Manually dc offset useful


#1

Hi All,

At this time i am thinking is the dc offset, which i tried to
set up for my db LFRX, useful ?
Or is it useful to disable the automatically dc offset loop ?

The dc offset changes every time depending on the temperatur
and the decimation and maybe other factors !?

So is the use of LFRX useful for measurement device ?

I want to measure some unknown peaks from dc to 1.5MHz, with
a gnuradio peak detector.

My big Problem is the unknown peak in the middle of my FFT-Plot,
which also may influence my Measurement ?

Any comments ?

Regards Markus


#2

feldmaus <feldmann_markus gmx.de> writes:

Any comments ?

I noticed that the dc offset changes if i change the frequency forward
and then back to last frequency.

Will the automatic dc loop enabled if i change the frequency ?

Regards Markus


#3

feldmaus <feldmann_markus gmx.de> writes:

Any comments ?

I also noticed the dc offset, which is needed, changes from
signal generator to signal generator.
Could this be true ?
How to avoid this ?

Regards Markus


#4

“feldmaus” removed_email_address@domain.invalid wrote:

I also noticed the dc offset, which is needed, changes from
signal generator to signal generator.
Could this be true ?
How to avoid this ?

With the LFRX, the DC offset will depend on the DC resistance of your
signal
source. You need 50 ohms (at DC) on the input to get (approximately)
zero
offset.

– Don W.