• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

convertin two analogue signals to digital signal and then multiplyin them

Status
Not open for further replies.

mpradhan1

New Member
Hi i am currently working on a project which deals with lock in amplification system, all this time i have been working on analogue electronics but now my supervisor wants me to convert the system into digital at the last minute

the main part of my project is the phase sensitive detection stage where i multiply a noisy signal with its reference signal to produce the output .... but now i guess i have to provide the a/d stage before it .... can anyone please give a short brief of how to do it ? the only thing i can think of is passing both the signals through a adc chip and then multiplying signals (not sure tho how to multiply them)

I would greatly appreciate the help :)
 

dknguyen

Well-Known Member
Most Helpful Member
You normally use a microcontroller to multiply digital signals and then also do whatever else you need to do with the number inside the microcontroller (after all, you need a digital system to work with digital data). You also need the microcontroller to operate the ADC chip (unless you are using a microcontroller with an ADC built into it).
 
Last edited:

crutschow

Well-Known Member
Most Helpful Member
It depends upon the signal frequency. Remember that the A/D sample frequency needs to be at least two times the highest signal frequency (Nyquist limit) for proper sampling of the signal. And you will likely need good, high-order filters to sharply roll off the signal above 1/2 the sample frequency at the A/D input to minimize aliased noise. (The higher the sample frequency, the less stringent the filter requirements for a given signal frequency since you start the rolloff at just above the highest signal frequency).

For high frequency sample rates you can use digital multiply chips, or a digital signal processor to do the multiplication (some digital processors have built-in A/D converters). For lower frequency rates you may be able to just use a microprocessor to do the multiplication.
 
Last edited:
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top