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
Q. Design the low-pass filter shown in Figure (by determining L) to have a half-power frequency of 10 kHz.

Q. Show Block diagram of proportional and integral controller? The block diagram of Figure illustrates a typical microprocessor system used to implement the digital PI controll

What is TSR? TSR: The TPA also as TSR stand for terminate and stay resident programs which remain in memory in an active state till activated by a hot-key sequence or other eve

Q. Analog communication systems? An analog message is a continuum of possible amplitudes at any given time, and analog signals are continuous in time and in amplitude, such as

a. Discuss the benefits and limitations of utilizing wind energy for electricity generation. b. Draw the block diagram representation of a thermal power generation unit. Illustr

(a) Give the characteristics of ideal OP-Amp? (b) Illustrate inverting operational amplifier with feedback. get the expression for voltage gain with feedback? Write short not

A 500KVA, 6 pole, 500v, 3 phase, wye-connected synchronous generator has a synchronous impedance of 0.1 + j1.5 ohms per phase. If the generator is driven at 1000 r.p.m., what is th

What is the Direction of a line of flux The direction of a line of flux is from the north pole to the south pole on the exterior of the magnet and is then supposed to continue

Q. Can you show Binary Number Formats? We in general write binary numbers as a sequence of bits (bits is short for binary digits) and we have defined boundaries for these bits.

NOP No Operation Instruction No operation  is performed  when this  instruction is executed. The instruction format is             NOP All  registers and flags  re