从峰值检测器的角度探讨硬件与软件的平衡

　　硬件与软件权衡。第2部分：峰值检测器

　　编者按：这是一个典型的架构决策：它的功能是在硬件中实现，以及在软件中实现。这两部分系列的第1部分着眼于使用比较器作为设计的考虑和权衡。在第2部分中，我们将使用峰值检测器作为示例。

　　正如本系列文章的第1部分所述，人们常常认为软件是实现核心功能的简单方法，尽管基于硬件的解决方案通常是更好的方法。

　　在给定的情况下，达到“最佳”答案需要设计者考虑许多设计因素和性能目标之间的权衡。本文将从峰值检测器的角度探讨硬件与软件决策，同时提供一些示例。

　　Defining the peak detector function

　　Like comparators， peak detectors are a basic circuit building block for many real-world signal processing applications. Peak detection determines that a signal has passed its peak value and signals the system to indicate this occurrence. They can be used to mark the presence of valid pulses within a continuous stream， capture radar signal returns， monitor heart pulses， or to indicate a new maximum such as in data from oscillations （buildings swaying due to an earthquake）。

　　Before designing a peak detector， it’s important to be very clear about the objectives of the project， as there is some overlap and ambiguity in terminology. First， there’s a maximum signal detector， which captures the maximum value of a signal indefinitely， until a new maximum occurs （Figure 1）。

　　An example might be a sensor that is tracking the maximum shock to which a package in transit is subjected. The lesser shocks are not of interest; only that maximum is of concern.