entering the feeder house. The yield increase recorded by the monitor was compared to the actual yield increase and location.
A yield monitor is generally available as an accessory on a combine harvester. The tests were conducted on three popular, commercially available units:

• A Case IH AFS system factory-installed on a Case IH 2188 combine.
• A John Deere GreenStar system factory-installed on a John Deere 9610 combine.
• An Ag Leader PF3000 system field-installed on a John Deere 7720 combine.