Is a unipolar signal bad as an input for a USRP receiver?

I am using LFTX and LFRX to transmit and receive data between two nodes.

I am modulating a bit stream with on-off keying (OOK) in which bit 1 is
modulated into HIGH voltage and bit 0 is modulated into LOW voltage
close
to zero.

What I concern is, USRP can process bipolar signal, has a low noise
amplifier (LNA) and an ADC at the receiving end. I’ve heard that LNA and
ADC take a heavy stress if they process a unipolar, a DC biased signal.I
want the statement to be clear. I have a particular condition that I
can’t
make a transmitted signal a bipolar NRZ signal instead of OOK…

PS. I make a thread in discuss-gnuradio since I’ve got no reply on
USRP-users several days or weeks ago (I don’t remember exactly…).

Regards,
Jeon.

Hi Jeon,

What I concern is, USRP can process bipolar signal, has a low noise
amplifier (LNA) and an ADC at the receiving end.
That’s not true. The USRP motherboard itself doesn’t have an amplifier;
amplifiers are, if they exist, on the daughterboards.
The LFRX doesn’t have an LNA – it just has an OpAmp configured as a
voltage follower.
I’ve heard that LNA and ADC take a heavy stress if they process a
unipolar, a DC biased signal
The ADC doesn’t mind static signals (in fact, signals are always
presented to the ADC as differential), and the OpAmp is speced to
withstand any signal within its input range. So you don’t have to worry
:slight_smile:

NRZ might be a good idea for other reasons, but these depend solely on
your application.

Best regards,
Marcus

PS: I’ll try to locate your thread on usrp-users. Normally we strive to
not miss anything on that mailing list.

Dear Marcus.

Thank you for your answer.

Yes, I mean daughterboards, not USRP. I made an expression too short :slight_smile:

And I am happy to hear that I don’t need to worry about what I’ve been
concerning.

Regards,
Jeon.

2015-07-03 0:27 GMT+09:00 Marcus Müller [email protected]:

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