Animal Identification and Estrus Detection System

The field of the invention is automatic systems for indicating estrus in animals, and more particularly, systems for electronically indicating estrus in dairy cows.

The accurate detection of estrus in animals is a significant factor in reproductive efficiency where artificial insemination is used. When applied to dairy cows, accurate detection of estrus is an important factor in determining the total milk production of the herd. A number of estrus, or heat, detection methods are presently used, but by far the most widely used method is to observe either manually or with a video recorder, the activity of the cow. In a large dairy herd this practice becomes difficult and inefficient.

As reported in the Journal of Dairy Science Vol. 60, No. 2 by Charles A. Kiddy of the U.S. Department of Agriculture, cows are appreciably more active at estrus than at other times during the estrus cycle. This was confirmed by tests run in which pedometers were attached to the hind leg of a number of cows and their activity was monitored over a period of time. In these tests the pedometer counted the number of leg movements and the pedometer was visually read twice a day when the cow was milked. The number of counts at each reading were found to increase by a factor of three or more during estrus.

The present invention relates to an electronic system for detecting estrus in animals in which a transponder carried by the animal counts the number of body movements of the animal during a selected time period and this activity count along with an animal identification number is transmitted to a transceiver unit where the data is processed and stored. More particularly, the electronic system includes a transponder attached to the animal which contains a motion detector, a digital counter, means for storing a preselected animal identification number and means responsive to an interrogation signal received from a transceiver for transmitting the activity count and the animal identification number to the transceiver. The transceiver incudes means for generating the interrogation signal and means for receiving, decoding and visually displaying the activity count and the animal identification number transmitted by the transponder.

The transponder unit is attached to the animal and the transceiver unit is positioned at a location which the animal periodically frequents. When applied to dairy cows, for example, the transponder may be in the form of a tag which is attached to a chain around the animal's neck. The transmit and receive coils of the transceiver may be positioned at the entrance to the milking parlor. In the early morning and evening the cow enters the milking parlor and passes by the transceiver coils. The transponder carried by the animal is interrogated and the identity of the cow along with the activity count, which indicates the number of substantial movements of the animal during the preceeding time period, is transmitted by the transponder and received at the receive coil. These numbers are recorded and the farmer may easily review them periodically to determine which cows are unusually active.

A general object of the invention is to provide a practical electronic system for detecting estrus in animals. The transponders must be low in cost, mechanically rugged and electrically reliable. Obviously the surroundings in which the system will operate demands that special measures be taken to insure proper operation over a wide temperature range, in an electrically noisy environment, and after repeated, sever physical shock. In addition, the economic environment requires that the system be competitive in cost with other methods of estrus detection.

A more specific object of the invention is to add estrus detection to the animal identification system disclosed in my co-pending U.S. patent application Ser. No. 815,796 filed July 15, 1977 and entitled "Animal Identification System," now U.S. Pat. No. 4,129,855.

The foregoing and other objects and advantages of the invention will appear from the following description. In the description reference is made to the accompanying drawings which form a part thereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such description does not necessarily represent the full scope of the invention, and reference is made to the claims herein for interpreting the breadth of the invention.

FIG. 1 is an electrical schematic diagram of the estrus detection system of the present invention;

FIG. 2 is an electrical schematic diagram of the transponder unit which forms part of the system of FIG. 1;

FIG. 3 is a flow chart of the system software executed by the microprocessor which forms part of the system of FIG. 1;

FIG. 4 is a flow chart of the PIO interrupt service routine which forms part of the system software of FIG. 3;

FIG. 5 is a schematic representation of the physical arrangement of the transceiver transmit and receive coils which form part of the system of FIG. 1; and

FIG. 6 is a memory map of the contents of a random access memory which forms part of the system of FIG. 1.

The system of the present invention employs the concept and much of the identical circuitry disclosed in my co-pending Animal Identification System patent application cited above and the disclosure of that co-pending application is hereby incorporated by reference.

Referring to FIG. 1, the system of the present invention includes a transponder unit indicated by the dashed lines 1 which is enclosed in a molded plastic case (not shown in the drawings) and which is attached to a chain that hangs around the neck of the animal. The system also includes a transceiver unit indicated by the dashed line 2 which is housed in an enclosure and positioned near the location which the animal frequents. When the animal approaches the vicinity of the transceiver unit 2, the transponder unit 1 carried by the animal is interrogated by an electromagnetic signal generated by a count transmitter coil 3 which is connected to the transceiver 2. The transponder unit 1 includes a count receive coil 4 and the transponder unit 1 is responsive to the interrogation signal to generate a series of reset pulses at a reset pulse transmitter coil 5 which indicate both the identity of the animal and the activity count of the animal. The reset pulses generated by the transponder unit 1 are received by a reset pulse receive coil 6 which connects to the transceiver unit 2. As will be described in more detail below, the transceiver unit 2 operates to decode the reset pulses to provide an animal identification number and an animal activity number which are generated in digital form to a character printer 7.

The physical construction of the transponder unit 1 including its count receive coil 4 and its reset pulse transmitter coil 5 is discussed in detai in my above cited co-pending patent application. In the present embodiment of the invention, however, the count transmitter coil 3 and the reset pulse receive coil 6 associated with the transceiver unit 2 are not located at individual feeding stations as disclosed in my prior application, but are instead, located at the entrance to the milking parlor. Referring particularly to FIG. 5, the count transmitter coil 3 and the reset pulse receive coil 6 are significantly larger and are attached to a door frame 8 which surrounds the entrance to the milking parlor. The coils 3 and 6 form an archway through which the animals pass on the way to the milking parlor and it is at this moment that the transponder unit 1 carried by the animal is interrogated and the animal activity count and animal identification number are conveyed to the transceiver unit 2. The physical characteristics of the count transmitter coil 3 and the reset pulse receive coil 6 are provided in Table A.

Referring again to FIG. 1, the transceiver unit 2 employs the concept disclosed in my above cited co-pending patent application. It includes an oscillator 10 which generates 800 kHz clock pulses to the input of a first divide by thirty-two counter 11 and to the input of a second divide by thirty-two counter 12. The output of the first counter 11 is a 25 kHz pulse train which is applied to the input of an a.c. amplifier 13. A pair of output terminals 14 and 15 on the a.c. amplifier 13 connect to the count transmitter coil 3, and the count transmitter coil 3 thus generates a continuous, unmodulated 25 kHz interrogation signal.

The output of the second divide by thirty-two counter 12 connects through an inverter gate 16 to the clock terminal 17 of a seven stage ripple counter 18. The counter 18 is thus incremented at a rate of 25 kHz in synchronizm with the 25 kHz signal generated by the count transmitter coil 3. The resulting count at any point in time appears at a set of seven output terminals which connect through leads 19 to the input port of a parallel input/output circuit (PIO) 20.

The transponder unit 1 is responsive to the 25 kHz signal generated by the count transmitter coil 3 to generate reset pulses to the reset pulse receive coil 6 which connects to the transceiver 2. Each reset pulse is a burst of 200 kHz electromagnetic energy which is applied to the inputs 21 and 22 of an a.c. amplifier and pulse detector 23. A capacitor 24 connects across the coil 6 to tune it to 200 kHz. The 200 kHz burst is amplified by the amplifier 23 and a reset pulse of approximately 20 microsecond duration is formed therefrom and generated at a detector output terminal 31. This detected reset pulse is applied to an STB terminal 25 on the PIO 20 and the binary number stored in the counter 18 at that moment is gated into and stored in the PIO 20. The PIO 20 also responds by generating a logic high voltage at a RDY terminal 26 and this voltage is applied to the input of a monostable multivibrator circuit 27. The Q output 28 on the monostable multivibrator circuit 27 connects to a reset terminal 29 on the counter 18 and to a reset terminal 30 on the divide by thirty-two counter 12.

The operation of the transceiver circuitry thus far described is virtually identical to the operation of the transceiver circuit described in my above cited co-pending patent application. The oscillator 10 is continuously running and the ripple counter 18 is thus continuously incremented. When no transponder unit 1 is in the vicinity of the transceiver coils 3 and 6, the ripple counter 18 repeatedly counts out and resets to zero, but its output is not entered into the PIO 20. When an animal carries a transponder unit 1 into range, however, the transponder unit 1 generates reset signals to the transceiver coil 6. The first reset pulse formed from the reset signals is applied to the PIO 20 and the contents of the ripple counter 18 is loaded into the PIO 20. More importantly, however, the first reset pulse resets the counter 18 to zero to synchronize it with a similar counter in the transponder unit 1 as taught by my prior patent application. The ripple counter 18 continues to be incremented by the oscillator 10, and as subsequent reset signals are received from the transponder unit 1, the contents of the counter 18 are inputted to the PIO 20 and the counter 18 is reset. A series of four-bit binary numbers are thus entered into the PIO 20 after the counter 18 is synchronized with the transponder 1. This series of four-bit bytes includes a flag byte, four data bytes which identify the animal carrying the transponder unit 1, and two data bytes which indicate the activity of the animal.

The transceiver unit 2 continuously interrogates the transponder unit 1 when it is within range of the count transmitter coil 3. The animal identification number and activity number are received repeatedly as the animal enters the milking parlor. As will be described in more detail hereinafter, noise immunity is achieved by requiring that four identical series of animal identification and animal activity bytes are received by the PIO 20 before the data is acknowledged to be valid and is acted upon.

Referring particularly to FIG. 2, the transponder unit 1 of the present invention employs the concept disclosed in my above cited co-pending patent application, but because both an identification number and an activity number are involved, the particular circuitry is different.

The interrogation signal received at the count receive coil 4 is applied across the input terminals of a full-wave bridge rectifier circuit 35. A capacitor 38 is connected in parallel with the count receive coil 4 and its value is selected to tune the resulting tank circuit to 25 kHz. One output terminal on the rectifier circuit 35 is connected to signal ground and its other output connects to a positive d.c. supply terminal 39. A filter capacitor 40 also connects to the positive d.c. supply terminal 39 as does a 5.6 volt battery 41.

One lead of the coil 4 is also connected directly to the clock terminal 36 of a four-bit presettable counter 37. When a 25 kHz interrogation signal is received at the transponder coil 4, it is rectified by the circuit 35 and the positive portion of each cycle is applied to the clock terminal 36 of the counter 37. The four-bit presettable counter 37 is preset to a selected count through a set of four terminals D.sub.1, D.sub.2, D.sub.3 and D.sub.4 and it is counted down by the rectified 25 kHz interrogation signal. When the counter 37 is counted down to zero, a logic high voltage is generated at an output terminal 42 which is applied to its own preset enable terminal 47.

This logic high voltage is also applied to the input of an inverter oscillator circuit which includes the reset pulse transmitter coil 5, a capacitor 43 and a set of three inverter gates 44-46. The series resonant circuit formed by the reset pulse transmitter coil 5 and the capacitor 43 is tuned to 200 kHz, and each time the output of the four-bit presettable counter 37 goes high, a burst of 200 kHz energy is inductively coupled by the reset pulse transmitter coil 5 to the transceiver unit 2. After the first such reset signal is transmitted, the presettable counter 37 becomes synchronized with the counter 18 in the transceiver unit 2. During subsequent intervals between reset signals, therefore, the counter 37 is counted down from a preset four-bit binary number and the counter 18 is counted up to the very same number. In this manner, a series of four-bit binary numbers loaded into the presettable counter 37 through its terminals D.sub.1 -D.sub.4 are effectively transmitted to the transceiver unit 2 and loaded into the PIO 20.

The output terminal 42 of the four-bit presettable counter 37 is also connected to a clock terminal 48 on a decade counter 49. The decade counter 49 includes ten output terminals Q.sub.0 -Q.sub.9 and a carry output terminal 50. The decade counter 49 is employed as a ring counter in which a logic high voltage is advanced along the output terminals Q.sub.0 -Q.sub.9 each time a logic high voltage is received at the clock terminal 48. That is, a "one" appears at the output Q.sub.0 and is shifted to the output Q.sub.1 when a logic high voltage is applied to the clock terminal 48. It is shifted to the output terminal Q.sub.2 when another logic high voltage is applied to the clock terminal 48, and it is advanced through the remaining outputs Q.sub.3 -Q.sub.9 as subsequent signals are applied to the clock terminal 48. When the "one" reaches the output Q.sub.5 a logic high voltage is generated at the carry terminal 50 and this terminal remains at a logic high voltage until the "one" is shifted through the remaining outputs Q.sub.6 -Q.sub.9 back to the output terminal Q.sub.0.

The decade counter 49 serves to sequentially apply four-bit bytes of data to the present terminals D.sub.1 -D.sub.4 on the counter 37. The preset inputs D.sub.1 -D.sub.3 connect through a set of lines 51-53 to the outputs of a three channel, two-line-to-one-line multiplexer 54 and to a set of three pull down resistors 55-57. The preset inputs D.sub.1 -D.sub.3 are thus held at a logic low voltage by the resistors 55-57 unless a logic high voltage is applied to them by the multiplexer circuit 54 or by the decade counter 49 through selectively connected diodes.

For example, the Q.sub.0 output on the decade counter 49 is connected through a set of three diodes 58 to the respective preset input terminals D.sub.1 -D.sub.3 and through an inverter gate 59 to the preset input terminal D.sub.4. When the "one" circulated by the decade counter 49 appears at the Q.sub.0 output terminal, the preset terminals D.sub.1 -D.sub.3 are driven to a logic high voltage and the preset terminal D.sub.4 is driven low. The four-bit presettable counter 37 is thus preset to the number seven and a logic high voltage will not be generated at the counter output terminal 42 until seven 25 kHz pulses have been applied to its clock terminal 36. When this occurs the decade counter 49 is advanced to generate its "one" at the Q.sub.1 output terminal. This first byte of data (i.e., the number seven) serves as a flag byte which identifies the beginning of the sequence of bytes to follow.

The following four outputs Q.sub.1 -Q.sub.4 on the decade counter 49 are "programmed" by means of diodes 60-62 to generate four bytes of data which comprise a unique identification number. In the preferred embodiment shown in FIG. 2, the Q.sub.1 output is not connected to any of the lines 51-53, the Q.sub.2 output is connected through diodes 60 to lines 51 and 53, the Q.sub.3 output is connected through a diode 61 to the line 53 and the Q.sub.4 is connected through a diode 62 to the line 52. As the "one" is advanced through the decade counter output terminals Q.sub.1 -Q.sub.4, therefore, the digits "zero," "five," "four," and "two" (i.e., I.D. No. 1320) are sequentially applied to the preset input terminals D.sub.1 -D.sub.3 on the presettable counter 37 and effectively coupled to the transceiver 2. It should be apparent to those skilled in the art that by selectively connecting diodes between the decade counter output terminals Q.sub.1 -Q.sub.4 and the three lines 51-53 that any animal identification number from 0 to 4095 can thus be programmed.

After the decade counter 49 has been advanced through its outputs Q.sub.0 -Q.sub.4 and the flag byte and the four animal identification bytes have been coupled to the transceiver unit 2, the "one" is advanced through the counter outputs Q.sub.5 and Q.sub.6. When this occurs two three-bit bytes of a six-bit "activity number" are applied to the presettable counter 37. More specifically, the Q.sub.6 output of the decade counter 49 is connected to the select terminal 65 on the multiplexer 54 and the carry output terminal 50 on the decade counter 49 is connected to the enable terminal 66 on the multiplexer 54. Three input terminals 67 on the multiplexer 54 connect to the three most significant digit output terminals 68 on a fourteen-bit binary counter 69 and the second set of three input terminals 70 on the multiplexer 54 connect to the next three most significant digit output terminals 71 on the binary counter 69.

When the "one" in the decade counter 49 is generated at its Q.sub.5 output terminal, a logic high voltage is generated at its carry output terminal 50 and is applied to enable the multiplexer circuit 54. The multiplexer select terminal 65 is at a logic low voltage, and as a result, the three least significant digits of the six most significant digits stored in the fourteen-bit binary counter 69 are coupled through the multiplexer input terminals 70 on the lines 51-53 which drive the preset inputs D.sub.1 -D.sub.3 on the presettable counter 37. After that three-bit number has been counted down to zero by the counter 37, the "one" in the decade counter 49 is advanced to the Q.sub.6 output terminal and the select terminal 65 on the multiplexer 54 is driven to a logic high voltage. As a result, the three most significant digits stored in the fourteen-bit binary counter 69 are coupled through the multiplexer inputs 67 to the lines 51-53 and are applied to the preset inputs D.sub.1 -D.sub.3 on the presettable counter 37. A six-bit binary coded activity number is thus indicated to the transceiver 2 following its receipt of the flag byte and the animal identification number.

The fourteen-bit binary counter 69 is driven by a motion sensing device which generates a logic high voltage to a clock input terminal 72 each time the animal carrying the transponder unit 1 makes a significant movement. More specifically, one lead of a mercury switch 73 connects to the clock terminal 72 through a filter comprised of capacitor 74 and resistor 75. The other lead on the mercury switch 73 connects to the positive d.c. supply terminal 39 and a reset terminal 76 on the fourteen-bit binary counter 69 is connected to signal ground. The mercury switch 73 is a commercially available product which includes a glass envelope 77 that contains a bead of mercury 78.

The transponder unit 1 is preferably attached to a chain around the animal's neck, and as the animal walks, the transponder unit 1 swings. The bead of mercury 78 is thrown about within the envelope 77 by this swinging motion and it opens and closes the switch 73 by bridging across two stationary terminals 79 and 80. Each time the switch 73 is closed, a logic high pulse is applied to the fourteen-bit binary counter 69 and the fourteen-bit binary number stored therein is incremented one count. The fourteen-bit binary counter 69 is thus continuously incremented and when the animal approaches the vicinity of the transceiver 1, the six most significant digits of the counter 69 are read out and coupled to the transceiver 1. The binary counter 69 is not reset after each reading, but is instead, automatically reset to zero when it reaches its maximum count.

To summarize the operation of the system, when the transponder unit 1 comes within range of the transceiver unit 2, interrogation pulses are applied to the four-bit presettable counter 37 in the transponder unit 1. These 25 kHz pulses are simultaneously applied to the counter 18 in the transceiver unit 2. These two counters become synchronized with one another after the presettable counter 37 is counted down to zero and the first reset pulse is generated back to the transceiver unit 2. The presettable counter 37 is immediately preset with another number and as it is counted down to zero by the 25 kHz pulses, the counter 18 in the transceiver unit 2 is synchronously counted up from zero. At the moment the presettable counter 37 reaches zero and transmits a reset pulse back to the transceiver 2, the counter 18 has reached the same count which was preset into the presettable counter 37. This count is loaded into the PIO 20 and processed by the microprocessor system now to be described. In this manner, the four-bit bytes of data applied to the preset input terminals D.sub.1 -D.sub.4 of the presettable counter 37 are sequentially loaded into the PIO 20 and processed to form an animal identification number and an animal activity number. The number "seven" applied to the presettable counter 37 when the "one" is generated at the Q.sub.0 output of the decade counter 49 serves as a flag, or keying byte. That is, the four data bytes which follow this keying byte constitute the animal identification number and the next two data bytes constitute the activity number.

While the transponder 1 is within range of the transceiver 2, the system continuously cycles through the sequence of coupling the flag byte, the four animal identification bytes, the two animal activity bytes, and the three unused bytes (i.e., outputs Q.sub.7 -Q.sub.9 of the decade counter 49). It is one of the features of the present invention that this data is not acted upon until four identical cycles are received. As a result, the system is relatively immune from electrical noise commonly found in the farm environment which may otherwise disturb the transmission and reception of a single byte.

Referring to FIG. 1, the four-bit bytes of data sequentially loaded into the PIO 20 are processed by a microprocessor based system which is structured around an eight-bit data bus 80 and a sixteen-bit address bus 81. A model number Z-80 microprocessor manufactured by Zilog is employed and it is directly coupled to the PIO 20 through the data bus 80, the address bus 81 and a set of control lines indicated generally at 82. The timing of the system elements is coordinated by a single phase clock 89 which operates at 2 MHz. An eight-bit by 2K read-only memory 83 is also connected to the microprocessor 84 through the buses 80 and 81 and through selected control lines. Similarly, an eight-bit by 512 line random access memory 85 is coupled to the microprocessor 84. The read-only memory 83 stores the machine instructions which are executed by the microprocessor 84 to carry out the data processing functions which will be described hereinafter, and the random access memory 85 stores data which is operated upon during processing.

A serial I/O controller (SIO) 86 driven by a 1200 kHz clock 89 also connects to the data bus 80 and the address bus 81. The SIO 86 is coupled through an RS-232-C line driver 87 to an alpha-numeric printer 7 and when the SIO circuit 86 is addressed through the bus 81 and enabled through control lines WR and IORQ, it outputs a seven-bit ASCII character to the printer 7. The interface circuit 87 operates to generate the seven-bit ASCII character serially over a line 88 and this line may be up to 50 feet in length. The printer 7 may therefore, be located remotely from the transceiver unit 2, which is particularly advantageous in a farm environment.

The microprocessor 84 sequentially reads machine instructions out of the read-only memory 83, and in response to operation codes in these instructions, it performs a number of functions. These functions include reading in bytes of data from the PI0 20, performing calculations on such data and writing partial results into the random access memory 85. The ultimate results of these calculations, the animal identification number and animal activity number, are outputed to the printer 7.

For a more detailed description of the instruction set employed by the microprocessor 84 and the manner in which the microprocessor 84 operates the PIO 20, the SIO 86 and the memories 83 and 85, reference is made to the Z80-CPU Technical Manual published in 1976 by Zilog.

The detailed functions performed by the data processor system is best explained with reference to the flow charts shown in FIGS. 3 and 4. These flow charts represent the functions carried out by the microprocessor 84 in response to machine instructions stored in the read-only memory 83, and for a detailed listing of these machine instructions, reference is made to Appendix A.

Referring particularly to FIG. 3, after the microprocessor 84 executes a series of instructions which initialize the system as indicated by process block 90, the system halts and waits for an interrupt as indicated by a process block 91. When a byte of data is loaded into the PIO 20, an interrupt request is generated to the microprocessor 84 and the system is vectored, or jumped, to a PIO interrupt service routine indicated in FIG. 3 by a process block 92. A flow chart of the PIO interrupt service routine 92 is shown in FIG. 4 and this flow chart will now be described in conjunction with the memory map of the random access memory 85 shown in FIG. 6.

The PIO interrupt service routine first disables further interrupts and then saves the contents of the microprocessor registers as indicated by process block 93. The eight-bit byte of data from the PIO 20 is then input to the microprocessor 84 as indicated by input block 94 and the least significant bit (i.e., bit zero) of a status register 98 stored in the random access memory 85 is then examined as indicated by decision block 95 to determine if it is equal to one. This particular bit in the status register 98 indicates whether or not the flat byte has previously been received from a transponder, and if it has, the value of the presently received byte is determined as indicated by decision blocks 101 and 102. On the other hand, if bit zero of the status register 98 is not equal to one, the presently received byte is examined, as indicated by decision block 96, to determine whether it is the flag byte. If it is not, the data is meaningless and the routine returns through a set of instructions indicated by process block 97. But if it is the flag byte, bit zero of the status register 98 is set to "one" and a byte counter 99 also stored in the random access memory 85 is set to zero. The machine instructions which accomplish these functions are indicated collectively in FIG. 4 by a process block 100. After these functions are completed the system returns through the process block 97 which includes instructions that enable further interrupts and reloads the microprocessor registers with the data they contained when the PIO interrupt service was first entered.

Referring again to FIG. 3, when the system returns from the PIO interrupt service routine instructions indicated by decision block 103 are executed to determine if bit 1 of the status register 98 has been set to one. As will be explained below, this does not occur until the flag byte, four bytes of the animal identification number and two bytes of the activity number are successfully received. Consequently, until all of this data is received, the system branches back to the process block 91 and awaits the next interrupt from the PIO 20.

Referring again to FIG. 4, when the next byte of data is input from the PIO 20 it is examined by instructions indicated by decision blocks 101 and 102 to determine its value. If it has a value greater than 15 as determined by decision block 101, an error has occurred and the system branches to a set of instructions indicated by a process block 104. These instructions reset bit zero of the status register to zero, and as a consequence, another flag byte must be received and the sequence restarted. Similarly, if the received byte is less than seven as determined by decision block 102, an error has occurred and the system branches back through process block 104 and process block 97. If on the other hand, the value of the data byte is greater than seven it is valid data and it is saved in a microprocessor "stack."

Instructions indicated by decision blocks 105 and 106 are then executed to determine which of the six data bytes it is. This is determined by examining the value of the byte counter 99 stored in the random access memory 85. If the byte counter is less than four as determined by decision block 106, the data is part of the animal identification number. In such case the byte counter 99 is incremented one count as indicated by process block 107 and the three least significant bits of the received byte are shifted into the upper end of the microprocessor B and C registers (not shown in the drawings). The system returns through the process block 97 and awaits the receipt of the next interrupt from the PIO 20.

After the four bytes which comprise the animal identification number have been received and shifted into the microprocessor B and C registers, the byte counter is greater than four when the system reaches decision block 106. The next two bytes of data are the activity number and these are shifted into the microprocessor D register (not shown in the drawings) as indicated by process block 109. The byte counter 99 is incremented as indicated by process block 110 and when it reaches the value of six, as determined during the next interrupt by decision block 105, the system branches to a set of instructions indicated by process block 111. These instructions right justify the animal identification number in the B and C registers and the animal activity number in the D register. As indicated by process block 112, bit one of the status register 98 is then set to one to indicate that a complete transmission has occurred. The animal identification number is then stored in the random access memory 85 at a location 113 and the activity number is similarly stored in the random access memory 85 at a location 114. The system then returns through process blocks 104 and 97.

Referring again to FIG. 3, when a complete transmission has occurred, bit one of the status register 98 has been set by the PIO interrupt service routine 92 and the system branches at decision block 103 to determine whether five successive, identical transmissions of the animal identification and activity numbers have occurred. More particularly, an instruction indicated by decision block 116 examines the contents of a transmission counter 120 to determine if this is the first successful data transmission. If it is, the system branches directly to a set of instructions indicated by process block 117, which transfers the ID number stored in register 113 to a previous ID number register 118 contained in the random access memory 85, and which transfers the activity number at location 114 to a previous activity number register 119. The transmission counter 120 is then incremented one count as indicated by process block 121 and it is then examined by instructions indicated by decision block 122 to determine if the fifth successful data transmission has occurred. If not, the system branches back to process block 91 to await the next interrupt from the PIO 20.

After subsequent complete transmissions of the animal identification number and the animal activity number have taken place as determined by decision block 103, the system branches to determine if the transmitted data is identical to previous data transmissions. More specifically, the newly received animal identification number is first compared with the previously received animal identification number stored in the register 118 by a set of instructions indicated by decision block 123. If they are identical, the system proceeds to a second set of instructions indicated by decision block 124 which compares the newly received animal activity number with the previous activity number stored in the register 119. If either one of these two numbers does not identically compare, the system branches to a set of instructions indicated by process block 125 which reset the transmission counter to zero and loops back to process block 91 to await the next interrupt from the PIO 20. That is, when a transmission error has occurred, the system is reset so that the entire process is repeated.

When five successive identical transmissions of the animal identification number and the animal activity number have occurred, as determined by the decision block 122, the numbers are presumed accurate and the system branches at decision block 122 to instructions indicated by process blocks 126, 127 and 128 which output these numbers to the printer 7. More specifically, instructions indicated by process block 126 first subtract the activity number from the activity number which was transmitted when the animal's transponder was previously interrogated. It will be recalled that the fourteen-bit binary counter 69 in the transponder unit is not reset after each successful transmission, and hence, it is the difference between the last reading and the present reading which is of value in measuring the animal's activity. This calculated activity number as well as the animal identification number are then converted to BCD digits and are loaded into a print buffer as indicated by process block 127. A printer driver routine is then called to output these digits in the proper order and format to the printer 7.

It should be apparent that numerous variations can be made from the preferred embodiment of the invention described herein. A microprocessor based transceiver is preferred because it is an inexpensive and reliable means of making the needed calculations and performing the error detection functions. However, hardwired circuits could also be employed. Also, the time multiplexed transmissions of 3-bit bytes of the animal identification number and animal activity number is desirable because of the large number of animals which are to be identified. If fewer animals, for example sixteen, were involved, a single ten-bit presettable counter in the transponder could be loaded with the six-bit activity number and a four-bit identification number. This number might then be transmitted all at once back to the transceiver when interrogated. When larger animal identification numbers are required, however, it takes too long to count down the resulting large presettable counter. By breaking down the numbers into bytes which are sequentially transmitted to the transceiver and reassembled, the time needed to communicate both numbers is shortened considerably. This allows the animal transponder to be interrogated many times as it passes the transceiver coils and this in turn enables the use of redundant transmissions as a means of eliminating erroneous data.