Analog : Data represented by continuously variable physical quantities, i.e. moving clock hands.
Digital: Data composed of bytes of information sampled at regular intervals.
Data acquisition for life science research and education has come a long way since the heyday of chart recorders and oscilloscopes. Chart recorders, while accurately rendering body signals using an ink stylus on long rolls of paper, lack the flexibility for closely analyzing or interacting with data. Oscilloscopes also pose similar limitations. The field of physiology study received a major assist with the advent of A/D (A-to-D) converters, which include industry-leading BIOPAC MP160, MP36/36R, or Smart Center Systems.
So what is an A/D converter? A/D converters are devices for converting analog signals to a digital format.
This principle can be applied to any type of analog information, such as recorded music or video, and lends itself especially well to conversion of physiological signals. The incoming analog signal (such as an ECG heartbeat) is “digitized,” which allows the signal to be accurately displayed on a computer monitor. During this process, the analog signal is “sliced” into samples per second (or Hz) by the A/D converter. The speed at which the signal slices are acquired is referred to as the sampling rate.
A good illustration of how a sampling rate works is to liken it to a dot-to-dot drawing, each dot appearing at regular intervals and tracing the amplitude and time outline of the incoming analog signal. The higher the sampling rate, the higher the concentration of dots, and the higher the resolution (quality) of the signal. The combined dots, or bytes, of digitized information are displayed onscreen as seamlessly precise waveforms that can be started, stopped, magnified, reduced, edited, autoscaled, transformed, or run through powerful automated analysis routines using BIOPAC AcqKnowledge Research Software.
A good acquisition sampling rate for most physiological data is 2000 samples/second, although certain body signals (such as lung volume measurements) require only 20 samples/second, while auditory studies benefit from a sampling rate as high as 20,000 samples/sec. The BIOPAC MP160 16-Channel Data Acquisition Unit supports sampling rates ranging from 0.1 samples/second to 200,000 samples/second. Try doing that with an analog chart recorder!
BIOPAC offers a wide array of wired and wireless equipment that can be used in your research. To find more information on solutions for recording and analyzing signals such as ECG, heart rate, respiration and more using any platforms mentioned in this blog post, you can visit the individual application pages on the BIOPAC website.