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I have to design a test bench for a device that has more than 1000 outputs. The voltage of these outputs will be about 10mV peak-to-peak, the frequency will be in the range of 100MHz (for the carrier) and between 0Hz to 10kHz for the envelope that I am interested in.

I plan to buy 16 acquisition boards (NI PXIe-6361, X Series Multifunction DAQ (16AI, 24 DIO, 2 AO), 2 MS/s single-channel sampling rate input) to collect the data coming from the device, but I need some advice regarding how to design efficiently the interface between the device and the DAQ.

I planned to use multiplexers to reduce the number of DAQs, because I know those parts are expensive.

Do you know if there are commercial products that can take out the envelope of multiple channels?

If no, I may have to design my own board probably with one mixer and one low-pass filter per channel.

What I would like to know is : what is the most effective way to design a huge number of amplifier/demodulators to get the envelope of 1000 low-voltage signals?

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    \$\begingroup\$ If you are already able to design a board with frequency mixing and filtering, why rely on $32000 worth of aquisition cards? Add ADCs and an FPGA for data processing and you have a standalone system. The development time is going to be significant in either case. \$\endgroup\$
    – jms
    Feb 12 '16 at 0:05
  • \$\begingroup\$ I like the ADCs/FPGA idea, but I am not sure if have the time and the skills to design a FPGA data processing system... I will take a look to the option, it might be feasible. \$\endgroup\$
    – supermario
    Feb 12 '16 at 0:23
  • \$\begingroup\$ Are all 1000 signals locked to the same carrier frequency? Are they all AM signals? \$\endgroup\$
    – Andy aka
    Feb 12 '16 at 9:43
  • \$\begingroup\$ Yes all signals are locked to the same frequency and AM signals. \$\endgroup\$
    – supermario
    Feb 12 '16 at 16:44
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If you use a Superheterodyne Receiver type design, you can mix & remove all or most of the 100MHz carrier signal in one or more het. stages (maybe a 70MHz stage for 30MHz IF, then a 29MHz stage to 'final' 1MHz IF).

This way, ou can use less costly filters & circuits to "narrow in on" your envelope of interest.

Then you can add a tuner to select between your predefined channels, to test a single channel at a time (using only one DAQ for all channels); or you can skip the tuner, and use a series of filters to split out all of your 1000+ signals for 'simultaneous' testing (at a few hundred times the price, due to needing 1000+ DAQs).

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  • \$\begingroup\$ It is close to my original idea, I planned to rectify the signal then use a low pass filter to take the envelop. And after do the multiplexing. But maybe I could do the multiplexing before to reduce the number of rectifier/filter. \$\endgroup\$
    – supermario
    Feb 12 '16 at 16:45
  • \$\begingroup\$ @supermario That's probably the key reason why superhet. receivers are still commanding the vast majority of tjs multi-channel rf receiving device market. By using a varible-frequency tuner stage (either variable mix-in freq, or adjustable filter) for an IF stage, you can receive many channels with 1 set of filters & save a huge cost in terms of component count, complexity, and $$ over most other systems. \$\endgroup\$ Feb 12 '16 at 16:58

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