Working of spectrum analyzer and its applications, Electrical Engineering

Q. Explain the working of spectrum analyzer and its applications.


Draw block diagram of spectrum analyzer and explain its operation write down its importance applications.


Explain the block diagram of frequency selective wave analyzer.


Sol. Spectrum Analyzer: The most common way of observing signals is to display them on an oscilloscope, with time as the Y-axis amplitude of the signal versus time. This is the time domain. It is also useful to display signals in the frequency domain. The instrument providing this frequency domain view is the spectrums analyzer. A spectrum analyzer provides a calibrated graphical display on its CRT, with frequency on the horizontal axis.

Displayed as vertical lines against these coordinates are sinusoidal components of which the input signal is composed. The height represents the absolute magnitude and the horizontal location represents the frequency.

   These instruments provide a display of the frequency spectrum over a given frequency band spectrum analyzers use either a parallel filter bank or a swept frequency technique. In a parallel filter bank analyzer, the frequency range is covered by a series of filters whose central frequencies and bandwidth are so selected that they overlap each other, as shown.

Referring to the block diagram of the sawtooth generator provides the sawtooth voltage which drives the horizontal axis element of the scope and this sawtooth voltage is frequency controlled element of the voltage tuned oscillator. As the oscillator sweeps from of its frequency band at a linear recurring rate, it beats with the frequency component of the input signal and produce an If, whenever a frequency component is met during its sweep. The frequency component and voltage tuned oscillator frequency beats together to produce a difference frequency, IF. The IF corresponding to the component is amplified and detected if necessary and ten applied to the vertical plates of the CRO, producing a display of amplitude versus frequency.

The spectrum produced if the input wave is a single tuned A.M. is given. One of the principal applications or spectrum analyzer has been in the instrument, the horizontal axis can display a range as wide a range as 2-3 GHz small portion of the spectrum's Signals at amplitude microwave frequency separated by only a few kHz can be seen individually.

   The frequency range covered by this instrument is from 1 MHz to 40 GHz. The basic block diagram range from 500 kHz TO 1 GHz, which is representative of a super heterodyne type.

    The input signal is fed into a mixer which is driven by a local oscillator; the oscillator is linearly tunable electrically over the range 2-3 GHz. The mixer input signal but of frequency which are the sum and difference of the input signal and lock oscillator frequency.

   The if amplifier is tuned to a narrow band around since the lock oscillator is tuned over the range of only inputs that are separated pass through the if frequency amplifier get rectified and produce a vertical deflection on the CRT.

 From this is observed that as the sawtooth signal sweeps the local oscillator also sweeps linearly from GHz. The tuning of the spectrum analyzer is a swept receiver, which sweeps linearly from 0 to 1 GHz. The sawtooth scanning signal is also applied to the horizontal plates of the CRT to from the frequency axis. (The spectrum analyzer is also sensitive to signals from 4-5 GHz referred to as the image frequency of the super heterodyne. A low pass filter with and a cutoff frequency above 1 GHz at the input suppresses these spurious signals.) Spectrum analyzers are widely used in radars, oceanography and biomedical fields.

Posted Date: 7/12/2012 6:25:06 AM | Location : United States

Related Discussions:- Working of spectrum analyzer and its applications, Assignment Help, Ask Question on Working of spectrum analyzer and its applications, Get Answer, Expert's Help, Working of spectrum analyzer and its applications Discussions

Write discussion on Working of spectrum analyzer and its applications
Your posts are moderated
Related Questions
Determine the Disadvantages of expert systems -  Lacks common sense in some decision making processes -  Errors in the knowledge base can result in incorrect decisions being

Circuit with inductive load  Electromagnetic induction When a conductor is moved across a magnetic field so as to cut by the lines of force (or flux, an electromotive force

Q. Write a short note on RS-232-C. Ans: RS-232 standard is a collection of connection standards between different pieces of equipment. EIA RS-232 serial communication standard

Q. For a 10-bit R-2R ladder-network D/A converter with an MSB resistor value of 10 k, what is the value of the LSB resistor?

LT Metering or Low Tension Metering The subsequent types of meters are generally used for LT consumers: Whole Current Meters i)   Single phase meters ii)   3-phase

The operating frequency range of a superheterodyne FMreceiver is 88-108MHz. The IF and LO frequencies are so chosen that f IF LO .Ifthe image frequency f  c must fall outside of

Explain procedure to take shut down and to test the power line before starting work? Ans: Study the circuit and find out the circuit breaker to be opened. Open and lock the c

Q. Explain the conditions under which an RC circuit behaves as Differentiator Differentiator is a circuit in which the output voltage is directly proportional to the derivative

(a) "Pulse Code Modulation (PCM), as used in telephony, samples a signal at 8 kHz using 256 quantization levels". i. Outline how this scheme works with the help of sketches and,

Q. An 8 - pole dc generator has 500 armature conductors and has a useful flux per pole of 0.065 web. What will be the emf generated if it is lap connected and runs at 1000 r.p.m.