Patent GB-1267425-A (GB)
Title: Improvements in or relating to radar displays
IPC: G01S7/22
Filed: 1969-04-30
Abstract: 1,267,425. Radar displays; cathode-ray tube displays. JAPAN RADIO CO. Ltd. 30 April, 1969 [15 May, 1968], No. 21979/69. Headings H4D and H4T.  In a device electronically generating signals producing an alpha numeric character display on a PPI scope, representing, e.g. date and time of occurrence of an image as a pattern of discrete elements, a radar PPI indicator generates sweep, trigger, and heading pulses Sx, Sh of which the former is applied to a radial delay circuit comprising a monostable multivibrator of time constant corresponding to the radial distance from origin of the character location; exciting a transistorized flip-flop gate 3 to excite an astable multivibrator radial pulse oscillator 4 defining radial width of the alpha numeric characters. Similarly, the latter signal Sh is applied to a circular delay circuit of time constant corresponding to the circular distance from the heading to the character location, exciting a gate 7 opening into circular pulse oscillator 8, which then starts. The output of oscillator 4 (Fig. 3, not shown) energizes a 4- stage dividing flip-flop combined with a diode transistor logical AND/OR matrix (Fig. 2, not shown) in a radial element signal encoder 5 delivering radial element signals encoded against the vertical components of the segmented mosaic of alphanumeric characters (Fig. 4, not shown). At the end of a flip-flop cycle, reset signal Sr 1  closes radial gate 3 to arrest oscillator 4 until the next sweep trigger signal St occurs. The pulse output of multivibrator oscillator 8 defining circular width components of the characters energizes a 3-stage dividing flip-flop combined with a diode logical AND/OR matrix (Fig. 2, not shown) in a circular element signal encoder 9 delivering circular element signals encoded against the horizontal components of the segmented mosaic of alpha numeric characters (Fig. 5, not shown), and when the necessary number of such signals are encoded, a reset signal from a character positioning means 15 (see below) is applied to gate 7 arresting oscillator 8 until the next heading trigger signal Sh. The encoder outputs are synchronizedly fed to mixer 10 containing plural sets of a diode logical AND circuit and transistorized inverter (Fig. 2, not shown) to produce (Fig. 6, not shown) successive segment signals in which the coded radial-element signals are defined in position and duration in circular direction by the circular positioning signals. The output operates a pattern signal composer 11 containing a matrix of diode AND circuits each with an OR inverter circuit (Fig. 2, not shown) arranged to generate a series of alphanumeric pattern signals corresponding to the characters, to be displayed in mosaic representation, which are fed to an automatic pattern selector 12 comprising diode gate and logic OR circuit (Fig. 2, not shown) controlled by a crystal clock generator 13 over a time memory 18 comprising flip-flop, gate inverter and multivibrator 18, pulsed from the circular delay circuit to prevent spurious indication due to display persistence. A time member 17 is provided, and the pattern character signals are also selectible by, a manual multiple switched pattern selector 14 to indicate, e.g. dating, and the automatically and manually selected pattern signals are applied to a character positioning means 15 (Fig. 2, not shown) comprising four segmental flip-flops and AND/OR diode logic determining their segmental positions as characters (Fig. 8, not shown). This is followed by an output controller 16 wherein the character signals are mixed over a double diode mixer and emitter follower circuit with radar video signals SV from the indicator 1 to a composite signal SC returned to the latter for display of the selected alpha numeric signal sequence (Fig. 9, not shown) the completion of a display of a specific series of characters returning a reset signal Sr 2  from character positioning means 15 to arrest the circular oscillator 8.