Generating Custom Packet Header

GNU Radio
1

Hello everyone,

I’ve made the default packet generator work for my radio. I now want to
make a custom header. The difference is described below:

GNU Radio Default Header: [Payload Length (12 bits) | Packet Number
(12
bits) | CRC (12 bits)]

My Custom Header: [ Sync Bits (1010101…) (128 bits) | PN Sequence
(16
bit) | PN Sequence (16 bit) | Payload Length (16 bits) ]

I am using my header for synchronization only. I don’t want the CRC
check
in there and I don’t want packet numbers.

My understanding of how to attack this is as follows:
1) Customize packet_header_default.cc which is responsible for making
the
custom header object
2) No change needed for the Packet_Header_Generator block
3) No change needed for the Packet_Header_Parser block

If this is correct, how should I replace packet_header_default.cc with
packet_header_mycustom.cc, since they are not blocks in GRC? Should I
think
of this the same way I would if I were making a custom GRC block, and
follow the custom block tutorials?

Thanks,
Rich

2

On 30.03.2015 11:51, Richard B. wrote:

If this is correct, how should I replace packet_header_default.cc with
packet_header_mycustom.cc, since they are not blocks in GRC? Should I
think of this the same way I would if I were making a custom GRC block,
and follow the custom block tutorials?

Kind of. The SWIG magic won’t work out-of-the-box, though. Bastian’s
gr-ieee-80211a does this, or check out how gr-digital does this.

Cheers,
M

3

Are you referring to the packet_header.i file in the swig folder of
gr-digital? Are there other spots that need to be changed as well?

Rich

On Mon, Mar 30, 2015 at 1:36 PM, Martin B. [email protected]

4

On 30.03.2015 14:56, Richard B. wrote:

Are you referring to the packet_header.i file in the swig folder of
gr-digital? Are there other spots that need to be changed as well?

I don’t think so. Also check Bastian’s 802.11 OOT for pointers.

M