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HX40TRM Miniature
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HX40TRC Aluminium Can
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HX40TRE British pipe threads
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Precision Positioning
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Wind speed Monitoring
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Doppler Applications
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The HX40TR is designed for
applications in air. It transmits 120db signal Wide Beam ±12
degrees at 40khz. Reception sensitivity level is -51db/V/microbar.
Range from 0m to 20m transceiver to transceiver operation, and
echoes from 0.1m to 10m are easily achieved with conventional low
cost circuitry. Please note that the crystal settling rate is a
limiting factor as to how close an object can be.
The HX40TRE series sensor is protected by
a heavy duty chromed brass housing, with 1/8" or 3mm thick
walls. This is a 1/2 inch hex junction using BPT standard British
pipe thread. Readily available mounting accessories make this
sensor easy to apply and install. The sensor can withstand rain,
but water film can block the pores of the protective screen,
reducing it's sensitivity until the water has evaporated or been
wiped off. It should be shielded from rain. |
In the following, two HX40TR transceivers are placed
facing each other at a fixed distance. One transceiver referred to as T1
is exited with various voltage levels, and the opposite transceiver
referred to as T2 is used to receive the signal. The graphs below plot
the output from T2.
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Above: T1 is exited with a 5Vp-p
CMOS square wave oscillating at 40Khz, 100 waves are transmitted.
The response as amplitude builds inside the T2 crystal is plotted
above. |
Above: 5Vpp CMOS/TTL square
wave is applied to T1 at various frequencies. The frequency
response is measured across the output wires of T2, and plotted
above |
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Above: Continuous excitation
voltage oscillating at 40Khz is applied to T1. The T2
resulting amplitude is plotted above. |
The above illustrates how the
output of T2 decays as distance increases between T1 and T2. T1 is
exited with oscillating voltage, amplitude 28V. |
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Above: T1 was excited with a
30Vp-p 40Khz step input at using signal conditioner HE40SCR, the
illustration above shows how long it takes the system to settle on
40Khz. Distance between T1 and T2 is1.5m. |
Above: T1 excitation using
HE40SCR 30Vp-p FSK (frequency shift keying) signal, low frequency
38647hz (duration 26 waves) and high frequency 40201hz (duration
26 waves). The response was monitored across output pins of T2,
placed 1.5m apart from T1, and plotted as shown above. Note that
the ripples are digitization errors. |
Cable
length between the HE240 series transducers and a signal conditioner, is
left to the user's discretion. At 10m lengths the added environmental
noise and signal reduction at 40khz is insignificant.
Beam Pattern
The sensor is located in the locus of the polar plot
shown below facing north, maximum signal strength is along the 0 degree
axis. As the observer with the measuring instruments moves east and west
i.e. perpendicular to the 0 line signal strength degrades. The beam
pattern character line shown below represents observation angles where
signal has degraded by 6 decibels.
Microchip PIC interface suggestions
The following example, shows how the PIC16C622
and the PIC16C71 can be interfaced to the HE2XX series
transducers. For 40Khz transducers C1 an C2 should be about 2nF,
R1 about 3Kohms and R2 about 5Kohms. R3 sets the level for the
analog comparator of the PIC16C622 and should be high, say 50Kohm.
If the A/D converter of the PIC16C71 is being used, R3 should be
removed.
There is an error in the schematic on the
right, capacitors marked 2.2pF on the input and output of the
operational amplifier, should be marked C1 and C2 respectively.
The 4.7k ohm resistor at the input of the opAmp should be marked
R1. |
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ATMEL AVR interface suggestions
The following example, shows how the AT90S2313
microcontroller can be interfaced to the HE2XX series transducers.
For 40Khz transducers C1 an C2 should be about 2nF, R1 about
3Kohms and R2 about 5Kohms. R3 sets the level for the internal
analog comparator of the AT90S2313 and should be high, say 50Kohm.
There is an error in the schematic on the
right, capacitors marked 2.2pF on the input and output of the
operational amplifier, should be marked C1 and C2 respectively.
The 4.7k ohm resistor at the input of the opAmp should be marked
R1. |
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INTEL 8051 interface suggestions
The following example, shows how the INTEL 8051
microcontroller can be interfaced to the HE2XX series transducers.
For 40Khz transducers C1 an C2 should be about 2nF, R1 about
3Kohms and R2 about 5Kohms. R3 sets the level for the analog
comparator and should be high, say 50Kohm.
There is an error in the schematic on the right, capacitors
marked 2.2pF on the input and output of the operational amplifier,
should be marked C1 and C2 respectively. The 4.7k ohm resistor at
the input of the opAmp should be marked R1.
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Electrical Specifications HX40TR
Parameters |
Values |
Units |
Operating Frequency |
39 |
kHz |
Input Voltage |
20 (max) |
Volts (RMS) |
Output (SPL) @20V |
118 |
db |
Receive (Sensitivity) |
-56 |
db/V/Ubar |
Impedance |
300 |
ohm |
Beam Angle |
±12 |
degrees |
Bandwidth |
2 |
kHz |
Settling Decay |
4 |
mS |
Temperature |
-40 to 100 |
°C |
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