ADC Clock Source and Bypassing IQ Demodulator
Is the ADC of the SPECTRAN V6 clocked from the 10 MHz reference input? In other words, are the ADC sample clock and the LO clock both clocked from the same source?
Also, I have a 5 GHz, narrow bandwidth signal (<100 kHz) that I wish to sample. Fortunately, I also have access to the clock source (local oscillator) that was used to generate the 5 GHz "modulated" signal. However, I am very sensitive to IQ imbalance, and I need to perform the IQ demodulation in software. Thus, I would like to bypass the LNAs, filter banks and the IQ demodulator. From the block diagram of the V6 it appears that you can bypass all filters and LNAs, but not the IQ mixer. Is this correct, or can I also shut off the LO and directly sample the signal with the ADC?
Alternatively, if the ADC and LO are both clocked from the 10 MHz reference, maybe I can just sample the I component, discard the Q component, and then perform I/Q demodulation in software. This is possible because my 10 MHz ref is coherent with the 5 GHz signal carrier. But it would be preferable to completely bypass the hardware IQ demodulator.
Is the ADC of the SPECTRAN V6 clocked from the 10 MHz reference input? In other words, are the ADC sample clock and the LO clock both clocked from the same source?
The 10MHz Refclock is not connected to the SPECTRAN V6 clock source. The 10MHz is used for the timebase (time stamps) only. In addition the time stamp can also be synced by the GPS option: https://v6-forum.aaronia.de/forum/topic/are-the-i-q-data-referenced-with-the-internal-gps-time-stamp/
Also, I have a 5 GHz, narrow bandwidth signal (<100 kHz) that I wish to sample. Fortunately, I also have access to the clock source (local oscillator) that was used to generate the 5 GHz "modulated" signal. However, I am very sensitive to IQ imbalance, and I need to perform the IQ demodulation in software. Thus, I would like to bypass the LNAs, filter banks and the IQ demodulator. From the block diagram of the V6 it appears that you can bypass all filters and LNAs, but not the IQ mixer. Is this correct, or can I also shut off the LO and directly sample the signal with the ADC?
Yes you can bypass the LNAs and the complete filterbank(s) within the SPECTRAN V6 block under "Calibration":
Unfortunately it is not possible (for users) to bypass the IQ mixer stage. We might add some possibility to do so in a later stage but this is not of high priority so far.
Alternatively, if the ADC and LO are both clocked from the 10 MHz reference, maybe I can just sample the I component, discard the Q component, and then perform I/Q demodulation in software. This is possible because my 10 MHz ref is coherent with the 5 GHz signal carrier. But it would be preferable to completely bypass the hardware IQ demodulator.
As mentioned before this is not possible but you might want to try our IQ Processing blocks which are of great help to sync or extract the I/Q data e.g. by adding some math or filters and even seperating I from Q:
