R.A.F. Henlow Signals Museum Exhibits

Elevation Timebase Unit Type 134

2. In the elevation scan method of presentation, the "range" timebase on the CRT is produced by the timebase unit (range) Type 136, but instead of the trace being stationary across the horizontal diameter of the tube, as in other applications, it is caused to pivot about a point at the bottom left hand side of the tube face, moving up and down in synchronism with the tilting of the aerial. This motion of the range trace is produced by a scanning waveform generated in the timebase unit (elevation) Type 134.

3. Aircraft responses are received on the radar aerial, and the resulting video signals are applied to the CRT as intensity modulation. The face of the CRT thus represents a vertical section of the sky, similar to a sector PPI display, except that the slant range is given by the distance along the X-axis, and not by the distance along the trace ; the slant range can thus be read directly from a "range marks" scale on the CRT face. The timebase trace is blacked out, except when a video signal causes the beam to "paint." The Y-plate deflection is proportional to the angle of elevation of the aerial, so that if a response "paints" upon the tube face, the height is given by its vertical distance above the X-axis. Over the range of elevation used, the Y-deflection is practically linear; the non-linear portion being blanked out.

Sec/Ref: 10D/18534

Console 61 Timebase Unit (Elevation) Type 134 (Photograph Number 0435)

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