Hi Arhum,
some limited amount of DC offset is sadly to be expected from any direct conversion
architecture (that's a result of LO leakage as well as systematic DC offset).
Since DC is the lowest of all possible frequencies, a high-pass filter can be used to
eliminate it. The design of that filter depends on what you want to do with the signal
afterwards – for example, for some communication system signals, the DC offset literally
doesn't matter.
Another option is, if your signal is sufficiently more narrowband than the Nyquist
bandwidth dictated by your receiver's sampling rate, to "offset-tune"; i.e., to put your
signal of interest to the positive (or negative) side of your LO frequency, and then
digitally shift the signal of interest to actual baseband and filter.
The USRPs bring that functionality out of the box, integrated into the device's digital
part, so you can just deal with the signal decimated to the bandwidth you need in your
computer. I'm not sure, but I don't think the HackRF allows for that. You'd have to
offset-tune within your full sampling rate, and in GNU Radio use something like the "freq.
X-lating FIR filter" to get the part of the spectrum you want.
Best regards,
Marcus
On 10.02.24 12:02, Arhum Ahmad wrote:
Hey all,
I'm currently working on frequency sensing using the HackRF SDR. However, when I
calculate the FFT, I encounter a DC offset that's higher than the actual signal strength
itself. This offset is interfering with my ability to detect the intended output
accurately. Could you please assist me in understanding how to remove this DC offset?
--
*Thanks and Regards**
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*Arhum Ahmad*
Ph.D. Scholar, Electrical Engineering Department, IIT Ropar
+91- <tel:+91-7015802356>7974897279 | arhum.19eez0...@iitrpr.ac.in
<mailto:2016eez0...@iitrpr.ac.in>
Lab No. 323, Communication Research Lab, J.C.Bose Building
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