2.1 RFID Tag Group Performance Measurement
33
signals, the laser rangefinder USES the pulse method for ranging, which is used to
obtain the maximum distance between the tag and the reader antenna when the tag
is read, and the CCD camera is used to collect the tag distribution image of the tag
group. The reflector plate simulates the surface of goods, is placed on the guide rail,
and is controlled by the driving motor to move back and forth on the guide rail. The
RFID tag is attached to the reflector board. When the tag enters the working area of
the reader antenna, the reader immediately sends a signal to the laser rangefinder after
detecting the signal of the RFID tag. The laser beam emitted by the laser rangefinder
falls on the reflector board and displays the measured distance data on the display.
Guide rail motion control switch in the display, you can control the beginning and
end of the car movement, as well as the car speed and direction of movement. After
the measurement is completed, the transmission power and the reading distance of
the system are recorded, the trolley is controlled to move to the furthest point of the
guide rail, and the measurement is started again.
Because the reading distance of the tag is obtained by the laser rangefinder, and the
measurement result of the laser rangefinder is affected by the laser sensor precision
in the rangefinder, so the measurement result can be more accurate by improving the
range, sensitivity, sampling frequency, and resolution of the sensor. In this experiment, the reading distance between the tag and the tag group was measured for
many times, and the average value of the reading distance was substituted into the
sensitivity formula of the tag group to reduce the influence of the error of the laser
rangefinder on the accuracy of the results.
The experimental test equipments are shown as follows:
(1) Laser ranging sensor: measuring range of 20 m, output frequency of 100 Hz,
resolution of 1 cm.
(2) Motion guide: the length of the guide is 15 m, and the motion speed is manually
selected from the range of 0.5, 1, and 1.5 m/s.
(3) Reader: the supported frequency range is 840−845 and 920−925 MHz, and
the frequency can be fixed. The output power is adjustable from 10 to 30 dBm.
(4) Antenna: the frequency range supported is 840−845 and 920−925 MHz.
(5) Tag: Alien UHF line-polarized tag.
(6) CCD camera: 5 million pixels, the imaging size is 1/3 inch, the exposure time
is 0.0063−4615 ms, and the pixel size is 3.75 m × 3.75 m.
The test environments are shown as follows:
(1) Temperature: the test environment temperature is 20−30 °C.
(2) Relative humidity: the relative humidity of the test environment is 25−75%.
(3) Interference: no obvious interference sources such as electromagnetic, metal,
and liquid.
The physical picture of the system is shown in Fig. 2.2.
33
signals, the laser rangefinder USES the pulse method for ranging, which is used to
obtain the maximum distance between the tag and the reader antenna when the tag
is read, and the CCD camera is used to collect the tag distribution image of the tag
group. The reflector plate simulates the surface of goods, is placed on the guide rail,
and is controlled by the driving motor to move back and forth on the guide rail. The
RFID tag is attached to the reflector board. When the tag enters the working area of
the reader antenna, the reader immediately sends a signal to the laser rangefinder after
detecting the signal of the RFID tag. The laser beam emitted by the laser rangefinder
falls on the reflector board and displays the measured distance data on the display.
Guide rail motion control switch in the display, you can control the beginning and
end of the car movement, as well as the car speed and direction of movement. After
the measurement is completed, the transmission power and the reading distance of
the system are recorded, the trolley is controlled to move to the furthest point of the
guide rail, and the measurement is started again.
Because the reading distance of the tag is obtained by the laser rangefinder, and the
measurement result of the laser rangefinder is affected by the laser sensor precision
in the rangefinder, so the measurement result can be more accurate by improving the
range, sensitivity, sampling frequency, and resolution of the sensor. In this experiment, the reading distance between the tag and the tag group was measured for
many times, and the average value of the reading distance was substituted into the
sensitivity formula of the tag group to reduce the influence of the error of the laser
rangefinder on the accuracy of the results.
The experimental test equipments are shown as follows:
(1) Laser ranging sensor: measuring range of 20 m, output frequency of 100 Hz,
resolution of 1 cm.
(2) Motion guide: the length of the guide is 15 m, and the motion speed is manually
selected from the range of 0.5, 1, and 1.5 m/s.
(3) Reader: the supported frequency range is 840−845 and 920−925 MHz, and
the frequency can be fixed. The output power is adjustable from 10 to 30 dBm.
(4) Antenna: the frequency range supported is 840−845 and 920−925 MHz.
(5) Tag: Alien UHF line-polarized tag.
(6) CCD camera: 5 million pixels, the imaging size is 1/3 inch, the exposure time
is 0.0063−4615 ms, and the pixel size is 3.75 m × 3.75 m.
The test environments are shown as follows:
(1) Temperature: the test environment temperature is 20−30 °C.
(2) Relative humidity: the relative humidity of the test environment is 25−75%.
(3) Interference: no obvious interference sources such as electromagnetic, metal,
and liquid.
The physical picture of the system is shown in Fig. 2.2.