Process and device for retrieving digital data in the presence of noise and distortions
First Claim
1. A process for establishing the average value of a voltage during the presence of a burst signal formed by a succession of alternating 1s and 0s, so that, after chopping to a level corresponding to said average value, successive 1 and 0 are of the same width, the average value being taken substantially between the beginning and the end of the burst, and this average value being stored at the end of the burst then brought to a reference value before the appearance of the following burst, comprising bringing the value considered to an initial level lower than or substantially equal to half the smallest foreseeable burst amplitude before the appearance of the burst then increasing this level in accordance with the signal received, in a time interval preceding the earliest probable time of appearance of the burst, so as to fix a threshold voltage greater than the initial level and taking into account the level of the noise and disturbances, and establishing the average value from said threshold value during a given duration, counted from the appearance of the first 1 of the burst.
0 Assignments
0 Petitions
Accused Products
Abstract
This process enables the average value of a voltage to be established during a burst formed by an alternation of 1s and 0s, this value being stored until the following burst appears.
According to the invention, the value considered is brought to an initial level less than or equal to half the smallest foreseeable burst amplitude, before appearance of the burst, then this level is increased depending on the signal received, in a time interval preceding the earliest probable time of appearance of the burst, e.g. by detecting the peak value of the received signal. A threshold signal taking into account the level of the noise and the disturbances is thus fixed. The average value is then taken during a definite period, counted from the first 1 of the burst.
132 Citations
15 Claims
- 1. A process for establishing the average value of a voltage during the presence of a burst signal formed by a succession of alternating 1s and 0s, so that, after chopping to a level corresponding to said average value, successive 1 and 0 are of the same width, the average value being taken substantially between the beginning and the end of the burst, and this average value being stored at the end of the burst then brought to a reference value before the appearance of the following burst, comprising bringing the value considered to an initial level lower than or substantially equal to half the smallest foreseeable burst amplitude before the appearance of the burst then increasing this level in accordance with the signal received, in a time interval preceding the earliest probable time of appearance of the burst, so as to fix a threshold voltage greater than the initial level and taking into account the level of the noise and disturbances, and establishing the average value from said threshold value during a given duration, counted from the appearance of the first 1 of the burst.
-
10. The device for receiving a video signal and for establishing the average value of voltage during a burst signal comprising:
first and second current sources;
a capacitor connected to said sources;
a chopper comparator one input of which is connected to a terminal of said capacitor and the other input of which receives the video signal to be analyzed;
first switching means for discharging the capacitor during a zero-ing signal;
second switching means for charging the capacitor intermittently during a signal present within the "line suppression" interval, by means of the peaks of the received signal; and
third switching means for alternately charging and discharging the capacitor, at the same current, as a function of the received signal level, during a synchronization burst, to charge the capacitor to the average value;
the capacitor storing the previous established threshold value and average value, when none of the current sources is connected to said capacitor by any of said switching means.- View Dependent Claims (11, 12, 13, 14, 15)
Specification