the system of the present invention is illustrated in fig1 as being connected to a center pivot or lateral mechanized irrigation system 10 ( herein sometimes simply referred to as “ pivot ” or “ center pivot ”). the invention includes a universal , self - contained remote terminal unit ( rtu ) with global position satellite ( gps ) receiver 20 which receives signals from gps positioning satellites 30 . the remote terminal unit is further connected to a low orbit data communication satellite 40 , a ground station 50 , a communication network 60 , a service operator location 120 , multiple mobile locations 140 , and a remote pivot operator monitoring location 130 . mechanized irrigation systems 10 are conventional and commercially available from a number of different manufacturers . mechanized irrigation systems 10 are commonly used in a center pivot configuration such as shown in fig1 wherein the center pivot point 12 extracts pressurized water 14 for delivery through a fluid delivery system 16 through spans of pipe 18 supported by wheeled drive towers 13 for delivery onto the ground . such center pivot irrigation systems 10 have wheels 11 at pivot drive towers 13 and the center pivot pipe spans 18 can add up to any desired length from center pivot point 12 to pivot end position 20 . another type of mechanized irrigation system not shown is one that moves in a lateral or linear orientation across a field . the present invention is not limited to the type of mechanized irrigation system ( center pivot 10 or lateral move , not shown ). the center pivot system 10 shown in fig1 will be used for purposes of illustrating and explaining the present invention . the center pivot irrigation system 10 is located at a first physical location 100 . the self - contained rtu 20 with gps receiver 31 and a current sensor 21 of the present invention is typically located on any outer drive tower 15 of the center pivot irrigation system 10 . the term “ self - contained ” means that the rtu 20 does not hard - wire interface to the electronics or the electrical wiring of the control or power circuitry for the mechanized irrigation system 10 . it provides a self - contained operation independent of and isolated from the electrical circuitry of the mechanized irrigation system 10 . in another embodiment , the rtu 20 could be located at the main control panel 27 at the center pivot point 12 . electrical current could be sensed by current sensor 21 in the main panel 27 to indicate the center pivot 12 is moving or stopped . however , without sensing the on off cycle of an intermediate drive tower 13 , the current sensor 21 could provide a false read of pivot status . also , located at the fixed center point of the center pivot 12 , the gps data would not track pivot arm movement over time . therefore , the preferred embodiment is for the rtu 20 and the current sensor 21 to be located on the pipe span 18 above an outer drive tower 15 , e . g ., the next - to - last drive tower . the details of the rtu 20 and the current sensor 21 of the present invention will be presented subsequently in fig8 and 9 . however , the rtu 20 has a satellite or terrestrial communication antenna 24 and a gps receiver and antenna 31 . the rtu 20 of the present invention has a “ wireless interface ” ( no hard - wire connections used ) with the center pivot irrigation system 10 using a current sensor device 21 connected to a cable 26 and located in or near the tower control box 22 . the current sensor 21 is used for detecting current flow to drive motor 23 and therefore movement of the drive tower 15 over time . in other words , the rtu 20 is mounted to a point along the roving or moving pipe span 18 of the center pivot 10 , but does not hard - wire interface with any of the tower control box 22 wiring used to control or power the drive motors 23 of center pivot irrigation system 10 . a second and redundant method of determining pivot movement or non - movement is by way of a gps receiver and antenna 31 , receiving gps satellite 30 signals by wireless path 32 . the rtu 20 records time phased gps position coordinates in non - volatile memory in rtu 20 . gps position “ readings over time are used by the microprocessor 550 ( fig5 ) in rtu 20 to determine movement or non - movement of drive tower 15 . these gps coordinate readings also provide data to determine drive tower 15 speed and , thereby , movement of pivot arm 18 . the low orbit communication satellite 40 is also a conventionally available service such as orbcomm , which is in communication with antenna 24 for delivery of data packets as shown by wireless path 42 . orbcomm is located at 21700 atlantic boulevard , dulles , va . orbcomm u . s . pat . no . 6 , 594 , 706 is incorporated herein by reference . the low orbit satellite 40 is also in communication by wireless path 44 with a ground station 50 at a remote second location 110 . it is well known that such ground stations 50 can receive the data packets transmitted from a remote device such as rtu 20 over antenna 24 to satellite 40 for delivery into a communication network 60 such as by means of communication line 62 . while the use of a low orbit satellite telemetry system is one approach , the present invention is not limited to this and it is to be understood that any suitable satellite or terrestrial telemetry transmitter ( receiver ) system can be utilized for collecting data from the rtu 20 of the present invention for delivery into a communication network 60 . the communication networks 60 are existing and well known and include private communication networks for communication over the internet . any suitable communication network 60 can be used for purposes of the present invention . a service operator 70 at another remote location 120 retrieves the data by way of communication path 64 from the communication network 60 and processes it for a responsible person or pivot operator 90 ( end - user ). the service operator 70 at location 120 has a central control computer 72 which processes the received data from the rtu 20 , on behalf of a center pivot operator 90 , for the delivery of the data by path 66 to multiple “ mobile locations ” 140 in a format that can be received and displayed by “ wireless devices ” 82 such as pagers , cellular phones using text messaging , pdas , hand held pcs , etc . examples of the format of such wireless messages can include email , sntp , smtp , ftp , text messages , graphical displays , etc ., that can be received by remote mobile devices 82 carried by mobile pivot operators 90 and others . the service operator 70 can deliver more detailed monitoring information received from communication network 60 , through path 64 and processed by central control computer 72 . this processed information can be delivered by communication path 68 to the center pivot operator &# 39 ; s 90 computer 92 at the location 130 . as an example , the service operator 70 could determine roving pivot arm 18 position ( azimuth ), speed and direction of travel , calculate area of the circle covered by the center pivot , cumulative water application in acre - inches based on hours of pumping ( wet time ), water application rate at current speed and acres irrigated and provide this information in summary and detail form to the pivot operator 90 at location 130 on an internet connected computer 92 . in fig1 , the system and method of the present invention provides the pivot operator 90 responsible for monitoring the operation of the pivot irrigation system 10 at location 100 with the ability at location 130 or at the mobile locations 140 to monitor the status of drive tower 15 by means of rtu 20 and a current sensor 21 and a gps receiver and antenna 31 so as to know when the center pivot irrigation system 10 is moving or when it is not moving ( movement provided by wheeled drive towers 13 ). other parameters such as pivot position ( azimuth ); speed and direction of travel are calculated by microprocessor 550 in rtu 20 from gps data received from gps satellites 30 over wireless path 32 . also , the pivot operator 90 at locations 130 and 140 can monitor water pressure and / or flow rate and cumulative flow as indicated by pressure / flow sensor 28 over hydraulic water line 29 to rtu 20 . in fig4 , the current sensor method of the present invention is set forth . the rtu 20 wakes up 300 . in this step , an internal clock or timer causes the rtu 20 to power - up at predetermined intervals such as every minute . this “ wake up ” feature is conventional and conserves the power supply 520 ( fig9 ) within the rtu 20 . the rtu 20 at location 100 then receives 310 the status of the current sensor 21 ( running or stopped ). in step 320 , the method of the present invention determines whether a status change has occurred . for example , the prior status could have been “ no movement ” ( no current flow over a set period of time ). if the current sensor data 310 currently being delivered indicates “ movement ”, a status change 320 has occurred . or , the prior status could have been “ movement ”. in which case , if the current sensor data 310 currently being delivered indicates no movement , then a status change 320 of “ no movement ” has occurred . in fig4 , the transmit data step 330 is event driven , so that whenever the rtu 20 determines that a pivot 10 has changed from a stopped to moving status or from a moving to stopped status , or whenever the rtu 20 determines that a center pivot 10 has changed from a wet to a dry water delivery status as indicated by sensor 28 and hydraulic water line 29 , the status data is sent by way of a data packet using wireless path 42 to communication satellite ( s ) 40 . the data packet includes stored data of center pivot sprinkler 10 running status , current gps position coordinates and water delivery status data so as to establish a wet or dry , running or stopped status to be delivered to the service operator 70 at location 120 . for the current sensor device for monitoring movement as illustrated in fig4 , a number of different mathematical algorithms can be used to determine when a status event occurs in stage 310 that requires a status change in 320 . the mathematical algorithm used depends upon the tolerance for the interval of the electrical current being sent to drive motor 23 that is being monitored . if an intermediate drive tower 13 nearer to the center pivot point 12 is being monitored and the speed control of the last drive tower 25 is set to a low percent speed setting at main panel 27 ( e . g ., six seconds on and 54 seconds off to the final drive motor ), then the tolerance for determining a non - movement status would be relatively long as compared to monitoring the last or next - to - last drive tower motor 23 of tower 15 of a center pivot sprinkler 10 . whatever mathematical algorithm is used to determine movement or non - movement of drive tower 15 , the micro processor 550 using stored current sensor 21 readings in memory 570 determines a status change event from either “ movement ” to “ non - movement ” or from “ non - movement ” to “ movement .” in fig5 the gps method of the present invention is set forth . this is a redundant method to the current sensor method of determining movement or non - movement set forth above . the gps system of the present invention provides a series of gps coordinate data readings received at the rtu 20 from gps satellite ( s ) 30 over wireless path 32 and transmitted by wireless path 42 to communication satellite 40 to ground station 50 and on to the central control computer server 72 by means of communication network 60 to enable the central control computer server 72 to calculate pivot arm 18 position ( azimuth ), speed of travel , direction of travel and rate of water application . referring to fig5 , the rtu 20 wakes up 300 ′. in this step , an internal clock or timer causes the rtu 20 to power - up at predetermined intervals such as every minute . this “ wake up ” feature is conventional and conserves the battery power supply 520 within the rtu 20 . the rtu 20 at location 100 then receives 310 ′ the current gps position coordinates . microprocessor 550 compares these current gps position coordinate readings to a prior gps position coordinate reading 310 ′ to determine a status change ( from movement to non - movement or non - movement to movement of drive tower 15 ). the gps coordinate readings that are compared over time are interpreted within known gps error tolerances by microprocessor 550 in rtu 20 to determine a position change that is interpreted to be movement or non - movement . in step 320 ′, the method of the present invention determines whether a status change has occurred . if the rtu 20 determines a change in status from moving to stopped or from stopped to moving has occurred 320 ′, then the changed status causes rtu 20 to transmit 330 ′ a data packet with current gps position coordinates to the central control computer 72 . for example , if the prior status determination was “ no movement ” and the current gps position coordinate readings indicate a “ new position ” ( prior and current gps position coordinates when compared result in a new position outside the error tolerance of the gps system ), then a change in status 320 ′ has occurred and a data packet is transmitted 330 ′. if , on the other hand , the prior status determination was “ no movement ” and the current gps position coordinate readings indicate the same position ( prior and current gps position coordinates when compared result in the same position within the error tolerance of the gps system ), then a no change in status 320 ′ has occurred and no data packet is transmitted by 330 ′. in fig5 the transmit data step 330 ′ is event driven , so that whenever the rtu 20 determines that a pivot 10 has changed from a stopped to moving status or from a moving to stopped status , or whenever the rtu 20 determines that a pivot 10 has changed from a wet to a dry water delivery status as indicated by sensor 28 and hydraulic water line 29 , the status data is sent by way of a data packet using wireless path 42 to the communication satellite ( s ) 40 . the data packet includes stored data of center pivot sprinkler 10 running status , current gps position coordinates and water delivery status data so as to establish a wet or dry , running or stopped status to be delivered to the service operator 70 at location 120 . for the gps method of monitoring movement as illustrated in fig5 , a number of different mathematical algorithms can be used to determine when a status event occurs in step 310 ′ that requires a status change in 320 ′. the mathematical algorithm used depends upon the error tolerance assumed for the gps position coordinate readings and the time interval between readings . if an intermediate drive tower 13 nearer to the center pivot point 12 is being monitored and the speed control of the last drive tower is set to a low percent speed setting at main panel 27 ( e . g ., six seconds on and 54 seconds off to the final drive motor ), then the tolerance for determining a non - movement status would be relatively long as compared to monitoring the last or next - to - last drive tower motor 23 of tower 15 of a center pivot sprinkler 10 . whatever mathematical algorithm is used to determine movement or non - movement of a drive tower 15 , the micro processor 550 using stored gps position coordinate readings in non - volatile memory 570 determines a status change event from either “ movement ” to “ non - movement ” or from “ non - movement ” to “ movement .” it is to be expressly understood that in one embodiment , all raw data even at close time intervals of one minute could be delivered to the service operator 70 at location 120 for processing by central control computer server 72 according to the methods of fig4 and 5 or that discussed immediately above . indeed , in another embodiment all such processing could occur at computer 92 at location 130 . fig3 is an illustration of the present invention wherein the central control computer server 72 plots the pattern of sequential gps position coordinates p 1 - p 5 . the sequential gps position coordinates can be a combination of “ events ” ( fig4 and 5 , step 330 ) and timed self - reports from rtu 20 . assuming roving pivot arm 18 is continuing to move , the points p 1 - p 5 make up a portion or all of the circumference of the circle formed by the path of the roving center pivot arm 18 at an outer point 20 . using three or more points from p 1 - p 5 along the arc making up the partial circumference c , three respective tangential lines pp 1 , pp 2 and pp 3 are plotted . from the point of intersection of lines pp 1 , pp 2 and pp 3 with the arc c of circular path ( any of p 1 - p 5 ˜), three perpendicular lines pl 1 , pl 2 and pl 3 are drawn . the point where lines pl 1 , pl 2 and pl 3 intersect is the theoretical center point cp of the circular path c made by the roving pivot arm 18 at outer location point 20 . any straight line from center point cp to the present location on the circumference c of the circle p 1 - p 5 ˜ is the azimuth az . the length of the azimuth az is the radius of the circle and represents the roving pivot arm 18 location 20 at a point along path p 1 - p 5 ˜. once the center point cp is determined , any gps real time position coordinates received from rtu 20 at central control computer 72 can be used to calculate the azimuth az for the roving pivot arm 18 . in fig2 , an overhead view of location 100 is shown with the pivot irrigation system 10 moving in the direction of arrow 200 . the movement 200 is typically slow such as one hundred feet per hour . hence , in ten hours the movement 200 can be over a distance 210 such as one thousand feet , which is shown by time t 2 . in other words , the movement 200 from time t 1 to time t 2 is ten hours worth of movement at one hundred feet per hour or one thousand feet . t 1 is a time reference and t 2 is a second time reference ten hours later . hence , if the pivot irrigation system 10 were properly operating , the person at the monitor location 130 would expect that at time t 2 the pivot would be at location l 2 having moved from location l 1 at time t 1 . in this example of ten hours from t 1 to t 2 , the satellite ground station 50 in communication with the rtu 20 has typically taken a number of readings at a frequency such as one every ten to fifteen minutes as illustrated by the dotted line on the circumference of travel 210 . assuming one every ten minutes , or six readings per hour then in ten hours , sixty readings are taken between time t 1 and time t 2 . all gps position coordinate readings taken at rtu 20 and transmitted to central control computer 72 are time encoded . these gps position coordinate readings with time stamp t 1 - t 2 ˜ combined with the theoretical coordinates for center point coordinates cp are also used by software at the central server to calculate the theoretical azimuth az of the pivot arm 18 , ground speed , direction of travel , and using the wet dry sensor and fixed water delivery rate the rate of water application by acre . as will be explained , in another embodiment , not every reading is transmitted to satellite 40 . referring to fig2 , with ground speed of an outer point 15 ( location of rtu 20 ) of the center pivot arm 18 of irrigation system 10 at one hundred feet per hour , and with a location l reading every ten minutes , the movement between adjacent readings is only seventeen feet per reading . as this is near the error tolerance of most conventional gps devices , the determination of location l requires more than one reading to occur in the system of the present invention to be assured of movement 200 and how much movement has occurred . therefore , the primary method and system in the present invention detects the presence of movement ( i . e ., whether the pivot irrigation system 10 is moving or not ) using the current sensor means . however , the gps means is also used as a redundant back - up to determine movement or non - movement over time as well as to determine the azimuth az of the pivot arm 18 from the center pivot point 12 , the direction of movement 200 ( i . e ., clockwise or counterclockwise ) and the ground speed of the outer end of the pivot arm 20 . the gps method for determining running or stopped status of a center pivot is significant because it provides a unique way of monitoring the status of a hydraulic powered center pivot or lateral move sprinkler . the current sensor means requires ac current flow and hydraulic pivots do not use ac current for drive or control power . the detection of the status change event in step 320 of fig4 and step 320 ′ in fig5 are two embodiments of the present invention . in another embodiment , the time readings ( self reports from rtu 20 ) t 1 - t 6 ( fig6 ) and time readings t 1 - t 6 ( fig7 ) could occur at ninety - minute intervals and steps 320 and 320 ′ are not used . each gps position coordinate reading would then be transmitted 330 and 330 ′, and any processing with respect to movement or non - movement of the pivot irrigation system 10 would use gps position coordinates logged over time at the service operator 70 location 120 using central control computer 72 . fig6 sets forth a table showing gps coordinate readings ( gps 1 - gps 6 ) corresponding to times ( t 1 - t 6 ). assume the rtu 20 takes readings every ten minutes and further assume that the ground speed is one hundred feet per hour . it is expected that if the center pivot irrigation system 20 is moving it should move about seventeen feet every reading . due to the tolerance error in the gps readings , the seventeen feet reading is small enough to be near the tolerance error . therefore , several sequential gps position coordinate readings are required . the processor 550 ( see fig9 ) calculates the fixed center pivot point cp and determines the azimuth az of the roving pivot arm 18 for each gps reading , the linear distance between recorded time - stamped gps coordinates stored in memory 570 and further calculates direction of travel and ground speed . with reference back to fig5 , in step 310 ′ the rtu 20 receives readings at times t 1 - t 6 . the processor 550 in the rtu 20 , over several readings , then processes the gps readings . for example as shown in fig7 , assume the pivot irrigation system 10 is moving ( i . e ., the status is “ moving ”) prior to t 1 in arc 400 , the gps 1 reading at time t 1 is compared with several prior readings and movement is verified so no status change occurs in stage 320 ′. at time t 2 the gps 2 reading is compared to several prior readings and movement is again verified . likewise , the rtu 20 reaches the same conclusion at reading time t 3 , gps 3 . and , at time t 4 , gps 4 again , movement is verified . at time t 4 , gps 4 , in one embodiment , the microprocessor 550 can look at the prior four gps readings ( i . e ., over forty minutes ) to verify that movement of about sixty - eight feet has occurred . prior gps readings with time stamps are stored in memory 570 . this distance is outside the error tolerance of the gps readings and verifies that movement is ongoing so there is no status change occurring in step 320 ′. in other words at four discrete times t 1 - t 4 , loop 302 ′ occurs in fig5 . assume at time t 5 , gps 5 the processor 550 in the rtu 20 with respect to that one reading senses no movement , but since this one reading is within the error tolerance of the gps system when compared to the prior three readings ( t 4 , t 3 and t 2 ), the rtu 20 determines movement has occurred and thus no status change in 320 ′. however with respect to reading at time t 6 , gps 6 when compared to readings at t 5 , t 4 and t 3 , in forty minutes only thirty four feet in movement has been detected , the rtu 20 in step 320 ′ concludes a status change of “ no movement ” has occurred based on readings at t 3 , t 4 , t 5 , and t 6 and step 330 ′ is entered . it is to be expressly understood that more or less than four readings could be utilized and more or less than ten minutes could be utilized depending upon the design configuration . a number of different mathematical algorithms could be used to determine when a status event occurs in step 310 ′ that requires a status change in 320 ′. the mathematical algorithm used depends upon the tolerance for error of the gps receiver , the time interval , and the ground speed . the above calculations can also include confidence and sequence factors . for example , with respect to confidence , if the status were moving , high confidence of no movement would be five successive readings within the tolerance error . a lower confidence would be three successive readings . with respect to sequence , if in the above example at time t 6 , gps 6 , a noticeable seventeen - foot change was observed , the sequence of events at times t 4 and t 5 in one embodiment of the algorithm , may be ignored . whatever mathematical algorithm is used , the processor 550 using stored gps readings in memory 570 determines a status change event from either “ movement ” to “ non - movement ” or from “ non - movement ” to “ movement .” furthermore , the detection of the status change in step 320 of fig5 is one embodiment of the present invention . in another embodiment , the time readings t 1 - t 6 and gps 1 - gps 6 could occur at thirty - minute intervals and step 320 ′ is not used . each reading would then be transmitted 330 ′, and any processing with respect to movement or non - movement of the pivot irrigation system 10 would occur at the service operator server 70 location 120 . again , the time interval of thirty minutes is subject to design configuration and gps accuracy considerations . it is to be expressly understood that in one embodiment , all raw gps data even at close time intervals of ten minutes could be delivered to the service operator server 70 for processing according to the method of fig5 or that discussed immediately above . indeed , in another embodiment all such processing could occur at the subscriber monitor 90 location 130 . in fig8 and 9 , the rtu 20 is shown mounted to a pipe 500 at drive tower 15 of the pivot irrigation system 10 . the rtu 20 is mounted by means of a strap 502 and is securely affixed thereto by means of a clamp 504 engaging the strap 502 . the rtu 20 is mounted in a horizontal position and has a solar panel 510 mounted horizontally on the top of the rtu 20 to continually charge a battery within the power supply 520 within the rtu 20 . the gps antenna 31 is interconnected to a gps receiver 530 , the satellite data receiver antenna 24 is connected to a satellite transmitter 540 and the rtu 20 contains a microprocessor 550 . also shown in fig8 is a water pressure switch and gauge 28 ( optional ) with a water hydraulic line 29 connected to the pipe 500 to sense the water pressure inside the pipe and a corresponding transducer 564 for converting the analog water pressure to an electrical or digital signal . the processor 550 is in communication 565 with the electrical circuit 564 . a current sensor 21 and connecting cable 26 is connected to a current sensor circuit board 555 . the current sensor board 555 detects the presence or absence of ac current flowing through a single conductor of the three - phase motor drop cable 58 connected to drive motor 23 . it is to be expressly understood that other components can be found in the rtu 20 and that the rtu 20 has an encapsulated housing which is environmentally sealed to protect its contents from external elements . the satellite transmitter 540 is a satellite radio transmitter and receiver . the processor 550 is programmed with suitable software to operate with respect to the discussion above with respect to the flow charts of fig4 and 5 . the processor 550 is connected to a non - volatile memory 570 . as shown in fig3 , what is delivered to the subscriber at the subscriber &# 39 ; s location 130 or at a mobile location could be a graphic display . the graphic display could be overlaid with a topological map of the field , a satellite view of the field , or an aerial view of the field . this provides important information to the subscriber as the subscriber may be aware of certain topological or soil conditions with respect to the field at the present detected location of the roving pivot arm 18 of pivot irrigation system 10 . in fig1 , a data packet 600 that is transmitted from antenna 24 over wireless link 42 to satellite 40 and then to ground station 50 is shown . the data packet 600 contains a field 610 containing the gps coordinates , a field 615 containing the current sensor status , a field 620 containing the water flow information and a field 630 for the time and date stamp . it is expressly understood that the arrangement of these fields is based on design choice , and that other information could be present in additional fields in the data packet 600 . with respect to collecting water pressure and / or flow information from pressure switch 28 and transducer 564 , the processor 550 at the time intervals t stores readings with a time stamp in memory 570 . unlike the gps readings , the water pressure / flow readings do not have a high tolerance error and in one embodiment of the present invention , whenever a water pressure / flow reading changes , processor 550 enters step 320 or 320 ′ and transmits the event to ground station 50 . the pressure switch 28 and transducer 564 in fig9 can be set to a digital input high or digital input low so as to operate as an on / off switch . in this embodiment , rather than that discussed previously , the processor 550 does not take individual pressure readings . rather , a pressure threshold for wet and dry status can be set for each individual pivot situation . at other predetermined time intervals such as every twenty - four hours , the processor 550 sends a “ heartbeat ” data packet to the ground station 50 and then to the service operator 120 simply to verify normal operation of the rtu 20 . heartbeat data packet transmissions are conventional . the heartbeat data packet includes the same information such as the current sensor reading indicating movement or non - movement status of the monitored outer tower , the gps coordinates ( time stamped ) and the wet / dry water delivery status . the gps coordinates are conventional latitude and longitudinal coordinates and can also be used to determine movement or non - movement status of hydraulic powered center pivot or lateral move sprinklers . the rtu 20 can also include additional sensor data , including wireless data received over a local radio system that relays soil moisture and temperature readings , bug counts , canopy shade , etc . such data could be gps defined in the respective field with the data incorporated into the graphic displays of pivot gps and water delivery status data . as fully discussed above , the rtu 20 of the present invention is located at or near the end tower 15 of the center pivot 10 and is a self - contained , universal rtu that will work with any of a number of conventional pivot or lateral move irrigation systems 10 from a wide variety of manufacturers . the term “ self - contained ” means that the rtu 20 does not interface to the electronics or the wiring of the control or power circuitry for the mechanized irrigation system 10 . it provides a self - contained operation independent of and isolated from the electrical circuitry of the mechanized irrigation system 10 . the rtu 20 does not interface with any control electronics of the pivot irrigation system 10 . it is , therefore , easily relocated to different center pivots to maximize monitoring benefits as to other irrigation systems . the rtu 20 is located in a position to provide ample sunlight to its solar panel 510 and to allow antennas 24 and 31 to optimally operate without encountering any adverse effects from the operation of the pivot irrigation system 10 such as water spray . in fig1 , a display 700 , in one embodiment , is provided to the subscriber in the mobile device 80 and / or the computer 92 at location 130 . in fig1 , the display 700 has the aerial map 710 displayed for a pivot 10 . a geographic information system ( gis ) source for map data could also be used . with each full rotation of the pivot irrigation system 10 , the service operator 70 provides an expected path 720 ( shown in dotted lines ). in other words , the service operator software in control computer 72 learns from prior rotations as to what is the expected rotation 720 . in another embodiment , rather than having an expected rotation based upon a number of prior rotations , the path 720 could simply be the last path of rotation . what is provided to the subscriber either in mobile device 80 or in computer 92 at location 130 is path 720 ( based upon historic travel or the immediately prior travel ). the current path 730 ( shown in solid line ) is also displayed having a start position 740 and a current position 750 . with the pivot 10 normally operating the current travel path 730 will overlay path 720 . when the current position 750 comes full circle back to start 740 , path 730 starts all over again . or , in another embodiment , the point 740 could be continually moving such as always trailing 180 ° from the current position 750 ( or any suitable trailing angle ). this provides important information to the subscriber . for example as shown in fig1 , a deviation 760 is occurring . this could be mechanical failure in that the end drive tower 13 of the pivot irrigation system 10 is moving out of the normally expected ground track for the end wheels 11 , which could be caused by the pivot irrigation system 10 jackknifing ( collapsing inward toward the center pivot point ) somewhere along its roving line 18 . in another aspect of the present invention shown in fig1 , the service operator 70 in its control computer 72 analyzes the data received and provides the same information as found in fig1 . however , in addition , based upon a prior number of historic full complete paths 720 of the pivot irrigation system 10 , the central control computer 72 software determines expected times for arrival of the end tower 13 of the pivot as it travels the full circular path 720 . in fig1 , these historic times are labeled t a - t b . any suitable number of historic times around the historic path 720 can be established by software in the control computer 72 . in fig1 , the current travel path 730 is on track at current time t bc that corresponds to time t b . however , end 15 carrying the rtu 20 of the present invention does not arrive at the historic expected time of t c . as shown in fig1 , the current time t cc for the end of the pivot 10 is at location 750 ( based upon gps coordinates ). a malfunction has obviously occurred with the pivot 10 such as a flat tire on the outer tower that slows down the pivot movement or other drive mechanism failing . the subscriber can immediately visit the pivot irrigation system 10 , site 100 to effectuate repairs . it is to be understood that in this situation of fig1 , the pivot irrigation system is still moving and so a “ status event ” had not been detected by either the current sensor means or by the gps means in fig4 and 5 , respectfully . in fig1 and 12 , suitable warning messages 770 or 780 could be utilized such as audible indicators , graphic indictors , text messages , alerts , email messages , paging messages , etc . it is understood that while a self - contained rtu 20 has been shown and described , it is also possible to locate the elements , such as the solar array and antennas remotely from the unit and they can be connected to the unit by suitable cables and connectors . it is to be understood that the central processing computer can utilize the received data concerning the status of the mechanized irrigation system to perform various calculations . through the use of the data the central processor can calculate the theoretical center point of the arc or circle plotted by a series of gps data points recorded over time . in addition the central data processor can calculate the theoretical azimuth between the center point of the arc or circle covered by the sprinkler and the position of the roving rtu as defined by the gps position coordinate data received in the most current data packets from the rtu . the center processor further calculates the area of the circle covered by the irrigation system using the azimuth as the radius and can currently determine the angular position of the azimuth from north which identifies the position of the roving pivot arm . the central processor can use the theoretical azimuth as the radius of a full circle covered by the irrigator to calculate the area of the irrigated circle . it can also use the gps data points and two respective azimuths to define a pie shaped area of the irrigated circle . thus the respective irrigated section of the circular field is determined using the time stamp sequential gps position data points and each respective azimuth to calculate the area . by using the water delivery rate from the irrigation system and the elapsed time between two data points the area in acres of a section defined by the two data points can be used to calculate the acre inches of water applied to the designated area . the central control processing computer can also calculate the water application in acre - inches resulting from the rotation speed calculated and by applying variables of water pumping rate , acreage irrigated and water application efficiency assumptions . in addition the central processing computer can calculate the time to complete a full circle by the irrigator . along with these calculations the central control processing computer can determine expected time for arrival of the roving pivot arm to reach various predetermined positions in the irrigated field . it is further understood that the rtu self reports data packets of pivot status and gps coordinates on a periodic timed basis such as every twelve hours . the above disclosure sets forth a number of embodiments of the present invention described in detail with respect to the accompanying drawings . those skilled in this art will appreciate that various changes , modifications , other structural arrangements , and other embodiments could be practiced under the teachings of the present invention without departing from the scope of this invention as set forth in the following claims .
a wireless interface remote monitoring system for self - propelled irrigation systems includes a remote terminal unit mounted on an outer drive tower of the irrigation system . the rtu includes a radio transceiver capable of sending and receiving data packets over a satellite or terrestrial telemetry backbone to and from a central control computer . the rtu further includes a current sensor and a gps receiver both for detecting movement or non - movement of the sprinkler , a microprocessor with nonvolatile memory for storing current data and gps coordinate data from readings taken in series over time , and a pressure or flow sensor for detecting the presence or absence of water flow at the outer drive tower of the sprinkler . the current sensor connected between the rtu and a tower drive motor , allows the rtu to calculate the “ movement ” or “ non - movement ” of the irrigation system over a specified time period . redundantly , the gps receiver records changes in position to indicate movement or non - movement within the gps error tolerance . once a change from movement to non - movement or vice - versa is determined , the rtu transmits the data by satellite or radio telemetry to a central control computer which logs the movement or non - movement of the monitored drive tower , the gps coordinate data and the water status readings , all with time and date stamp . the central control computer creates “ page message ” and “ text message ” updates as necessary on the status of individual irrigation systems and “ groups ” of irrigation systems that are in turn delivered to wireless devices and computers for sprinkler operators .