Apparatus for reproducing signals pre-stored in a memory

An apparatus for reproducing signals which are pre-stored in a memory, said apparatus comprising:

• a memory pre-stored with signal made up of a level code and a gain change code, said level code being an original analog signal which is amplified, sampled, and digitally coded, said original analog signal being amplified to an extent such that a maximum value of the original analog signal is smaller than a full scale value in a small level region within a predetermined period, said original analog signal having a level smaller than threshold values in said small level region, said gain change code having predetermined values and replacing said level code at least for a certain period from a predetermined time in said small level region;
• a detecting circuit for detecting said gain change code from a signal which is read out from said memory, and for producing an output detection signal when said gain change code is detected;
• and
• variable gain and digital-to-analog converting means supplied with the signal read out from said memory, for producing a reproduced signal having a signal waveform which is essentially the same as the signal waveform of said original analog signal, said variable gain and digital-to-analog converting means being variably controlled of a gain thereof after receiving the output detection signal of said detecting circuit so as to attenuate the level of the signal read out from said memory to an extent complementary to the amplification performed at the time when the signal is pre-stored in said memory, said variable gain and digital-to-analog converting means comprising a replacing data generating circuit for generating a replacing data responsive to the output detection signal of said detecting circuit, switching circuit means for selectively producing said replacing data during a period in which the output detection signal of said detecting circuit is received, and for selectively producing said level code read out from said memory during a period in which the output detection signal of said detecting circuit is not received, and signal converting means for converting an output signal of said switching circuit means into an analog signal, and for producing the reproduced signal in which the level is returned to the level of said original analog signal by being essentially varied of the gain to a predetermined value after receipt of the output detection signal of said detecting circuit.

An apparatus as claimed in claim in which said memory pre-stores said gain change code which replaces said level code for a certain period in said small level region from a time when said original analog signal first reaches a center level, and said variable gain and digital-to-analog converting means comprises signal converting means for subjecting the signal read out from said memory to a digital-to-analog conversion so as to obtain an analog signal and variable gain means supplied with the output detection signal of said detecting circuit as a gain control signal, said variable gain means being varied of a gain thereof so as to attenuate the level of the analog signal from said signal converting means to an extent complementary to the amplification performed at the time when the signal is pre-stored in said memory after receipt of said detection signal compared to a time before said detection signal is received, and a switching circuit supplied with the output detection signal of said detecting circuit as a switching signal, for selectively producing a signal having a level corresponding to said center level during a period in which said detecting circuit produces said detection signal, and for selectively producing an output analog signal of said variable gain means during a period in which said detecting circuit does not produce said detection signal, as the reproduced signal.