Spectrum analyser frequency range must extend well beyond the fundamental frequency of the signal (10 times of fundamental frequency). Spectrum analyzer are classified in to Swept or superheterodyne spectrum analyser, Fast Fourier Transform (FFT) analyser, Real-time analyser, Audio spectrum analyser. The more commonly used technology is the swept spectrum analyser. Swept spectrum analyser can work up to GHz range. Swept spectrum analyser only works with continuous signals and it cant provide phase information. Swept spectrum analyser is less expensive.
FFT analyzer is short lived, or one-shot phenomena (faster). FFT analyzer capture phase information. FFT analyzer have limited bandwidth. FFT analyzer can store the data
logic probe, signature analyser and logic analyser
Logic probe tester is used for probing and analyzing logic circuits. It is capable of indicating up to four different states – logic low, logic high, tristate, pulses. Leds are used to indicate different states Logic low (green), logic high (red), pulses (amber), tristate (all leds are off). Tristate occurs when output is of and pulses shows the line is active. Input impedance of logic probe is 1 MΩ. Power supply range of logic probe is 5 – 15v. Maximum supply voltage of logic probe is 20v. Maximum input frequency of logic probe is 20 MHz. Minimum detectable pulse width of logic probe is 30 ns. Read lead of logic probe have a voltage of 5v. Signature analyser is used to find bugs in digital and logic circuits. Signature analysers are able detect digital waveform patterns and represent in hex values. Hex values of signature analyser is called signature, normally it have four digits. Hex values are generated by using a shift register, node of the motherboard (to be tested) is connected directly to shift register. Signature analyser consist of a shift register, input control circuit (where clock and input sample feed), threshold detector, OR gate and a feedback shift register
Signature analyser can self test its on working. Logic analyser is used to debug complex digital and logic circuits (microprocessor). X axis of logic analyser is time and y is logic high/low. Logic analyser have multiple channels (30 to 200+) so at a time it can analyse more digital lines (each lines for each channel). Analogue information are not displayed by logic analyser. Logic analyser trace embedded software operations. Logic analysers are of 3 types – modular logic analyser, portable logic analyser, pc based logic analyser. Modular logic analyser have more channels, high functionality but it is costlier. Logic analyser have 2 modes – timing mode and state mode. In timing mode signals are sampled at regular intervals according to the internal or external clock
In state mode one or more clocks are present and sampling occurs at edges of clock. Triggering is one of the key role advantage of logic analyser. Triggering is done just after the selection of mode. Speed of logic analyser depends on timing resolution. Logic analyser should have a memory which will increase the cost. Logic analyser probe consist of a comparator which compares the voltage of waveform in the board with threshold voltage
signal generator and distortion meter
The signal generators are used in designing, repairing of electronic devices, and in troubleshooting. Types of signal generators – functional signal generator, arbitrary waveform generator, RF signal generator, audio signal generator and video signal generator. Function generator consist of electronic generator, which generates sine, triangular, saw tooth and square wave. But in modern devices these are generated by DSP. Function generator consist of frequency control network, two constant current source, an integrator, a diode wave shaper, voltage comparator multivibrator
Arbitrary waveform generators are a device that generates arbitrary streams of digital information. Arbitrary waveform don’t have any fixed shape. Arbitrary generator have 2 independent channels. Arbitrary generator have limited bandwidth and high cost. Arbitrary waveform generator is used in the semiconductor component, communication, and system tests.
RF signal generator uses phase locked loop and direct digital synthesis to generate waveforms. RF generator is of three types – analog signal generator, vector generator and logical signal generator
Vector signal generator is also called digital signal generator , which generates complex digital modulated signals (QPSK, QAM)
Logical signal generator is also called digital pattern generator, which generates pulses with variable duration and variable rise and fall time. Logical signal generator is used for functional validation and testing Distortion factor meter is used to find the frequency which produce harmonic distortion to our signal and works to overcome it. Distortion factor meter is based on fundamental frequency suppression by high pass filter. Distortion factor meter is also used as C. millivoltmeter and used in musical and electrical instruments. Distortion meter have two parallel circuits in the input, first circuit measure total signal which is calibrated to 100%, second circuit is a high pass filter