SLOA341 October   2024 LOG300

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Description
    1. 2.1 Basics of Ultrasound Sensing
    2. 2.2 Advantages and Disadvantages of Ultrasonic Sensing
    3. 2.3 Ultrasonic Transducer
      1. 2.3.1 Transducer Construction
      2. 2.3.2 Transducer Frequencies
    4. 2.4 Transducer Topologies
    5. 2.5 Blind Zone Effect on Minimum Distance
    6. 2.6 Transducer Drive
    7. 2.7 Ultrasonic Echo and Signal Processing
      1. 2.7.1 Digital Gain or Fixed Gain
      2. 2.7.2 Time-Varying-Gain
      3. 2.7.3 Automatic Gain Control or Logarithmic Amplifier
      4. 2.7.4 Logarithmic Amplifier vs Logarithmic Detector
  6. 3LOG Detector Amplifier and the Advantages Over Conventional Opamps
  7. 4Application
    1. 4.1 Double Paper Feed and Paper Thickness Detector
      1. 4.1.1 Schematic Implementation
      2. 4.1.2 Material Thickness Detector
    2. 4.2 Bubble Detector
    3. 4.3 Material Detection
    4. 4.4 Distance or Proximity Detection
  8. 5Summary
  9. 6References

3 LOG Detector Amplifier and the Advantages Over Conventional Opamps

Using a logarithmic detector amplifier over a conventional operational amplifier (op-amp) for ultrasonic sensing offers several advantages:

  • Wide Dynamic Range
    Logarithmic detectors can handle a wide range of signal amplitudes, making them a designed for application where the signal strength can vary significantly. This is particularly useful in ultrasonic sensing where the received signal strength can vary due to distance, material properties and surface texture.
  • Improved Sensitivity
    Log detectors can detect very small changes in signal amplitude, which enhances the sensitivity of the ultrasonic sensor. This is beneficial for detecting weak echoes that can be missed by conventional op-amps.
  • Non Linear Output
    The output of a log detector is proportional to the logarithm of the input signal, which means the output can compress a large range of input signals into a smaller, more manageable output range. This makes the process easier to analyze the signals.
  • Noise Reduction
    Logarithmic detectors can help reduce the impact of noise on the signal as compared to multi stage fixed gain amplifier. Since they compress the signal range, they can make the process easier to distinguish between the actual signal and noise.

These advantages make logarithmic detectors a preferred choice in many applications, especially where high sensitivity and wide dynamic range are required like in ultrasonic sensing.