[Hackrf-dev] DVB-T and DVB-T2

Sun Jul 5 10:08:51 EDT 2015

Cool, I'll delete the email I was about to send! I had forgotten that you
were trying to tx DVB-T. However, I remember that when I was playing with
DVB-T I was able to use framerates from 25 to 60, but maybe it depends on
the TV your are using.

I used an RTL-SDR dongle for receiving and found that avconv worked
perfectly but using ffmpeg I could only get a pixellated image, go figure!

Simon.

On 5 July 2015 at 15:04, Craig Barber <radiocraig28 at gmail.com> wrote:

> Bingo... I had to change the video frame rate from 60 down to 25 which I
> found is apparently what is broadcasted in the UK for Digital TV... and now
> I have video!
>
> On Sun, Jul 5, 2015 at 2:54 PM, Craig Barber <radiocraig28 at gmail.com>
> wrote:
>
>> Hi Simon,
>>
>> The mpeg2 TS plays fine in mplayer and VLC and I get video and sound, but
>> on my test bench TV I only hear the audio. I've tried a couple of different
>> bitrates for the video too but no luck.
>>
>> I've edited dvbt-hackrf_tx_sk.py to use channel_mhz = 8 as I understand
>> that is what is normally used in the UK for UHF DVB-T. Any other option
>> other than that and I don't seem to see any signal at all on the test TV.
>>
>> Craig
>>
>> On Sun, Jul 5, 2015 at 2:51 PM, Simon Kennedy <simon at thekennedys.info>
>> wrote:
>>
>>> HI Craig,
>>>
>>> just seen your emails. Try using mplayer to play the ts from the fifo
>>> file. This will enable you to double check that the first part of the
>>> process is ok, ie. the creation of the mpeg2 ts.
>>>
>>> Where have you put channel_mhz = 8?
>>>
>>> Earlier today I had someone else email me to tell me that they have had
>>> success with the commands and program I put on my blog post so I know it
>>> does work for someone else!
>>>
>>> Regards
>>> Simon.
>>>
>>> On 5 July 2015 at 14:41, Craig Barber <radiocraig28 at gmail.com> wrote:
>>>
>>>> Thankyou, I just found it (https://en.wikipedia.org/wiki/DVB-T), I now
>>>> have stable sound (getting there!) but no video oddly! The command I'm
>>>> using to create the TS before broadcast is as follows:
>>>>
>>>> avconv -f alsa -i hw:0,0 -f video4linux2 -s 640x480 -i /dev/video0 -vf
>>>> drawtext=fontfile=/usr/share/fonts/truetype/freefont/FreeMonoBold.ttf:text="TEST
>>>> ":x=440:y=420:fontsize=48:fontcolor=white at 0.6:box=1:boxcolor=black at 0.4
>>>> -vcodec mpeg2video -r 60 -b 2500000 -acodec mp2 -ar 48000 -ab 48000 -ac 2
>>>> -muxrate 4976000 -mpegts_transport_stream_id 1025 -mpegts_service_id 1
>>>> -mpegts_pmt_start_pid 4096 -mpegts_start_pid 400 -f mpegts -y test3
>>>>
>>>> I'm then using QPK, with 1/2 code rate and 1/4 guard interval which
>>>> expects a bitrate of 4.976mbps so should be correct?
>>>>
>>>> On Sun, Jul 5, 2015 at 2:16 PM, n0p [Luis Bernal] <lbernal at gmail.com>
>>>> wrote:
>>>>
>>>>> The modulator bitrate depends of it's parameters, there's a nice table
>>>>> with the formula but i can't find it now since I'm on mobile
>>>>> El 5/7/2015 14:48, "Craig Barber" <radiocraig28 at gmail.com> escribió:
>>>>>
>>>>>> Thanks for the fast response n0p but I cannot find that parameter?
>>>>>>
>>>>>> On Sun, Jul 5, 2015 at 1:34 PM, n0p [Luis Bernal] <lbernal at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> The ts mux bitrate has to match the modulator's
>>>>>>> Avconv parameter -muxrate
>>>>>>> El 5/7/2015 14:11, "Craig Barber" <radiocraig28 at gmail.com> escribió:
>>>>>>>
>>>>>>>> The good news is I got it working, sort of, using channel_mhz = 8 -
>>>>>>>> however the picture and audio judders really badly, and basically plays
>>>>>>>> back really slow! I don't have a stream of UUUUUUUUUUU appearing in my
>>>>>>>> console window, so can't be buffer underruns, any ideas Simon?
>>>>>>>>
>>>>>>>> On Sun, Jul 5, 2015 at 12:30 PM, Craig Barber <
>>>>>>>> radiocraig28 at gmail.com> wrote:
>>>>>>>>
>>>>>>>>> Hi Simon,
>>>>>>>>>
>>>>>>>>> I've tried your script today with my test TV but see no signal
>>>>>>>>> whatsoever on the TV although the hackrf is definitely transmitting. I've
>>>>>>>>> also tried with a pre-recoded mpeg2 file from avconv but no luck.
>>>>>>>>>
>>>>>>>>> Any suggestions?
>>>>>>>>>
>>>>>>>>> Craig
>>>>>>>>>
>>>>>>>>> On Tue, Jun 30, 2015 at 10:57 PM, Simon Kennedy <
>>>>>>>>> simon at thekennedys.info> wrote:
>>>>>>>>>
>>>>>>>>>> I feel slightly embarrassed as I subscribed to this list using an
>>>>>>>>>> email address that is redirected to my main email, so consequently replies
>>>>>>>>>> sent from my main email address were not coming from the correct address.
>>>>>>>>>> Hence, none of the replies I posted have been seen on the list. Oops!
>>>>>>>>>>
>>>>>>>>>> Here is my reply about this thread:
>>>>>>>>>>
>>>>>>>>>> Hi Craig,
>>>>>>>>>>
>>>>>>>>>> Check out Clayton's web page (who created the sdr-examples you
>>>>>>>>>> refer to) here
>>>>>>>>>> <http://www.irrational.net/2014/03/02/digital-atv/>
>>>>>>>>>>
>>>>>>>>>> I amended his BladeRF script and I have put my HackRF version
>>>>>>>>>> here
>>>>>>>>>> <https://www.dropbox.com/s/bdnzoa0kn01dfav/dvbt-hackrf_tx_sk.py?dl=0> for
>>>>>>>>>> download
>>>>>>>>>> My version transmits DVB-T on the lowest Freeview channel in the
>>>>>>>>>> UK at 474MHz (obviously only while using a dummy load). I successfully
>>>>>>>>>> received the transmission of my webcam image this way using an RTL-SDR
>>>>>>>>>> dongle.
>>>>>>>>>>
>>>>>>>>>> The command I used was very heavily influenced (ok, basically
>>>>>>>>>> copied) from Clayton's examples:
>>>>>>>>>> avconv -f alsa -i hw:0,0 -f video4linux2 -s 640x480 -i
>>>>>>>>>> /dev/video0 -vf
>>>>>>>>>> drawtext=fontfile=/usr/share/fonts/truetype/freefont/FreeMonoBold.ttf:text="TEST
>>>>>>>>>> ":x=440:y=420:fontsize=48:fontcolor=white at 0.6
>>>>>>>>>> :box=1:boxcolor=black at 0.4 -vcodec mpeg2video -r 60 -b 2000000
>>>>>>>>>> -acodec mp2 -ar 48000 -ab 48000 -ac 2 -mpegts_transport_stream_id 1025
>>>>>>>>>> -mpegts_service_id 1 -mpegts_pmt_start_pid 4096 -mpegts_start_pid 400 -f
>>>>>>>>>> mpegts -y in.fifo
>>>>>>>>>>
>>>>>>>>>> I used a standard web cam to capture the image, sent the output
>>>>>>>>>> to a fifo file (in.fifo) and consumed the output through the python program
>>>>>>>>>> with the command:
>>>>>>>>>> ./dvbt_hackrf_tx_sk.py in.fifo
>>>>>>>>>>
>>>>>>>>>> The fifo file can be created using the command mkfifo in.fifo
>>>>>>>>>>
>>>>>>>>>> Run the avconv command and the python program in the same
>>>>>>>>>> directory as you created the fifo file in.
>>>>>>>>>>
>>>>>>>>>> I have also transmitted DVB-S which I have documented on my blog
>>>>>>>>>> here
>>>>>>>>>> <http://photohamrad.blogspot.co.uk/2015/06/transmitting-video-with-hackrf-blue.html>
>>>>>>>>>>
>>>>>>>>>> Simon.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 30 June 2015 at 17:35, Simon Kennedy <simon at thekennedys.info>
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> Can you tell us the command you used to get this error please.
>>>>>>>>>>> I remember that I got a smilar error but cannot look up how I
>>>>>>>>>>> solved it until I get home in a couple of hours.
>>>>>>>>>>> The key point is that the program is trying to open a UDP port
>>>>>>>>>>> to receive the data and error relates to the asignment of the argument you
>>>>>>>>>>> supply to the program to the variable 'port' in the program.
>>>>>>>>>>>
>>>>>>>>>>> Simon.
>>>>>>>>>>>
>>>>>>>>>>> On 30 June 2015 at 16:49, Craig Barber <radiocraig28 at gmail.com>
>>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> Here's the error I get:
>>>>>>>>>>>>
>>>>>>>>>>>> Traceback (most recent call last):
>>>>>>>>>>>>   File "./dvbt-hackrf.py", line 123, in <module>
>>>>>>>>>>>>     main(sys.argv[1:])
>>>>>>>>>>>>   File "./dvbt-hackrf.py", line 31, in main
>>>>>>>>>>>>     port    = int(args[0])
>>>>>>>>>>>> ValueError: invalid literal for int() with base 10: 'testdvbt'
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> _______________________________________________
>>>>>>>>>> HackRF-dev mailing list
>>>>>>>>>> HackRF-dev at greatscottgadgets.com
>>>>>>>>>> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> HackRF-dev mailing list
>>>>>>>> HackRF-dev at greatscottgadgets.com
>>>>>>>> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
>>>>>>>>
>>>>>>>>
>>>>>>
>>>>
>>>> _______________________________________________
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>>>>
>>>>
>>>
>>
>
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