Using an oscilloscope for calibration and verification purposes, we measured the initial voltage V0
=448mV
from Figure 5(a), at time location t0. From Figure 5(b), we measured reflected voltages V1
=30.4mV at time location
t
1 and V2
=70.4mV at time location t2. We measured ¨t
1
=6.76μs from Figure 5(a-b), and from Figure 5(b) we
measured ¨t
2
= 1.440μs. Knowing the actual thickness of steel=19.50mm and tungsten=3.85mm, we calibrated for
ȣ
1
=5769m/s and ȣ
2
=5347m/s using equation (4) and measured ¨t
1 and ¨t
2 from the oscilloscope. Our measurement
results of ȣ
1
=5769m/s and ȣ
2
=5347m/s for steel and tungsten closely match the values found in [2] (i.e. ȣ
1
=5890
m/s, ȣ
2
=5180 m/s), such that the slight difference is due to the manufacturing process of the two metals. Using
equations (12) and (15) we calculated signal losses in the two mediums Į1
=1.59dB/cm, and Į2
=9.46dB/cm. Thus,
the total signal loss through the two mediums is 13.4dB for one echo reflection. Another 16.5dB is required to bring
the 448mV to a rail-to-rail voltage swing of 3.0V; thus, a minimum gain of approximately 30dB was needed. Since
other factors in the NDT-module design will contribute to the echo signal loss, such as the Muxes, two BPFs, DET,
and LPF, the digitally controlled PA compensates for approximately 15dB of dynamic range
Using an oscilloscope for calibration and verification purposes, we measured the initial voltage V0
=448mV
from Figure 5(a), at time location t0. From Figure 5(b), we measured reflected voltages V1
=30.4mV at time location
t
1 and V2
=70.4mV at time location t2. We measured ¨t
1
=6.76μs from Figure 5(a-b), and from Figure 5(b) we
measured ¨t
2
= 1.440μs. Knowing the actual thickness of steel=19.50mm and tungsten=3.85mm, we calibrated for
ȣ
1
=5769m/s and ȣ
2
=5347m/s using equation (4) and measured ¨t
1 and ¨t
2 from the oscilloscope. Our measurement
results of ȣ
1
=5769m/s and ȣ
2
=5347m/s for steel and tungsten closely match the values found in [2] (i.e. ȣ
1
=5890
m/s, ȣ
2
=5180 m/s), such that the slight difference is due to the manufacturing process of the two metals. Using
equations (12) and (15) we calculated signal losses in the two mediums Į1
=1.59dB/cm, and Į2
=9.46dB/cm. Thus,
the total signal loss through the two mediums is 13.4dB for one echo reflection. Another 16.5dB is required to bring
the 448mV to a rail-to-rail voltage swing of 3.0V; thus, a minimum gain of approximately 30dB was needed. Since
other factors in the NDT-module design will contribute to the echo signal loss, such as the Muxes, two BPFs, DET,
and LPF, the digitally controlled PA compensates for approximately 15dB of dynamic range
การแปล กรุณารอสักครู่..

Using an oscilloscope for calibration and verification purposes, we measured the initial voltage V0
=448mV
from Figure 5(a), at time location t0. From Figure 5(b), we measured reflected voltages V1
=30.4mV at time location
t
1 and V2
=70.4mV at time location t2. We measured ¨t
1
=6.76μs from Figure 5(a-b), and from Figure 5(b) we
measured ¨t
2
= 1.440μs.ทราบความจริงของเหล็ก = = 19.50mm ทังสเตนและ 3.85mm เราปรับให้
ȣ
1
= 5769m / s และȣ
2
= 5347m / s โดยใช้สมการ ( 4 ) และวัดตั้ง t
t
2 1 และตั้งจากออสซิลโลสโคป . การวัดผลของȣ
1
= 5769m / s และȣ
2
= 5347m / s สำหรับเหล็กทังสเตนและใกล้เคียงกับค่าที่พบใน [ 2 ] ( เช่นȣ
1
= 5890
m / s
2
= ȣ 5180 m / s ) such that the slight difference is due to the manufacturing process of the two metals. Using
equations (12) and (15) we calculated signal losses in the two mediums Į1
=1.59dB/cm, and Į2
=9.46dB/cm. Thus,
the total signal loss through the two mediums is 13.4dB for one echo reflection. Another 16.5dB is required to bring
the 448mV to a rail-to-rail voltage swing of 3.0V; thus, a minimum gain of approximately 30dB was needed. Since
other factors in the NDT-module design will contribute to the echo signal loss, such as the Muxes, two BPFs, DET,
and LPF, the digitally controlled PA compensates for approximately 15dB of dynamic range
การแปล กรุณารอสักครู่..
