Lock detector for bit synchronizer
US4675558A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 1985 |
| Grant date | Jun 23, 1987 |
| Priority date | — |
| Expiry date | Oct 21, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S331/02
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A lock detector (12) used in conjunction with a bit synchronizer (14) for determining when a random binary input signal (2) is in lock with a clock (7) generated by the bit synchronizer (14). A window comparator (3, 5; or 23, 25, 27) determines whether the amplitude of the input signal (2) is within or without an amplitude window, and generates a signal (33) as a result of said determination. This signal (33) is sampled at periodic sampling points (X, Y). The set of X sampling points and set of Y sampling points are interleaved and usually separated by half a bit period. The X samples and Y samples are averaged and compared. Means (19) are provided for declaring a lock condition when the X average exceeds the Y average by a preselected threshold (V.sub.REF), which occurs when the X points are positioned near mid-points of data bits (35) and the Y points are positioned near data transitions (39). The circuit (12) will not lock on false sidebands and can operate at very low signal-to-noise ratios.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.