2 Sep
2017
2 Sep
'17
7:59 p.m.
Here's a little more background on the project. First, the DVB-T2
transmitter is part of GNU Radio itself. I developed the original DVB-T2
transmitter as an OOT (Out of Tree) module back in the winter of 2014/2015.
https://github.com/drmpeg/gr-dvbt2
Since then, the code has been integrated into the GNU Radio mainline
along with DVB-T, DVB-S, DVB-S2, DVB-S2X, ATSC and cable QAM
transmitters. There are also receivers for ATSC and DVB-T. The above OOT
module is now deprecated.
Here's an example DVB-T2 flow graph. This one implements the exact same
parameters as used by the BBC for their television transmitters in the
UK. It has 40.2 Mbps of throughput in an 8 MHz channel.
http://www.w6rz.net/dvbt2bbc.png
The blocks in the lower right hand corner implement the interface to the
SDR hardware. The UHD: USRP SInk is for Ettus Research products and the
osmocom Sink is for other SDR's like bladeRF and hackRF.
The flow graph for the OFDM modem looks like this.
http://www.w6rz.net/dvbt2ule.png
The IP over TS Packet Source block is implemented in the gr-ule OOT module.
https://github.com/drmpeg/gr-ule
The other DVB-T2 blocks are just the regular DVB-T2 blocks merged
together to avoid buffering between blocks (to reduce latency). Those
blocks are implemented in the gr-dvbt2ll OOT module.
https://github.com/drmpeg/gr-dvbt2ll
The network interface is provided by a kernel driver. The driver
implements both the ULE protocol and the MPE protocol, but MPE is not
complete for some reason.
https://github.com/torvalds/linux/blob/master/drivers/media/dvb-core/dvb_ne…
The dvb_net driver just exposes a regular Ethernet interface, so all the
routing tools of Linux are available. To connect to the Internet, all I
had to do was make the interface the default route on the "remote" node,
enable IP4 forwarding on the "local" node that's connected to the
Internet, and add the 44.4.15.8/29 route to my Asus RT-AC66U router.
http://www.w6rz.net/dvb0_0.png
Ron W6RZ
On 09/01/2017 08:21 AM, Andrew Ragone wrote:
> Er, looks like I stand corrected ... I think this is the project
> implementing the GNU Radio functionality: https://github.com/drmpeg/gr-ule
>
> On Fri, Sep 1, 2017 at 9:17 AM, Andrew Ragone <ajr9166(a)rit.edu> wrote:
>
>> Ron, this is great work! I know you mentioned there is room for
>> optimization on the buffering / GNU Radio side of things, but it doesn't
>> look like any of the links provided were for the actual radio design you
>> worked on. Were you planning on throwing that up on GitHub or your website?
>> I have a Pervices Noctar SDR which I wouldn't mind playing with your
>> project on (and helping optimize).
>>
>> -Andrew
>> Kc2LTO
>>
>> On Fri, Sep 1, 2017 at 7:01 AM, Brian Kantor <Brian(a)ucsd.edu> wrote:
>>
>>> Sounds a lot like the ALOHA network from back in June 1971.
>>> - Brian
>>>
>>> On Fri, Sep 01, 2017 at 08:57:38AM -0400, Mark Phillips wrote:
>>>> This has been thought of before I'm sure.
>>> _________________________________________
>>> 44Net mailing list
>>> 44Net(a)hamradio.ucsd.edu
>>> http://hamradio.ucsd.edu/mailman/listinfo/44net
>>>
>>
>
