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TDC1000 Measurement accuracy

Seishin
Genius 4135 points
Other Parts Discussed in Thread: TDC1000

Hello,

Now, we are considering the ultrasonic sensor to the gas flow meter.

I can't decide the detection method between CORRELATION TYPE and TRIGGER TYPE.

And so I have questions about TDC1000.

　＜Specifications＞

　　Target Gas : CH4

　　Placement　 :　45°Angle

　　Diameter (D): 20-600mm

Resonant frequency:200kHz(In-House transducer)
　　
Flow speed : 20-30m/s

Q1.I think that output voltage swing of approximately 20V is necessary to improve measurement accuracy.

　　Is it enough to measure in the output voltage swing of 5V?

Q2.Do you have a function to correct or improve the distortion of the received waveform by noise

　　caused in TDC1000?

Best regards,
Seishin

  • 0
    TI__Expert 3350 points
    In cross-correlation method the echo signal is digitized using an ADC and the delta-TOF between the downstream and upstream is found by "cross correlating" the upstream and downstream signals- often three point cross correlation is used.
    In zero-cross TOF measurement method ( TDC1000 approach) the echo signal is filtered and amplified to about 2 V and then using two comparators "STOP" pulses are generated to measure TOF for upstream and downstream referenced to a START pulse. Therefore, to achieve optimal accuracy the signal at the input of the comparators needs to maintain at approximately 2 V range. This should be done by a combination of driving the sensor with proper-level of energy and in the mean time filtering and amplifying the signal with right amount of gain, please refer to the application note snaa284 at the link below for more details:
    www.ti.com/.../snaa284.pdf