log and antilog amplifiers
zhi-yi,
Yes, x is the input.
~
Regarding compression-decompression: In this context, we're referring to a situation in which we are processing an input signal that has a large dynamic range, and a large Signal/Noise ratio is desired for low level inputs. You can not simply amplify the input, because the output would saturate. The idea of compression is to provide a non-linear output vs input characteristic, so that low level signals have a high gain, and high level signals have a low gain. A logarithmic response has this characteristic. Once the processing of the signal has been performed, the signal can be "decompressed" by using the inverse of the log function, which is an anti-log or exponential function.
Regards,
Kral
Added after 15 minutes:
zhi-yi,
Yes, x is the input.
~
Regarding compression-decompression: In this context, we're referring to a situation in which we are processing an input signal that has a large dynamic range, and a large Signal/Noise ratio is desired for low level inputs. You can not simply amplify the input, because the output would saturate in the presence of high level inputs. The idea of compression is to provide a non-linear oputput vs input characteristic, so that low level signals have a high gain, and high level signals have a low gain. A logarithmic response has this characteristic. Once the processing of the signal has been performed, the signal can be "decompressed" by using the inverse of the log function, which is an anti-log or exponential function.
Regards,
Kral