High bandwidth oscilloscope

A system for acquiring an analog signal, comprising:

• an analog input to receive an analog input signal spanning a frequency range, the frequency range including a first frequency band and a second frequency band higher than and substantially non-overlapping with said first frequency band;
• a first signal path to transport a first signal occupying the first frequency band;
• a second signal path to transport a second signal occupying the second frequency band;
• a frequency translator to translate the second signal to a lower frequency band;
• a digitizing system to digitize the first signal and second signal, the digitizing system having a frequency range less than the analog input signal frequency range;
• a second frequency translator for substantially restoring the digitized second signal to the second frequency band;
• and
• a digital combiner to join the first signal and the second signal and form a digital representation of the analog input signal, the digital representation substantially spanning the frequency range of the analog input signal.

A method for acquiring an analog signal by a digital acquisition system, comprising the steps of:

• splitting a received analog signal into a plurality of frequency bands comprising a lower frequency band signal and at least one higher frequency band signal;
• digitizing the lower frequency band signal;
• interleave error correcting the digitized lower frequency band signal;
• upsampling the corrected signal;
• low pass filtering the upsampled signal;
• and
• crossover phase correcting the low pass filtered upsampled signal to generate a processed lower frequency band signal;
• frequency converting the at least one higher frequency band signal to a translated lower frequency band signal so that a high frequency content thereof is translated from a higher frequency band to a translated lower frequency band;
• generating a reference tone that carries the phase information required to determine the phase of a first local oscillator with a constant offset used to frequency convert the at least one higher frequency band signal to the translated lower frequency band signal;
• inserting the reference tone into the translated lower frequency band signal;
• digitizing the translated lower frequency band signal and reference tone;
• extracting the phase information used to determine the phase of the first local oscillator;
• determining the phase of the first local oscillator with a constant offset;
• generating a second local oscillator in accordance with the determined phase and constant offset;
• interleave error correcting the digitized translated lower frequency band signal and reference tone higher frequency band signal;
• upsampling the interleave error corrected signal;
• low image filtering the upsampled signal to reject frequency content outside the higher frequency band of the at least one higher frequency band signal;
• notch filtering the low image filtered signal to remove the reference tone;
• frequency converting the notch filtered signal in the translated lower frequency band back to a translated higher frequency band signal in the higher frequency band using the second local oscillator;
• high image filtering the translated higher frequency band signal to remove any unwanted image information to generate a processed translated higher frequency band signal;
• combining the processed lower frequency band signal and the processed translated higher frequency band signal into a substantially similar representation of the received analog signal over substantially all of the bandwidth of the received analog signal;
• and
• storing the digital representation in a computer readable medium.