Sunday, 14 March 2010
This picture has nothing to do with DATV.
I thought I would show it anyway.
It is a picture of one of my eBay purchases.
It is in fact an 8.5 GHz YIG oscillator.
Starting top left is a dual voltage PSU then the YIG itself
followed by the PLL unit for controlling it.
Below that is one of my old Vocoder boards.
The AMBE chip is not being used, I am just using the
PIC microcontroller to drive the PLL chip.
The whole thing is controlled from a Windows GUI App.
The YIG swings by about 1 GHz.
There I got that off my chest.
Back to DATV. It now seems I need more than just
ISO 13818-1 to understand DATV. A lot of the
information like the service descriptor tables
(SDT) are encoded as 'private' data which is not
included in the MPEGII spec.
Enter ETSI EN300 468 this is where it is described.
I have some working transport packet files *.ts which
came with the M0DTS package and I have been using
these to figure out what I need to send.
First thing this morning I jumped out of bed (all keen like)
and wrote a little utility which I have called "Bitnapper"
Bitnapper allows me to pull to pieces transport packets
bit by bit. I pass it the *.ts packet, a simple syntax file
and it then creates an output file for me with the packet
A lot of the mpeg analysers on the internet seem to
want to massage the data before they display it.
Bitnapper is not like that, it is dumb and shows you
exactly what is in the packet.
Last night I wrote what seemed like reams and reams
of code to format DVB descriptor files. I am going to
have to take a break from doing DVB as I am falling
behind with some more important stuff like my
I bought a slightly wider angle lens for my video
camera, again on eBay.
Hopefully I will be able to have everything in focus at
once just to annoy the BATC committee.
I though CQ-TV this quarter was a lot better than it has
been for a while. I do sympathise with the editor about
the lack of material. In the past I have tended to get my
stuff ghost authored.
I think that is enough waffle for today.