ask_help_begin
DMOD   M-ary amplitude shift keying (ASK) modulation.
       Y = DMOD(X, Fc, Fd, Fs, METHOD), METHOD = 'ask', modulates input
       digital signal X to carrier frequency Fc (Hz) using ASK method. X has
       sample frequency Fd (Hz). The function output Y has sample frequency
       Fs (Hz). Fs / Fd should be a positive integer. The size of the
       resulting signal Y is Fs/Fd times of the size of the original signal X.
       All elements in X are non-negative integers. The range of input
       integers is in [0, M-1], in which M equals 2^K such that max(X) < 2^K,
       where K is the minimum integer that satisfies max(X) < 2^K. The peak
       value of the modulated signal is 1. When Fs is a two element vector,
       the second element is the initial phase (rad) in the modulation. For 
       fast modulation/demodulation simulation, DMODCE/DDEMODCE are suggested.

       Y = DMOD(X, Fc, Fd, Fs, METHOD, M), METHOD = 'ask', specifies that the
       input digits are in range [0, M-1].

       DMOD(METHOD, M), METHOD = 'ask', plots the ASK constellation.
ask_help_end

psk_help_begin
DMOD   M-ary phase shift keying (psk) modulation.
       Y = DMOD(X, Fc, Fd, Fs,METHOD), METHOD = 'psk', modulates input digital
       digital signal X to carrier frequency Fc (Hz) using PSK method. X has
       sample frequency Fd (Hz). The function output Y has sample frequency
       Fs (Hz). Fs / Fd should be a positive integer. The size of the
       resulting signal Y is Fs/Fd times the the size of the original signal
       X. All elements in X are non-negative integers. The range of input
       integers is in [0, M-1], in which M equals 2^K such that max(X) < 2^K,
       where K is the minimum integer that satisfies max(X) < 2^K. The peak
       value of the modulated signal is 1. When Fs is a two element vector,
       the second element is the initial phase (rad) in the modulation. For 
       fast modulation/demodulation simulation, DMODCE/DDEMODCE are suggested.

       Y = DMOD(X, Fc, Fd, Fs, METHOD, M), METHOD = 'psk', specifies that the
       input digits are in range [0, M-1].

       DMOD(METHOD, M), METHOD = 'psk', plots the PSK constellation.
psk_help_end

qask_help_begin
DMOD   M-ary quadrature amplitude shift keying (qask) modulation.
       Y = DMOD(X, Fc, Fd, Fs, METHOD), METHOD = 'qask', modulates the digital
       signal X to carrier frequency Fc (Hz) using QASK method with square
       constellation. X has sample frequency Fd (Hz). The function output Y
       has sample frequency Fs (Hz). Fs/Fd should be a positive integer. The
       size of resulting signal Y is Fs/Fd times the size of the original 
       signal X. All elements in X are non-negative integers. The range of
       input integers is in [0, M-1], in which M equals 2^K such that
       max(X) < 2^K, where K is the minimum integer satisfies max(X) < 2^K.
       The peak value of the modulated signal is listed in the table below.
       When Fs is a two element vector, the second element is the initial
       phase (rad) in the modulation. For fast modulation/demodulation
       simulation, DMODCE/DDEMODCE are suggested.

       Y = DMOD(X, Fc, Fd, Fs, METHOD, M), METHOD = 'qask', specifies that the
       input digits are in range [0, M-1].

       DMOD(METHOD, M), METHOD = 'qask', plots the QASK square constellation.
       The maximum number in the constellation are as follows:
           M = 2,   maximum = 1;   M = 4,   maximum = 1;
           M = 8,   maximum = 3;   M = 16,  maximum = 3;
           M = 32,  maximum = 5;   M = 64,  maximum = 7;
           M = 128, maximum = 11;  M = 256, maximum = 15;

       Y = DMOD(X, Fc, Fd, Fs, METHOD, In_Phase, Quad), METHOD = 'qask/arb',
       modulates the input digital signal  X using the QASK method with 
       arbitrary constellation. The arbitrary constellation is defined in the
       variables In_Phase and Quad. The constellation point for message I is 
       defined by In_Phase(I+1) and Quad(I+1), which specifies the in-phase 
       and quadrature component respectively.

       The user defined arbitrary constellation of the QASK can be plotted by
       using DMOD('qask/arb', In_phase, Quad).

       Y = DMOD(X, Fc, Fd, Fs, METHOD, NIC, AIC, PIC), METHOD = 'qask/cir'
       demodulates the input digital signal X using the QASK method with
       circle constellation. The numbers in circle, amplitude in circle, and
       a signature phase in circle are defined in NIC, AIC, and PIC
       respectively. The three vectors NIC, AIC and PIC have the same
       length. The constellation in each circle is evenly distributed in
       each ring with one of the point located has its phase as the signature
       phase. When PIC is not given, PIC is assumed to be an all zero vector.
       When AIC is not given, the default value AIC = [1:length(NIC)] is used.

       The circle constellation of the QASK can be plotted by using
       DMOD(METHOD, NIC, AIC, PIC).
qask_help_end

fsk_help_begin
DMOD   M-ary frequency shift keying (FSK) modulation.
       Y = DMOD(X, Fc, Fd, Fs,METHOD), METHOD = 'fsk', modulates input digital
       signal X to carrier frequency Fc (Hz) using FSK method. X has sample
       frequency Fd (Hz). The function output Y has sample frequency Fs (Hz).
       Fs/Fd should be a positive integer. The size of the resulting signal Y
       is Fs/Fd times the size of the the original signal X. All elements in X
       are non-negative integers. The range of input integers are in [0, M-1],
       in which M equals 2^K such that max(X) < 2^K, where K is the minimum
       integer satisfies max(X) < 2^K. The peak value of the modulated signal
       is 1. When Fs is a two element vector, the second element is the
       initial phase (rad) in the modulation. The default tone space is
       TONE = 2*Fd/M. The tone space is the frequency separation between
       successive frequencies. The frequency range of the output signal
       is in range [Fc, Fc+TONE*(M-1)]. For best result, Fs > Fc > Fd is
       recommended. For fast modulation/demodulation simulation,
       DMODCE/DDEMODCE are suggested.

       Y = DMOD(X, Fc, Fd, Fs, METHOD, M), METHOD = 'fsk', specifies that the
       input digits are in range [0, M-1]. 

       Y = DMOD(X, Fc, Fd, Fs, METHOD, M, TONE), METHOD = 'fsk', specifies the
       tone space TONE, the frequency separation between successive frequency
       in FSK.

       DMOD(METHOD, M, TONE), METHOD = 'fsk', plots fsk constellation.
fsk_help_end

msk_help_begin
DMOD   Minimum shift keying (MSK) modulation.
       Y = DMOD(X, Fc, Fd, Fs, METHOD), METHOD = 'msk', modulates input
       signal X to carrier frequency Fc (Hz) using MSK method. X has sample
       frequency Fd (Hz). The function output Y has sample frequency Fs (Hz).
       Fs/Fd should be a positive integer. The size of the resulting signal Y
       is Fs/Fd times the size of the original signal X. All elements in X are
       binary numbers. The peak value of the modulated signal is 1. When Fs is
       a two element vector, the second element is the initial phase (rad) in
       the modulation. The tone space is Fd. MSK is a special case of FSK. For
       best results, Fs > Fc > Fd is recommended. For fast 
       modulation/demodulation simulation, DMODCE/DDEMODCE are suggested.

       Y = DMOD(METHOD, Fd), METHOD = 'msk', plots msk constellation.
msk_help_end

sam_help_begin
DMOD   Up sample a signal X form frequency Fd to sample frequency Fs.
       Y = DMOD(X, Fc, Fd, Fs, METHOD), METHOD = 'sample', takes the input
       signal X with sample frequency Fd (Hz) and outputs signal Y with sample
       frequency Fs (Hz). When X is a matrix, the function takes each column
       as individual signal. The output Y will have the same number of column 
       numbers as X. Fs must be larger than Fd and Fs/Fd should be an integer.
       When Fd is a two element vector, the second element should be an
       integer which means the offset timing is Fd(2)/Fs. The default
       offset is zero. Fc is not used.
sam_help_end

Wes Wang 10/5/95