ddemodce.hlp

数字通信第四版原书的例程

ask_help_begin
DDEMODCE M-ary ASK demodulation (complex envelope).
       Z = DDEMODCE(Y, Fd, Fs, METHOD, M), METHOD = 'ask', demodulates the 
       complex envelope of a ASK modulated signal with digital message sample
       frequency Fs (Hz) and simulation sample frequency Fs (Hz). This
       function requires Fs > Fd, and Fs / Fd be a positive integer. When
       Fd is a two element vector, the second element is the offset value
       for the decision point. The offset should be an integer. The offset
       timing is Fs(2) / Fs. The default offset is zero. The M-ary number
       for the ASK is M. The demodulated digital messages are in range 
       [0, M-1]. No low-pass filter is used in this call.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, M, NUM, DEN), METHOD = 'ask', specifies
       the numerator (NUM) and denominator (DEN) of a low-pass filter in the
       demodulation. The sample time for the filter is 1/Fs.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, ...), METHOD = 'ask/costas', specifies 
       the Costas loop in the demodulation.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, ...), METHOD = 'ask/eye', plots 
       eye-pattern diagram before demapping.

       The constellation of the ASK can be plotted by using DMODCE('ask', M).
ask_help_end

psk_help_begin
DDEMODCE M-ary PSK demodulation (complex envelope).
       Z = DDEMODCE(Y, Fd, Fs, METHOD, M), METHOD = 'psk', demodulates the
       complex envelope of a PSK modulated signal with digital message sample
       frequency Fs (Hz) and simulation sample frequency Fs (Hz). This
       function requires Fs > Fd, and Fs / Fd be a positive integer. When Fd
       is a two element vector, the second element is the offset value for
       the decision point. The offset should be an integer. The offset timing
       is Fs(2) / Fs. The default offset is zero. The M-ary number for the
       PSK is M. The demodulated digital messages are in range [0, M-1]. No
       lowpass filter is used in this call.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, M, NUM, DEN), METHOD = 'psk', specifies
       the numerator (NUM) and denominator (DEN) of a low-pass filter in the
       demodulation. The sample time for the filter is 1/Fs.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, ...), METHOD = 'psk/eye', plots 
       eye-pattern diagram before demapping.

       The constellation of the PSK can be plotted by using DMODCE('psk', M).
psk_help_end

qask_help_begin
DDEMODCE M-ary QASK demodulation (complex envelope).
       Z = DDEMODCE(Y, Fd, Fs, METHOD, M), METHOD = 'qask', demodulates the
       complex envelope of a square constellation QASK modulated signal with
       digital message sample frequency Fs (Hz) and simulation sample
       frequency Fs (Hz). This function requires Fs > Fd, and Fs / Fd be a
       positive integer. When Fd is a two element vector, the second element
       is the offset value for the decision point. The offset should be an
       integer. The offset timing is Fs(2) / Fs. The default offset is zero.
       The M-ary number for the square constellation QASK is M. The
       demodulated digital messages are in range [0, M-1]. No low-pass filter
       is used in this call. The output of this function is a matrix with the
       odd number column being the in-phase component of the demodulated
       message signal and the even number column being the quadrature
       component of the demodulated signal.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, M, NUM, DEN), METHOD = 'qask',
       specifies the numerator (NUM) and denominator (DEN) of a lowpass
       filter in the demodulation. The sample time for the filter is 1/Fs. 

       The QASK square constellation can be produced by DMODCE('qask', M).

       Z = DDEMODCE(Y, Fd, Fs, METHOD, In_Phase, Quad), METHOD = 'qask/arb'
       demodulates the complex envelope of the modulated signal Y 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.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, In_Phase, Quad, NUM, DEN), 
       METHOD='qask/arb', specifies the numerator (NUM) and denominator (DEN)
       of a low-pass filter in the demodulation. The sample time for the
       filter is 1/Fs.

       The constellation of the PSK can be plotted by using
           DMODCE('qask/arb', In_phase, Quad).

       Z = DDEMODCE(Y, Fc, Fs, METHOD, NIC, AIC, PIC), METHOD = 'qask/cir'
       demodulates the complex envelope of a QASK modulated signal Y 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 points having 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.

       Z = DDEMODCE(Y, Fc, Fs, METHOD, NIC, AIC, PIC, NUM, DEN),
       METHOD = 'qask/cir', specifies the numerator (NUM) and denominator
       (DEN) of a low-pass filter in the demodulation. The sample time for
       the filter is 1/Fs.

       The constellation of the PSK can be plotted by using
           DMODCE('qask/cir', NIC, AIC, PIC)
       
       Z = DDEMODCE(Y, Fd, Fs, METHOD, ...), METHOD = [METHOD, '/eye'], plots 
       eye-pattern diagram before demapping.
qask_help_end

fsk_help_begin
DDEMODCE M-ary FSK demodulation (complex envelope).
       Z = DDEMODCE(Y, Fd, Fs, METHOD, M), METHOD = 'fsk', demodulates the
       complex envelope of a FSK modulated signal with digital message sample
       frequency Fs(Hz) and simulation sample frequency Fs (Hz). This function
       requires Fs > Fd, and Fs / Fd be a positive integer. When Fd is a two
       element vector, the second element is the offset value for the decision
       point. The offset should be an integer. The offset timing is Fs(2) /Fs.
       The default offset is zero. The M-ary number for the FSK is M. The 
       demodulated digital messages are in range [0, M-1]. A default tone space
       value TONE = 2 * Fd /M is used. For a correct solution, Fs / Fd must be
       greater than M.

       Z = DDEMODCE(Y, Fc, Fd, Fs, METHOD, M, TONE), METHOD = 'fsk', specifies
       the tone space of the fsk in TONE.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, M, Tone), METHOD = 'fsk/eye', plots 
       eye-pattern diagram before demapping. Different from other eye-pattern
       diagrams, the eye-pattern diagram for FSK demodulation is the
       correlation value of the input signal to each possible digital signal.
       It is very expensive to plot FSK correlation eye-pattern diagram both
       in computation time and memory space.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, M, Tone), METHOD = 'fsk/noncoherent'
       computes the demodulation using noncoherent method.

       The constellation of the FSK can be plotted by using 
            DMODCE('fsk', M, Tone).
fsk_help_end
msk_help_begin
DDEMODCE Demap for MSK demodulation.
       Z = DDEMODCE(Y, Fd, Fs, METHOD), METHOD = 'msk', demodulates the
       complex envelope of an MSK modulated signal with digital message sample
       frequency Fs Hz) and simulation sample frequency Fs (Hz). This function
       requires Fs > Fd, and Fs / Fd be a positive integer. When Fd is a two
       element vector, the second element is the offset value for the decision
       point. The offset should be an integer. The offset timing is Fs(2) /Fs.
       The default offset is zero. The M-ary number for the MSK is 2. The
       demodulated digital messages are binary numbers. A default tone space
       value TONE = Fd is used. To result a correct solution, Fs / Fd must be
       greater than 2.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, M, TONE), METHOD = 'msk/eye', plots 
       eye-pattern diagram before demapping. Different from other eye-pattern
       diagrams, the eye-pattern diagram for MSK demodulation is the
       correlation value of the input signal to both '0' and '1' decision.
       It is very expensive to plot MSK correlation eye-pattern diagram both
       in computation time and memory space.

       Z = DDEMODCE(Y, Fd, Fs, METHOD, M, Tone), METHOD = 'msk/noncoherent'
       computes the demodulation using noncoherent method.
msk_help_end

sam_help_begin
DDEMODCE Down sample a signal from sample frequency Fs to sample frequency Fd.
       Z = DDEMODCE(Y, Fd, Fs, METHOD), METHOD = 'sample', takes the input
       signal Y with sample frequency Fs (Hz) and outputs signal Z with sample
       frequency Fz(Hz). When Y is a matrix, the function takes each column as
       individual signal. The output Z will have the same number of column 
       number as Y. 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 be Fd(2)/Fs. The default offset
       is zero. Fc is not used.
sam_help_end

eye_help_begin
DDEMODCE Eye-pattern plot.
       DDEMODCE(Y, Fd, Fs, METHOD), METHOD = 'eye', plots each column element
       in Y by eye-pattern plot. When Y is a multi-column matrix, the colors
       for the columns are in the order of yellow, magenta, cyan, red, green,
       and blue. The time distance between two successive rows is 1/Fs. The
       plot time window is 1/Fd. It is required that Fs > Fd, and Fs/Fd must
       be an integer. When Fd is a two element vector, the second element is
       an integer that specifies that the offset for the beginning point is
       Fd(2)/Fs. The default offset is zero.
eye_help_end
sca_help_begin
DDEMODCE Scatter plot.
       DDEMODCE(Y, Fd, Fs, METHOD), METHOD = 'scat', produces scatter plot
       for the input signal Y. The time interval between two successive
       rows in Y is 1/Fs. The function takes a point to plot at sample
       frequency Fd. It is required that Fs > Fd. Fs/Fd must be an integer.
       When Fd is a two element vector, the second element is an integer
       that specifies that the offset for the plotting point is Fd(2)/Fs.
       The default offset is zero. When Y is a multi-column matrix, the colors
       for the columns are in the order of yellow, magenta, cyan, red, green,
       and blue. Fc has not used. When Y is a two column matrix, the scatter
       plot is a two-dimensional plot.        

       DDEMODCE(Y, Fd, Fs, METHOD, SYMBOL) selects the plot symbol. SYMBOL can
       be one of the following characters: '.', '*', '+', 'x', 'o'.
sca_help_end

Wes Wang 10/3/95