# BPSK, QPSK, 8PSK and QAM Calculator

A little tool for various calculations revolving around PSK and QAM modulation schemes commonly found in ENG, SNG, and BAS applications. Useful for bandwidth calculations in satellite (VSAT) and terrestrial broadcast applications. The calculator takes factors such as Forward Error Correction (FEC) and roll-off values into account. It’s also extremely useful for amateur radio operators wishing to deploy digital modulation schemes (DATV, etc.).

 Information Rate (Mbit/s) Modulation BPSKBFSKQPSK8 PSK16 PSK4 QAM16 QAM32 QAM64 QAM128 QAM256 QAM FEC-Rate None1/22/33/45/67/88/9 Reed-Solomon FEC None188/204 Guard None1/321/161/81/4 Roll-off None20 %25 %30 % Data Rate (Mbps) Symbol Rate (Msym/s) 3 dB Bandwith (MHz) Occupied Bandwith (MHz) Allocated Bandwith (MHz)
CAVEAT: Please note that this calculator is calculating the Nyquist bandwidth. The Nyquist bandwidth is the minimum bandwidth than can be used to represent a signal. This is the correct bandwidth for transmitters which deploy a Nyquist bandwidth filter, which is the case for most professional transmitters.

If not filtered, the main lobe will have a bandwidth of twice the Nyquist bandwidth. For instance, a BPSK signal with an information rate of 1 Mbps will have a Nyquist bandwidth of 1 MHz. If unfiltered, the bandwidth of the main lobe is twice the Nyquist bandwidth or twice the symbol rate. In the case of a BPSK signal with an information rate of 1 Mbps this would be 2 MHz.

For a given bandwidth (B), the highest theoretical symbol rate (fsym) is 2B.

fsym = 2B