Apparatus for displaying waveforms of time-varying signals emloying a television type display

Claim 2

Apparatus for displaying time-varying signals including in combination means for receiving a time-varying signal; sampling means for periodically sampling said signal; means for converting the samples of the signal to digital representations thereof; memory means for storing a predetermined number of said digital representations; input cOntrol means for loading the most recent digital representation into the memory means in place of the oldest digital representation stored therein; display means of the type producing images on a display surface by selectively writing on the display surface while repeatedly sweeping a raster scanline pattern over the display surface; output means coupled to the memory means and the display means for causing two digital representations read out of the memory means for each scanline of the raster scanline pattern to produce an image on the display surface during tracing of the scanline from a point representative of the value of one digital representation to a point representative of the value of the other digital represenation; and output control means for reading out two digital representations from the memory means for each scanline of the raster scanline pattern and for causing digital representations to be read out in synchronism with the sweeping of the raster scanline pattern to cause images of the most recent digital representations to appear at one edge of the display and images of the oldest digital representations to appear at the opposite edge of the display.

Claim 3

Apparatus for displaying time-varying signals in accordance with claim 1 wherein said display means traces each individual scanline of said pattern in a direction substantially orthogonal to the line of direction from said one edge of the display to said opposite edge of the display.

Claim 4

Apparatus for displaying time-varying signals in accordance with claim 2 wherein said output means includes first counting means for measuring a first time period representative of the value of one of the digital representations read out of the memory means for each scanline and for producing a first output signal at the termination of the first measured time period, second counting means for measuring a second time period representative of the value of the other of the digital representations read out of the memory means for each scanline and for producing a second output signal at the termination of the second measured time period, and flip-flop means coupled to the first and second counting means and operable to produce an unblanking signal in response to a first output signal and to terminate the unblanking signal in response to a second output signal; said display means being operable to produce images by writing on the display surface during an unblanking signal; and including means for synchronizing the start of measuring each of said time period with the tracing of each scanline to cause an unblanking signal to produce images along the scanline between points corresponding to the values of the two digital representations.

Claim 5

Apparatus for displaying time-varying signals in accordance with claim 3 wherein said first counting means includes first means for receiving a count representative of the value of one of the digital representations read out of the memory means for each scanline, and second means for receiving periodic clock pulses and for producing said first output signal when the number of clock pulses received equals the count received from said first means; said second counting means includes first means for receiving a count representative of the value of the other of the digital representations read out of the memory means for each scanline, and second means for receiving periodic clock pulses and for producing said second output signal when the number of clock pulses received equals the count received from said first means of the second counting means; and including means for applying periodic clock pulses to the second means of the first and second counting means when activated; and further wherein said means for synchronizing is operable to activate said means for applying periodic clock pulses at the same point during each trace of a scanline.

Claim 6

Apparatus for displaYing time-varying signals in accordance with claim 4 wherein said output means includes first register means coupled to said memory means for receiving and storing one of the digital representations read out of the memory means for each tracing of a scanline, second register means coupled to said memory means for receiving and storing the other of the digital representations read out of the memory means for each tracing of a scanline, and comparison means coupled to the first and second register means and to said first means of the first counting means and said first means of the second counting means, said comparison means being operable to compare the digital representations stored in the first and second register means and to transmit counts representative of the value of each of the two digital representations to said first means, the smaller count being transmitted to the first means of the first counting means and the larger count being transmitted to the first means of the second counting means.

Claim 7

Apparatus for displaying time-varying signals in accordance with claim 5 wherein said memory means includes a random access memory means having a plurality of stages, each of which is capable of storing a digital representation; said input control means is operable to load digital representations in sequence into said stages, each digital representation being loaded into a stage in place of the oldest digital representation stored in the memory means; said output control means is operable to cause digital representations to be read out of two adjacent stages for each scanline by addressing pairs of adjacent stages in succession, the first stages to be addressed in each succession being changed during subsequent successions in accordance with the replacement of old digital representations by new digital representations, while the digital representations remain in the same stages except to be removed from the memory means and replaced by more recent digital representations, in order that images of the most recent digital representations appear at said one edge of the display and images of the oldest digital representations appear at said opposite edge of the display.

Claim 8

Apparatus for displaying time-varying signals in accordance with claim 6 wherein said input control means includes input counting means for counting input clock pulses through a recurring sequence of states equal in number to the number of the plurality of stages in the random access memory means, input pulse means coupled to the input counting means for applying periodic input clock pulses thereto, said input counting means being coupled to the random access memory means and being operable to control the address of the stage in which a digital representation from said means for converting is loaded in accordance with the state of the input counting means whereby each input clock pulse causes a digital representation to be loaded into the next stage in a repeating succession corresponding to the recurring sequence of states of the input counting means; and said output control means includes means coupled to the input counting means for determining the state of said input counting means, and output address means coupled to the random access memory means and to said last-mentioned means and operable to address pairs of adjacent stages in sequence in accordance with the state of the input counting means in synchronism with the sweeping of the raster scanline pattern to cause pairs of digital representations to be read out of the memory means in sequence and images thereof to appear on the display with images of the most recent digital representations at said one edge of the display and images of the oldest digital representations to appear at said opposite edge of the display.