Patent Publication Number: US-9888623-B2

Title: Systems for monitoring seeds and methods thereof

Description:
PRIORITY STATEMENT 
     This application is a continuation application of and claims priority under 35 U.S.C. §120/121 to U.S. application Ser. No. 14/991,210 filed Jan. 8, 2016, the contents of which are hereby incorporated herein by reference in their entirety and for all purposes. 
    
    
     FIELD 
     Example embodiments are related to systems for monitoring seeds and methods of monitoring the seeds. Such methods and systems may be used in agricultural seeders and planters, for example. 
     BACKGROUND 
     Advances in agricultural seeding machinery have made it possible to seed large swaths of farmland with each pass of a seeding machine. Air seeders typically include a dry holding tank for maintaining seeding material and a hose with applicator for applying the seeding material into furrows or blowing seeding material onto the surface of a prepared field. Modern air seeders may further include controls that allow the operator to configure the machine. Further, air seeders may allow simultaneous application of seed, fertilizers, and any other material useful in ensuring rapid germination and healthy growth cycle. 
     Optical monitoring systems can detect and count the number of seeds dispensed or planted by the seeder, or the planting density of the seeds, for each row of the planter or the entire planter. 
     SUMMARY 
     Exposure of optical monitoring systems to contaminants such as dust, dirt, debris and organic material from the seed and environment, can degrade the system performance. In field operation, a layer of dust accumulates on the optical windows of certain prior art sensing systems causing light from emitters to be refracted in unpredictable directions such that seed counts are duplicated or undetected. 
     At least some example embodiments disclose a seed counting system having a plurality of light receivers. The light receivers are arranged such that if a performance of one of the light receivers is degraded by dust or debris, at least one other light receiver compensates to avoid inaccuracies in a seed count or seed density. 
     At least some example embodiments disclose a seed counting system having three parallel channels of signal conditioning. Each of the channels has a selected gain and bandwidth associated with a seed type. 
     At least one example embodiment discloses a seed counting system including a light source configured to emit light along a plane of an interior of a seed tube, a light receiver configured to receive the light and generate a sensing signal corresponding to the received light, the receiver opposing the light source on the plane of the interior of the seed tube, a processing system including a plurality of conditioning channels, the processing system configured to process the sensing signal using at least a selected one of the plurality of conditioning channels to generate a first conditioned signal and a controller configured to generate a seed count value based on the first conditioned signal. 
     At least another example embodiment discloses a seed counting system including a light source configured to emit light along a plane of an interior of a seed tube, a plurality of light receivers around the plane of the interior of the seed tube, each of the plurality of light receivers configured to receive light in at least two sectors of a plurality of sectors of the plane and generate a sensing signal corresponding to the received light, a processing system including a plurality of conditioning channels, the processing system configured to process the sensing signals to generate conditioned signals and a controller configured to generate a seed count value based on the generated conditioned signals. 
     At least another example embodiment discloses a method of monitoring seeds. The method includes emitting light, by a light source, along a plane of an interior of a seed tube, receiving light, by a plurality of light receivers, in at least two sectors of a plurality of sectors of the plane and generating a sensing signal corresponding to the received light, processing the sensing signals to generate conditioned signals and generating a seed count value based on the generated conditioned signals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.  FIGS. 1-11  represent non-limiting, example embodiments as described herein. 
         FIG. 1  illustrates a side view of an air seeding machine including a seed monitoring system according to an example embodiment; 
         FIG. 2  illustrates a seed monitoring system according to an example embodiment; 
         FIG. 3  illustrates a cross-sectional view of a seed tube showing a light transmitter and light receiver of the seed monitoring system according to an example embodiment; 
         FIG. 4  illustrates a conditioning circuit in the seed monitoring system shown in  FIG. 2  according to an example embodiment; 
         FIG. 5  illustrates a seed monitoring system according to an example embodiment; 
         FIG. 6  illustrates a cross-sectional view of a seed tube showing a light transmitter and a plurality of light receivers of the seed monitoring system according to an example embodiment; 
         FIGS. 7A-7C  illustrate coverage areas of the plurality of light receivers shown in  FIG. 6 , according to an example embodiment; 
         FIG. 8  illustrates a conditioning circuit in the seed monitoring system shown in  FIG. 5  according to an example embodiment; 
         FIG. 9  illustrates a method of determining a seed count value according to an example embodiment; and 
         FIGS. 10A-10B  illustrate a method of determining a seed count value according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Various example embodiments will now be described more fully with reference to the accompanying drawings in which some example embodiments are illustrated. 
     Accordingly, while example embodiments are capable of various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments to the particular forms disclosed, but on the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the claims. Like numbers refer to like elements throughout the description of the figures. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. 
     It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Portions of example embodiments and corresponding detailed description are presented in terms a processor specifically programmed to execute software, or algorithms and symbolic representations of operation on data bits within a computer memory. These descriptions and representations are the ones by which those of ordinary skill in the art effectively convey the substance of their work to others of ordinary skill in the art. An algorithm, as the term is used here, and as it is used generally, is conceived to be a self-consistent sequence of steps leading to a result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of optical, electrical, or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
     In the following description, illustrative embodiments will be described with reference to acts and symbolic representations of operations (e.g., in the form of flowcharts) that may be implemented as program modules or functional processes including routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types and may be implemented using existing hardware. Such existing hardware may include one or more Central Processing Units (CPUs), digital signal processors (DSPs), application-specific-integrated-circuits, field programmable gate arrays (FPGAs) computers or the like. 
     It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, or as is apparent from the discussion, terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical, electronic quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
     Note also that the software implemented aspects of example embodiments are typically encoded on some form of tangible (or recording) storage medium or implemented over some type of transmission medium. The tangible storage medium may be magnetic (e.g., a floppy disk or a hard drive) or optical (e.g., a compact disk read only memory, or “CD ROM”), and may be read only or random access. 
       FIG. 1  illustrates a side view of an air seeding machine including a seed monitoring system according to an example embodiment. 
     The illustration and description thereof is presented for explanation only and is not intended to limit the scope of example embodiment. Practitioners will appreciate that the disclosed monitoring system may be implemented as a component of any type of seeding machine, wherein seed product is dispersed onto/into a growing medium. In one embodiment, an existing seeding machine may be retrofitted with the disclosed seed monitoring system. In another embodiment, the hardware components for the disclosed seed monitoring system are implemented within a seeding machine during the manufacture process. 
     As shown in  FIG. 1 , a seeder assembly  110  includes a holding tank  115  that holds varying quantities of seed material to be dispensed by an air seeding machine  105 . More specifically, the holding tank  115  maintains seed and any other application suitable for the purposes described herein, such as fertilizers and herbicides. Relative to the description of the seed monitoring system, the air seeding machine  100  will be described relative to the functions of dispensing seeds  120  of any suitable type. 
     In one embodiment, the flow of seeds  120  from the holding tank  115  is controlled by a rotary dispenser  125 . The controlled flow of the seeds  120  from the rotary dispenser  125  distributes the seeds  120  into a primary manifold  130  by way of a suitable conduit  132 . A plurality of primary seed conduits  134  are connected to the primary manifold  130  to receive the flow of seeds  120  from the holding tank  115 . In accordance with one embodiment, the number of primary seed conduits  134  is directly related to the number of rows that the seeding machine  100  is configured to simultaneously seed. 
     A blower  136  is connected to the primary manifold  130  by a hose  138 . The blower  136  provides air pressure to the primary manifold  130  so as to cause the seeds  120  to move through the primary manifold  130  and into the primary seed conduits  134  under air pressure. Each primary seed conduit  134  is connected to a separate secondary manifold  140 . A plurality of secondary seed conduits  142  are connected to each of the secondary manifolds  140 . In the embodiment, pluralities of secondary seed conduits  142  are connected to each secondary manifold  140 . In various configurations, each secondary seed conduit  142  may be connected to a configurable blade-like device that carves furrows in the soil, such that the seeds  120  are dispensed at an appropriate depth into the soil. 
     In an example embodiment, a monitoring system  148  is positioned on each secondary seed conduit  142  to monitor the seed flow through the secondary seed conduits  142 . The term conduit and tube may be used interchangeably and are not limiting to the particular shape of the enclosure used to convey the seeds. 
     As will be described in detail below, the seed monitoring system  148  includes various optical emitters and receivers configured in such a way that enables the monitoring system to accurately count seeds as they pass through the secondary seed conduit  142 . While generally described herein as being positioned on the secondary seed conduit  142 , those of ordinary skill in the art will appreciate that the disclosed seed monitoring system according to example embodiments may be positioned within any conduit, hose, or the like where a seed passes from a holding tank  115  to the seed applicator  144 . Moreover, the seed monitoring system may be configured to function at multiple locations within a seeding machine  100  simultaneously, such that the multiple seed monitoring systems may, for example, provide a more accurate seed count. 
       FIG. 2  illustrates an example embodiment of a seed monitoring system shown. 
     A seed monitoring system  200  includes a light source  210 , a light receiver  220 , a conditioning circuit  230  and a controller  250 . The controller includes an input/output (e.g., analog inputs)  255 , a microprocessor  260  and a memory  265 . The microprocessor  260  may exchange data with the I/O  255  and the memory  265  using a data bus  270 . The microprocessor  260  may execute instructions stored in the memory  265  to perform the functions described below. The terms “memory,” “storage medium” or “computer-readable medium” may represent one or more devices for storing data, including read only memory (ROM), random access memory (RAM), magnetic RAM, core memory, magnetic disk storage mediums, optical storage mediums, flash memory devices and/or other tangible machine readable mediums for storing information. The term terms “memory,” “storage medium” or “computer-readable medium” may include, but is not limited to, portable or fixed storage devices, optical storage devices, and various other mediums capable of storing, containing or carrying instruction(s) and/or data. 
     The light source  210  emits light alone a plane of an interior of the seed tube  142 . The light source  210  may include an array of light emitting diodes (LEDs). 
     The light receiver  220  receives the light and generates a sensing signal I sens  from the amount of light received by the light receiver  220 . The light receiver  220  may be a single photodiode. However, example embodiments are not limited thereto. 
       FIG. 3  illustrates a cross-sectional view of a seed tube showing the light source  210  and the light receiver  220  of the seed monitoring system  200  according to an example embodiment. 
     The light source  210  is positioned along one side of an interior periphery  305  of the seed tube  142  such that an emitter window  315  illuminates an entire interior area  310  in the x-y plane (i.e., a cross-section of the seed tube  142 ). The interior area  310  is defined by the interior periphery  305 . The light source  210  includes the emitter window body  315  secured within an emitter housing  320 . The emitter housing  320  includes an array Light Emitting Diodes (LED) or similar  325 , which is configured to generate constant light of a specific wavelength. For example, to avoid compromising the input values of receiver  220 , the LED may produce light in the Infrared (IR) range of the spectrum as to be distinguished from light contamination from visible light sources. The LEDs  325  may be mounted to a PC board with conductive strips forming electrical connections with the LEDs  325  mounted thereon. 
     The light receiver  220  is positioned at an opposite side of the periphery  305  from the light source  210 . The light receiver  220  may include a window body  335  secured within a receiver housing  340 . The receiver housing  340  includes an optic receiver  345  such as, for example, a photodiode, phototransistor, and other semiconductor type cells. 
     In the example embodiment shown in  FIG. 3 , the seed monitoring system includes the light source  210 , which is configured to illuminate the light receiver  220 . The positioning of the light source  210  and the light receiver  220  form a planar sensing area, particularly when light source  210  produces a wide-beam light. 
     As will be appreciated by those of ordinary skill in the art, the light source  210  may comprise an illumination source, which is housed within an enclosure. Because an LED chip provides 360 degrees of planner illumination, the housing  320  is configured to restrict the illumination angle to 180 degrees in the x-y plane. The window  315  is positioned on an open side of the housing  320  and may be produced from translucent plastic, glass, or mineral. The emitter window  315  may include a texture or additive during manufacture to diffuse light from the LED. 
     Dependent on the configuration of the light receiver  220 , the light source  210  may be configured to provide constant or intermittent illumination. Moreover, the brightness of the light source  210  may be controlled by way of voltage adjustments for incandescent type light bulbs or by way of current adjustment for an LED. In embodiments where modification of light source  210  properties is desirable or used, the LEDs may be controlled by a driver circuit and/or controller circuit such as the controller  250 . 
     Similar to the light source  210 , the light receiver  220  may include the sealed housing  340 . The receiver housing  340  includes a window to allow light to pass through the sealed housing to the optic receiver  345 . In various example embodiments, the window may also be further configured to filter specific wavelengths of light. For example, the window may filter light such that light falling outside of the wavelength range is blocked. This is most often facilitated by treating the window  315  with a tint or shade that causes certain wavelengths of light to reflect, thereby causing the undesirable light to reflect off of the inner surface rather than pass through it. Varying technologies exist for measuring light and/or properties of light and the selection of a sensor type may be based on the specific implementation of the disclosed monitoring system. 
     When a seed  340  falls through the seed tube  142  between the light source  210  and the light receiver  220 , there will be a change in the radiation incident upon the optic receiver  345 . In other words, the seed  340  will momentarily block a part of the radiation traveling across the seed tube  142 . The change in radiation incident on the optic receiver  345  indicates that a seed has passed. 
     Referring back to  FIG. 2 , the light receiver  220  generates the sensing signal I sens  based on the light sensed by the optic receiver  345 . The sensing signal I sens  indicates the amount of light sensed by the optic receiver  345 . 
     Referring back to  FIG. 2 , the light receiver  220  sends the sensing signal I sens  to the conditioning circuit  230 . The conditioning circuit  230  has a plurality of conditioning channels that are arranged in parallel. Each conditioning channel includes a filter (e.g., an amplifying filter or an active filter) that has a bandwidth and a gain associated with properties of the seed (seed type) and the seed delivery system. 
     Gravity-fed and pneumatically-fed are two types of seed delivery systems. The bandwidth ref the corresponding filter is tuned differently for gravity-fed versus pneumatically-fed. 
     In a gravity-fed system, for example, parameters used for determining the bandwidth include seed size (e.g., sizes of wheat, soy and canola), a seed velocity and a probability of overlapping seeds. 
     Thus, a conditioning channel for soy may also be used for other relatively larger seeds such as corn whereas a conditioning channel for canola may be used for other relatively smaller seeds. 
     The gain and bandwidth of each conditioning channel is selected to generate a desired (e.g., optimal) signal-to-noise ratio for a specific seed size and to generate desired (e.g., optimal) output signals V ST1 -V ST3  that the controller  250  can use for determining a seed count value for the seed type. The gain and used bandwidth of the conditioning channels are calculated for specific seed types and expected seed velocities. 
       FIG. 4  illustrates an example embodiment of the conditioning circuit  230 . The conditioning circuit  230  includes a preamplifier circuit  410  and first, second and third conditioning channels  420   a - 420   c.    
     The preamplifier circuit  410  includes a transistor Q 1 , an operational amplifier U 1 , resistors R 1 -R 3 , resistors R 15 -R 17  and capacitors C 1 , C 9  and C 10 . The preamplifier circuit  410  receives the sensing signal I sens  and a power supply voltage V power  (e.g., 12V). A voltage drop across the transistor Q 1  is a voltage that will be pre-amplified and conditioned. 
     The sensing signal I sens  is input to a node N 1  of the preamplifier circuit  410 . The transistor Q 1  may be an n-p-n transistor and may operate as a diode. A collector of the transistor Q 1  and a base of the transistor Q 1  are also connected to the node N 1 . The transistor Q 1  outputs a signal proportional to the light modulation created by the change in radiation incident on the light receiver  220 . 
     The resistor R 1  is connected between the node N 1  and a positive input of the preamplifier U 1 . 
     The resistor R 15  and the capacitor C 9  form a power supply low-pass filter that suppresses a high-frequency noise on a power supply line to the amplifiers U 1 , U 2 , U 3  and U 4 . A first end of the resistor R 15  is connected to the power supply voltage V power . A second end of the resistor R 15  is connected to first ends of the capacitor C 9  and resistor R 16 , respectively. Moreover, the second end of the resistor R 15  is connected to positive power supply inputs of the amplifiers U 1 , U 2 , U 3  and U 4 . 
     A second end of the resistor R 15  is connected to first ends of the capacitor C 10  and the resistor R 17 . The capacitor C 10  and the resistor R 17  are connected in parallel between the second end of the resistor R 16  and a node N 6 . The resistors R 16 -R 17  and the capacitor C 10  form a voltage divider and low-pass filter to get a voltage supply voltage (e.g., 5V) for the receiver  220 . For example, the voltage supply generated by the resistors R 16 -R 17  and the capacitor C 10  may be provided to a cathode of a photodiode. 
     The node N 6  is connected to ground and a first end of the resistor R 2 . A second end of the resistor is connected to the negative input of the amplifier U 1  and first ends of the resistor R 3  and the capacitor C 1 , respectively. Second ends of the resistor R 3  and the capacitor C 1 , respectively, are connected to a second node N 2 . A ratio of resistances of the resistors R 3 /R 2  determines a gain of the preamplifier circuit  410 , the capacitor C 1  limits a bandwidth of the preamplifier circuit  410 . 
     The preamplifier U 1  operates by amplifying a voltage at the node N 1  (e.g., 0.5-0.6 V) to a voltage at the second node N 2  (e.g., 2-2.4V). Each of the conditioning channels  420   a ,  420   b  and  420   c  is connected to the second node N 2 . The resistors R 6 -R 7  and the capacitor C 4  form a voltage divider and low-pass filter to get a bias voltage (e.g., 0.8V) for the amplifiers U 2 -U 4  of the conditioning channels  420   a ,  420   b  and  420   c , respectively. The capacitor C 4  and the resistor R 7  are connected in parallel between ground and a second end of the resistor R 6 , which is connected to second ends of resistors R 8 , R 14  and R 10 , respectively. 
     When detecting seeds, a larger seed will generate a larger/longer shadow over the optic receiver  345  than a smaller seed. Thus, if a same conditioning channel were used for each type of seed, varying signal strengths would be detected. More specifically, a large shadow will generate a large signal whereas a small shadow will generate a low signal. As a result, the smaller seeds may not be detected. 
     If a conditioning circuit gain is not desired (e.g., not optimal), a large seed might saturate the amplifier and the frequency content of the signal would be distorted. That will decrease the accuracy of multiple seed detection. Small seed signals might be below the detection threshold or their frequency content might be insufficient for multiple seed detection. 
     Therefore, the each of the conditioning channels  420   a ,  420   b  and  420   c  has a selected bandwidth and a selected gain corresponding to the associated seed type (e.g., seed size). Thus, a smaller seed will be detected by the conditioning channel associated with the smaller seed. 
     The first conditioning channel  420   a  includes capacitors C 2 -C 3 , resistors R 4 -R 5  and R 8  and an amplifier U 2 . A first electrode of the capacitor C 2  is connected to the second node N 2  and a second electrode of the capacitor C 2  is connected to a first end of the resistor R 4 . A second end of the resistor R 4  is connected to a third node N 3 , which is a negative input of the amplifier U 2 . A positive input of the amplifier U 2  is connected to a first end of the resistor R 8 . A second end of the resistor R 8  is connected to the resistor R 6 . An output of the amplifier U 2  outputs a conditioned signal V ST1  corresponding to a first seed type. The resistor R 5  and the capacitor C 3  are connected in parallel between the output of the amplifier U 2  and the node N 3 . 
     The first conditioning channel  420   a  has a selected gain and a selected bandwidth associated with the first seed type such as wheat Gain and used bandwidth of each conditioning channel is calculated for a specific range of seed dimensions and expected seed velocities. Thus, the capacitances of the capacitors C 2 -C 3  and the resistances of the resistors R 4 -R 5  are selected such that the first conditioning channel  420   a  has the selected gain and the selected bandwidth. 
     The second conditioning channel  420   b  includes capacitors C 7 -C 8 , resistors R 12 -R 14  and an amplifier U 4 . A first electrode of the capacitor C 7  is connected to the second node N 2  and a second electrode of the capacitor C 7  is connected to a first end of the resistor R 12 . A second end of the resistor R 12  is connected to a fourth node N 4 , which is a negative input of the amplifier U 4 . A positive input of the amplifier U 4  is connected to a first end of the resistor R 14 . A second end of the resistor R 14  is connected to the resistor R 6 . An output of the amplifier U 4  outputs a conditioned signal V ST2  corresponding to a second seed type. The resistor R 13  and the capacitor C 8  are connected in parallel between the output of the amplifier U 4  and the node N 4 . 
     The second conditioning channel  420   b  has a selected gain and a selected bandwidth associated with the second seed type such as soy. Thus, the capacitances of the capacitors C 7 -C 8  and the resistances of the resistors R 12 -R 13  are selected such that the second conditioning channel  420   b  has the selected gain and the selected bandwidth. 
     The third conditioning channel  420   c  includes capacitors C 5 -C 6 , resistors R 9 -R 11  and an amplifier U 3 . A first electrode of the capacitor C 5  is connected to the second node N 2  and a second electrode of the capacitor C 5  is connected to a first end of the resistor R 9 . A second end of the resistor R 12  is connected to a fifth node N 5 , which is a negative input of the amplifier U 3 . A positive input of the amplifier U 3  is connected to a first end of the resistor R 10 . A second end of the resistor R 10  is connected to the resistor R 6 . An output of the amplifier U 3  outputs a conditioned signal V ST3  corresponding to a third seed type. The resistor R 11  and the capacitor C 6  are connected in parallel between the output of the amplifier U 3  and the node N 5 . 
     The third conditioning channel  420   c  has a selected gain and a selected bandwidth associated with the third seed type such as canola. Thus, the capacitances of the capacitors C 5 -C 6  and the resistances of the resistors R 9  and R 11  are selected such that the third conditioning channel  420   c  has the selected gain and the selected bandwidth. 
     As shown in  FIG. 4 , separate active band-pass filter circuits are illustrated for each seed type, where a resistor-capacitor feedback (e.g., parallel R-C circuit or pairs (C 3 , R 5 ; C 8 , R 13 ; C 6 , R 11 )) between the amplifier output and negative input of the operational amplifier and a series resistive-capacitive circuit (e.g., C 2 , R 4 ) at the negative input controls the frequency response of the filter. The gain of the operational amplifier can be controlled by a ratio of resistors (e.g., R 5 /R 4 , R 11 /R 9  and R 13 /R 12 ). 
     Referring back to  FIG. 2 , the conditioning circuit  230  sends the output of each conditioning channel V ST1 -V ST3  to the analog inputs of the controller  250 . 
     The processor  260  selects an output having a maximum non-saturated amplitude out of the outputs of the conditioning channels V ST1 -V ST3 . The processor  260  then determines a seed count value based on the selected conditioned signal V ST1 -V ST3 . The processor  260  may utilize a known/conventional method to analyze the selected conditioned signal V ST1 -V ST3  to determine the seed count value. 
     Moreover, a user may select which seed type is being planted. However, the controller  250  issues a warning if the selected channel saturates or outputs small amplitudes (i.e., the user selected the wrong seed type). The controller  250  may select the seed type based on which of the conditioned signals V ST1 -V ST3  satisfy expected values stored in the memory  265 . 
     In  FIG. 2 , the seed monitoring system includes a light source configured to emit light along a plane of an interior of a seed tube, a light receiver configured to receive the light and generate a sensing signal corresponding to the received light, the receiver opposing the light source on the plane of the interior of the seed tube, a processing system including a plurality of conditioning channels, the processing system configured to process the sensing signal using at least a selected one of the plurality of conditioning channels to generate a first conditioned signal and a controller configured to generate a seed count value based on the first conditioned signal. 
     In an example embodiment, the plurality of conditioning channels are connected to a common input and have a plurality of outputs, respectively, and the outputs are coupled to the controller. 
     In an example embodiment, the processing system further includes a preamplifier configured to amplify the sensing signal and output the amplified sensing signal to the common input. 
     In an example embodiment, the plurality of conditioning channels are associated with seed size ranges, respectively. 
     In an example embodiment, each of the plurality of conditioning channels has a selected bandwidth and a selected gain corresponding to the associated seed size range. 
     In an example embodiment, the seed size ranges are different. 
     In an example embodiment, the light receiver is a single photodiode. 
       FIG. 5  illustrates a seed monitoring system according to another example embodiment. 
     A seed monitoring system  500  includes a light source  510 , a plurality of light receivers  520   a ,  520   b ,  520   c , conditioning circuits  530   a ,  530   b ,  530   c  and a controller  550 . The controller includes an input/output (e.g., analog inputs)  555 , a processor  560  and a memory  565 . The memory may store a sector-based evaluator  567  and a photodiode alert module  569  as programs (i.e., instructions). The processor  560  may exchange data with the I/O  555  and the memory  565  using a data bus  570 . The processor  560  may execute instructions stored in the memory  565  to perform the functions described below. 
     The light source  510  emits light alone a plane of an interior of the seed tube  142 . The light source  510  may include an array of light emitting diodes (LEDs). 
     The light receivers  520   a - 520   c  receive the light and generate sensing signals V sens   _   a1 -V sens   _   an , V sens   _   b1 -V sens   _   bn , V sens   _   c1 -V sens   _   cn  from the amount of light received by the light receivers  520   a - 520   c.    
       FIG. 6  illustrates a cross-sectional view of a seed tube showing the light source  510  and the light receivers  520   a - 520   c  of the seed monitoring system  500  according to an example embodiment. 
     The light source  510  is positioned along one side  605   a  of the interior periphery of the seed tube  142  such that an emitter window  615  illuminates an entire interior area (planar sensing area)  610  along the x-y axis (i.e., a cross-section of the seed tube  142 ). The planar sensing area  610  is defined by sides  605   a ,  605   b ,  605   c  and  605   d  of the interior periphery. The light source  510  includes the emitter window body  615  secured within an emitter housing  620 . The emitter housing  620  includes an array Light Emitting Diodes (LED) or similar  625 , which is configured to generate constant light of a specific wavelength. For example, to avoid compromising the input values of the light receivers  520   a - 520   c , the LED may produce light in the Infrared (IR) range of the spectrum as to be distinguished from light contamination from visible light sources. The LEDs  625  may be mounted to a PC board with conductive strips forming electrical connections with the LEDs  625  mounted thereon. 
     Due to the sensors of the disclosed seed monitoring system being positioned on the tube  142  that transports seed and other materials from a storage tank to a field, exposure to significant dust and other particulates is certain. As such, the light source  510 , light receivers  520   a - 520   c  and any other electronic components described herein may be enclosed and sealed. However, to emit and detect light, the light source  510  and the light receivers  520   a - 520   c  use windows to allow light to pass through blocking contaminants. The sensor components are protected, but the windows are regularly exposed to particulates within the tube  142 , causing a gradual decline in receiver  220  signals. 
     Similar to the light source  510 , each of the light receivers  520   a - 520   c  may comprise one or more light sensors that are enclosed within a sealed housing  240 . Each receiver housing  540  includes a window  635  to allow light to pass through the sealed housing to the sensor. As will be appreciate, the light sensors may comprise one of several different types of light sensors. Varying technologies exist for measuring light and/or properties of light and the selection of a sensor type may be based on the specific implementation of the disclosed monitoring system. 
     Positioned at various other positions along the inside periphery  605  of the tube  142 , the light receivers  520   a - 520   c  each include a receiver window body  635  secured within the receiver housing  640 . 
     Each of the light receivers  520   a - 520   c  is divided into a plurality of light sensing segments  630 . Each of the light sensing segments  630  corresponds to a separate light sensor such as photodiode, phototransistor, and other semiconductor type cells or a segment of a light sensor and thus, has a separate output signal. The light sensing segments are on a same substrate with minimal spacing between the segments. For example, the outputs of the light sensing receiver  520   a  are I sens   _   a1 -I sens   _   an , with each of the light sensing segments outputting one of the sensing signals I sens   _   a1 -I sens   _   an . 
     Dust or other contamination on an optical sensing system scatters the light and changes its direction. In the prior art sensing system, contamination of a transmitter window diffuses the light, which changes the sensitivity pattern and causes false seed detection. 
     The light source  510  is configured to illuminate the light receivers  520   a - 520   c . The light source  510  uses wide beam LEDs  625 . As a result, the light source  510  and the light receivers  520   a - 520   c  form a planar sensing area. The area  610  may correspond to the planar sensing area. 
     As shown in  FIG. 7A , each of the light receivers  520   a - 520   c  is positioned to receive illumination through at least one sector within the planar sensing area  610 . 
       FIG. 7A  illustrates the planar sensing area  610  being divided into sectors  610   a ,  610   b ,  610   c  and  610   d . Due to the arrangement of the light receivers  520   a - 520   c , the light receiver  520   a  detects seeds in the sectors  610   a  and  610   b , the light receiver  520   b  detects seeds in the sectors  610   a ,  610   b ,  610   c  and  610   d ; the light receiver  520   c  detects seeds in the sectors  610   a  and  610   d.    
     As will be appreciated by those of ordinary skill in the art, the light source  510  may comprise an illumination source, which is housed within the enclosure  620 . Because an LED chip provides 360 degrees of planner illumination, the housing  620  is configured to restrict the illumination angle to 180 degrees. The window  615  is positioned on an open side of the housing  620  and may be produced from translucent plastic, glass, or mineral. The emitter window  615  may include a texture or additive during manufacture to diffuse light from the LEDs. 
     Dependent on the configuration of the light receivers  520   a - 520   c , the light source  510  may be configured to provide constant illumination. Moreover, the brightness of the light source  510  may be controlled by way of voltage adjustments for incandescent type light bulbs or by way of changing current for an LED. In embodiments where modification of light source  210  properties is desirable or used, the LEDs may be controlled by a driver circuit. 
     Although the side of the tube  142  having the light source  510  does not include a light receiver, the area in front of the light source  510  is also monitored due to the overlap in coverage of the illumination sectors  610   a - 610   d . This overlap effectively creates a forth “virtual” sector, which serves to square-in the planar area  610 . The planar area  610  is defined by having the light source  510  on the side  605   a  and having each of the light receivers  520   a - 520   c  positioned along the other three sides  605   b ,  605   c ,  605   d.    
       FIG. 7B  illustrates light sensing areas for the segments  530  in the light sensing receivers  520   a  and  520   c . As shown in  FIG. 7B , the segments  530  are segments  701   1 - 701   n  for the light receiver  520   a , segments  703   1 - 703   n  for the light receiver  520   b  and segments  705   1 - 705   n  for the light receiver  520   c . In  FIG. 7B , n equals four, but example embodiments are not limited thereto. 
     With respect to the light receiver  520   a , a sensing area of the segment  701   1  is defined by a line  715  and the light source  510 . A sensing area of the segment  701   2  is defined by lines  720  and  750 . A sensing area of the segment  701   3  is defined by lines  725  and  755 . A sensing area of the segment  701   n  is defined by lines  730  and  765 . 
     With respect to the light receiver  520   c , a sensing area of the segment  705   1  is defined by a line  710  and the light source  510 . A sensing area of the segment  705   2  is defined by lines  745  and  780 . A sensing area of the segment  705   3  is defined by lines  740  and  775 . A sensing area of the segment  705   n  is defined by lines  735  and  770 . 
     As a result, sensing areas of the light sensing receivers  520   a  and  520   c  overlap. 
     As shown  FIG. 7B , the sensing areas of the segments  701   1 - 701   n  and  705   1 - 705   n  are trapezoidal. 
     The segments  701   1 - 701   n  produce the sensing signals I sens   _   a1 -I sens   _   an , respectively. The sensing signals I sens   _   a1 -I sens   _   an  correspond to the light sensed by the respective segment. 
     The segments  705   1 - 705   n  produce the sensing signals I sens   _   c1 -I sens   _   cn , respectively. The sensing signals I sens   _   c1 -I sens   _   cn  correspond to the light sensed by the respective segment. 
       FIG. 7C  illustrates light sensing areas for the segments  703   1 - 703   n  in in the light sensing receiver  520   b.    
     A sensing area of the segment  703   1  is defined by line  786  and a surface of the light receiving element  520   a  that forms a boundary of the area  610 . A sensing area of the segment  703   2  is defined by lines  784  and  788 . A sensing area of the segment  703   3  is defined by lines  782  and  790 . A sensing area of the segment  703   n  is defined by line  780  and a surface of the light receiving element  520   c  that forms a boundary of the area  610 . The segments  703   1 - 703   n  produce the sensing signals I sens   _   b1 -I sens   _   bn , respectively. The sensing signals I sens   _   b1 -I sens   _   bn  correspond to the light sensed by the respective segment. 
     As shown  FIG. 7C , the sensing areas of the segments  703   1 - 703   n  are quadrilateral. 
     As shown in  FIGS. 5-7B , the monitoring system  500  includes three light receivers. In accordance example embodiments, three light receivers are capable of monitoring the planar space  610  within the tube and produce different signals depending on a seed location in the planar space  610 . An overlap in the sectors ensures that the entire space  610  is adequately covered and that clusters of passing seeds can be more accurately detected and counted. 
     The arrangement illustrated in  FIGS. 5-7B  is not limited to the discussion herein. For example, in another example embodiment, each light receiver  520   a ,  520   b  and  520   c  is not divided into segments. 
     In an example embodiment, each segment  701   1 - 701   n ,  703   1 - 703   n  and  705   1 - 705   n  includes a separate light sensor such as a photodiode. More specifically, to improve reliability for detecting and counting multiple seeds, each light receiver  520   a - 520   c  is divided in four segments  701   1 - 701   n ,  703   1 - 703   n  and  705   1 - 705   n , respectively, which acquire light independently. Each segment  701   1 - 701   n ,  703   1 - 703   n  and  705   1 - 705   n  detects the light source  510  output through a subsection of the sensing area and significantly increases the overlap in sensing areas of the segments. A seed that passes in an area that closely aligns with the vertical center of the light source  510  may cast a shadow on each of the light receivers  520   a - 520   c  and synchronous signals in all receivers indicate the seed in that area. Therefore, a pattern of simultaneous signals in some of receiver segments or channels is used for multiple seed detection and localization. 
     In another embodiment, detection of multiple passing seeds is facilitated by way of temporal analysis of light modulation. For example, a group of seeds crossing a sensing plane scatters light, thereby producing a modulation that is proportional to a number of seeds and time delays between the first and subsequent passing seeds. Differentiation of the modulated signal reveals fine features of the signal and allows more accurate detection of overlapping seeds. 
     Referring back to  FIG. 5 , the light receivers  520   a - 520   c  provide the sensing signals I sens   _   a1 -I sens   _   an , I sens   _   b1 -I sens   _   bn , I sens   _   c1 -I sens   _   cn  from the segments  701   1 - 701   n ,  703   1 - 703   n ,  705   1 - 705   n , respectively, to the conditioning circuits  530   a - 530   c . The conditioning circuits  530   a - 530   c  are associated with the light receivers  520   a - 520   c , respectively. Thus, the conditioning circuit  530   a  receives the sensing signals I sens   _   a1 -I sens   _   an . The conditioning circuit  530   b  receives the sensing signals I sens   _   b1 -I sens   _   bn . The conditioning circuit  530   c  receives the sensing signals I sens   _   c1 -I sens   _   cn . 
       FIG. 8  illustrates an example embodiment of the conditioning circuit  530   a . The conditioning circuit  530   a  is a four-segment amplifier having channels  805 ,  810 ,  815  and  820 . The channels  805 ,  810 ,  815  and  820  are the same. Therefore, for the sake of brevity, only the channel  805  will be described in detail. 
     The channel  805  includes a transistor U 80 , resistors R 80 -R 88 , capacitors C 80 -C 83  and amplifiers U 80 -U 81 . The conditioning circuit  530   a  receives the sensing signal I sens   _   a1  at a node N 80 . A base and a collector of the transistor U 80  are connected to the node N 80 . A first end of the resistor R 80  is connected to the node N 80  and a second end of the resistor R 80  is connected to a positive input of the amplifier U 80 . A first end of the resistor R 81  is connected to an emitter of the transistor U 80  and a second end of the resistor R 81  is connected to a node N 81 . A negative input of the amplifier U 80 , a first end of the resistor R 82  and a first end of the capacitor C 80  are connected to the node N 81 . An output of the amplifier U 80 , a second end of the resistor R 82  and a second end of the capacitor C 80  are connected at a node N 83 . A first end of the capacitor C 83  is connected to the output of the amplifier U 80  and a second end of the capacitor C 83  is connected to the first end of the resistor R 83 . A second end of the resistor R 83  is connected to a node N 84 , which is connected to a negative input of the amplifier U 81 . The resistor R 86  and the capacitor C 81  are connected in parallel between the node N 84  and a node N 85 , which is connected to an output of the amplifier U 81 . A positive input of the amplifier U 81  is connected to a first end of the resistor R 85 . A second end of the resistor R 85  is connected to a node N 86 . The resistor R 84  is connected to the voltage power supply Vpower at a first end and to the node N 86  at a second end. The capacitor C 83  and the resistor R 87  are connected in parallel between the node N 86  and ground. The resistor R 88  is connected to the node N 85 . The channel outputs the conditioned signal V ST   _   a1  at a second end of the resistor R 88 . 
     The conditioning circuits  530   b  and  530   c  are the same as the conditioning circuit  530   a . For the sake of brevity, the conditioning circuits  530   b  and  530   c  are not described in further detail. 
     Referring to  FIG. 5 , the conditioning circuits  530   a - 530   c  send the conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn  to the analog inputs of the controller  550 . 
     The processor  560  may execute a sector-based evaluator  567  to use a pattern of simultaneous amplitudes of the conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn  for multiple seed detection and localization. For example, patterns of simultaneous amplitudes (Sensitivity Map) for a single seed are generated by the controller  550  using principles of ray optics. Simplest patterns are produced by seeds which fall in corners of the tube. For example, if a seed falls in the right low corner ( FIG. 7B ) it induces signals only in the segments  703   1  and  701   n . A seed falling in the middle of the tube cannot induce signals in the segments  701   1 ,  701   2 ,  705   1  and  705   2 . Simultaneous signals in the segments  701   1 ,  701   2 ,  705   1  and  705   2  without signals in the receivers  703   n  and  705   n  indicate that two seeds are falling in opposite corners. 
     In another example embodiment, the processor  560  may detect multiple seeds using a temporal analysis of light modulation. More specifically, a group of seeds crosses the sensing plane  610  and scatters light producing a modulation that is proportional to a number of seeds and time delays between the first and the following seeds. The controller  550  may perform differentiation of the conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn  to detect overlapping seeds. 
     Moreover, the processor  560  executes the sector-based evaluator  567  (stored in the memory  565 ) to determine if any of the conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn    250  is saturated or outputs a small amplitude. If any of the conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn    250  is saturated or outputs a small amplitude, the processor  560  utilizes a photodiode alert module  569  (stored in the memory  565 ) to issue a warning that the selected channel saturates or outputs small amplitudes. 
       FIG. 9  illustrates a method of determining a seed count value and application rate according to an example embodiment. The method of  FIG. 9  may be performed by the system  500 . The method of  FIG. 9  is described as being performed by the system  500 . 
     At S 900 , the processor  560  selects the conditioned channels V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn  which correspond to a seed type and application rate for data analysis. More specifically, the processor  560  monitors the selected conditioned channels and detects time periods when valid signals (higher than a set threshold) appear simultaneously. The signals should overlap. 
     At S 905 , the processor  560  determines the signal pattern of the valid simultaneous signals of the selected conditioned channels. The processor  560  generates a pattern of simultaneous amplitudes at S 905 . 
     At S 910 , the processor  560  correlates the determined pattern with a sensitivity map of the sensor that is saved in the memory  565 . The sensitivity map is a plurality combinations of expected values for the conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn  based on various scenarios including a number seeds and locations of the seeds. 
     The processor  560  compares peaks of the selected conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn  to determine the location of the seeds. Simultaneous peaks for at least one of the selected conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn  indicates that a seed is present. Because each of the segments  701   1 - 705   n  is positioned in a different location around the planar sensing area  610 , the location of seed will affect the amount of light received by some of the segments  701   1 - 705   n . At a time point where at least one of the selected conditioned signals has a peak detected by the microprocessor  560 , the microprocessor compares the values of the selected conditioned signals at the time point of the peak. By comparing the values of the selected conditioned signals at the time point of the peak, the microprocessor  560  determines the location of the seed. For example, the microprocessor determines the ratios of the simultaneous values of the selected conditioned signals to each other. The ratios indicate a position of the seed. 
     The expected ratios of the selected conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn  for different positions of a seed within the planar sensing area  610  (signal patterns) are saved in the memory  565 . 
     If amplitudes in one of the channels are consistently lower than expected threshold values stored in the memory  565 , the processor  560  determines the channel is considered faulty and executes the PD alert module  569  to send a warning to an operator. 
     At S 915 , the processor  560  determines a seed application rate and seed count value  915 . S 915  is described in more detail with respect to  FIGS. 10A-10B . 
       FIGS. 10A-10B  illustrate a method of determining a seed count value according to an example embodiment. 
     At S 1000 , the processor  560  initializes variables chanNum, seedEvent, lastSeedEvent, numPeaks, peakNum, referenceTime, peakBufferCount and signatureCount. 
     At S 1005 , the processor  560  takes a sample of all of the conditioned signals V ST   _   a1 -V ST   _   an , V ST   _   b1 -V ST   _   bn , V ST   _   c1 -V ST   _   cn , sets the channel number chanNum to one and sets the seed event variable seedEvent to be false. 
     At S 1010 , the processor  560  determines if the channel number chanNum is greater than the number of conditioned signals (e.g., twelve). If the channel number chanNum is less than twelve, the processor  560  determines if the voltage of the sample of the channel number is greater than a threshold voltage at S 1015 . The threshold voltage may be determined based on empirical data. 
     If the voltage of the sample of the channel number is greater than the threshold voltage, the processor  560  determines if the last sample of the channel number was below the threshold at S 1020 . If the last sample was below the threshold, the processor  560  determines that the sample corresponds to an event start time for the channel number at S 1025 . The processor  560  then sets the seed event variable seedEvent to be true and copies the sample into an event buffer at S 1030 . The event buffer may be in the memory  565 . 
     If the last sample was not below the threshold, the processor  560  also proceeds to S 1030 . 
     At S 1035 , the processor increases the channel number chanNum by one. 
     If the voltage of the sample of the channel number is not greater than the threshold voltage at S 1015 , the processor  560  determines if the last sample of the channel number was above the threshold at S 1040 . If the last sample was not greater than the threshold voltage, the processor increases the channel number by one at S 1035 . If the last sample was above the threshold, the processor  560  determines that the sample corresponds to an event stop time for the channel number and sets the seed event variable seedEvent to be false at S 1045 . 
     At S 1050 , the processor  560  performs peak detection on the event buffer for the channel. The processor  560  monitors values of successive samples in the channel and, if after a rising sequence of values, the processor  560  sees two or three a number of values (e.g., two or three) of falling sequence the processor  560  records a peak for the channel and the time of the peak. 
     The processor  560  stores the times and associated channels of the peaks in the peak buffer. 
     At S 1055 , all channels have been analyzed by the processor  560 . Thus, a pattern of the channels is established. Once the channel number chanNum exceeds the number of channels, the processor  560  determines if the seedEvent is false (no seed was detected) and if the lastSeedEvent is true at S 1055 . If the condition is true at S 1055  the processor  560  processes the peak buffer at S 1060  and determines the number of seeds in the seed event (peakBufferCount). At S 1065  the processor  560  updates the totalSeedCount and starts new cycle by returning to S 1000 . 
       FIG. 10B  illustrates an example of processing the peak buffer. 
     At S 1100 , the processor  560  sorts the peak buffer according to the times of the peaks, sets the variable numPeaks to the number of peaks in the peak buffer, sets peakNum to one, sets referenceTime to the first time in the sorted buffer and sets peakBufferCount to zero. 
     At S 1105 , the processor  560  determines if the current peak number peakNum is greater than the number of peaks numPeaks. If the current peak number peakNum is not greater than the number of peaks numPeaks, the processor  560  determines if the time for the current peak number peakNum minus referenceTime is greater than a cluster threshold at S 1110 . The cluster threshold determines the maximum duration of a multi-seeds event. 
     If the difference between the time for the current peak number peakNum and referenceTime is less than or equal to the cluster threshold, the processor  560  adds the associated channel to a channel list and changes the current peak number by incrementing peakNum by one. 
     If the difference between the time for the current peak number peakNum and referenceTime is greater than the cluster threshold, the processor  560  updates referenceTime to be the time for the current peak number peakNum at S 1120  and analyzes the signature of the channel list and sets a new peak buffer count (number of seeds) to be the current peakBufferCount plus the signatureCount. A signature is a pattern of simultaneous signals in different channels that represent a seed event. Patterns are developed from the sensitivity map for single and multi-seeds events. The signatureCount represents a number of seeds in the seed event and the channel list includes all channels which are being analyzed during the seed event to determine a signature. Once the processor  560  has performed S 1120 , a multi-seed even has ended and the peakBufferCount transferred for S 1065 . 
     If the selected peak number peakNum is greater than the number of peaks numPeaks, the processor  560  analyzes the signature and determines a number of seeds in the event at S 1125 . More specifically, the processor sets a new peak buffer count (number of seeds) to be the current peakBufferCount plus the signatureCount. The method returns to S 1065 . 
     Referring back to  FIG. 10A , after the peak buffer is processed by the processor  560 , the processor  560  increases the total seed count value totalSeedCount by the peakBufferCount and sets the lastSeedEvent to be equal to the seedEvent at S 1065 . If the condition is false at S 1055 , the processor  560  proceeds to S 1065 . 
     According to an example embodiment, a seed monitoring system includes a light source configured to emit light along a plane of an interior of a seed tube, a plurality of light receivers around the plane of the interior of the seed tube, each of the plurality of light receivers configured to receive light in at least two sectors of a plurality of sectors of the plane and generate a sensing signal corresponding to the received light, a processing system including a plurality of conditioning channels, the processing system configured to process the sensing signals to generate conditioned signals and a controller configured to generate a seed count value based on the generated conditioned signals. 
     In an example embodiment, the controller is configured to determine positions of seeds within the seed tube based on the generated conditioned signals. 
     In an example embodiment, the seed tube includes a first wall, a second wall, a third wall and a fourth wall, the second wall is between the first wall and the third wall and the fourth wall is between the third wall and the first wall, the light source is on the first wall, and the plurality of light receivers are on the second wall, the third wall and the fourth wall, respectively. 
     In an example embodiment, each of the plurality of light receivers includes a plurality of light sensing elements, wherein each light sensing element is positioned to receive at least a portion of the light in the at least two sectors associated with the light receiver. 
     In an example embodiment, the light source and the plurality of receivers define the entire plane and the plurality of sectors cover the entire plane. 
     In an example embodiment, the controller is configured to detect an abnormality in at least one of the plurality of light receivers and generate the seed count value based on the generated conditioned signals from the other plurality of light receivers. 
     Example embodiments being thus described, it will be obvious that the same may be varied in many ways. For example, the system  200  may also take into account seed type when determining a seed count value. Such variations are not to be regarded as a departure from the spirit and scope of example embodiments, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the claims.