Working of a sweep frequency generator, Electrical Engineering

Q. With suitable diagram explains the working of a sweep frequency generator.

Sol. A sweep frequency generator or sweeper is a special type of signal generator in which the output frequency is cyclically swept through a range of frequencies.

     The instruments may have a display built into it to show the variation of amplitude with frequency or it may provide signals for use with an external oscilloscope. Shows the block diagram of typical sweep generator.

     The time base is usually adjustable to give output sweep times in the range from 10 ms to greater than 100s. it is also often possible to control the sweep manually from the front panel of the instrument. The time base is frequently a triangular or a sawtooth waveform.

   Two modes are used to set the swept frequency range:

(i)           The stop- start Mode: in this mode the stop and start frequencies are set from the front panel and the instrument sweeps between these limits. This mode is used for wide sweep widths.

 (ii) Delta Frequency Mode: in this mode the centre frequency and the maximum excursion about this frequency are set from the front panel. It is used for narrow sweep widths.

The frequency range of the swept frequency generator usually extends over the three bands, 0.001 Hz to 100 kHz (low frequency to audio), 100 kHz to 1500 MHz (RF RANGE) and 1200 GHz (microwave range). Three approaches may be used to cover a wide band of swept frequencies from a single instrument.

(a)  Manually Switching:  Between different frequency oscillators, the problem occurs when the frequency range needed overlaps two bands.

(b)           Stacked Switching: The bands are automatically selected by electronic switches so that one can sweep the whole instruments range as one continuous band.

(c)          Heterodyne control: Illustrated in given. Two high frequency signals are mixed to give a lower difference frequency O/P as one continuous band.

Output level control is used in swept frequency generator to keep the output amplitude to the values set on the front dial. Usually RF amplitude of the output. This is compared with a signal corresponding to the required amplitude and the error is fed back to an electronic attenuator circuit to keep the output constant.

Posted Date: 7/12/2012 6:24:11 AM | Location : United States







Related Discussions:- Working of a sweep frequency generator, Assignment Help, Ask Question on Working of a sweep frequency generator, Get Answer, Expert's Help, Working of a sweep frequency generator Discussions

Write discussion on Working of a sweep frequency generator
Your posts are moderated
Related Questions
Reverse Recovery Characteristics At the end of forward  conduction in diode  reverse current  flows for  a short  time. The  device  doesn't  attain its full blocking  capabili

A rocket on a test stand is modeled as a column clamped at x = 0 and free at x = L, and subjected to compressive force P applied at the free end. The direction of load P remains

The    French    scientist,    Ampere,    (1775- 1836), conducted a series of experiments on the force between current carrying conductors. He found that: force per metre of wire (

Ginny Jones currently works as the VP-Product Strategy for a well-established enterprise software company. She and her friend, Tom Robinson, currently CFO at a competing firm (and

why armature lamination notched in outer periphery

Q. The inductance per unit length in H/mfor parallel plate in?nitely long conductors in air is given by L = µ 0 d/w = 4π×10 -7 d/w, where d and w are inmeters.Compute L (per unit

Explain the term half duplex transmission. A half duplex channel can receive and send, but not at similar time. It's as a one-lane bridge where two-way traffic should give way

Two byte  Instructions In these  instruction the first byte  specifies  the operations code  and the  second byte  specifies the operand. To identify  two byte  instructions o

Q. (a) An audio amplifier with R i = 10 k, R o = 0, and ¯A(ω), as shown in Figure (a), is used in the circuit shown in Figure with R S = 1 k,R L = 16 , and C = 0.2 µF. Sk

A 2300-V, three-phase, wye-connected, round rotor synchronousmotor has a synchronous reactance of 3 per phase and an armature resistance of 0.25  per phase. The motor operates on