Patent ID: 8514508

Claim:
A system, comprising a hard disk control circuit configured to generate a first symbol; a read channel circuit configured to encode the first symbol to generate an encoded symbol; and a preamplifier circuit configured to operate in a loopback mode to determine whether the preamplifier circuit is operating properly, wherein, while operating in the loopback mode, the preamplifier circuit is configured to i) amplify the encoded symbol, and ii) transmit the amplified, encoded symbol back to the read channel circuit, and wherein the read channel circuit is configured to i) decode the amplified, encoded symbol to generate a second symbol, and ii) provide the second symbol to the hard disk control circuit, and the hard disk control circuit is configured to i) perform a comparison between the first symbol and the second symbol, and ii) generate an indication of whether the preamplifier circuit is operating properly based on the comparison between the first symbol and the second symbol.