ademod.hlp

数字通信第四版原书的例程

amdsb-sc_help_begin
ADEMOD Amplitude demodulation, double sideband suppressed carrier.
       Z = ADEMOD(Y, Fc, Fs, METHOD, NUM, DEN), METHOD = 'amdsb-sc', 
       demodulates an AM DSB-SC modulated signal Y with carrier frequency
       Fc (Hz) and sample frequency Fs (Hz). When Fs is a two element vector,
       the second element in the vector is the initial phase (rad) in the
       demodulation. NUM and DEN are the numerator and denominator of the
       low-pass filter respectively. The sample time of the filter is 1/Fs.
       When NUM is zero, empty, or not given, this function uses the default
       low-pass filter which is [NUM, DEN] = BUTTER(5, Fc*2/Fs).

       When METHOD = 'amdsb-sc/costas', Costas loop will be used in the
       demodulation.
amdsb-sc_help_end
amdsb-tc_help_begin
ADEMOD Amplitude demodulation, double sideband with transmission carrier.
       Z = ADEMOD(Y, Fc, Fs, METHOD, NUM, DEN, OFFSET), METHOD = 'am' or
       'amdsb-tc',  demodulates a DSB-TC modulated signal Y with carrier 
       frequency Fc (Hz) and sample frequency Fs (Hz). When Fs is a two
       element vector, the second element in the vector is the initial
       phase (rad) in the demodulation. OFFSET is the value subtracted
       from Z after the demodulation. When OFFSET is omitted, the function 
       sets the default OFFSET = abs(min(Z)). NUM and DEN are the numerator
       and denominator of the low-pass filter respectively. The sample time
       of the filter is 1/Fs. When NUM is zero, empty, or not given, this
       function uses the default low-pass filter, which is 
       [NUM, DEN] = BUTTER(5, Fc*2/Fs).

       When METHOD = 'amdsb-sc/costas', Costas loop will be used in the
       demodulation.
amdsb-tc_help_end
amssb_help_begin
ADEMOD Amplitude demodulation, single sideband suppressed carrier.
       Z = ADEMOD(Y, Fc, Fs, METHOD, NUM, DEN), METHOD = 'amssb', demodulates
       a SSB-AM modulated signal Y with carrier frequency Fc (Hz) and sample 
       frequency Fs (Hz). When Fs is a two element vector, the second element
       in the vector is the initial phase (rad) in the demodulation. NUM and 
       DEN are the numerator and denominator of the low-pass filter
       respectively. The sample time of the filter is 1/Fs. When NUM is zero,
       empty, or not given, this function uses the default low-pass filter
       which is [NUM, DEN] = BUTTER(5, Fc*2/Fs).
amssb_help_end
qam_help_begin
ADEMOD Quadrature amplitude demodulation.
       Z = ADEMOD(Y, Fc, Fs, METHOD, NUM, DEN), METHOD = 'qam', demodulates
       a QAM modulated signal with carrier frequency Fc (Hz) and sample
       frequency Fs (Hz). When Fs is a two element vector, the second element
       in the vector is the initial phase (rad) in the demodulation. NUM and
       DEN are the numerator and denominator of the low-pass filter 
       respectively. The sample time of the filter is 1/Fs. When NUM is zero,
       empty, or not given, this function uses the default low-pass filter
       which is [NUM, DEN] = BUTTER(5, Fc*2/Fs).

       The output vector Z is an even column matrix, the odd column contains
       the recovered in-phase component, and the even column contains the
       recovered quadrature component.
qam_help_end
fm_help_begin
ADEMOD Frequency demodulation.
       Z = ADEMOD(Y, Fc, Fs, METHOD, NUM, DEN), METHOD = 'fm', demodulates a
       FM modulated signal Y using frequency demodulation method with carrier
       frequency Fc (Hz) and sample frequency Fs (Hz). When Fs is a two
       element vector, the second element in the vector is the initial phase
       (rad) in the demodulation. NUM and DEN are the numerator and
       denominator of the low-pass filter respectively. The sample time of
       the filter is 1/Fs. When NUM is zero, empty, or not given, this
       function uses the default low-pass filter which is
       [NUM, DEN] = BUTTER(5, Fc*2/Fs).

       Z = ADEMOD(Y, Fc, Fs, METHOD, NUM, DEN, SENSITIVE), METHOD = 'fm',
       specifies the sensitivity in the modulation. This should match the
       modulation sensitivity assignment to result a correct answer.
fm_help_end
pm_help_begin
ADEMOD Phase demodulation.
       Z = ADEMOD(Y, Fc, Fs, METHOD, NUM, DEN), METHOD = 'pm', demodulates a
       PM modulated signal Y using phase demodulation method with carrier
       frequency Fc (Hz) and sample frequency Fs (Hz). When Fs is a two
       element vector, the second element in the vector is the initial phase
       (rad) in the demodulation. NUM and DEN are the numerator and
       denominator of the low-pass filter respectively. The sample time of the
       filter is 1/Fs. When NUM is zero, empty, or not given, this function
       uses the default low-pass filter which is
       [NUM, DEN] = BUTTER(5, Fc*2/Fs).

       Z = ADEMOD(Y, Fc, Fs, METHOD, NUM, DEN, SENSITIVE), METHOD = 'pm',
       specifies the sensitivity in the modulation. This should match the
       modulation sensitivity assignment to result a correct answer.
pm_help_end

Wes Wang 9/29/95