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HX25TRM Miniature
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HX25TRC Aluminium Can
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HX25TRE 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 HX25TR is designed for
applications in air and gasses. It transmits 118db signal Wide Beam ±23
degrees at 25.7khz. Reception sensitivity level is
-56db/V/microbar. Range from 0m to 100m transceiver to
transceiver operation, and echoes from 0.1m to 50m are achieved
with conventional low cost circuitry. When
applying this transducer for echo analysis, the crystal
settling rate is a limiting factor as to how close an object can
be.
The HX25TRE series sensor is protected by a
heavy duty chromed brass housing, with 1/8" or 3mm thick
walls. It is a hex nipple 1/2 inch British Pipe Threads. 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 HE225TR 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 25.7Khz, 70 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 25.7Khz 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 20V @ 25.7khz. |
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Above: T1 was excited with a
30Vp-p 25.7Khz step input at using signal conditioner HES025, the
illustration above shows how long it takes the system to settle on
25.7Khz. Distance between T1 and T2 is 1.5m. |
Above: T1 excitation using
HES025 30Vp-p FSK (frequency shift keying) signal, low frequency
26936hz (duration 20 waves) and high frequency 27800hz (duration
20 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. |
Microchip PIC interface suggestions
The following example, shows how the PIC16C622
and the PIC16C71 can be interfaced to the HE2XX series
transducers. For 25Khz transducers C1 an C2 should be about 2nF,
R1 about 5Kohms and R2 about 7Kohms. 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 25Khz transducers C1 an C2 should be about 2nF, R1 about
5Kohms and R2 about 7Kohms. 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 25Khz transducers C1 an C2 should be about 2nF, R1 about
5Kohms and R2 about 7Kohms. R3 sets the level for the analog
comparator and should be high, say 50Kohm.
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Electrical Specifications HE225TR
Parameters |
Values |
Units |
Operating Frequency |
25.7 |
kHz |
Input Voltage |
20 (max) |
Volts (RMS) |
Output (SPL) @20V |
118 |
db |
Receive (Sensitivity) |
-56 |
db/V/Ubar |
Impedance |
300 |
ohm |
Beam Angle |
±23 |
degrees |
Bandwidth |
2 |
kHz |
Settling Decay |
6 |
mS |
Temperature |
-40 to 100 |
°C |
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