双语畅销书《艾伦图灵传》第7章:运转起来(28)
The figure of 2000 Hz was in fact the one he intended to use, and his encipherment process would start with the speech signAl being sampled 4000 times a second.
The Delilah would then have to effect the addition of these sampled speech amplitudes to another stream of key amplitudes.
黛丽拉则把这些采样的声音振幅叠加到一组密钥振幅上。The addition would be done in modular fashion, meaning that while speech sample amplitude of 0.256 units and key amplitude 0.567 units would be added to give 0.823 units, the addition of 0.768 and 0.845 would give 0.613, not 1.613.
这个叠加的过程就是模加，比如说0.256单位的声音振幅和0.567单位的密钥振幅叠加起来就是0.823单位，而0.768和0.845叠加就是0.613，而不是1.613。
The result of all this would be a train of sharp 'spikes', of heights varying between zero and one unit:
得到的结果是一组锋利的脉冲，高度在0到1个单位之间注：The next problem was that of how to transmit the information of these 'spike' heights to the receiver.
接下来的问题是，如何把这些脉冲发送给接收者。In contrast to the X-system, Alan planned no quantisation of amplitudes here. He wanted to transmit them as directly as possible.
与X系统相比，艾伦的计划中并没有将振幅离散化，他想要尽量直接地发送它们。In principle the 'spikes' themselves could be transmitted, but being of such short duration, a few microseconds in fact, they would require a channel which could carry very high frequencies.
从理论上说，这些脉冲本身是可以发送的，但是它们的持续时间很短，实际上只有几微秒，因此需要很高频率的发送频道。No telephone circuit could do this.
没有哪个电话线路能够做到这一点。To use a telephone channel the information of the 'spikes' would have to be encoded into an audio-frequency signal.
如果要使用电话频道，脉冲信息就必须编码成音频信号。Alan's proposal was to feed each 'spike' into a specially devised electronic circuit with an 'orthogonal' property.
艾伦的想法是，把这些脉冲输入一种特殊的正交电路，This meant that its response to a spike of unit amplitude would be a wave with unit height after one time interval, and with zero height at every other unit time interval:
一个单位振幅的脉冲，会反馈为一段在1单位时间点上具有单位高度的波，而在其它单位时间点上的高度均为0：
