| 摘要 |
A digital method for measurement of phase time for radio pulse signal transmission relates to measurement technique and can be used in ultrasonic nondestructive testing of materials, structures and objects. Calculation of phase time for transmission is carried out in two stages each comprising two cycles. In the first cycle digital codes of obtained fetches are accumulated at random-access storage with AD converter sampling rate, and frequency, duration and pulse period of emitted radio signal is generated from one sampling rate signal generator. In the second cycle a signal phase is calculated, and read signal frequency of ROM, wherein reference signal sine and cosine code values are stored, and frequency of random-access storage are obtained by division of sampling rate. Emitted radio pulse and measured signal are applied to one AD converter input for conversion into digital code in two steps. At first step signal from reference generator is applied to AD converter input at the same time for the determination of initial phase thereof. At second step determined is a phase of measured signals which exceed threshold sensitivity, and transmission time of radio pulse signals is calculated according to formula. The technical result is in enhancement of measurement accuracy and resistance to interference, extension of upper frequency range of measured signals and simplification of the method hardware implementation. |
