When using DAC/ADC pairs, which way is more resistant to noi

[Frank]

I am inexperienced with analog thingy.

My digital clock is 40MHz, modulates a 10mbps bit stream into some
waveforms.
The modulated output value lies between two narrow bands, 0-63 for input
zero
or 960-1023 for input ones, when input bit flips, output also change between
lower
band and higher band. When input bit remain unchanged, output flactuates
within
their narrow bands.

Now my task is to send this waveform through TI DAC290x-EVM (DAC chip) and
Analog AD9218 (ADC chip), and make the demodulator demodulate the ADC
outputs.

My digital outputs are in 2's compliment, I can easily convert that into
binary value (thus
between 448-576) if it's advantageous.

Which is better option?

[Jerry Avins]

Frank wrote:

I am inexperienced with analog thingy.

My digital clock is 40MHz, modulates a 10mbps bit stream into some
waveforms.
The modulated output value lies between two narrow bands, 0-63 for input
zero
or 960-1023 for input ones, when input bit flips, output also change between
lower
band and higher band. When input bit remain unchanged, output flactuates
within
their narrow bands.

Now my task is to send this waveform through TI DAC290x-EVM (DAC chip) and
Analog AD9218 (ADC chip), and make the demodulator demodulate the ADC
outputs.

My digital outputs are in 2's compliment, I can easily convert that into
binary value (thus
between 448-576) if it's advantageous.

Which is better option?
I find it hard to suggest something because I don't understand the

constraints. To you want to transmit the ADC output for its own sake, or
do you want to reproduce the waveform it's representing?

Without looking up the data sheets, I don't know how many bits you have.
Two's complement is the most common form of signed binary. for positive
numbers within range, the two representations are identical. What
conversion did you have in mind?

Jerry
--
Engineering is the art of making what you want from things you can get.
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