[Hackrf-dev] How do HackRF One transmits/receives a packet ?

[Dominic Spill]

On 12 November 2015 at 12:50, 김상혁 <tkdgur7896 at gmail.com> wrote:
> Hi, I’m newb HackRF.
> I have questions about HackRF One below:
>
> 1) HackRF packet foramt
>         I tried sending/receiving a text file using gnuradio-companion and it worked.
>         Tx)
>         file source(.txt) —> packet encoder—>GMSK MOD—>osmocom sink
>         Rx)
>         osmocom source —> GMSK DEMOD—>packet decoder —>file sink
>         At the end of Tx(osmocom sink) and start of Rx(osmocom source), I wonder HackRF Kit dealing with which data format.

HackRF support a data format known as IQ data.  It consists of pairs
of radio samples taken from the ADCs or passed to the DACs.  These
samples represent a digitised form of the analogue radio waves that
are received/transmitted.

In your example above there are four blocks for each flowgraph, the
interact as follows:
The file source block reads the text file in to a buffer and passes it
to the packet encode.
The packet encoder splits the test in to packets and adds additional
information required for transmitting the packets, such as a preamble,
syncword and maybe a packet header.
The GMSK mod block is a modulator.  The packets are fed in to the
modulator which converts the binary packet data to a digitised radio
signals.
Finally, the osmocom sink takes these digitised waves and passes them
to the Hack~RF hardware, which turns them in to analogue waves, moves
them to the desired frequency and transmits them.

The receive flowgraph is the same in reverse.

> 2) hackrf_transfer command
>         When I use hackrf_transfer command, there is no encoding or modulation option. Are these unnecessary ?
>         And which file format can be used ?

hackrf_transfer takes a similar data format to the osmocom_sink block
above - digitised radio samples as IQ data.  The format is slightly
different as the size of the samples varies; osmocom_sink uses 32bit
floats whereas hackrf_transfer uses 8bit integers to match the
hardware.

> 3) Is there packet transit tutorial ?
>         I want to make a packet and transit using HackRF.

You seem to already be transmitting packets using the HackRF through
GNU Radio.  Is that not achieving what you would like?

Dominic