Main Radar Home

 Radar theory Home

AP3302 Pt3 Contents

AP3302 Pt3 Section 2Contents

Contact the Editor

AP 3302 Pt. 3

Section 2

CHAPTER 5

Clamping Circuits



Applications of Clamping Circuits

Clamping circuits have many uses in radar. The following paragraphs consider a few examples.

a. Pulse shaping. In Chapter 4 (p 88) we saw that the output from a triode squarer is not a perfect square wave. It can however be made more square by other circuits. We often need to 'tidy up' a waveform in this way and the process is known as pulse shaping, and may include both limiting and clamping. Fig 11 shows an example. The output from the squarer varies between + 200V and + 300V and is considerably curved below the + 225V level. This waveform is positively clamped to - 25V so that the curved portion is negative with respect to earth (zero volts) and the remainder is positive. The clamped waveform is then negatively limited to zero volts so that the curved portion is cut off and we are left with a good square wave of 75V amplitude, positive-going with respect to earth.

b. CRT blanking pulse. A blanking pulse is normally applied to the grid of a c.r.t. to cut off the electron beam during the resting time between traces. The required input Vg to the grid of the c.r.t. is shown in Fig 12b, where VT is the level of voltage needed during the trace to give the required brightness.


 

Previous page

To top of this page

Next Page

Constructed by Dick Barrett
Email:
editor@ban_spam_radarpages.co.uk

(To e-mail me remove "ban_spam_" from my address)

ęCopyright 2000 - 2002 Dick Barrett

The right of Dick Barrett to be identified as author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.