Rockwell |
There are two compression methods available for Rockwell compatible modems: Rockwell ADPCM and PCM 8 (unsigned)
The program supports 2, 3 and 4 bits-per-sample ADPCM compression and 8 bits-per-sample PCM. The quality of PCM data is generally better, so you should use this setting if your modem supports it.
Method | Bit Depth | Sampling Frequencies | Comment |
---|---|---|---|
PCM 8-bit unsigned | 8 | 7200 | Very good sound quality |
Rockwell ADPCM | 4 | 7200 | Good sound quality |
Rockwell offers 8-bit unsigned PCM sound. It delivers the best quality available. However, you may experience some troubles when playing sound through the phone line with the sound card output turned on. In such a case, either select Rockwell compatible (ADPCM) model or clear Options -> Properties -> Compatibility -> Synchronize modem and sound card playback. This will turn OFF sound synchronization between the modem and sound card, and allow for smooth playback. Some limitation will apply, though.
To detect Russian Caller ID, I recommend selecting Rockwell compatible (ADPCM) modem.
Note that not every Rockwell compatible modem supports 8-bit PCM data. In such a case select ADPCM compression with 4 bps.
Rockwell does not support 3-bit ADPCM compression. You should use 4-bit compression if ADPCM is your decision.