Материалы по теме:
A Pico board can however allow better control at lower frequencies within the typical AM radio station (~1000 KHz). While square waves are well-suited for frequency-modulating any PCM audio file (ignoring the unwanted harmonics), they cannot be used well for amplitude modulation. They can only encode ON or OFF instead of different audio amplitudes (think 1-bit envelope). Alright, no emitting arbitrary “.wav” files. We can at least emit a single audio frequency at a time using On-Off Keying. Let’s make some retro game sounds!，更多细节参见体育直播
。快连下载安装对此有专业解读
(save $100 with education discount)
But also why it’s not that hard，更多细节参见服务器推荐