Patent GB-1343658-A (GB)
Title: Apparatus for the synchronised display of function values on  the screen of a cathode ray tube
IPC: G01R13/28
Filed: 1971-11-24
Abstract: 1343658 Curve plotting on C.R.T. screen FRIED KRUPP GmbH 24 Nov 1971 [25 Nov 1970] 54667/71 Heading G4H  Apparatus for plotting on a C.R.T. screen variations of a dependent variable (y) over an independent variable (x) which is preferably time, is adapted such that information presented by an information transducer may be immediately displayed and also stored for a duration equal to that of the time base of the screen. As shown information varying over time, e.g. from echo sounding equipment, is inserted at 3 and applied to an A/D converter 17. A freerunning clock pulse generator 4À1 generates a train of pulses 5 which define quantized points in the time base of the apparatus which train is applied to a "divide by n" counter 4À2 and to an adding circuit where a composite pulse train 9 is produced having a pulse 6 from the unit 4À2 interposed between every nth pulse 5 and the first pulse of the next set of n pulses. This train 9 is applied as shifting pulses to a register 7 having n-stages 7À1-7À0n to which the output of the converter 17 is presented, and to a second A/D converter 15 which provides quantized time-base potentials to the x-deflecting plates of a C.R.T. 12, the converter 15 being such that it resets after every n pulses to the start of its cycle. The register 7 is provided with a feedback loop 13 to retain information shifted therethrough and the information adjacent read-out 7b is presented to a D/A converter 11 and as deflecting voltages to the y-plates of #C.R.T. 12. A switch 10 remains in the position shown at all times except when a pulse 6 is received in the pulse train 9, which pulse also acts as a shift pulse and switches 10 to its alternative position to allow the output at 17 to be read into the stage adjacent read-out 7b and to present this output coincidentally at the D/A converter 11. Thus if stage 7À1 is adjacent 7b at a particular pulse 6, after a further n pulses 5, the stage 7À2 will be at 7b at the instant of switching at 10 and the new data will be read into one of the stages 7À1-7À0n at each shifting cycle in the order 7.1, 7À2, 7À3 ... 7À0n. Pulse train 9 is also applied at 15 and the resultant display is derived from the stored contents of the register 7 with new information displayed at points on a curve which which move one position to the right with each shifting cycle. Since these new values are also read out on to the screen at the time they are received at 17 a monitoring of the phenomenon displayed, e.g. by audible means may also be effected simultaneous with their occurrence. A further "divide by n" counter 18 may be provided to provide an output pulse when the new information has just been inserted at stage 7À0n i.e. the complete curve has been displayed. This pulse may be used to trigger the measuring equipment for another operation or as a synchronizing signal for periodically occurring data. In a modification, Fig. 4 (not shown), data is only read into the shift register when it is made available at the A/D converter 17 and a comparator (31) is used to operate the switch 10 when the position of the C.R.T. display coordinate x corresponds with the input value y i  the system otherwise working in a similar manner.