| 释义 |
pulse A brief, temporary change in a quantity or value from its normal or initial level for a period of time, and then a decay of that value back to the original level. Purely digital systems that do not rely on the modulation of an underlying carrier fit this definition.Telegraphy, for example, relies on the making and breaking of an electrical current so that the normal or initial level is a current off (no current) condition and the pulse is either a short or long current on (yes current) condition (dot or dash, respectively), 74570c16.qxd 9/11/07 12:27 PM Page 397 |