What is called gain? How to Mattel full digital ultrasonic flaw detector gain adjustment?

Gain is a digital ultrasonic flaw detector echo amplitude adjustment (sensitivity), in the analog instrument is usually called "attenuation", the two concepts are just the opposite, that is, increase the gain, the echo amplitude increases; and attenuation increases, the echo amplitude is down. In flaw detection work, the use of gain adjustment can control the sensitivity of the instrument, measuring the relative height of the signal, used to determine the size of the defect, or measure the attenuation properties of the material, etc., expressed in decibels (dB). Select the basic → gain, the interface appears in the basic gain, gain step, sweep gain, surface compensation parameters, select a parameter and turn the knob, you can adjust the value of the parameter Manual Gain Adjustment Press the button, the instrument automatically jumps to the basic gain adjustment interface and select the basic gain items, rotate the rotary wheel to adjust the basic gain to the appropriate value. If you need to adjust the gain step, you can select the gain step item and then rotate the wheel to adjust; or press the key repeatedly, the gain step can be switched between 6dB, 2dB, 1dB, 0.1dB and 0dB. A gain step of 0dB is equivalent to the base gain being locked, thus preventing the base gain from being changed by mistake. Automatic Gain Adjustment This function is designed to quickly adjust the return in the gate to a predetermined height. The method of use is as follows: adjust the gate to lock the echo to be measured, and then press the key, the instrument will automatically adjust the gain, so that the maximum echo amplitude in the gate is adjusted to 80% of the height of the screen (this height can be set in the parameters of the automatic wave height: Auxiliary ?ú Function ?ú Automatic Wave Height). In the process of automatic gain adjustment, the top of the waveform display area has the word "AUTO-XX%", of which "XX%" indicates the value of the automatic wave height. The word "AUTO-XX%" is displayed at the top of the waveform display area during the adjustment process. During the adjustment process, pressing the key can immediately terminate the automatic gain adjustment. Note: When used in conjunction with the Wave Memory function, it should be noted that the Auto Gain is adjusted for the current active waveform and does not operate on the memorized echo. In addition, the probe should be kept still after triggering the automatic gain function, and then moved after the instrument has adjusted the existing waveform to the reference wave height specified by the user. The system sensitivity of this flaw detector consists of three parts: basic gain, sweep gain and surface compensation gain. The total gain is 110dB maximum, in which the basic gain and compensation gain are displayed in the upper right corner of the screen, as shown in the figure on the right, and its format is: xx.x+ xx.x dB A BA item is the basic gain, and B item is the compensation gain. Sweep gain is equivalent to the adjustment of sweep sensitivity during flaw detection and is designed to facilitate the search for defects. Surface compensation gain refers to the compensation of flaw detection sensitivity due to the influence of workpiece surface roughness and other factors. Surface compensation needs to be set in the menu according to the surface roughness condition of the workpiece. When there is no DAC/AVG curve, the adjustment effect of basic gain and compensation gain is the same and will not affect the flaw detection result. When there is DAC/AVG curve, there is a significant difference between the three: 1. Adjusting the basic gain, the DAC/AVG curve and echo amplitude change synchronously. When probing, in order to find a certain echo, it is necessary to adjust the gain, but it is not possible to change the relative equivalent value of the echo and the DAC/AVG curve (without changing the set probing standard), at this time, it should be in the basic gain state, and the gain should be adjusted. 2. Adjusting the sweeping gain, it can make the echo in the gate higher or lower, and the DAC/AVG curve is unchanged, and its equivalent value is also unchanged. 3. During flaw detection, the compensation gain should be adjusted (sensitivity compensation) when surface compensation is required due to the difference between the on-site workpiece condition and the test block test.