| 摘要 |
<p>A method of determining the reception time of a signal containing a predetermined code, e.g. a Barker code. The code may be present at the start of a telegram to be received by a mobile radio from a base station. The signal is correlated with a corresponding code stored in memory. The correlation is carried out at different offsets in time. This gives a correlation curve (figure 2). The apex represents peak correlation. The timing of optimum correlation is determined by extrapolating the sides to the apex. The invention also provides a zero crossing detector for timing zero crossing events whereby sufficiently accurate timing of receipt of the code is possible to enable meaningful correlation.</p> |
