ECG recordable signal derivative

According to the signal derivatives that can be recorded at one time, the ECG is divided into single-lead and multi-lead types (such as three-lead, six-lead, and twelve-lead). The ECG signal amplification channel of the single-lead ECG machine has only one channel, and the ECG waveforms of each lead should be recorded one by one. That is, it cannot reflect the changes of the lead ECG at the same time. Multi-lead ECG machines have multiple amplification channels. For example, six-lead ECG machines have six amplifiers, which can reflect the simultaneous changes of the six-lead ECG signals at a time.