qrs detector improvements

This will be the single thread for discussing improvements for qrs detectors. I will probably only be working on the xqrs class in the near future.

Current thoughts:

• The filter used to accentuate the qrs (we'll call this the moving wave integration filter) is currently an upright ricker with a fixed width: wavelet_filter = signal.ricker(self.qrs_width, 4). There are many things we could improve upon, such as:
  • Inverting it if we figure out the r wave is inverted
  • Designing a set of template beats for different ecg channels.

从 xqrs 类开始，检查 wavelet_filter = signal.ricker(self.qrs_width, 4) 在 QRS 检测器中是如何使用的。该 issue 列出了可能的方向，包括针对倒置 R 波进行反转，以及为不同 ECG 通道使用模板，但没有定义一项具体更改或完成测试。