the voice signal is digitized and compressed (by) using a model that...
你理解错误。本句中的compressed并不是形容词。is digitized and (is) compressed 为并列的二个被动语态谓语动词,using...为现在分词短语作方式状语修饰谓语动词,而不是修饰形容词。
On a D-AMPS mobile phone,the voice signal picked up by the microphone is digitized and compressed using a model thant is more sophisticated than the delta modulation and predictive encoding schemes.
这里面斜体加粗的部分是现在分词短语,但是它修饰了前的形容词compressed,一般来说,分词短语是修饰名词的。这里为什么现在分词短信修饰了形容词compressed,请解答,谢谢