Method and arrangement for generation of a time mean-value free binary signal
First Claim
1. A method for generating a time mean value-free binary signal (OUT) from an input signal (IN), comprising the steps of:
- generating a first binary signal (O, O4) from an input signal and a control signal;
filtering the first binary signal (O, O4) through a first filter (8, 48) with substantially low pass characteristic, generating a first filtered signal (S, S4);
filtering a time mean value-free reference signal (J, J4) through a second filter (7, 47) with substantially low pass characteristic, generating a second filtered signal (FJ, FJ4); and
generating the control signal (C, C4) based on a difference signal between the first filtered signal (S, S4) and the second filtered signal (FJ, FJ4), said control signal being substantially proportional to the sum of the difference signal multiplied by a first constant and a second constant multiplied by the integral of said difference signal;
wherein the first filter (8, 48) and said second filter (7, 47) are substantially equal, and said time mean value-free binary signal (OUT) is constituted of said first binary signal (O, O4).
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Abstract
The present invention relates to the generation of a time mean value-free binary signal (O) from an input signal (IN). The device (10) comprises a feed-back loop adjusting the pulse ratio of the output signal by comparing its mean value to the mean value of a time mean value-free reference signal (J) and feeding-back the difference between said two mean values. The mean values are approximated by low pass filtering the binary signal (O) and the reference signal (J) with two filters (8, 7). If the filters (8, 7) are non-linear, the mean values of the filtered signals (S, FJ) can deviate from the mean values of the reference signal (O) and the reference signal (J). By constructing the filters (8, 7) as regards non-linearities, to be equal, the aforementioned discrepancy will be compensated, since the signals will deviate to the same degree from their theoretical values, when time mean value free.
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Citations
17 Claims
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1. A method for generating a time mean value-free binary signal (OUT) from an input signal (IN), comprising the steps of:
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generating a first binary signal (O, O4) from an input signal and a control signal;
filtering the first binary signal (O, O4) through a first filter (8, 48) with substantially low pass characteristic, generating a first filtered signal (S, S4);
filtering a time mean value-free reference signal (J, J4) through a second filter (7, 47) with substantially low pass characteristic, generating a second filtered signal (FJ, FJ4); and
generating the control signal (C, C4) based on a difference signal between the first filtered signal (S, S4) and the second filtered signal (FJ, FJ4), said control signal being substantially proportional to the sum of the difference signal multiplied by a first constant and a second constant multiplied by the integral of said difference signal;
wherein the first filter (8, 48) and said second filter (7, 47) are substantially equal, and said time mean value-free binary signal (OUT) is constituted of said first binary signal (O, O4). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
generating said time mean value-free reference signal (J, J4) by frequency dividing a second binary signal with regular flanks.
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7. The method of claim 1, further comprising, before said step of filtering said time mean value-free reference signal, the step of:
generating said time mean value-free reference signal (J, J4) by frequency dividing said first binary signal (O, O4).
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8. The method of claim 1, wherein the signal levels of said time mean value-free reference signal (J, J4) are substantially identical to the signal levels of said first binary signal (O, O4).
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9. The method of claim 1, wherein the cut-off frequency of said first filter (8, 48) and the cut-off frequency of said second filter (7, 47) are both low in relation to the frequency of said input signal (IN).
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10. A device (10, 40) for generating a time mean value-free binary signal from an input signal (IN), said device (10, 40) comprising:
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a limiter (3, 43) for generating a first binary signal from the input signal and a control signal (C, C4);
a first filter (8, 48) of substantially low pass characteristic, connected to the output of said limiter (3, 43) and generating a first filtered signal (S, S4);
a second filter (7, 47) of substantially low pass characteristic generating a second filtered signal (FJ, FJ4) by filtering a time mean value-free reference signal (J, J4), said control signal (C, C4) being generated from a difference signal between said first filtered signal (S, S4) and said second filtered signal (FJ, FJ4); and
a regulator (9) connected via a first input to said first filter (8) and connected via a second input to said second filter (7), said regulator (9) generating said control signal (c) from said difference signal, said control signal being substantially proportional to the sum of said difference signal multiplied by a first constant and a second constant multiplied by the integral of said difference signal;
wherein said first filter (8, 48) and said second filter (7, 47) are substantially equal, and said time mean value-free binary signal of the device (OUT) consists of said first binary signal (O, O4). - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification