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7 votes

What cause the spectrum peak of `center frequency`?

In addition to the clock leakage mentioned in the other answer, a DC offset spike can also show up in the downmixed IQ if the mixer(s) and/or the ADC(s) aren’t perfectly balanced (exactly equal gains ...
hotpaw2's user avatar
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5 votes
Accepted

What cause the spectrum peak of `center frequency`?

Internal interference in the radio. There's a clock ticking at that frequency in order to downmix the signal, and spurious emissions from that clock is being picked up by other circuitry. The clock is ...
Thomas's user avatar
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1 vote

What cause the spectrum peak of `center frequency`?

Every SDR has this "DC spike" more or less visible. In GNU Radio there are the blocks "Remove DC Spike" and "Remove DC Spike Auto Sync" for suppression. The respective ...
chrboesch's user avatar
  • 111
1 vote

What cause the shape of frequency spectrum convex or concave?

The edges of your spectrum is where the performance of the receiver is hitting the limit. there is a trade-off between flatness and total bandwidth. they could have made the bandwidth smaller to keep ...
Jack0220's user avatar
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1 vote
Accepted

What cause the shape of frequency spectrum convex or concave?

Answer to part 2: The USRP SDR uses an downconverting IQ modulator before the ADCs. An error in quadrature phase or quadrature levels of the two IQ modulator clock signals or gain and delay balance ...
hotpaw2's user avatar
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