Basics of signal analyzers especially spectrum analyzers.

1. SPECTRUM
ANALYSERS

2. INTRODUCTION
SIGNAL ANALYSERS
- instrument to analyze a signal.
- most of the electric signals are complex
waveforms, made up of fundamental and its
harmonics.
- to measure the amplitude, phase or frequency of
each harmonic or fundamental individually, signal
analyzers are used.
- all signal analysis instruments measure the basic
frequency properties of a signal, but use different
techniques to do so.
- USES : spectral purity of carrier wave, spectral
power distribution of AM & FM wave, signal
distortion and SNR.

3. INSTRUMENTS FOR SIGNAL
ANALYSIS
WAVE ANALYSER
- is a voltmeter which can be accurately
tuned to measure the amplitude of a
single frequency in a complex waveform,
within a band of 10 Hz- 40 MHz.
- Types:
# Frequency selective: m/m of AF range
(20 Hz- 20 kHz).
# Heterodyne: m/m in megahertz range.
- Uses : electrical, sound, vibration
measurement.

4. INSTRUMENTS FOR SIGNAL
ANALYSIS
DISTORTION ANALYSER
- measures the total harmonic power
present in the test wave rather than
the distortion caused by each wave.
- operating range: 5 Hz – 1 MHz.
- types
1). Fundamental suppression type
2). Intermodulation Distortion type.

5. INSTRUMENTS FOR SIGNAL
ANALYSIS
AUDIO ANALYSER
-similar to Distortion Analyser, but can
measure additional functions, such as
NOISE too.
MODULATION ANALYSER
- tune to the required signal and recover the
whole amplitude modulated (AM),
frequency modulated (FM) or phase
modulated (PM) envelope for display or
analysis.

6. INSTRUMENTS FOR SIGNAL
ANALYSIS
SPECTRUM ANALYSERS
- instrument to analyze the frequency spectrum of RF
and audio signals.
- SPECTRUM ANALYSIS : study of energy distribution
across the frequency spectrum of the given signal.
- signal is shown in frequency domain
frequency v/s amplitude plot
vertical axis- amplitude (in db)
horizontal axis- frequency (Hz)
- as the scan moves along horizontal axis, the display
shows the level of any signals at that particular
frequency.
- information about BW, effects of modulation and
frequency components, which are useful in designing
and testing of RF and pulse circuitary.

7. SPECTRUM ANALYSERS

8. SPECTRUM
ANALYSERS
Types
- RF – 10 Mhz-40 Ghz
used in communication, navigation, radar
and industrial instrumentation frequency
bands.
- Audio frequency – 20 Hz-20kHz.
Swept or superheterodyne SA
- RF spectrum analyzer.
- Uses superheterodyne principle as used in
radio receivers.
- Sweeps the frequency that is analyzed
across the required band to produce a view
of the signals with their relative strengths.

9. SPECTRUM ANALYSERS

10. SPECTRUM ANALYSERS

11. SPECTRUM ANALYSERS
ADVANTAGES
- Able to operate over wide frequency
range.
- Wide bandwidth.
- Inexpensive compared to others.
DISADVANTAGES
- Cannot measure phase.
- Cannot measure transient events.

12. SPECTRUM ANALYSERS
Fast Fourier Transform SA
- uses digital signal processing
techniques to provide in depth
waveform analysis with greater
flexibility.
- Fast capture of waveform.
- Able to capture non repetitive events.
- Can give phase.
- Waveforms can be stored.

13. SPECTRUM
ANALYSERS

14. SPECTRUM ANALYSERS
Applications:
- Study of RF spectrum produced in microwave
instruments.
In microwave instruments, horizontal axis
displays from 30 kHz up to a range of 2-3
GHz.
- Bio medical fields.
- Industrial instrumentation.
- Radar, oceanography.
- RF spectrum analyser
range- 500khz – 1 Ghz

15. RF SPECTRUM
ANALYSER

16. TEKTRONIX 2712

17. THANK YOU