[Hackrf-dev] Re-tuning frequency

Paul Connolly eeipcy at gmail.com
Wed Jul 15 19:44:10 EDT 2015


How long it takes to change frequency from X MHz to Y MHz will vary
depending on the change involved.

The HackRF One has two analog mixers RFFC5071 (85MHz to 4200MHz LO
[84MHz to 5400MHz]) and the MAX2837 (2300MHz to 2700MHz IF [2150MHz to
2750MHz])
RF switches to switch in or bypass a low pass filter up to 2.3GHz and a
high pass filter from 2.7GHz up.
(And RF switches to change from RX to TX)
(And selectable baseband filters (inside the MAX2837)).

To change frequemncy will require changes in one or more of the above
parts.

What you are really asking is how long after a change is requested, will
the change have happen and everything have settled into a steady state,
before data being output is valid and not in some unknown intermediate
state, with bad data.

From what I have read, it could be wrong, if it was done in firmware it
would be between 100 to 200 microseconds. But if it was being changed
via USB 2.0 on the host the hardware latency of USB protocol, USB
drivers, non-realtime OS, needs to be taken into account, so 1 to 2
milliseconds, or one order of magnitude slower.


On 15/07/2015 17:10, Pierre Talbot wrote:
> How much time is needed to change the frequency of the Hackrf as in an
> application of scanner or frequency hopping? I'm not planning to change the
> firmware to gain speed but to use gnuradio.
>
> Is the re-tuning time the same in Rx and Tx?
>
> Is the re-tuning time depends on the frequency difference such as +- 10 Mhz
> vs +- 100 Mhz
>
>
>
> _______________________________________________
> HackRF-dev mailing list
> HackRF-dev at greatscottgadgets.com
> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev

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