low/high side injection 指的是什么？

不知道就先去goole查一下。
High-side and low-side injection
The amount that a signal is down-shifted by the local oscillator depends on whether its frequency f is higher or lower than fLO. That is because its new frequency is |f − fLO| in either case. Therefore, there are potentially two signals that could both shift to the same fIF one at f = fLO + fIF and another at f = fLO − fIF. One or the other of those signals, called the image frequency, has to be filtered out prior to the mixer to avoid aliasing. When the upper one is filtered out, it is called high-side injection, because fLO is above the frequency of the received signal. The other case is called low-side injection. High-side injection also reverses the order of a signal's frequency components. Whether or not that actually changes the signal depends on whether it has spectral symmetry or not. The reversal can be undone later in the receiver, if necessary.

谢谢楼上..
可能我提问内容的不够正确..
我想知道
High-side and low-side injection
这些术语中文怎么翻译呢?