[linux-dvb] Re: dec2000-t success

[bruce@staff.cs.usyd.edu.au (Bruce Janson)]

    From linux-dvb-bounce@linuxtv.org Sun Apr 27 11:47:35 2003
    ...
    From: darian <darian4@optusnet.com.au>
    ...
    To: Reiner Klenk <pdq808@t-online.de>
    CC: linux-dvb@linuxtv.org
    ...
    Reiner Klenk wrote:
    ...
    > after some guessing and fiddling: dec2000-t rendering perfectly via ts2ps
    > and mplayer ! Sound too !
    
    Is the code yet available to modify the DEC2000-t parameters to set
    channel spacing=7MHz, enable VHF tuning range, etc for application in
    non-UK locales (eg Australia)?
    ...

Ian, Rainer,
    According to the booklet that accompanies my Thomson DVB-T
receiver (and after the device completed its scan, somewhat
confirmed by the diagnostic screens displayed by the receiver
itself), in Australia some (all?) of our DVB-T channels are:

  Freq. (MHz)		Network
  -----------		-------
  177.5			Seven Network
  191.5 (or 191.625?)	Nine Network
  219.5			Ten Network
  226.5			ABC
  536.625(?)		SBS Melbourne, SBS Perth
  564.5			SBS Adelaide
  571.5			SBS Sydney
  585.5			SBS Brisbane

So, if we adopt the definitions:

   30- 300 MHz	= VHF
  300-3000 MHz	= UHF

found on

  http://www.oulu.fi/~spaceweb/textbook/radiof.html

(apparently defined by the august sounding "International
Telecommunication Union (ITU)") we see that the Sydney channels
fall into both the VHF (Seven, Nine, Ten and ABC) and UHF (SBS) ranges.

If we assume that "channel spacing" refers to the distance between
the centre frequencies of two channels then we notice that Seven,
Nine, Ten and ABC are separated by exact multiples of 7 MHz:
respectively 2, 4 and 1 (with an origin at 135.5 MHz).
The UHF channels also appear to be separated by exact multiples of
7 MHz (with their origin at 333.5 MHz).

The Thomson booklet suggests that Sydney DVB-T channels
require at least these DVB-T COFDM parameters:

  Transmission mode:	8K
  Modulation:		64 QAM
  Hierarchy:		No
  Inner FEC scheme:	2/3, 3/4
  Guard Interval:	1/8, 1/16

According to

  http://www.hauppauge.co.uk/dec2000t.htm

the Hauppauge DEC 2000-t features include:

  BASIC SPECIFICATIONS
  ...
    Input center frequency range	51-858 MHz 
    Channel bandwidth			7/8 MHz 
  ...
    COFDM 2k and 8k			Yes
    QPSK and QAM 16/64			Yes
  ...
    Guard Interval Modes		1/32, 1/16, 1/8, 1/4 active
						symbol duration 
    FEC modes				1/2, 2/3, 3/4, 5/6, 7/8 
  ...
  INTERFACES
  ...
    USB Interface for use with PC	Vers. 1.1
  ...

which does include the abovementioned Sydney transmission
mode, modulation, FEC and guard interval requirements.

However, according to

  http://www.linux-usb.org/linux.conf.au.02/talk/html/slide_5.html
  http://www.usb.org/faq/ans2#q1

the DEC 2000-t's USB 1.1 interface will impose a 12 Mbits/s limit on
its USB->PC interface.  I do not know the maximum (compressed)
throughput that can be required by a 7 MHz, DVB-T transport stream
(23 Mbits/s?), but I suspect that it does exceed 12 Mbits/s.
If true, this would impose an unfortunate limitation on the DEC 2000-t.
(USB 2.x at 480 Mbits/s would have avoided this...)

On

  http://www.hauppauge.com/html/..\html\buy_row.htm

(alas, the USA Hauppauge site...) three Australian
vendors are listed:

  International Software Warehouse 
  Australia 
  Ph: 1300 300 003 
  Fax (02) 9700 8801
  http://www.iswh.com.au
  
  New Magic Pty Ltd 
  Australia 
  Tel: (03) 9885 5888 
  Fax: (03) 9886 9111 
  E-mail: sales@newmagic.com.au 
  Website: http://www.newmagic.com.au/
  
  A Better Computer Solution, Australia 
  Tel: +61+3+ 9754 2566 
  Fax: +61+3+9754 3566 
  http://www.abcs.com.au

I would guess that they would be the best places to begin
a search for a DEC 2000-t in Australia (before ordering one
in from the UK).

Cheers,
Bruce Janson, School of Information Technologies, Email:  bruce@cs.usyd.edu.au
F09 Madsen Building, Eastern Avenue               Phone:  +61-2-9351-3423/4
University of Sydney, N.S.W., 2006, AUSTRALIA     Fax:    +61-2-9351-3838


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