Minimum Shift Key Modulation/ Minimum-shift keying (MSK)
Minimum Shift Key Modulation is another type of digital modulation technique used to convert a digital signal into analog signals. It is also called Minimum-shift keying (MSK) or Advance Frequency Shift Keying because it is a type of continuous-phase frequency-shift keying.
Key features of Minimum Shift Key Modulation or Minimum-shift keying (MSK)
Working of Minimum-shift keying (MSK)
Let's take an example to demonstrate the working of Minimum-shift keying and draw a curve for a given bit stream. Let's consider a bit stream 1011010. Here, we have to find the MSK curve for this bit stream.
Rules for drawing MSK Curve
Step 1: First, draw the curve according to the bit value of amplitude. If the bit is zero, it would have amplitude while is the bit is zero, it does not have amplitude.
Step 2: Now, start with the odd bit. If the bit's value is one, draw the curve above the x-axis twice as long as the original one. If the bit's value is zero, draw the curve below the x-axis twice as long as the original size.
Step 3: Now, draw the curve for high and low frequency, as shown in the following graph. It would remain the same for any problem.
Step 4: This is the final step. Now, draw the final curve according to the frequency generating table. In the following diagram, the blue colored curve represents the final obtained MSK curve.
Gaussian Minimum Shift Keying (GMSK)
Gaussian Minimum Shift Keying or GMSK is very much similar to standard minimum-shift keying (MSK), but the digital data stream is first shaped with a Gaussian filter before it is applied to a frequency modulator.
The GMSK form of modulation is based on frequency shift keying that has no phase discontinuities. It provides efficient use of the spectrum as well as enabling high-efficiency radio power amplifiers.
It has much narrower phase shift angles than most MSK modulation systems.
Usage of Gaussian Minimum Shift Keying (GMSK)
GMSK is mainly used in the following technologies:
Advantage of Gaussian Minimum Shift Keying (GMSK)
The disadvantage of Gaussian Minimum Shift Keying (GMSK)