Sampling:
Sampling is the process of converting a continuous-time signal into a discrete-time signal by taking samples at regular intervals of time. Each sample represents the amplitude of the continuous-time signal at a particular instant.

Process:
The process of converting a continuous-time signal into a discrete-time signal involves the following steps:

1. Sampling:
Sampling is the first step in converting a continuous-time signal into a discrete-time signal. In this step, the continuous-time signal is sampled at regular intervals of time. The sampling rate or frequency determines how often the samples are taken. The sampling process involves measuring the amplitude of the continuous-time signal at each sampling instant and converting it into a discrete value.

2. Quantization:
After sampling, the continuous amplitude values are quantized to a finite number of discrete levels. Quantization involves dividing the range of the continuous amplitude values into a finite number of levels and assigning each sample to the closest level. The number of quantization levels determines the resolution or accuracy of the discrete-time signal.

3. Encoding:
In the encoding step, each quantized sample is represented using a binary code. The binary code represents the amplitude of the sample in a digital form. The encoding process assigns a unique binary code to each quantized sample, which can be further processed or transmitted.

4. Decoding:
Decoding is the reverse process of encoding. In this step, the binary codes representing the quantized samples are converted back into their original quantized values. Decoding is necessary to reconstruct the original discrete-time signal from its digital representation.

5. Reconstruction:
The final step in converting a continuous-time signal into a discrete-time signal is reconstruction. Reconstruction involves reconstructing the continuous-time signal from the discrete-time signal. This can be done using various interpolation techniques, such as zero-order hold, first-order hold, or sinc interpolation.

Conclusion:
In conclusion, converting a continuous-time signal into a discrete-time signal involves the process of sampling, quantization, encoding, decoding, and reconstruction. Sampling is the first and most crucial step in this process, where the continuous-time signal is sampled at regular intervals to obtain discrete samples.