Function File: msg = qaskdeco (c, m)
Function File: msg = qaskdeco (inphase, quadr, m)
Function File: msg = qaskdeco (…, mnmx)

Demaps an analog signal using a square QASK constellation. The input signal maybe either a complex variable c, or as two real variables inphase and quadr representing the in-phase and quadrature components of the signal.

The argument m must be a positive integer power of 2. By default the same constellation as created in qaskenco is used by qaskdeco. If is possible to change the values of the minimum and maximum of the in-phase and quadrature components of the constellation to account for linear changes in the signal values in the received signal. The variable mnmx is a 2-by-2 matrix of the following form

|min in-phase,max in-phase|
|min quadrature,max quadrature|

If sqrt (m) is an integer, then qaskenco uses a Gray mapping. Otherwise, an attempt is made to create a nearly square mapping with a minimum Hamming distance between adjacent constellation points.

See also: qaskenco.

Package: communications