读出英文，说出中文意思，整个过程录音并上传 1、A periodic waveform is one that repeats itself

at a fixed interval, called a period (T ). The frequency (f ) is the rate at which it repeats itself and is measured in hertz (Hz). The relationship between f and T is expressed as follows: 2、In digital systems, all digital waveforms are synchronized with a basic timing waveform, called the clock. The clock is a periodic waveform. The clock waveform itself does not carry information.