Patent Publication Number: US-2002008167-A1

Title: Ground based remote sensing system

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates generally to methods and devices for monitoring various physical parameters of an agricultural field. More particularly, embodiments of the present invention relate to a ground based remote sensing system for use in gathering agricultural crop data.  
       [0003] 2. Prior State of the Art  
       [0004] There currently exists a variety of remote sensing systems used to gather agricultural crop data. Use of ground based remote sensing systems to obtain and continuously update agricultural crop data is well known. Ground based systems, in particular, provide tremendous advantages over aircraft, satellite, and other remote sensing systems. For example, cloud cover and other atmospheric interferences and disturbances frequently inhibit and/or prevent timely and effective gathering of agricultural crop data. It is generally acknowledged that a ground based remote sensing system whose sensors are in close proximity to the crop or ground to be monitored is not susceptible to these types of atmospheric interferences and is, in this regard at least, superior to aircraft and satellite based systems.  
       [0005] Another advantage presented by ground based sensing systems is that they tend to be substantially less expensive than aircraft or satellite based systems. In particular, the infrastructure for ground based systems is relatively simple technically, and employs readily available materials and components. On the other hand, aircraft and satellite based systems are logistically much more complex and typically employ relatively sophisticated technology, systems, and materials.  
       [0006] Ground based remote sensing systems are particularly attractive because they provide the farmer with a large measure of control over data gathering. Because ground based remote sensing systems are deployed in the farmer&#39;s fields, the farmer has ready access to the system and the data gathered thereby. Thus, the farmer is able to rapidly gather, analyze and update agricultural crop data. On the other hand, remote sensing systems such as those based upon satellite and air plane data gathering are typically not within the sole control of the farmer. Satellite based systems are particularly problematic. Specifically, the schedule by which the satellite revisits the agricultural crop and updates the data gathered therefrom is governed by such factors as satellite speed and movement of the earth, i.e., factors which the farmer cannot control. Thus, data gathering, and updating, by such systems is completely dictated by the satellite schedule, and not by the farmer. Further, if the satellite happens to pass by when clouds obscure the crop, the farmer is then forced to wait for data until the satellite again revisits the area. This is not a satisfactory arrangement where the farmer must make critical decisions based upon rapidly changing crop and/or soil conditions.  
       [0007] Satellite and aircraft based sensing systems are problematic for at least one other reason. In particular, because of their physical remoteness from the crop and/or soil from which data is being gathered, the resolution of the agricultural crop data and images gathered by those systems is poor.  
       [0008] While ground based remote sensing systems thus present a number of important advantages over aircraft or satellite based remote sensing systems, known ground based remote sensing systems suffer from a variety of significant shortcomings. First, many known ground based remote sensing systems employ a large number of sensors. Typically, the sensors are deployed along the entire length of a center pivot irrigation system or a linear move irrigation system. Because a large number of sensors are required with these types of ground based remote sensing systems, the expense associated with such systems accordingly is increased significantly. Not only is the expense increased by the presence of multiple sensors, but the logistics and design considerations, and thus the cost, involved in connecting a plurality of sensors are likewise increased as well. Furthermore, because each of the sensors represents a potential failure point, costs associated with maintaining those sensors and the system as a whole are necessarily increased.  
       [0009] In addition to the inherent, system-wide, disadvantages typically encountered in known ground based remote sensing systems, the component parts of known ground based remote sensing systems present problems as well.  
       [0010] As indicated earlier, many known ground based remote sensing systems employ a plurality of sensors, the sensors being disposed at regular intervals along a center pivot or linear move irrigation arm. However, other systems employ a single sensor package that travels along the irrigation arm on a track. Known tracks typically comprise two continuous track rails which are joined together at intervals. The track rails are typically constructed of angle iron or the like. This type of construction introduces a number of problems.  
       [0011] First, it is well known that linear move irrigation systems and center pivot irrigation systems tend to shake and vibrate as they travel over the uneven ground typically found in agricultural fields. Furthermore, those irrigation systems are also subject to thermal stresses as the cold water flows through the piping system and as the piping system absorbs heat and energy from the sun. The irrigation systems are thus in a constant dynamic state, moving and flexing under these influences. However, the typical track system employs no structure or device which permits it to readily accommodate the stresses and movement to which the irrigation system is subjected. Accordingly, the tracks employed by known ground based remote sensing systems tend to deform and otherwise expand or contract in such a way as to disrupt, or prevent, the gathering of agricultural crop data by the sensors that travel along the track. In more extreme cases, the tracks may fracture after repeated exposure to thermal and other stresses.  
       [0012] Another problem associated with known track systems used by ground based remote sensing systems is that the two rail type tracks are generally ineffective in preventing vertical excursions of sensor packages suspended beneath the tracks. Because of the uneven ground over which irrigation systems typically travel, the sensor package suspended from the track thus described is thus subjected to sudden and violent vertical excursions. Movement of the sensor package in this manner can disrupt and/or prevent the gathering of agricultural crop data by the sensors. In more extreme cases, the sensor package is damaged and requires repair or replacement. As suggested above, farmers often require updated agricultural crop data on a frequent basis, due to ever-changing weather and crop conditions. Thus, sensor package down time, as may result from inadequate track designs, seriously compromises the ability of the farmer to effectively manage the agricultural crops.  
       [0013] Problems with known ground based remote sensing systems are not limited solely to the tracks along which the sensors are transported, however. The mounts by which the sensors are secured in position are critical as the sensors must remain constantly aligned with the agricultural crop or soil so that complete and accurate agricultural crop data may be reliably gathered. However, the typical mounts and/or mounting systems by which the sensors are secured in position present at least three significant problems.  
       [0014] First, some known sensor mounts are unnecessarily complex. For example, some of these mounts comprise two different parts, an alignment portion and a mount by which the alignment portion is attached to the carriage. As a result of their complexity, these types of devices are likely to be more expensive to manufacture and maintain. Furthermore, some of these known mounts also incorporate servo motors and computer controls wherein the computer controls the positioning of the sensor by sending signals to the servo motors which in turn adjust the sensor in a direction consistent with the signals sent by the computer. Clearly, the addition of servo motors and computer controls further complicates these types of devices and may well result in increased production costs and/or maintenance costs.  
       [0015] Another problem with known mounts, as suggested above, is that these devices are not self-adjusting. Rather, these devices rely on computer controls or the like to place the sensors in the desired position and/or orientation with regard to the agricultural crop and/or field.  
       [0016] Last, known mounts do not incorporate any type of error compensating feature. In particular, if sensors secured by known sensor mounts are out of position, whether because of inaccurate computer control data or because thermal or other physical conditions have caused displacement of the sensor, there is no way to detect and/or compensate for data errors induced by the misalignment of the sensors. Because the farmer is required to make important decision based on the data gathered, errors such as these are unacceptable.  
       [0017] Finally, the control systems which are used to transport sensors along the tracks of known ground based remote sensing systems present some problems as well. For example, currently available power supply transformers for variable speed, dualdirectional motors, such as are required for transverse movement of the sensors, typically require that direction of travel, speed, starting, and stopping be manually controlled. This is problematic where mapping, i.e., with the sensors, occurs at night or at other times and/or locations when it is not feasible to have an operator present to effect manual control.  
       [0018] In view of the foregoing problems with known ground based remote sensing systems, such as those typically utilized with linear move and/or center pivot irrigation systems, what is needed is an improved ground based remote sensing system. Specifically, the ground based remote sensing system should be constructed so as to minimize physical and technical complexity, and therefore, construction and maintenance costs associated with the system. Further, the ground based remote sensing system should be constructed in such a manner so as to ensure that agricultural crop data collection by the sensors is not interrupted or otherwise compromised by outside conditions and influences including, but not limited to, thermal stresses, and movement of the ground based remote sensing system through agricultural fields. Also, the ground based remote sensing system should ensure that the sensor or sensors remain in operative communication with the agricultural crop and/or soil during the entire time that agricultural crop data is being gathered by the system. Finally, the ground based remote sensing system should ensure that the sensor or sensors can be reliably and consistently aligned and re-aligned with respect to the agricultural crops and/or the soil from which agricultural crop data is being collected.  
       BRIEF SUMMARY AND OBJECTS OF THE INVENTION  
       [0019] The present invention has been developed in response to the current state of the art, and in particular, in response to these and other problems and needs that have not been fully or completely solved by currently available ground based remote sensing systems. Thus, it is an overall object of an embodiment of the present invention to provide a ground based remote sensing system that resolves at least the problems identified herein.  
       [0020] It is another object of the present invention to provide a ground based remote sensing system adapted for use in conjunction with field irrigation systems.  
       [0021] It is also an object of the present invention to provide a ground based remote sensing system that is relatively simple in design and operation.  
       [0022] Further, it is an object of the present invention to provide a ground based remote sensing system which will help ensure that agricultural crop data collection is not interrupted or otherwise compromised by factors such as thermal stresses, movement, or the like.  
       [0023] Similarly, it is an object of the present invention to provide a ground based remote sensing system which will reliably maintain operative communication with the agricultural crop and/or soil.  
       [0024] Finally, it is an object of the present invention to provide a ground based remote sensing system that can quickly, reliably, and automatically gather and update agricultural crop data.  
       [0025] In summary, the foregoing and other objects, advantages, and features are achieved with an improved ground based remote sensing system for use in gathering and updating agricultural crop data. Embodiments of the present invention are particularly suitable for use with linear move irrigation systems, and the like.  
       [0026] In a preferred embodiment, the ground based remote sensing system includes a track, a carriage, a plurality of sensors mounted to the carriage, and a control system for transporting the carriage along the track. Preferably, the track of the inventive ground based remote sensing system is mounted to and supported by the main overhead irrigation pipe of a linear move sprinkling system so that the axis of the track is substantially transverse to the path of travel of the linear move irrigation system.  
       [0027] In one embodiment, the track comprises three rails arranged in a triangular configuration. Preferably, the carriage is mounted about the three rails in such a manner that vertical movement of the carriage is precluded and movement of the carriage is confined solely to a lateral direction along the length of the rails which comprise the track. Preferably, contiguous rails of the track are spaced slightly apart from each other and include a joint to permit expansion and contraction of the track in response to thermal stresses and motion of the irrigation system to which the track is mounted.  
       [0028] In a preferred embodiment, two additional copper pipes are mounted parallel to the rails of the track and transmit electricity to a motor of the carriage via electrically conductive wheels located on the carriage. The ground based remote sensing system preferably includes a direction control circuit and a speed control circuit in operative communication with the carriage motor so as to move the carriage substantially continuously, and automatically, back and forth along the track as the linear move irrigation pipe moves down the field.  
       [0029] The ground based remote sensing system preferably includes a mount for the sensors to ensure that the sensors are securely mounted to the carriage and remain in operative communication with the agricultural crop and/or soil from which data is being gathered. In a preferred embodiment, the ground based field remote sensing system includes a data logger so as to record agricultural crop data acquired by the sensors and/or the camera.  
       [0030] These and other objects, features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0031] In order to more fully understand the manner in which the above-recited and other advantages and objects of the invention are obtained, a more particular description of the invention will be rendered by references to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention and its presently understood best mode for making and using the same will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:  
     [0032]FIG. 1A is a perspective view indicating one embodiment of a track attached to a linear move irrigation system:  
     [0033]FIG. 1B is a cross-section view of one embodiment of a track and indicating the relationship between the track and one embodiment of a carriage adapted for travel along the track;  
     [0034]FIG. 1C is a side view of the carriage mounted to the track;  
     [0035]FIG. 2 is a block wiring diagram of one embodiment of a system to collect and process agricultural crop data, and indicating the functional relationships between a sensor package, a data logger, a global positioning system, a computer, an optical proximity sensor, and reflective straps;  
     [0036]FIG. 3 is a schematic drawing of one embodiment of a mount for use with sensors in agricultural applications, and generally indicates the relationships between the mount, a sensor package, and the carriage;  
     [0037]FIG. 4 is a wiring diagram indicating one embodiment of a circuit adapted to automatically reverse the direction of the carriage as it reaches either end of the track;  
     [0038]FIG. 5 is a wiring diagram of one embodiment of a circuit adapted to provide power to the rails so as to control the speed of the carriage as it travels back and forth along the track;  
     [0039]FIG. 6 depicts an alternative embodiment of a track in accordance with the teachings of the present invention; and  
     [0040]FIG. 7 indicates additional details of an alternative embodiment of a track and carriage in accordance with the teachings of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0041] Reference will now be made to figures wherein like structures will be provided with like reference designations. It is to be understood that the drawings are diagrammatic and schematic representations of various embodiments of the invention, and are not to be construed as limiting the scope of the present invention.  
     [0042] In general, the present invention relates to an improved ground based remote sensing system for use in gathering agricultural crop data. As used herein, ‘agricultural crop data’ includes insect data, plant data, soil data, or other types of data including, but not limited to, moisture data. Further, as used herein, a ‘remote sensing system’ refers generally to systems which employ sensors remote or removed from the crop or field being monitored, as opposed to systems employing sensors disposed directly in the field or crop. Ground based remote sensing systems are those wherein the sensors are attached to a structure which moves in relatively close proximity to the ground. FIGS. 1 a  through  5  indicate embodiments of a ground based remote sensing system conforming to the teachings of the invention.  
     [0043] Reference is first made to FIG. 1A, which depicts features of one embodiment of the present invention. The ground based remote sensing system is indicated generally as  100 . Ground based remote sensing system  100  includes a track  200  secured to irrigation system  300 . In one embodiment, irrigation system  300  comprises a linear move irrigation system or the like, configured for substantially linear movement through agricultural field  900 . However, it is contemplated that ground based remote sensing system  100  can profitably be employed with a wide variety of irrigation systems  300 , including but not limited to center pivot irrigation systems, or the like. Note that a variety of means may be employed to perform the function of irrigation system  300 , as disclosed herein. Irrigation system  300  is on example of a means for transporting track  200  through an agricultural field. It should thus be understood that irrigation system  300  simply represents one embodiment of structure capable of performing this function and should not be construed as limiting the scope of the present invention in any way. Further, it is contemplated that alternative embodiments of ground based remote sensing system  100  may be transported throughout agricultural field  900  by agricultural machinery including, but not limited to, tractors and the like.  
     [0044] As further indicated in FIG. 1A, track  200  comprises three rails  202  arranged in a triangular configuration, with the apex of the triangle pointing downwards to the ground. Note that this invention contemplates as within its scope any other material that would provide the functionality of rails  202  as described herein. However, it is contemplated that other structures besides tubes may profitably be employed to provide the functionality of track  200  as described herein. In particular, this invention contemplates as within its scope tracks comprising a variety of different structural shapes, including but not necessarily limited to, channels, or the like.  
     [0045] Track  200  further comprises a plurality of trusses  204  spaced at regular intervals so as to provide support for rails  202 . Each truss  204  is secured to a support arm  206 . Support arms  206  are adjustable in length so as to permit movement of track  200  further away from, or closer to, irrigation system  300 .  
     [0046] With continuing reference to FIG. 1A, support arms  206  are preferably constructed of one inch square steel tubing. However, any other size, material and/or geometry that would provide the functionality of support arms  206  as described herein is contemplated as being within the scope of the present invention. Support arms  206 , are in turn attached to main overhead pipe  302  of irrigation system  300  by means of U-bolts  208  or the like. The positioning of U-bolts  208  may desirably be adjusted so as to lower or raise track  200  relative to the ground. Any other attachment device or method that would provide the functionality of U-bolts  208  is contemplated as being within the scope of the present invention. Alternatively, track  200  could be mounted above main overhead pipe  302  of irrigation system  300 . This could be accomplished in a variety of ways, including, but not limited to, mounting track  200  either directly to main overhead pipe  302 , or indirectly by the use of support arms  206 , or the like.  
     [0047] Abutting sections of rails  202  are connected to each other by couplers  210 , as indicated in FIG. 1A. Couplers  210  slide within rails  202  in order to permit relative movement of abutting sections of rails  202  without compromising the effectiveness or mobility of carriage  400  (see FIGS. 1B and 1C). Movement of rails  202  may be caused by a variety of factors including, but not limited to, thermal expansion and contraction, and movement of irrigation system  300 . Further, rails  202  are subject to temporary deformation as a result of changes in the water load inside main overhead pipe  302  of irrigation system  300 . This temporary deformation can likewise cause relative movement between rails  202 . Abutting sections of rails  202  are prevented from moving completely apart by elastic strap  212 . In one embodiment, couplers  210  comprise metal tubing or the like. However, the present invention contemplates as within its scope any other structure and/or device that would provide the functionality of couplers  210  as disclosed herein.  
     [0048] In a preferred embodiment, track  200  is configured for use with a linear move irrigation system  300  comprising two or more abutting spans. In order to accommodate angular offsets, and relative movement, between the abutting spans of irrigation system  300 , connectors  214  are inserted into abutting rails  202 , as indicated in FIG. 1A. Connectors  214  preferably comprise an elastic and flexible material and/or structure that serves to allow track  200  to flex and thereby accommodate relative angular movement between abutting spans of irrigation system  300  move as irrigation system  300  moves across the uneven terrain often encountered in fields such as agricultural field  900 . Connectors  214 , while elastic and flexible, are also sufficiently strong to support the weight of carriage  400 . Further, connectors  214  have substantially the same circumference as the inside of rails  214  and thus will not compromise the mobility of carriage  400  as it travels along track  200 . Finally, because connectors  214  are disposed inside rails  202 , they are also able to readily accommodate relative horizontal movement between the abutting rails.  
     [0049] In a preferred embodiment, connectors  214  comprise metal springs or the like. However, the present invention contemplates as within its scope any other structure or device that would provide the functionality of connectors  214  as disclosed herein.  
     [0050] With continuing reference now to FIG. 1A, jumper wire  216 , or the like, is used to provide electrical continuity between abutting rails  202 . In like fashion, connector  214 ′ and jumper wire  216 ′ are used to connect abutting conducting rails  218 . Connector  214 ′ possesses substantially the same functionality, as disclosed herein, as connector  214 . However, connector  214 ′ is also electrically conductive so as to facilitate transmission of power along conducting rails  218 .  
     [0051] With reference now to FIGS. 1B and 1C, a carriage, indicated generally as  400 , is mounted for linear movement along track  200 . Carriage  400  is preferably constructed of square steel tubing or the like, but other types and shapes of materials that would provide the functionality of carriage  400 , as described herein, are contemplated as being within the scope of the present invention.  
     [0052] Carriage  400  preferably comprises six wheels  402 , two of wheels  402  being in contact with each rail  202 . In a preferred embodiment, wheels  402  comprise a circumferential semi-circular groove adapted to receive a portion of the diameter of rails  202  so as to ensure reliable and substantial contact therebetween. Carriage  400  further comprises conducting wheels  404  which preferably comprise copper or the like. Conducting wheels  404  are in contact with conducting rails  218 , conducting wheels  404  comprising a circumferential semi-circular groove adapted to receive a portion of the diameter of conducting rails  218  so as to ensure substantial contact therebetween. Conducting rails  218  are mounted substantially parallel to rails  202 , so as to transmit power from conducting rails  218  to carriage motor  406 . Conducting rails  218  are electrically isolated from rails  202  by mechanical vibration isolators  220 . Carriage motor  406  is in operative communication with at least two wheels  402  so as to drive wheels  402  in response to transmission of power to carriage motor  406 . The circuit by which power is provided to conducting rails  218  is discussed in greater detail below.  
     [0053] Note that a variety of means may be employed to perform the function of moving transmitting power to carriage motor  406 . Conducting rails  218  simply comprise an example of a means for performing that function. It should be understood that the embodiments of conducting rails  218  are presented solely by way of example and should not be construed as limiting the scope of the present invention in any way.  
     [0054] In an alternative embodiment, one of rails  202  is electrically isolated from the remaining two rails  202 . The remaining two rails  202  are then used to transmit power to carriage motor  406 , one rail  202  being the “hot” rail and the other rail  202  functioning as the ground, thereby foreclosing the need for use of conducting rails  218 .  
     [0055] As indicated generally in FIG. 1B, a sensor package  502  and data logger  503  are mounted to carriage  400 . In particular, sensor package  502  is attached to mount  600  which, in turn, is removably secured to boom  601  (see also FIG. 3, discussed below) depending from carriage  400 . Boom  601  serves to remove sensor package  502  a predetermined distance away from carriage  400  so as to prevent the structure of irrigation system  300  from compromising accurate data gathering by sensor package  502 . Specific details regarding the construction and operation of mount  600 , sensor package  502  and data logger  503  are provided below.  
     [0056] In general however, sensor package  502  acquires agricultural crop data as carriage  400  travels back and forth along an axis defined by track  200 . Substantially simultaneously with the back and forth motion of carriage  400  along the axis defined by track  200 , irrigation system  300  is advancing across the agricultural field along a predetermined pathway so that the collective movements of sensor package  502 , as viewed from above, describe a generally wave-like form. In one embodiment, track  200  is substantially transverse to the predetermined pathway of irrigation system  300 .  
     [0057] As sensor package  502  acquires agricultural crop data, that data is fed to data logger  503  which is in operative communication with sensor package  502 . Data logger  503  collects and stores the agricultural crop data until that data can be downloaded. The types of agricultural crop data that may be acquired by sensor package  502  are virtually unlimited. As contemplated herein, ‘agricultural crop data’ includes, but is not limited to, both plant and soil data such as plant and/or soil nitrogen content, plant and/or soil moisture content, insect infestation level, fungus and disease distribution, or the like. Further, ‘agricultural field’ as contemplated herein includes the soil and/or the crop(s). Accordingly, the gathering of agricultural crop data from an ‘agricultural field’ refers to gathering soil and/or crop data.  
     [0058] With reference now to FIG. 2, the operation of sensor package  502  and data logger  503  is described in further detail. In one embodiment, sensor package  502  takes reflectance measurements of one square meter field areas. Alternatively, sensor package  502  may take emittance measurements, or may employ various combinations of emittance and reflectance measurements as required to suit a particular application. To this end, sensor package  502  preferably comprises a plurality of sensors capable of emitting and/or receiving energy wavelengths ranging from blue to thermal infrared. Specifically, the energy transmitted by sensor package  502 , or transmitted by external sources including, but not limited to, incoming solar energy, impinges on soil  902  and/or crop  904  of agricultural field  900 . In one embodiment, agricultural crop data gathered by sensor package  502  is determined by comparing the energy of the wavelength thus transmitted with the energy of the wavelength reflected and/or emitted by soil  902  and/or crop  904 . Note that sensor package  502  may include a variety of other types and combinations of sensors, including, but not limited to, cameras, sensors employing radio detecting and ranging (RADAR) functionality, sensors employing light detecting and ranging (LIDAR) functionality, and the like.  
     [0059] One embodiment of sensor package  502  includes sensors sensitive to wavelengths of 460, 520, 630, 660, 710, 830, 880, and 1,640 nanometers, these sensors being indicated generally as  502 A,  502 B, and  502   n . Sensors  502 A,  502 B, and  502   n  are preferably embedded in aluminum structure  504  so that the thermal stability of sensors  502 A,  502 B, and  502   n  may be maintained. In one embodiment, aluminum structure  504  comprises an aluminum plate housed in an aluminum cylinder. Thermal stability is an important consideration as a lack thereof may impart errors to the readings taken by sensors  502 A,  502 B, and  502   n . Note that this invention contemplates as within its scope any other materials, or combinations thereof, that would provide the functionality of aluminum as described herein.  
     [0060] Sensor package  502  preferably also includes an upward-looking sensor  506  that detects the intensity of solar radiation and is thus useful to calibrate sensors  502 A,  502 B, and  502   n  so as to compensate for any effect imposed thereon by solar radiation or similar influences.  
     [0061] One embodiment of the present invention comprises a plurality of reflective straps  508 , or the like. Reflective straps  508  are located at regular intervals, preferably about one meter, along rails  202  so that as optical proximity sensor  510 , mounted to carriage  400 , passes over reflective straps  508 , optical proximity sensor  510  triggers data logger  503  to record the agricultural crop data acquired by sensor package  502  at that instant. Note that this invention contemplates as within its scope any other device or devices which would provide the functionality of optical proximity sensor  510  and reflective straps  508  as disclosed herein.  
     [0062] In a preferred embodiment, a global positioning system (GPS)  512  is in operative communication with data logger  503  so that as data is acquired by sensor package  502  and recorded by data logger  503 , data logger  503  is also able to aggregate agricultural crop and/or field data with location data provided by GPS  512 . The aggregated data is then downloaded to computer  514  which processes the data so as to determine the precise location from which the data logged originated. In one embodiment of the present invention, computer  514  uses the agricultural crop data and the data provided by GPS  512  to construct a map of one or more attributes of the agricultural crop or field. For example, a map indicating the distribution and concentration of nitrogen, or even insects, in a particular crop could be developed. Because the aggregated data is, or may be, collected with every pass of irrigation system  300  (not shown) over agricultural field  900 , the farmer has access to substantially realtime information regarding the condition of the agricultural crop and/or soil.  
     [0063] Turning now to FIG. 3, one embodiment of structure for mounting sensor package  502  to a mobile structure, such as carriage  400 , is indicated in detail. The mount is indicated generally as  600 . Mount  600  includes a body  602  which is suspended from boom  601 . As previously indicated, boom  601  is secured to carriage  400 . By suspending sensor package  502  out and away from irrigation system  300 , boom  601  serves to substantially prevent irrigation system  300  structures from interfering with data gathering by sensor package  502 .  
     [0064] In an alternative embodiment, boom  601  is pivotally attached to carriage  400  so that sensor package  502  can be readily positioned as required to suit operational requirements and/or environmental conditions. In another embodiment, a plurality of booms  601  are employed at various orientations with respect to irrigation system  300 , each boom  601  having a sensor package  502  depending therefrom.  
     [0065] With continuing reference to FIG. 3, mounted inside body  602  is a rotative couple, indicated generally as  604 . Rotative couple  604  includes two seats  606 . In one embodiment, seats  606  comprise rings made of Teflon, or the like. However, other materials such as plastics are contemplated as being within the scope of the present invention. Interposed between seats  606  is ball  608 . The compression exerted by seats  606  on ball  608  can be readily adjusted by means of adjustment screws  610  which act to move seats  606  closer together or further apart. Sensor package  502  is connected to ball  608  by connecting rod  612  so that in operation, the movement of sensor package  502  can be controlled by adjusting the compressive force exerted on ball  608  by seats  606 . Seats  606  thus act as brakes on the motion of ball  608  and thereby control the sensitivity of ball  608  to motion imposed by outside influences. This desirable effect is achieved with respect to sensor package  502  as well because, as previously noted, sensor package  502  is connected to ball  608 . As suggested above, adjustment screws  610  may desirably be rotated to increase or decrease the sensitivity of ball  608 , as required by operating conditions. Note that the present invention contemplates within its scope any other structure, devices, or combinations thereof that would provide the functionality of rotative couple  604  as disclosed herein. Finally, note that in some cases, mount  600  has been effective in facilitating a relative decrease in angular deflection of sensor package  502  by as much as 70%.  
     [0066] Mount  600  further comprises an inclinometer  614  mounted to sensor package  502 . inclinometer  614  records in memory  616  sensor package  502  alignment data taken at each agricultural crop data reading position. The sensor package  502  alignment data recorded in memory  616  can then be used to make corrections to agricultural crop data recorded by sensor package  502 . This invention contemplates within its scope any other structure and/or devices having the functionality of inclinometer  614  and memory  616  as disclosed herein.  
     [0067] To briefly summarize then, mount  600  incorporates at least two valuable features. First, mount  600  is effective in substantially minimizing misalignment of sensor package  502  during operation. Further, in those cases where misalignment of sensor package  502  is unavoidable due to extreme environmental conditions, operating conditions, or other outside influences, mount  600  provides the capability of detecting misalignment of sensor package  502  and correcting agricultural crop data gathered by sensor package  502  when sensor package  502  is misaligned.  
     [0068] The aforementioned features are particularly valuable when sensor package  502  comprises one or more sensors that must be disposed in a substantially vertical position in order to perform properly, such as when sensor package  502  is performing reflectance type data collection. Mount  600  thus cooperates with boom  601  to ensure that sensor package  502  is disposed in such a manner as to prevent irrigation system  300  from interfering with data gathering by sensor package  502  and to ensure that sensor package  502  is optimally aligned with agricultural field  900  and/or soil  902  and/or crop  904 .  
     [0069] Details of a control system  1000  for moving carriage  400  back and forth on track  200  are indicated in FIGS. 4 and 5. The control system  1000  comprises a traverse direction control circuit, indicated generally as  700  in FIG. 4, and a speed control circuit  800  (FIG. 5). Note that a variety of means may be employed to perform the function of moving carriage  400  (not shown) along track  200  (not shown). Control system  1000  simply comprises an example of a means for performing that function. It should be understood that the embodiments of control system  1000  are presented solely by way of example and should not be construed as limiting the scope of the present invention in any way.  
     [0070] As indicated in FIG. 4, traverse direction control circuit  700  includes a north limit switch  702  and south limit switch  704 . In a preferred embodiment, north limit switch  702  is normally closed and south limit switch  704  is normally open.  
     [0071] Note that a variety of means may be employed to perform the function of north limit switch  702  and south limit switch  704 . North limit switch  702  and south limit switch  704  simply comprise an example of a means for performing that function. It should be understood that the embodiments of north limit switch  702  and south limit switch  704  are presented solely by way of example and should not be construed as limiting the scope of the present invention in any way.  
     [0072] North limit switch  702  and south limit switch  704  are mounted, respectively, at each end of track  200  (not shown) and are in electrical communication with powered relays  706 . Energy to powered relays  706  is provided by relay power circuit  708 . In one embodiment, relay power circuit  708  provides 24 volt direct current (DC) power. Traverse direction control circuit  700  further includes dynamic brake  710  so that when carriage  400  operably contacts either north limit switch  702  or south limit switch  704 , dynamic brake  710  is activated in traverse direction control circuit  700 . The use of limit switches in this application is particularly advantageous because the limit switches, upon coming into operable contact with carriage  400 , automatically generate a signal indicating that the carriage must stop and reverse direction. Thus, no manual intervention is required to stop the carriage and then reverse its direction along track  200 . In operation, dynamic brake  710  serves to stop motion of carriage  400  by cutting off the power supply to rails  218  for a user specified time interval controlled by signal interval/off delay timer  712 .  
     [0073] Signal interval/off delay timer  712  is connected to powered relay  716 A so that when the user specified time interval has elapsed, dynamic brake  710  is deactivated, and power is provided to conducting rails  218 . At about the same time, the polarity of the power provided to conducting rails  218  is automatically reversed by power relay  716  so that when dynamic brake  710  is deactivated, carriage  400  (not shown) will then reverse its direction of travel.  
     [0074] In one embodiment, dynamic brake  710  comprises a  120  ohm,  25  watt resistor, or the like, across conducting rails  218 . The time delay in the action of dynamic brake  710  introduced by signal interval/off delay timer  712  is advantageous for at least two reasons: first, the time delay allows carriage  400  to come to a complete stop before changing directions; and, second, the time delay effectively inserts a noticeable and reliable time interval between data acquisition points, indicating the point in the agricultural crop data file where carriage  400  changed direction.  
     [0075] Traverse direction control circuit  700  thus automatically reverses the direction of carriage  400  (not shown) and inserts a user specified time interval between the time that motion of carriage  400  (not shown) ceases and the time that motion in the opposite direction commences. In one embodiment, the user specified time interval is about 3 seconds so that carriage  400  (not shown) moves substantially continuously back and forth along conducting rails  218 . The time interval for which dynamic brake  710  is activated is controlled by setting signal interval/off delay timer  712 . One signal interval/off delay timer that would provide functionality described herein is Omron model H3CA-A SPDT  
     [0076] As further indicated in FIG. 4, traverse direction control circuit  700  comprises a power relay  716 . Energy to the poles of power relays  716  and  716 A is provided by speed control circuit  800 , the details of which are discussed below. Power relay  716  is in communication with power relay  716 A, and power relay  716 A serves to provide 90 volt DC power to conducting rails  218 , when dynamic brake  710  is disengaged, and thence to carriage motor  406  (not shown). In a preferred embodiment, carriage motor  406  (not shown) is a 90 volt DC gear motor, 180 RPM, ¼ horse power, permanent magnet type. As suggested above, signal interval/off delay timer  712  cooperates with dynamic brake  710  to prevent, for a user specified time interval, power relay  716 A from providing power to conducting rails  218 , when dynamic brake  710  is engaged.  
     [0077] Details of speed control circuit  800  are provided in FIG. 5. In particular, speed control circuit  800  comprises an alternating current (AC) input  802 . In one embodiment, AC input  802  provides 480 volts. Flow of power from AC input  802  is controlled by main switch  804  which is further in communication with transformer  806 . In one embodiment, transformer  806  comprises a 2 kVA transformer and serves to step down the 480 volt AC provided by AC input  802  to 120 volt AC power. The 120 volt AC power is then provided to speed controller  808 . Speed controller  808  converts the 120 volt AC input to any of a range of desired direct current (DC) outputs. In one embodiment, the desired DC output is about 90 volts. The output of speed controller  808  is input to relay  716  (FIG. 4), whose operation has been previously described. Because speed controller  808  is capable of a variable DC output, the power supplied to conducting rails  218  (FIG. 4), and thus the speed of carriage  400  (not shown), may desirably be adjusted.  
     [0078] Note that the present invention contemplates within its scope any other circuits and/or systems that would provide the functionality of traverse direction control circuit  700  and/or speed control circuit  800  as disclosed herein. Such circuits are not limited solely to electrical or electronic circuits, and may include, but are not limited to, hydraulic control systems and their associated components.  
     [0079] Further, a variety of means may be employed to perform the function of moving the sensor package  502  along track  200 . Carriage  400  and control system  1000  comprise an example of a means for performing that function. It should be understood that the embodiments of carriage  400  and control system  1000  are presented solely by way of example and should not be construed as limiting the scope of the present invention in any way.  
     [0080] The foregoing discussion has focused on various aspects of a preferred embodiment of a ground based remote sensing system. Directing attention now to FIGS. 6 and 7, an alternative embodiment of a track  200  for use in ground based remote sensing system  100  is indicated generally at  200 ′. With reference first to FIG. 6, track  200 ′ includes a plurality of risers  203 , one of which is attached to each tower  303  of a span of irrigation system  300 , and a suspension cable  205  suspended between adjacent risers  203 . Risers  203  preferably comprise structural aluminum shapes or the like. A plurality of rails  207  are suspended from suspension cable  205 . In a preferred embodiment, two rails  207  are employed, at least one of which is made of aluminum or an aluminum alloy. However, it will be appreciated that other numbers of rails  207  could be profitably employed to provide the functionality of rails  207  as disclosed herein. As discussed below, rails  207  are preferably configured to conduct electricity, provided by speed control circuit  800 , with one of the rails being ‘hot’, and the other functioning as a ground.  
     [0081] Sections of rail  207  of abutting spans of irrigation system  300  are joined by connectors  214 ′ and jumpers  216 ′ as indicated in FIG. 1A. Within each span of irrigation system  300 , abutting sections of rail  207  are joined by couplers  210 , as indicated in FIG. 1A. In this embodiment, couplers  210  are electrically conductive. A plurality of cables  209 A are used to attach rails  207  to suspension cable  205 . Elastic cables  209 B connect rails  207  to main overhead pipe  302  of irrigation system  300  and facilitate vertical alignment and positioning of rails  207 . Cables  209 A and elastic cables  209 B preferably comprise steel or the like. However, any other material that would provide the functionality, respectively, of the aforementioned cables, is contemplated as being within the scope of the present invention.  
     [0082] Directing attention now to FIG. 7, additional details of track  200 ′ are indicated. Rails  207  are connected to each other by way of clamps  211  or the like. Preferably, clamps  211  are C-shaped. Clamps  211  serve to maintain a desired distance between rails  207  so that carriage  400 ′ can readily travel along track  200 ′. Clamps  211  are electrically non-conductive or, alternatively, are insulated from contact with rails  207  so as to prevent short-circuiting of rails  207 . Control system  1000 , discussed elsewhere herein, serves to control the speed and direction of carriage  400 ′ along track  200 ′. Power is transmitted from control system  1000  to motor  406  of carriage  400 ′ by way of conducting wheels  404 , which are in contact with rails  207 .  
     [0083] As further indicated in FIG. 7, an alternative embodiment of carriage  400 , indicated generally at  400 ′, is employed with track  200 ′. Carriage  400 ′ includes a counterweight  408  mounted for horizontal movement so as to counteract the rotational tendency imposed on carriage  400 ′ by sensor package  502 , and thereby balance carriage  400 ′. Carriage  400 ′ also comprises a boom  601  from which sensor package  502  depends. Details regarding boom  601 , sensor package  502 , and mount  600  (used to attach sensor package  502  to boom  601 -not shown in FIG. 7) are discussed elsewhere herein.  
     [0084] Note that, in one embodiment, a plurality of lights  603  are disposed along boom  601  so as to illuminate soil  902  and/or crops  904  and thereby facilitate data gathering during low light periods such as at night, or when atmospheric conditions such as clouds or dust are present. Alternatively, the plurality of lights  603  can be disposed on carriage  400 ′ and/or at the end of boom  601  in vertical alignment with sensor package  502 . A plurality of lights  603  can be used to facilitate data gathering in at least one other way as well. In particular, employment of lights  603  with an intensity of approximately three ( 3 ) times the magnitude of solar radiation serve to cancel out the effect of solar radiation reflected by soil  902  and/or crops  904 . In so doing, the plurality of lights  603  serve to eliminate errors in data gathering that are attributable to solar radiation.  
     [0085] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.