**8. Analog-digital converter**

An analog-digital (A/D) converter converts analog signals (EMG goniometry, force transducer) into digital data. The digitized signal can then be processed by the computer.

Application of Surface Electromyography in the Dynamics of Human Movement 401

**Figure 7.** Properly aligned A/D converter range and amplification gain [3].

10, 12, 14 or 16 bits, etc., with the most common being 12- and 16-bit.

changes at levels of 153 μV. (10 V divided by 65,536 levels), [4].

equivalent to the resolution of the A/D conversion but applied to time.

**8.2. Sampling rate** 

limited time.

seconds.

The resolution of an A/D converter indicates the lowest variation in analog signal that the converter can detect, which is generally presented in bits. Thus, converter resolutions can be

A converter with a 5V input range and a resolution of 12 bits can represent the input signal in 4096 (212) divisions and levels or detect changes of 2.4 mV (10 V divided by 4096 levels). A 16-bit converter may represent the same signal in 65536 (216) divisions and detect

In practice, the input signal to the A/D converter varies over time; the goal is to record this variation. Since a computer's storage capacity is finite, the recording can only continue for a

The discretization of time is carried out by sampling the signal at regular intervals. The reverse of this interval is the sampling rate. For example, at a sampling rate of 100 samples per second (i.e., 100 Hz), the interval between samples is 10 ms. The sampling rate is

However, due to the limited space available for data storage, there is a compromise between the sampling rate and the duration of acquisition. For example, for sampling rate of 100 samples per second, the maximum acquisition will be 166 minutes and 40 seconds. By increasing the rate to 1000 samples per second, the maximum is 16 minutes and 40
