Method and apparatus for decoding an encoded NRZ signal
AssigneeHoneywell Inc.
InventorsIain Ross MacTaggart, David E. Tetzlaff
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Abstract
A bit serial decoder is disclosed decoding an encoded non-return to zero (NRZ) signal without the use of external clock. Transitions within the encoded NRZ signal cause a differential voltage signal to be output. This differential voltage increases at a constant rate between two transitions. At the second transition the magnitude of the differential voltage is compared to a preset value to determine a number of consecutive like bits. These consecutive bits can then be transmitted in one step to a storage means.
Claims18
A method for decoding an encoded non-return to zero (NRZ) signal comprising the steps of:
- receiving an NRZ signal;
- detecting first and second transitions in the NRZ signal;
- generating a first signal which changes at a known rate upon the detection of a first transition in the NRZ signal and generating a second signal which changes in magnitude at a known rate in response to the detection of a second transition;
- measuring the magnitude of the first signal at the detection of the second transition and measuring the magnitude of the second signal at the detection of the first transition;
- determining the number of consecutive first bits from the magnitude of the first signal at the second transition;
- and
- determining the number of consecutive second bits from the magnitude of the second signal at the first transition.
A decoder for an encoded non-return to zero (NRZ) signal comprising:
- first signal output means which detects a first transition in the NRZ signal and outputs a first signal which changes in magnitude at a predetermined rate;
- second signal output means which detects a second transition in the NRZ signal and outputs a second signal that changes in magnitude at a predetermined rate;
- first means for measuring the magnitude of the first signal at the second transition and converting the magnitude of the first signal to a number of consecutive first bits;
- and
- second means for measuring the magnitude of the second signal at the first transition and converting the magnitude of the second signal to a number of consecutive second bits.
An apparatus for decoding an encoded non-return-to-zero (NRZ) signal comprising:
- first signal output means which outputs a signal whose magnitude is proportional to the interval between first and second transitions in the NRZ signal;
- second signal output means which outputs a signal whose magnitude is proportional to the interval between the second and first transitions in the NRZ signal;
- first and second signal quantizers electrically connected the first and second signal output means respectively, which convert the magnitudes of the first and second signals to one or more consecutive first or second bits respectively;
- and
- storage means for storing and outputting first and second bits received from said first and second signal quantizers.
Dependencies are inferred from the claim text.