In software, in signal processing, judging effective echo signal only according to the maximum peak value is one of the main reasons for the unreliable measurement of guided wave radar level sensor and the large measurement blind area. Therefore, based on the limitations of existing hardware conditions, a method is proposed to exclude false echoes and determine level echoes by combining echo characteristic parameters to form multiple conditions, improve the reliability of level echo judgment, effectively eliminate interference and reduce gross errors. In view of the inevitable noise interference which leads to signal jitter and burr, a 9-point moving average filter is proposed to preprocess the signal, and the minimum slope point is used as the echo fix point to calculate the propagation time. To solve the problem of the fluctuation of the calculated value, the median value is proposed to reduce the random error according to the characteristics of the Gaussian distribution. The results show that when the theoretical error is 2 ~ 4 cm, the actual measurement error is less than 1cm, which effectively improves the measurement accuracy.

In the aspect of hardware, the high width of transmitting pulse, the large time interval of equivalent time sampling circuit and the low sampling frequency of single chip microcomputer are the reasons that lead to the low accuracy of guided wave radar level meter. It is necessary to improve the hardware platform, such as reducing the transmitting pulse width, increasing the sampling frequency, and reducing the time interval of the equivalent time sampling circuit, so as to improve the measurement accuracy. Here it is also necessary to remind everyone that in addition to the hardware and software influencing factors, there are some other factors, such as the design of the circuit itself and the quality of the components have a direct impact on the signal-to-noise ratio of the output high-frequency signal. The dielectric constant of the measured medium directly affects the echo waveform. The influence of mechanical installation mainly lies in the obstruction dry interference, and the obstacle generates reflected signals, which can easily lead to the error of the reflected signals of the measured medium. Thus increasing the probability of incorrect measurement.

Guided wave radar level sensor measurement error is affected by software and hardware factors, of course, there are some other factors mentioned above, how to improve and reduce the error, precisely improve the measurement accuracy of guided wave radar level meter. I hope that the theoretical knowledge mentioned in the article can give you some help, can make you better use of guided wave radar level meter, the correct selection is also very important, but also the key to the best performance of guided wave radar level sensor.