[vdr] Re: AC3 over DVB-s is possible - Part2

[Wolfgang Fiesel <fie@iis.fhg.de>]

Roland Praml wrote:

> > Hello,
> >
> > as I promised last week,
> > now AC-3 over Digital Output (SPDIF) for DVB-S is reality (recordings
> > and DVD playback).
> > Of course if the recordings doesn't include any AC-3 data the SDPIF
> > output will be operate like before (raw PCM).
> > I'm using DVB-S version 2.1 (Hauppage)
> >
>
> Hi,
> this would be great if it really works.
> I will try that the next days, but i've a 1.3 DVB-s. Will it work there,
> too?
> Also i've heard that the output level is 3Vss (not conforming to the
> SPDIF specs).
> Should I build a voltage divider with 2 resistors, or doesn't that matter.
> (formerly my SB-live had no problem to accept the signal)

In detail the IEC 958 specification says in case of unbalanced line (two wire
transmission):
- max. signal amplitude:
The signal amplitude shall be 0.5 V +- 20% peak-to-peak, when measured across
a 75 Ohm resistor connected at the output terminal, without any
interconnecting cable present.
- min. input signal
Minimum input voltage shall be 0.2 V peak to peak.

On the other side the balanced transmission (AES-EBU for professional
equipement) shows a maximum peak level up to 10 V and was used sometimes by
myself for SPDIF input.
Therefore my experience says don't worry about this level. But if you want to
do it really correctly you have to use a special line transformer instead of
voltage divider.

>
> cu
> Roland