As a communication engineer our princple interest is signal and their measuring instrument; Thus Spectrum Analyzer is an instrument which graphically provides the energy distribution of a signal as a function of the frequency on its CRT. The spectrum analyzer provides information about all these things, by displaying the signal in the frequency domain. The measurement of dominant frequencies and their responses. The component levels and energy strength Frequency stability Bandwidth and Spectral purity Modulation index and attenuation Harmonic and intermodulation distortion Various signal generation and so on Which is not easy to measure at time domain

1. Hello!
I am Tahrimur Rahman
My
Roll: 12102907
Session: 2011-12
3rd year 2nd semester
Dept. of Electronics and Communication Engineering
J.K.K.N.I.U.

2. Spectrum Analyzer

3. Outline:
My process is easy & simple
What? Why? How? Where?

4. What?
Spectrum
The observed distribution of a phenomenon
across a range of measurement. Likely, power
spectrum, frequency spectrum etc.
Analyzer
An analyzer is a person or device that analyses
given data. It examines in detail the structure of
the given data and tries to find patterns and
relationships between parts of the data.
As a communication engineer our princple interest is signal and their measuring instrument; Thus
Spectrum Analyzer is an instrument which graphically provides the energy distribution of a signal as a
function of the frequency on its CRT.

5. ◇ The measurement of dominant frequencies and their
responses.
◇ The component levels and energy strength
◇ Frequency stability
◇ Bandwidth and Spectral purity
◇ Modulation index and attenuation
◇ Harmonic and intermodulation distortion
◇ Various signal generation and so on
Which is not easy to measure at time domain
Why?
The spectrum analyzer provides information about all these
things, by displaying the signal in the frequency domain.

6. “
Now a question may arise. Can we not
use an Osciloscope for above purposes ?

7. No; because of
First
A spectrum analyzer displays
received signal strength (y-axis)
against frequency (x-axis). An
oscilloscope displays received
signal strength (y-axis) against
time (x-axis).
Second
The spectrum analyzer
measurements are in frequency
domain, whereas the oscilloscope
measurements are in time
domain.
Fourth
Spectrum analyzer uses complex
circuitry compared with an
oscilloscope. As a result of this,
the cost of a spectrum analyzer is
usually quite high.
Fifth
Normally, an oscilloscope can not measure very low voltage levels
(say,−100 dBm) and are intended for low-frequency, high-amplitude
measurements. A spectrum analyzer can easily measure very low
amplitudes (as low as −120 dBm), and high frequencies (as high as
150 GHz).
Third
A Spectrum analyzer is useful for
analyzing the amplitude response
of a device against frequency.
The amplitude is normally
measured in dBm in spectrum
analyzers, whereas the same is
measured in volts when using
oscilloscopes.

8. How?
The spectrum analyzer is
said to operate in the
frequency domain
because it allows one to
measure the harmonic
content of an electric
signal, that is, the power
of each of its spectral
components. In this case,
the vertical and
horizontal scales read
powers and frequencies.

9. A simplified block diagram of Spectrum
Analyzer
It consists of the following parts:
1. Front-end mixer
2. Voltage controlled oscillator
3. Saw-tooth generator
4. IF amplifier
5. Detector
6. Video amplifier
7. Cathode Ray Tube (CRT)

10. Limitations
Every device has ……………………….. So It also.

11. Where?
It is common to see spectrum analyzer in the fields of following applications:
◇ Device Frequency Response Measurements: broadband amplifier, narrowband filter etc.
◇ Monitoring: transmitted power and received power of a microware tower. In this way,
you can verify that the frequency and signal strength of your transmitter are according to
the specified values.
◇ Other specialized applications : RFI , EMI, EMC etc.
◇ Interference Measurements: telecom microwave towers, TV stations, airport guidance
systems etc.
◇ Satellite: Return-loss measurement, Satellite antenna alignment etc.
And so on.

12. Thanks!
Any questions?
You can find me at:
◇ www.facebook.com/tahrimur-rahman
◇ tahrimurrahman@gmail.com