Signal transfer device measurement system and method

A system for measuring the signal transfer characteristics of a device under test (DUT) having an analog input port and an analog output port comprising:

• a stimulus waveform generator that produces a stimulus waveform, the stimulus waveform comprising a time sequence of pairs of narrow bandwidth, modulated signals, wherein the stimulus waveform is applied to the input port of the device under test, thereby producing an output response signal at the output port of the device under test;
• an analog-to-digital converter (ADC) for digitizing the output response signal and producing digital data;
• and
• a signal processor for processing the digital data, thereby producing measured results,
• wherein each pair of signals of the sequence of pairs of narrow bandwidth, modulated signals comprises a reference frequency modulated signal, and a variable frequency modulated signal,
• wherein the reference frequency modulated signal is a double sideband, suppressed carrier, modulated signal having a reference carrier frequency, the reference frequency modulated signal being modulated by a low frequency modulation signal, the low frequency modulation signal being a sine wave,
• wherein the variable frequency modulated signal is a double sideband, suppressed carrier, modulated signal having a variable carrier frequency, the variable frequency modulated signal being modulated by the low frequency modulation signal, and the variable carrier frequency being variable from pair to pair in the sequence of pairs, and
• wherein a sampling frequency, ƒs, of the ADC determines the reference carrier frequency ƒr of the reference frequency modulated signal through the application of f r , out = f s N ⁢ ( N 4 + G )
• where ƒr is related to an output reference carrier frequency ƒr,out produced by the DUT as described by
• ƒout=L±ƒin
• where ƒr,out is related to ƒr as ƒout is related to ƒin and where L is a frequency translation inherent in the DUT as is the choice of “+” or “−”, and where N is a fast Fourier transform (FFT) size used by an FFT performed by the signal processor and G is a small integer, and
• wherein the variable carrier frequency ƒv of the variable frequency modulated signal of each of the sequence of pairs of signals is determined by f v , out ⁡ ( k ) = ( kS + S 2 ) ⁢ f s N
• where k is an index of the pair of signals in the sequence given by k = 0 , 1 , … ⁢ ⁢ ( N 2 ⁢ S - 1 )
• and where S is an integer number of frequency cells between frequency steps across a band of interest of the DUT and where ƒv is related to ƒv,out as ƒin is related to ƒout.

A system for measuring the signal transfer characteristics of a device under test having an analog input port and a digital output port comprising:

• a stimulus waveform generator that produces a stimulus waveform, the stimulus waveform comprising a sequence of pairs of narrow bandwidth, modulated signals, wherein the stimulus waveform is applied to the input port of the device under test, thereby producing an output signal at the output port of the device under test;
• and
• a signal processor for processing the digital data, thereby producing measured results,
• wherein each pair of signals of the sequence of pairs of narrow bandwidth, modulated signals comprises a reference frequency modulated signal, and a variable frequency modulated signal,
• wherein the reference frequency modulated signal is a double sideband, suppressed carrier, modulated signal having a reference carrier frequency, the reference frequency modulated signal being modulated by a low frequency modulation signal, the low frequency modulation signal being a sine wave, and
• wherein the variable frequency modulated signal is a double sideband, suppressed carrier, modulated signal having a variable carrier frequency, the variable frequency modulated signal being modulated by the low frequency modulation signal, the variable carrier frequency being variable from pair to pair in the sequence of pairs, and
• wherein a sampling frequency, ƒs, of the device under test determines the reference carrier frequency ƒr of the reference frequency modulated signal through the application of f r , out = f s N ⁢ ( N 4 + G )
• where ƒr is related to an output reference carrier frequency ƒr,out produced by the device under test as described by
• ƒout=L±ƒin
• where ƒr,out is related to ƒr as ƒout is related to ƒin and where L is a frequency translation inherent in the device under test as is the choice of “+”, and where N is a fast Fourier transform (FFT) size used by an FFT performed by the signal processor and G is a small integer, and
• wherein the variable carrier frequency ƒv of the variable frequency modulated signal of each of the sequence of pairs of signals is determined by f v , out ⁢ ( k ) = ( kS + S 2 ) ⁢ f s N
• where k is an index of the pair of signals in the sequence given by k = 0 , 1 , … ⁢ ⁢ ( N 2 ⁢ S - 1 )
• and where S is an integer number of frequency cells between frequency steps across a band of interest of the DUT and where ƒv is related to ƒv,out as ƒin is related to ƒout.

A method for measuring signal transfer characteristics of a device under test (DUT) having all input port and an output port comprising the steps of:

• generating a stimulus waveform, the stimulus waveform comprising a time sequence of pairs of narrowband modulated signals, each of the pairs comprising a reference frequency modulated signal, and a variable frequency modulated signal, wherein the reference frequency modulated signal is a double sideband, suppressed carrier, modulated signal having a reference carrier frequency modulated by a low frequency modulation signal, and wherein the variable frequency modulated signal is a double sideband, suppressed carrier, modulated signal having a variable carrier frequency modulated by the low frequency modulation signal, the variable carrier frequency being variable from pair to pair in the sequence of pairs;
• applying the stimulus waveform to the input port of the DUT such that an output response signal is generated at the output port of the DUT;
• sampling and digitizing the output response signal to produce digital data;
• and
• processing the digital data, thereby producing measured results,
• wherein a sampling frequency, ƒs, of the step of sampling determines the reference carrier frequency ƒr of the reference frequency modulated signal through the application of f r , out = f s N ⁢ ( N 4 + G )
• where ƒr is related to an output reference carrier frequency ƒr,out produced by the DUT as described by
• ƒout=L±ƒm
• where ƒr,out is related to ƒr as ƒout is related to ƒin and where L is a frequency translation inherent in the DUT as is the choice of “+” or “−”, and where N is a fast Fourier transform (FFT) size used by an FFT performed by the signal processor and G
• wherein the variable carrier frequency ƒv of the variable frequency modulated signal of each of the sequence of pairs of signals is determined by f v , out ⁢ ( k ) = ( kS + S 2 ) ⁢ f s N
• where k is an index of the pair of signals in the sequence given by k = 0 , 1 , … ⁢ ⁢ ( N 2 ⁢ S - 1 )
• and where S is an integer number of frequency cells between frequency steps across a band of interest of the DUT and where ƒv is related to ƒv,out as ƒin is related to ƒout.