使用 AFSK 将数字数据调制为音频
我想将数字数据调制成音频。然后通过任何音频通道进行通信，并在目的地再次从音频解调为数据。为此，我希望使用计算机声卡和软件调制解调器，而不使用任何硬件实现。在互联网上，我发现这可以通过称为音频频移键控（AFSK）的技术来实现。我想知道我能否从 AFSK 获得超过 1200bps 的比特率，如果不能，这个限制背后的原因是什么。 有没有比 AFSK 更有效的技术来实现此目的？
I want to modulate digital data into audio. Then communicate it through any audio channel and demodulate at the destination from audio to data again. To do this I hope to use computer sound card and software modem without using any hardware implementation. In the internet, I found that this can be through the technique called Audio Frequency-Shift Keying(AFSK). I want to know that can I obtain bit rate more than 1200bps from AFSK and if it is no what the reason behind that this limitation.
Is there any technique efficient than AFSK for this purpose ?
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目前最常用的 AFSK 形式是 Bell202 调制解调器，波特率为 1200。还有一些其他标准也使用 1200 波特率，有些标准的运行速度低于每秒 1200 位，但据我所知，没有一个标准运行速度超过 1200 位。
但是，据我所知，没有理由不能'编写一个软件调制解调器以更高的波特率发送和接收。 Bell202 使用位填充（允许数据流连续使用不超过 5 位的相同音调）来帮助防止发送器和接收器彼此不同步，因此更高的波特率可能 需要较低阈值的位填充（每 4 或 3 位）。
另一个考虑因素是您使用的声卡应使用等于或您选择的波特率倍数的采样率。这是 1200 波特如此常见的原因之一，因为 1200Hz 和 48000Hz 是音频硬件的常见采样率。
所以 1200 波特不是限制。这只是一个标准。
The most common currently-used form of AFSK is the Bell202 modem at 1200 baud. There are a few other standards which also use 1200 baud, and some that run at less than 1200 bits per second, but none that I know of that run greater than 1200.
However, as far as I know, there's no reason you couldn't write a software modem to transmit and receive at a higher baud rate. Bell202 uses bit stuffing (allowing the data stream to use the same tone no more than 5 bits in a row) to help keep the transmitter and receiver from falling out of sync with each other, so a higher baud rate might require bit stuffing at a lower threshold (every 4 or 3 bits).
Another consideration is that the sound cards you're using should use a sampling rate equal to or a multiple of the baud rate you choose. This is one of the reasons 1200 baud is so common, as 1200Hz and 48000Hz are common sample rates with audio hardware.
So 1200 baud isn't a limit. It's just a standard.