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Browse Prior Art Database

Programmable Signal Generator

IP.com Disclosure Number: IPCOM000090116D
Original Publication Date: 1969-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 34K

Publishing Venue

IBM

Related People

Baskin, HB: AUTHOR [+3]

Abstract

The arrangement is for generating an arbitrarily specified electrical signal or waveform. A direct vector plotting terminal such as a computer controlled display unit is utilized. In the operation of such a terminal, a stream of graphic orders is sent to it through its control unit. When a line is to be drawn, a vector order is issued which specifies X and Y coordinates. These coordinates represent the end point to which the electron beam is to be positioned. Coordinates are expressed in raster units RU, a raster unit being the distance between any two adjacent addressable points on the display screen. The beam movement is from the previously addressed end point to the presently addressed end point.

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Programmable Signal Generator

The arrangement is for generating an arbitrarily specified electrical signal or waveform. A direct vector plotting terminal such as a computer controlled display unit is utilized. In the operation of such a terminal, a stream of graphic orders is sent to it through its control unit. When a line is to be drawn, a vector order is issued which specifies X and Y coordinates. These coordinates represent the end point to which the electron beam is to be positioned. Coordinates are expressed in raster units RU, a raster unit being the distance between any two adjacent addressable points on the display screen. The beam movement is from the previously addressed end point to the presently addressed end point. In this operation, if the beam is turned on while it is being moved, a vector is displayed between two successively addressed end points.

The following characteristics of the electron beam deflection system are employed. The changes in the X and Y beam deflection signal levels, required to display a vector, are chosen to be directly proportional to the changes in the X and Y coordinates of its end points as specified by the corresponding vector orders. Changes in the beam deflection signals are directly proportional to time. A change of beam position involves changes in both the X and Y components. The time to make the change is proportional to the amount of change in that component which changes the most.

The output signal waveform is derived from the deflection signal driving one of the axes, designated the signal axis. Timing is controlled by the deflection signal on the other axis, termed the timing axis. Thus, a change in the signal waveform is specified by a change in the signal axis component of the graphic vector order and the time required to make the change is controlled by the change in the timing axis component of that same vector order. This time is not less than that required for the change specified by the signal axis component. The signal waveform is amplified to any desired current or voltage level.

In the following example, the display surface contains a grid of 1000 RU by 1000 RU. A change of ten millivolts in the deflection signal produces a change of one RU in the beam position. A deflection of one RU requires 0.1 microsecond. The X axis is the signal axis and the Y axis is the timing axis.

The drawing shows the desired waveform. The beam is initially at position 0,0 and all points in...