hardware frequency and channel filter offset option

[Alessandro Ranzo]

Hi!,
i've just bought my rtl2832 dongle from china for 7 €, it works fine though i've tested it through stock antenna.

In gqrx there is hardware frequency and filter offset to select the desired frequency, what is the meaning of them? Can you tell how to use them in the best way? If i have to select 100mhz frequency wich way is better?
1)hardware frequency 100mhz + 0 mhz offset
2)hardaware frequency 99mhz + 1 mhz offset

Sorry for my english i hope you will help me understand!

[Alexandru Csete]

On Sun, May 4, 2014 at 12:23 PM, Alessandro Ranzo <ranz...@gmail.com> wrote:
> Hi!,
> i've just bought my rtl2832 dongle from china for 7 €, it works fine though
> i've tested it through stock antenna.
>
> In gqrx there is hardware frequency and filter offset to select the desired
> frequency, what is the meaning of them? Can you tell how to use them in the
> best way? If i have to select 100mhz frequency wich way is better?
> 1)hardware frequency 100mhz + 0 mhz offset
> 2)hardaware frequency 99mhz + 1 mhz offset

Alessandro,

The hardware frequency is what the hardware oscillator is set to. It
also corresponds to the center of the spectrum you see (where you have
the blue line). If the sample rate is 2 MHz you will see a 2 MHz wide
spectrum centered around the hardware frequency.

Often, the signal you want to receive is much narrower that the total
bandwidth. The filter offset can be used to "software tune" within the
received 2 MHz bandwidth. Often is is desired to receive offset from
the center frequency because of a DC spike with some receivers.

I use the "big digits" to make large tuning steps, then if I see a
signal in the spectrum I just click on it (wdhich corresponds to
filter offset). There is really no "best way" - whatever works for
you.

Alex