超声检测设备的时基线性直接影响缺陷定位的准确度。标准GB/T 27664.1－2011仪器部分的8.7节和9.6节，以及GB/T 27664.3－2012组合设备部分的3.2节指出了测试时基线性的不同方法。采用了标准中提出的3种不同方法对同一台超声检测仪的时基线性进行测试，对这3种时基线性的测试方法做出了详细对比。结果表明，标准中仪器部分8.7节的方法适用于数字式超声检测仪，其验收标准为时基线性偏差小于全屏宽度的±0.5%；9.6节的方法适用于A型脉冲式模拟和数字式超声检测仪，验收标准为时基线性偏差小于全屏宽度的±1%；组合设备部分3.2节的方法适用于现场或车间条件使用的超声仪器和探头组合设备，验收标准为时基线性偏差小于全屏宽度的±2%。

For ultrasonic testing equipment, the linearity of time base directly affects the accuracy of defect location determination. Three test methods are described in the term 8. 7 and term 9. 6 of GB/T 27664. 1-2011, as well as in the term 3. 2 of GB/T 27664. 3-2012. The above-mentioned three ways were used to conduct testing and make comparison on the linearity of time base of the same digital ultrasonic instrument. The results showed that term 8. 7 is applicable to the measurement of digital ultrasonic instrument, with which the acceptance standard is within ±0. 5% of the full screen width; the term 9. 6 can be applied to the A-type pulse analogue and digital ultrasonic instrument, with which the acceptance standard is within ±1% of the full screen width; and the term 3. 2 is suitable for the ultrasonic instruments combined with detector practically used on site or in plants, with which the acceptance criteria is within ±2% of full screen width.