Apparatus for automatic measurement of the video-signal-to-noise ratio in a television channel

• US 3,995,105 A
• Filed: 11/28/1975
• Issued: 11/30/1976
• Est. Priority Date: 09/16/1971
• Status: Expired due to Term

• Current Assignee: Alexandr Alexandrovich Avseevich, Jury Borisovich Zverev, Mark Iosifovich Krivosheev, Rudolf Lvovich Marein
• Original Assignee: Alexandr Alexandrovich Avseevich, Jury Borisovich Zverev, Mark Iosifovich Krivosheev, Rudolf Lvovich Marein
• Inventors: Krivosheev, Mark Iosifovich, Avseevich, Alexandr Alexandrovich, Zverev, Jury Borisovich, Marein, Rudolf Lvovich
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Masinick, Michael A.
• Application Number:
  US05/636,226
• Time in Patent Office: 368 Days
• Field of Search: 178/6, 178/DIG. 4, 325/67, 325/363
• US Class Current: 348/193
• CPC Class Codes: G01R 29/26 Measuring noise figure; Measuring signal-to-noise ratio
• CPC Class Codes: H04N 17/00 Diagnosis, testing or measuring for television systems or their details

Abstract

An apparatus for automatic measurement of the video signal-to-noise ratio in a television channel comprises a video signal pre-processing unit, the inputs thereof being connected to the outputs of a unit measuring the peak-to-peak amplitude of the video signal, a sync separator and a control unit respectively. Another output of the sync separator is connected to a series combination of the following units controlled by the control unit; a short pulse shaper, a pulse-amplitude modulator, a switch, a pulse stretcher, a means for converting the pulse amplitude to a number of pulses, a means for producing the differences between samples, an analyzer of the differences between samples, a digital function generator and a digital display. The output of the means for producing the differences between samples is connected to one of the inputs of the unit measuring the peak-to-peak amplitude of the video signal, another input of which is coupled by way of the video signal pre-processing unit to the input of the pulse-amplitude modulator, another output of the unit measuring the peak-to-peak amplitude of the video signal being connected to one in the inputs of the switch.

Claims

1. An apparatus for automatic measurement of the video signal-to-noise ratio in a television channel, said apparatus comprising:

a control unit having inputs and outputs;

means for measuring the peak-to-peak amplitude of a video signal, said measuring means having inputs and outputs, a first input of said measuring means being supplied with the video signal, a second input of said measuring means being connected to a first output of said control unit;

a sync separator having inputs and outputs, a first input thereof being supplied with the video signal and a second input thereof being connected to a second output of said control unit, a first output of said sync separator being connected to a first input of said control unit, a second output of said sync separator being connected to a third input of said measuring means;

a short pulse shaper having an input thereof connected to a third output of said sync separator;

pulse-amplitude modulator means for modulating short pulses with the video signal, said modulator means having a first input thereof connected to an output of said short pulse shaper;

a pulse stretcher having two inputs and an output, the first input thereof being coupled to an output of said modulator means and the second input thereof belong connected to a third output of said control unit;

means for converting pulse amplitude to a number of pulses, said converting means having two inputs and an output, the first input thereof being connected to the output of said pulse stretcher and the second input thereof being connected to a fourth output of said control unit;

means for producing a difference between samples so that each next sample is substracted from the previous one, said means for producing the difference between samples having two inputs and three outputs, the first input thereof being connected to the output of said converting means and the second input thereof being connected to a fifth output of said control unit, the first output thereof being connected to the third input of said measuring means.

a function generator including a digital squarer, a digital integrator and a digital logarithmic circuit, said function generator being controlled by said control unit and having an input thereof coupled electrically to the second output of said means for producing a difference between samples, said means for producing the difference between samples, said digital squarer of said function generator having a first input thereof connected to a sixth output of said control unit and a second input thereof coupled electrically to the second output of said means for producing the difference between samples, said digital integrator of said function generator having a first input thereof connected to a seventh output of said control unit and a second input thereof connected to an output of said digital squarer, said digital logarithmic circuit of said function generator having a first input thereof connected to an eighth output of said control unit and a second input thereof connected to an output of said digital integrator; and

a digital display having a first input thereof connected to an output of said logarithmic circuit and a second input thereof connected to a ninth output of said control unit.

2. An apparatus as claimed in claim 1, further comprising:

a video-signal pre-processing unit having three inputs and an output, the first input thereof being connected to a fourth output of said sync separator, the second input thereof being connected to a first output of said measuring means so as to separate noise packets from the video signal and to amplify them, the third input thereof being connected to a tenth output of said control unit, the output of said video-signal preprocessing unit being connected to a second input of said pulse-amplitude modulator means so as to supply noise packets to the second input of said modulator means; and

a switch connected between a second output of said measuring means and the first input of said pulse stretcher, said switch having a second input thereof connected to the output of said pulse amplitude modulator means and a third input thereof connected to an eleventh output of said control unit.

3. An apparatus as claimed in claim 2, further comprising and analyzer of the difference between samples which is connected between the second output of said means for producing the difference between samples and the second input of said digital squarer, said analyzer having inputs and outputs, the second output thereof being connected to a second input of said control unit and the second input thereof being connected to a twelvth output of said control unit, a third input of said control unit being connected to a second output of said means for producing the difference between samples, thereby to enable automatic measurements of the video signal-to-noise ratio on a moving picture.