explain delta modulation
Delta modulation is a digital signal processing technique that is used for the conversion of analog signals into digital signals. In this technique, the amplitude of the analog signal is sampled at a regular interval, and the difference between the successive samples is quantized.
Delta modulation uses a simple algorithm where the digital value of the signal is generated based on the change in amplitude of the signal at every sample point. This is done by comparing the analog signal with the previous sample value, and if the signal has increased, a binary value of “1” is assigned, and if the signal has decreased, “0” is assigned.
Delta modulation is a straightforward technique and requires a smaller amount of memory to store the signal. However, the main disadvantage of this technique is that it is highly sensitive to noise due to its small signal values. Therefore, this technique is not suitable for use in high-noise environments.
Delta modulation is a simple and efficient method used for digitizing analog signals. It is a type of analog-to-digital conversion technique that encodes the difference between the current sample and the previous sample of the analog signal instead of quantizing the absolute amplitude of the signal.
Here is a step-by-step explanation of delta modulation:
1. Sampling: At the beginning, the continuous analog signal is sampled at regular time intervals to obtain a series of discrete samples. The sampling rate should be high enough to capture the details of the signal accurately.
2. Prediction: In delta modulation, a predictor is used to estimate the next sample based on the previous sample. The predictor's output is subtracted from the actual sample, giving the prediction error or delta value.
3. Quantization: The delta value is then quantized into a binary digital value. The quantization step size determines the resolution of the encoded signal. A smaller step size provides higher resolution but requires more bits to represent the delta value.
4. Encoding: The encoded delta value is transmitted or stored as a binary signal. It can be a single-bit representation, where a positive delta value is represented by a '1' and a negative delta value is represented by a '0'. Alternatively, it can be multi-level encoding where multiple bits are used to represent the delta value.
5. Reconstruction: At the receiver or during playback, the encoded signal is decoded using the same quantization step size. The binary representation of the encoded signal is converted back to the delta value.
6. Accumulation: The delta value is then added to the previous reconstructed sample to obtain the current reconstructed sample.
7. Feedback Loop: The reconstructed sample is fed back into the predictor to estimate the next sample and repeat the process.
Delta modulation offers a simple implementation with low complexity as it only requires a subtractor, quantizer, and adder. However, it can introduce distortion, especially if the step size is large or the signal has rapid changes. This distortion is known as slope overload distortion.
It is worth noting that there are variations of delta modulation, such as adaptive delta modulation, which dynamically adjusts the step size based on the characteristics of the input signal to improve the accuracy of encoding.