How to use oscilloscope to present rawvideo from pulseradar?

[StoppTidigare]

Hi all could somebody discuss the above topic
with me

A pulseradar typically have a rotating antenna, as the pulse is leaving the antenna the electron beam must be steered from the center of the screeen to its periphery

Information about the angle of antenna is used to rotate the electron beam as it scans from the center to the periphery.

What kind of input to an oscilloscope steers the beam from the center and out ?

Kindest regards,
StoppTidigare

 

[House_Cat]

Re: How to use oscilloscope to present rawvideo from pulsera

A radar display is not just a simple oscilloscope. An oscilloscope uses deflection plates in the CRT to electrostatically deflect the electron beam directed at the screen.

A radar display console uses magnetic deflection to sweep the beam across the screen - somewhat like the sweep in a television receiver. The display beam is rotated by a synchro that rotates the magnetic deflection assembly in sync with the antenna. The sweep is initiated with the transmitted pulse; a T/R switch then switches the antenna to receive; the returning pulse is sent to the display and appears as intensity modulation of the sweep that was begun by the transmitted pulse.

A circuit to use an oscilloscope would be complex. You could probably dream up a deflection circuit for an oscilloscope that would generate a variable sawtooth sweep. The sawtooth could be time delayed from the initiation of the sweep such that the trace deflected radially from the center of the screen. You would then have to vary the amplitude and polarity of the sawtooth to correspond with the antenna rotation by using a synchro or digital angle encoder signal from the antenna to determine the corresponding x and y value for the sawtooth. You modulate the z axis with the received pulse to get the actual radar display.

If you want this as a hobby radar, why not do it like the first radars? They didn't rotate continuously. The antenna was hand steered by the operator who looked at the mechanical angle indicator when he got a return on his scope. The oscilloscope would work fine as a display for such a simple setup. You would just start the oscope sweep with the transmitted pulse; the T/R switch would automatically connect the receiver; the return pulse from the receiver could then be connected to either the y or z axis scope input to get either a pulse or bright spot indicatinig the target return. You would read range by the time position of the return signal on the sweep.

 

[StoppTidigare]

Re: How to use oscilloscope to present rawvideo from pulsera

Hi all, and thanks House_cat for your discussion.

Is there any interface circuit that I can buy for more ease of communication with the oscope display ?

Kindest regards,

StoppTidigare