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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a range finding device particularly useful in
golfing to measure the distance to the green which the golfer is
approaching.
2. Description of the Prior Art
After teeing off on a typical four or five-par hole, the golfer is often
left with a second shot of up to 200 yards or more. In selecting the club
for the next shot, it is important for the golfer to accurately determine
the distance to the pin on the green, so that he may reach the green
without overshooting, or undershooting.
There have been several methods of ascertaining the distance to the pin. By
far the most common method is simply to estimate the distance based upon
prior knowledge of the particular golf course or based upon certain
landmarks adjacent to the fairway. Such estimates are typically very
inaccurate.
Another approach in determining the yardage to the green for the golfer's
next shot is for the golfer to pace off the distance one step at a time,
and then estimate that each step is a yard. This procedure is extremely
time consuming, and thus detracts from the enjoyment of the game by the
following group of golfers.
A few hand-held devices have been developed for the golfer to use in
distance determination. For example, one particular type of range finder
is a slide viewing window having a vertical extent calibrated in yards
while the space between the upper and lower viewing lines is adjusted. The
golfer sights through an opening in the range finder and adjusts the upper
and lower viewing lines until they correspond substantially to the upper
and lower extent of the pin located on the green. Once this is done, the
viewer looks to the side of the indicator to read the range in yards,
thereby allowing him to select the appropriate club for his next shot.
While this is a comparatively simple device, it still requires a
relatively steady hand of the golfer to hold the sight window in place
while aligning the upper and lower movable lines.
Another range finding device is disclosed in U.S. Pat. No. 3,868,692, one
of the coinventors thereof being a coinventor of the present invention.
That device comprises a portable unit adapted to receive a RF signal
emitted by a transmitter on the pin and to estimate the distance to the
pin based on the intensity of the signal. While this device is superior to
other prior art devices, it still lacks sufficient accuracy.
None of these prior art devices take into account the effects of the wind
in the determination of the distance to the pin. Any head wind or tail
wind can effectively increase or decrease the distance for the purposes of
club selection. Furthermore, a cross wind may require shot placement to
the left or right of the pin. In addition, all of the prior art range
finding devices require the golfer to estimate the proper club selection
based upon the indicated yardage.
SUMMARY OF THE INVENTION
It is among the objects of the present invention to provide a golf distance
indicator system which overcomes the limitations, complications and
inaccuracies of the prior art methods and devices. The system of this
invention includes a remote unit to be carried by the golfer, which remote
unit is compact, lightweight and easy to use. The golf yardage indicator
is highly accurate, being capable of measuring from the golfer to the hole
to within an error of 2 percent. The design of the distance indicator
system utilizes LSI and MSI technology to provide small, lightweight and
highly reliable units. The remote unit takes into account the wind
direction and strength and provides a wind corrected distance measurement
to the golfer, so that the golfer receives an indication of the effective
distance to pin and of the lateral distance to the side of pin to which
the shot must be placed in order to compensate for cross drift of the ball
in flight. In addition, the unit automatically displays the proper club
selection to the golfer based upon the effective distance to the pin
corrected for wind condtions.
These and other objects are accomplished by the present invention which
provides a golf distance indicator system having a base unit mounted at or
near the point on the green and a remote unit carried by the golfer. Upon
command, the remote unit transmits a radio frequency (RF) pulse to the
base unit. The base unit immediately returns an acoustic or sonic signal,
preferably an ultrasonic signal, in response to the received RF pulse.
The remote unit includes internal circuitry for determining the distance
from the base unit to the remote unit from the time interval between the
transmission of the RF pulse and the reception of the ultrasonic signal
based upon the speed of sound through air since the radio signal travels
essentially instantaneously. This circuitry includes an oscillator for
producing a timing singnal having frequency related to the speed of sound.
Preferably, the timing signal has one cycle for each yard travelled by the
sound wave. A counter which counts the oscillations of the timing signal
is enabled simultaneously with the transmission of the RF pulse and is
disabled in response to the reception of the ultrasonic signal. The actual
distance measurement in yards is then read directly from the counter.
The golf distance indicator system includes the capability to input wind
direction and wind strength conditions in the remote unit, from which the
unit circuitry determines corrections in effective range and direction of
the shot due to the wind. In addition, the remote unit automatically
selects the proper club for the shot based upon the wind corrected
distance.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective diagrammatic view illustrating the relationship
between the base unit and the remote unit of the golf yardage indicator
system of the present invention in measuring the actual distance between
the golfer and the pin on the green being approached.
FIG. 2 is a perspective view of the remote unit of FIG. 1 to a larger scale
illustrating its external features.
FIG. 3 is a perspective view of the base unit of FIG. 1 to a larger scale
and of the flag pole on which it is mounted.
FIG. 4 is a diagrammatic block diagram illustrating the internal operation
of the remote unit of FIG. 2.
FIG. 5 is a detailed circuit diagram of a portion of FIG. 4 including the
switching and encoding unit.
FIG. 6 is a detailed circuit diagram of a portion of FIG. 4 including the
distance determination unit.
FIG. 7 is a timing sequence diagram illustrating the operation of the
distance determination unit of FIG. 6.
FIG. 8 is a detailed circuit diagram of a portion of FIG. 4 including the
wind measurement and wind correction units.
FIG. 9 is a detailed circuit diagram of a portion of FIG. 4 including the
distance correction unit, the club selection unit and the display unit.
FIG. 10 is a detailed circuit diagram illustrating the internal operation
of the base unit of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring initially to FIG. 1, the golf distance indicator system of the
present invention comprises a hand-held remote unit 10 which is carried by
the golfer and a base unit 11 which is placed near or is attached to the
flag pole 12. The system may be installed on the golf course, in which a
separate base unit is installed at each hole on the course, or if the
system has not been installed on the golf course, the golfer may provide
his own portable base unit which may be set up at the green to which he is
shooting and thereafter moved to the next hole. Upon command by the
golfer, the remote unit 10 emits a radio frequency (RF) pulse 14 toward
the base unit 11. The base unit 11 upon receiving the pulse 14 from the
remote unit 10 emits an acoustic, sonic or other pressure-type signal 15
toward the remote unit 10. Preferably, the base unit 11 emits an
ultrasonic signal to avoid disturbing other golfers. Upon receipt of the
ultrasonic signal 15 the remote unit measures the time interval between
the sending of the RF pulse 14 and the receipt of the ultrasonic signal
15. From this time interval the internal logic in the remote unit 10
determines the distance between the remote unit and the base unit 11 based
upon the speed of the ultrasonic signal through air, the transmission of
the RF pulse being essentially instantaneous. An accurate measurement of
the distance between the golfer and the flag pole 12 is thereby provided.
The external features of the remote unit 10 can be seen in greater detail
in FIG. 2. The remote unit 10 comprises an outer casing 17 having a front
panel 18 containing keys actuating the control switches for operation of
the unit and a three-digit LCD or LED display 19. The control switches
include a "distance uncorrected" switch 21. When the golfer strikes the
key activating the switch 21, the remote unit 10 emits the RF pulse 14 and
measures the distance to the flag pole 12 from the returning ultrasonic
signal 15. The resulting distance in yards is determined and can be read
from the LED display 19. For example, if after hitting his drive, a golfer
is left with a shot which measures exactly 148 yards to the pin, the
golfer carrying the remote unit 10 may press the key activating the switch
21 and read 148 on the display 19.
The front panel 18 of the remote unit 10 also contains a wind direction
dial 22. After pointing the remote unit 10 at the pin, the golfer adjusts
the wind direction dial 22 so that it points in the direction from which
the wind is blowing. The remote unit 10 also has a wind strength switch 23
capable of four adjustments indicating the strength or velocity of the
wind. Adjacent to the distance uncorrected switch 21 are keys for a pair
of wind correction switches, comprising a wind range correction switch 25
and a wind direction correction switch 26. After setting the wind
direction dial 22 and the wind strength switch 23, the player may strike
the key activating wind range correction switch 25 and the display 19 will
show the number of yards which must be added or subtracted from the
uncorrected distance to the pin to compensate for the wind. Similarly,
upon striking the wind direction correction switch 26, the golfer may read
from the display 19 the number of yards that he must aim his shot to the
right or left of the pin to compensate for the cross drift of the ball in
flight due to the wind. For example, if the golfer having a 148-yard shot
is playing with a 10 mph wind blowing left-to-right and toward the golfer
at an angle of approximately 30.degree., the golfer sets the wind strength
switch 23 to the "medium" setting and sets the wind direction dial 22
appropriately, as shown in FIG. 2. Upon pressing the key activating the
wind range correction switch 25, the display 19 would read "12", meaning
that the shot will play 12 yards longer than its actual 148 yards of the
wind. Upon pressing the key activating the wind direction correction
switch 26, the display would read "10", indicating that the shot should be
aimed 10 yards to the left of the pin to compensate for the wind.
The remote unit 10 also has a "distance corrected" switch 28. Upon pressing
the key to activate the switch 28, the golfer may read from the display 19
the distance between the remote unit 10 and the base unit 11 on the pin as
corrected for the input wind conditions. For example, if the remote unit
10 measures exactly 148 yards to the pin, and the wind range correction
indicates that the shot will play 12 yards longer than it actually is, the
golfer will see the number 160 at the display 19 upon striking key which
activates the distance corrected switch 28, indicating that the shot will
play like a windless 160 yard shot.
The remote unit also has a club selection switch 29. Upon pressing the key
initiating the switch 29, the golfer can see at the display 19 an
indication of the proper club that should be slected for the particular
shot. If the proper club is a No. 3 wood, the displayed symbol will be
"1". If the proper club is an iron, the displayed symbol will be a
one-digit number indicating the proper numbered iron. If the proper club
is a wedge, the displayed symbol will be "10". For example, for the shot
having a corrected distance of 160 yards, if the player strikes the switch
29, the display will show "5" which means that a No. 5 iron is the
appropriate club for the shot.
The base unit 11 is shown in greater detail in FIG. 3. The base unit 11 is
preferably mounted directly on the flag pole 12, and comprises a battery
and electronic package 31 mounted on the lower portion of the flag pole 12
and a sonic transducer unit 32 is mounted near the top of the flag pole.
The upper portion of the pole 12 also contains an RF antenna encapsulated
in a non-metallic upper section 33 of the pole. The sonic transducer unit
32 is oriented to project the ultrasonic signal toward the fairway in
which the golfer is approaching the green. To assure that the transducer
is properly oriented, the bottom of the pole 12 contains a key 34 so that
the pole is correctly oriented when placed in the hole. The base unit 11
is powered by conventional rechargeable batteries, and if desired, the
unit can be made to operate with batteries recharged by solar cells
mounted on the pole.
The internal circuitry of the remote unit 10 is summarized schematically in
FIG. 4. The switches 21, 25, 26, 28 and 29 are connected to a switching
and encoding unit 38 which provides appropriate encoded signal SD in
relation to whichever switch has been activated by the golfer. An output
signal DUS indicating the activation of DU switch 21 is sent to a distance
determination unit 39. Unit 39 activates an RF transmitter 40 which emits
the RF pulse toward the base unit 11. When the return ultrasonic signal is
sent to the remote unit, it is picked up by a sound receiver 41, and an
electrical signal is transmitted to the distance determination unit 39.
The internal logic of the unit 39 measures the time interval between the
command sent to the RF transmitter 40 and the signal received by receiver
41 and converts this time interval to uncorrected distance data DU, which
is output from the unit 39.
The wind information inputed through the wind direction dial 22 and the
wind strength switch 23 is sent to a wind measurement unit 43 where it is
combined and converted to a plurality of wind measurement signals MR, ZR,
MD and ZD. The unit 43 also provides a signal PNR indicating a positive or
negative wind range correction, depending upon whether the wind is blowing
toward the pin or toward the golfer. The wind measurement signals from the
unit 43 are sent to a wind correction unit 44 along with the uncorrected
distance data DU from the unit 39. The unit 44 converts the input
information to wind range correction data WR indicating the longitudinal
wind effect on the distance between the golfer and the pin, and wind
direction correction data WD indicating the distance the shot must be
aimed offline to compensate for the lateral wind effect.
The uncorrected distance data DU and the wind range correction data WR are
sent to a distance correction unit 46 along with the signal PNR indicating
the positive or negative wind range correction. Unit 46 adds or subtracts
the wind range correction from the uncorrected distance in accordance with
the signal PNR to obtain corrected distance data DC. The data DC is sent
to a club selection unit 47 which outputs club selection data CL based
upon the corrected distance to the pin.
The data DU, DC, CL, WR and WD are all sent to a display unit 48 containing
the LED display 19. The selection of which data will appear in the display
19 is controlled by the display selection signal SD from the switching and
encoding unit 38.
The remote unit of FIG. 4 is shown in greater detail in the circuit
diagrams of FIGS. 5-8.
FIG. 5 shows in detail the switching and encoding unit 38. Switches 25, 26,
28 and 29 are connected between a positive supply voltage and ground with
one terminal of each switch providing the inputs to a decoder 51 which may
be a 74154 unit manufactured by Texas Instruments, Inc. With a low-level
enable input EN, decoder 51 provides output signals indicating the closing
of one and only one of the switches. When any one of the switches is
closed, an input line to the decoder 51 goes to low level, and the decoder
supplies a low output signal on the corresponding output line. When the
switch is released, the input signal returns to high level and the
corresponding output signal is returned to high level. Lines 52 having
diodes 53 are supplied to handle the current surge which occurs when the
switch is opened. If the enable input EN is high level, the decoder 51
will be disabled and all output lines will go to high level. Three of the
output lines from decoder 51 are encoded by a pair of NAND gates 54 and 55
which supply a two-bit display selection control signal SD. Signal SD
comprises two lines capable of four states relating which of the four
switches 25, 26, 28 or 29 have been actuated, and thus which of the four
pieces of information are selected for display. Another output from
decoder 51 is the signal DUC which indicates whether any of the four
switches have been actuated. The signal DUC is high level if any of the
switches 25, 26, 28 or 29 have been closed, or if the decoder 51 is
disabled, and is low level if none of the switches 25, 26, 28 or 29 is
actuated and the decoder 51 is enabled. The signal DUC thus indicates
whether wind corrected information has been selected for display. A high
level DUC indicates that wind corrected information is desired because one
of the switches 25, 26, 28 or 29 have been actuated, while a low level DUC
indicates that uncorrected information is desired.
The "distance uncorrected" switch 21 is connected to a latch comprising two
NOR gates 57 and 58. The latch produces a stable output signal DUS from
the status of the switch 21 and eliminates any make-break cycles from
contact bounce. The DUS signal is sent to the base of an inverter
transistor 61 having its emitter connected to a positive supply voltage.
The collector of the transistor 61 is connected to the base of an inverter
transistor 62. The collector of the transistor 62 is connected to enable
input of decoder 51 through a diode 64, a capacitor 65 and an inverter 66.
When switch 21 is actuated, the signal DUS goes to low level, and the
transistors 61 and 62 are turned on. This presents a low-level input to
the inverter 66 producing a disable signal to the input EN of the decoder
51. After the capacitor 65 is charged, a high level input is provided to
the inverter 66 producing a low-level enable signal to the input EN of the
decoder 51. When the decoder 51 is enabled, the signal DUC goes to low
level because none of the other switches 25, 26, 28 or 29 is closed. The
low level DUC signal indicates that uncorrected distance information is
desired for display.
The output of the transistor 62 also controls a power timeout circuit which
provides power to the positive voltage sources for a fixed time duration
after any of the switches have been actuated. The collector of the
transistor 62 is connected through diodes 68 and 69 to the base of a
transistor 70, which has its emitter connected to the positive voltage
supply from the remote unit battery (+V.sub.B) and which has its collector
connected to supply the various positive voltage sources in the unit,
identified as +V.sub.T. The switches 25, 26, 28 and 29 are also connected
to the base of the transistor 70 through diodes 69 and 72. When the
transistor 62 goes on or when any of the switches 25, 26, 28 or 29 is
actuated, the base of the transistor 70 is grounded, and the transistor is
switched on.
A time delay unit 74 is used to maintain the transistor 70 on for a set
period of time after any of the switches have been actuated. The time
delay unit 74 is triggered through an input connected across a resistor 75
to the timed-out voltage supply +V.sub.T. The trigger input is normally
grounded through a capacitor 76. The time delay duration of the unit 74 is
set by a predetermined input bias through a variable resistance 78 and a
capacitor 79. The capacitor 79 is connected to the switches through a
diode 80 to assure repeatable time out periods. The time delay unit 74
functions essentially as a one-shot. Upon a high-level pulse at the
trigger input, the unit 74 releases a short circuit across the capacitor
79 and drives the output to high level. When the voltage across the
capacitor 79 increases, the unit 74 drives the output to low level and
discharges the capacitor 79. The duration of the high-level output from
the unit 74 is thus set by the period of time required to substantially
charge the capacitor 79. The output of the unit is connected through a
diode 82 to the base of an inverter transistor 83, which has its collector
connected to the base of the transistor 70. The high-level output of the
time delay unit 74 is thus inverted by the transistor 83 and used to
maintain the transistor 70 on for the time delay set by the unit 74.
In the operation of the power time out circuit, the transistor 62 is
initially off and the switches 25, 26, 28 and 29 are open, so that the
base of the transistor 70 receives high-level bias voltage from the
battery voltage supply, and no power is being supplied from the battery to
the remainder of the circuitry. Upon actuation of any of the switches 21,
25, 26, 28 or 29, a low level input is presented to the base of the
transistor 70, switching the transistor on and supplying power to the
circuitry, including the resistor 75 connected to the trigger input of the
time delay unit 74. The rising voltage to the trigger, providing a
high-level output through the diode 82 to the transistor 83. The
transistor 83 is turned on, and maintains the transistor 70 in a
conductive state to power the circuitry. The time delay unit 74 times out
after a predetermined interval set by the variable resistance 78 and the
capacitor 79. The output of the unit 74 then drops to low level, turning
off the transistor 83. The high-level input to the base of the transistor
70 from the collector of the transistor 83 causes the transistor 70 to be
turned off, removing power from the supply line connected to the collector
of the transistor 70, so that power is no longer supplied to the unit.
FIG. 6 shows in detail the distance determination unit 39. The signal DUS
from NOR gates 57 and 58 is supplied to a capacitor 91 which results in
signal DUP which has a high-level pulse upon the opening of the switch 21.
The pulse signal DUP serves as a reset input for a timing signal generator
or timer 92, which may be a voltage controlled oscillator such as a
standard 4060 unit, set to generate a timing signal .phi..sub.1 of a
predetermined frequency by means of an externally connected capacitor 93
and variable resistor 94. The speed of sonic signals through air is known
to be 1090 ft/sec or 363.33 yd/sec, so that a sonic signal travels one
yard every 2.75 msec. The timer 92 is set to produce the negative edge of
a high-level signal every 2.75 msec, resulting in an output frequency of
363.33 Hz for the timing signal .phi..sub.1. Thus the timer 92 produces a
cycle for each yard travelled by the ultrasonic signal from the base unit
11. The initial negative edge (high to low-level transition) of the of the
timing signal .phi..sub.1 is synchronized with the positive edge (low to
high-level transition) of the signal DUS through the reset input R of the
timer 92. The timer 92 also produces a second timing signal .phi..sub.2
having a frequency equal to that of the primary timing signal .phi..sub.1
divided by 2.sup.8 or 1.42 Hz, so that signal .phi..sub.2 has a positive
edge every 0.7 seconds.
The timing signal .phi..sub.1 provides the toggle input T to a flip-flop 96
having a fixed high-level input J, a grounded input K, and a clear input C
connected to the pulse signal DUP from the capacitor 91. The preset input
P is connected through a capacitor 97 to a positive voltage supply so that
the flip-flop 96 is initially set with a high-level output Q during
initial power-on of the remote unit. The flip-flop 96 output Q goes to low
level upon a positive pulse signal DUP received at the clear input C and
thereafter returns to high level at the next negative edge of the timing
signal .phi..sub.1 received at the toggle input T.
The output Q from the flip-flop 96 provides the toggle input T to a second
flip-flop 99, also having a fixed high-level input J, a grounded input K,
and a grounded preset input P. The clear input C of the flip-flop 99 is
connected to both the capacitor 97 and the low frequency timing signal
.phi..sub.2 from the timer 92, through an OR gate 100. During the initial
remote unit power-on, the output Q of the flip-flop 99 is set to low
level, and the inverted output Q is set to high level, because of the
high-level clear input C from the capacitor 97. Thereafter, the output Q
goes to high level, and the inverted output Q goes to low level, upon
receiving a negative edge signal at the toggle input T. The output Q
returns to low level and the inverted output Q returns to high level when
the low frequency timing signal .phi..sub.2 received at the clear input C
goes to high level.
The output Q from the flip-flop 99 is connected to the base of an inverter
transistor 103, the collector of which is connected to an inverter power
transistor 104. The emitter of the transistor 104 is connected to a higher
positive voltage supply, such as 12 volts, and the collector is connected
to another power transistor 105, which is an emitter-follower transistor
with the collector also connected to the higher positive voltage supply.
The emitter of the transistor 105 is connected through an inductor 106 to
the RF transmitter 40 which generates the RF pulse signal to the base unit
11. When the output Q from the flip-flop 99 goes to high level, it turns
on the transistors 103 and 104, so that the base of the transistor 105
receives a high level input and current is supplied from the emitter of
the transistor 105 to the inductor 106. As the inductor 106 charges, the
transmitter 40 is activated.
The transmitter 40 may be a standard inexpensive CB "walkie-talkie" unit
which is fixed in the transmit position. A suitable oscillator circuit
(not shown) may be connected to the microphone input of the transmitter 40
to generate a proper electrical signal to modulate the RF carrier signal.
The transmitter 40 receives its power from the line from the inductor 106,
so that the transmitter is turned on through the control of the output Q
of the flip-flop 99.
The output Q from the flip-flop 99 provides the toggle input T to a third
flip-flop 108, which also has a fixed high-level input J, a grounded input
K, and a grounded preset input P. The clear input C of the flip-flop 108
is connected both to the pulse signal DUP and to the output of the sound
receiver unit 41, through an OR gate 110. The sound receiver unit 41
contains means 111 for sensing the ultrasonic signal emitted by the base
unit 11 in response to the RF pulse from the transmitter 40 and for
supplying an electrical signal when the ultrasonic signal is sensed. The
inverted output Q of the flip-flop 108 is connected to the enable or clock
input CLK of the lower counter 112a of an interconnected set of BCD
counters 112. When the input CLK goes to low level, each counter in the
set of counters 112 registers a count on the negative edge of the other
enable input EN. The input EN of the lower counter 112a is supplied by the
timing signal .phi..sub.1 from the timer 92, so that the lower counter
112a counts one bit on each negative edge of the timing signal .phi..sub.1
while the output Q of the flip-flop 108 is low level. Since the timing
signal .phi..sub.1 is set to provide a negative edge every 2.75 msec, this
represents one yard of distance travelled by the sound pulse from the
remote unit. The counters 112b and 112c assume the count for the next
decades with the clock input CLK grounded and the enable input EN of each
counter connected to the highest bit of the next lower counter, so that a
count is registered when the highest bit returns to low level. The reset
input R of each of the counters 112 is connected to the pulse signal DUP,
so that the count is set to zero when the DU switch 21 is released.
The operation of the distance determination unit can be described with
reference to timing sequence of FIG. 7. When the golfer pushes and
releases the key activating the DU switch 21, the signal DUS goes to low
level and returns to high level, and the output DUP from the capacitor 91
transmits a high-level pulse. The timer 92 is reset and the timing signals
.phi..sub.1 and .phi..sub.2 begin in synchronization with the signal DUP.
The signal DUP at the input C clears the flip-flop 96, providing a
low-level output Q. After the capacitor 91 has been substantially charged,
the input C of the flip-flop 96 returns to low level, and the output Q of
the flip-flop 96 will return to high level upon the next negative edge
toggle input T signal from the timing signal .phi..sub.1.
The output Q of the flip-flop 99 is initially low level. When the flip-flop
96 is cleared, the input T to the flip-flop 99 drops to low-level,
toggling the flip-flop and causing the output Q of the flip-flop 99 to go
high since the input J is fixed high. The high level output Q from the
flip-flop 99 is inverted twice by the transistors 103 and 104 and
activates the RF transmitter 40 after energizing the inductor 106. The
inverted output Q from the flip-flop 99 also goes to low level when
flip-flop 96 is cleared.
After the primary timing signal .phi..sub.1 has undergone half of 256
cycles, so that the counters 112 have reached the value of 128 yards, the
low frequency timing signal .phi..sub.2 goes to high level, clearing the
flip-flop 99 and driving its output Q low. The low level output Q from the
flip-flop 99 turns off the signal to the transmitter 40.
The inverted output Q of the flip-flop 108 is initially high level. When
the signal DUP gives a positive pulse and the inverted output Q of the
flip-flop 99 goes low, the input T of the flip-flop 108 drops to
low-level, toggling the flip-flop and sending the output Q to its low
level. The low level input CLK to the counter 112a activates the counters
112 to begin counting one bit for each negative edge on the timing signal
.phi..sub.1.
When an ultrasonic signal is sensed by the receiver 41, it provides a
high-level clear signal to the input C of the flip-flop 108 which returns
the inverted output Q to its high level, deactivating the counter 112a.
The accumulated count in the counters 112 is then equal to the uncorrected
distance in yards between the base unit 10 and the remote unit 11 as
measured by the time interval between the transmittal and the receipt of
the ultrasonic signal. The uncorrected distance data is read from the
counters 112 on a plurality of BCD lines labeled DU. The signals on the
lines DU are inverted by inverters 114 to provide inverted data DU.
Selective bits of the data DU and DU are sent to the wind correction unit
44 as shown in FIG. 8. The unit 44 includes a plurality of gates 125-132
for encoding the data to form three-bit address data AD. The three-bit
data AD is used in combination with other data to address read-only memory
(ROM) units containing the yardage corrections for range and direction
based upon the input wind conditions.
The wind direction and the wind strength are input from the wind direction
dial 22 and the wind strength switch 23 to the wind measurement unit 43
(FIG. 8). The wind direction data is supplied from the dial 22 to an
eight-line-to-three-line priority encoder 134, which may be a 74148 unit
manufactured by Texas Instruments or other similar unit. The upper bit of
the three-bit output from the encoder 134 indicates whether the wind range
correction is positive or negative, and this signal is sent on line PNR
from the unit 43 to the distance correction unit 46. The wind strength
data from the switch 23 is encoded by a pair of NAND gates 135 and 136 to
form a two-bit output representing the wind strength setting. The encoded
wind direction and wind strength data from the encoder 134 and the gates
135 and 136 are used to address a read-only memory unit 137, which is
preferably a 32 .times. 8 ROM. The eight bits of data output from the ROM
unit 137 are supplied to the wind correction unit 44 and are used to
address and control the ROM units containing the wind range and direction
correction data.
The wind range correction data are stored in two ROM units 139a and 139b,
each preferably 32 .times. 8, which are addressed by the three-bit data AD
and by the lower two bits of the three-bit wind range measurement data MR
from the ROM unit 137. The upper bit MR2 is used to control which of the
two ROM units 139a or 139b is enabled. The signal MR2 is connected to the
enable input EN of the ROM unit 139a through a NAND gate 141, and an
inverted signal MR2 from an inverter 143 is connected to the enable input
EN of the ROM unit 139b through a NAND gate 142. If the signal MR2 is high
level, the ROM unit 139a is operative, and if the signal MR2 is low level,
the inverted signal MR2 is high level, and the unit 139b is operative.
The operation of both ROM units 139a and 139b is also controlled by a zero
range correction signal ZR which is also input to the NAND gates 141 and
142. The zero range signal ZR is output from the ROM unit 13 | | |
