MSK (Minimum Shift Keying) is a type of continuous frequency shift modulation that is used to transfer radio signals from satellites and radio broadcasting to mobile devices and vice versa. Unlike other forms of frequency modulation, MSK produces a half sine wave that limits problems associated with non-linear distortion.

What is GMSK?

GMSK (Gaussian Minimum Shift Keying) is a type of MSK that uses the same basic concepts, but applies a Gaussian filter to a signal before its frequency is modulated. A Gaussian filter uses a square wave to shape a signal to a more desirable output, allowing it to be transmitted to mobile devices without any flaws.

Applications

GMSK is used in most MSK applications in order to perfect the transmission of digital data from satellites and radio broadcasting towers to mobile devices as well as from mobile devices to satellites and radio broadcasting towers. GMSK is used in remote controlled devices, cellular phones, Bluetooth headsets, and a wide variety of other applications.

Advantages

GMSK is advantageous because it reduces sideband power or the power that frequencies directly above or below a given channel produce, which prevents interference from signal carriers on adjacent frequencies. This is mostly advantageous to cell phone companies, which must ensure that their signals do not pick up any interference from other companies.

Disadvantages

Although GMSK reduces sideband power, it increases modulation memory in digital devices in which a previously received signal acts as interference for subsequently received signals. This phenomenon can cause digital devices to confuse various signals with each other and prevent the device from performing the correct functions. To correct this issue, signals that GMSK shapes must also be equalized with complex algorithms on the receiving device, requiring more hardware and more advanced software.