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Updated FAQ (markdown)

Michael Ossmann
2013-07-03 21:50:28 -07:00
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FAQ.md

@@ -44,7 +44,7 @@ You are seeing a DC offset (or component or bias). The term "DC" comes from "Di
```
-2, -1, 1, 6, 8, 9, 8, 6, 1, -1, -2, -1, 1, 6, 8, 9, 8, 6, 1, -1, -2, -1, 1, 6, 8, 9, 8, 6, 1, -1
```
This periodic signal contains a strong sinusoidal component spanning from -2 to 9. If you were to plot the spectrum of this signal, you would see one spike at the frequency of this sinusoid and a second spike at 0 Hz (DC). If the signal were centered around 0, there would be no DC offset. Since it is centered around 3.5 (the number midway between -2 and 9), there is a DC component.
This periodic signal contains a strong sinusoidal component spanning from -2 to 9. If you were to plot the spectrum of this signal, you would see one spike at the frequency of this sinusoid and a second spike at 0 Hz (DC). If the signal spanned from values -2 to 2 (centered around zero), there would be no DC offset. Since it is centered around 3.5 (the number midway between -2 and 9), there is a DC component.
Samples produced by HackRF are measurements of radio waveforms, but the measurement method is prone to a DC bias introduced by HackRF. It's an artifact of the measurement system, not an indication of a received radio signal. DC offset is not unique to HackRF; it is common to all quadrature sampling systems.