Analog signals

The image reader, which converts the induced latent image in the TP into analog signals and subsequently into a time sequence of digital signals ... 

G.S. Kino, Acoustic waves devices, imaging and analog signal processing (Prentice-Hall, Englewood Cliffs, New Jersey, 1987). 

The modern Russian MIA flaw detectors use pulse version of the method [1-3], which peirnits to produce very portable (0.7 - 1.5 kg) and simple instruments, convenient especially for in-service testing. The objects to be tested are multilayer structures of reinforced plastics, metals and other materials honeycomb panels, antenna fairings, propellers, helicopter rotors and so on. In mentioned instruments amplitude-frequency analog signal processing is used. 

A mass spectrum consists of a series of peaks at different m/z values, with the height of the peak proportional to the number of ions. A partial mass spectrum is shown in Figure 44.3 and is seen to be an analog signal that varies as the peaks rise from and fall to the baseline. Between the peaks are relatively long intervals when there is only the baseline. As described above, the signal is first digitized. 

Analog signal. A signal that can be expressed as a continuously variable mathematical function of time. 

Digital signal. A signal that represents information in a computer-compatible form as a sequence of (binary) numbers that can describe discrete samples of an analog signal. 

In each case, transmission of a single value in only one direction is required. Such requirements can be met by analog signal transmission. A span is defined for the value to be transmitted, and the value is basically transmitted as a percent of this span. For the measured variable, the logical span is the measurement span. For the controller output, the logical span is the range of the final actuator (e.g., valve fully closed to valve fully open). 

Transmitter/Actuator Networks With the advent of smart transmitters and smart actuators, the limitations of the 4-20 milliamp analog signal transmission retard the full utilization of the capabilities of the smart devices. For smart transmitters, the following capabilities are required ... 

Kino, G. S., Acoustic Waves Devices, Imaging and Analog Signal Processing, Prentice-HaU, Englewood Cliffs, NJ, 1987. 

In many instances the quality of the signal has to be improved before the chemical information can be derived from it. One of the possible improvements is the reduction of the noise. In principle there are two options, the enhancement of the analog signal by electronic devices (hardware), e.g. an electronic filter, and the... 

The output from the TAC is an analog signal that is proportional to the time difference between the start and stop pulses. The next step consists of digitizing the TAC output and storing the event in a multichannel analyzer (MCA). After repeating this process many times, a histogram of the arrival times of photons is accumulated in the memory of the MCA. In fluorescence lifetime spectroscopy the histogram usually contains 512-2048 channels... 

A discriminator circuit selects the minimum pulse height. When the input pulse exceeds the discriminator preset level, the discriminator generates an output pulse. The discriminator input is normally an amplified and shaped detector signal. This signal is an analog signal because the amplitude is proportional to the energy of the incident particle. 

This rule is equally applicable to all types of true nitronates and is the most characteristic parameter of the C=N—>-0 fragment. This is particularly typical of the 13C NMR signals of the a-C atoms, which are shifted to higher field by more than 30 ppm compared to the analogous signals of the corresponding oximes. 

Figure 5.8. Shape and area of a chromatographic peak depending on the scan speed, (a) Analog signal (b) 13 mass spectra are recorded during the elution of the analyte (c) 7 mass spectra are recorded during the elution of the analyte (d) 3 mass spectra are recorded during the elution of the analyte.

Fig. 14.9. Schematic representation of the analog-to-digital conversion process. The continuous analog signal output by the detector is sampled, converted into digital data points and transferred to the data system.

---