Johannes Stezenbach wrote:
On Thu, May 25, 2006, christophpfister@xxxxxxxxxxx wrote:
On Tue, May 23, 2006, christophpfister@xxxxxxxxxxx wrote:
Those params are *all* needed for tuning (except the pad of course). Most
of them should be self-explanatory. Just a note to the following ones:
+ enum dvbfe_obc_mode obc_mode;
Needed to indicate in which mode the transponder is sending. But don't worry,
this information is provided (see below).
Where does it come from? Is it the value of the
backwards_compatibility_indicator from
the S2 satellite delivery system descriptor?
Yes.
I'm trying to spell out what your proposal means:
- during scan you get the value of backwards_compatibility_indicator
and store it (NBC is default if there is no S2 descriptor)
Yes
- for tuning you pass the value of backwards_compatibility_indicator
verbatim to the API in the obc_mode field
IOW: The demod hw/fw has a seperate BC mode which is enabled
by DVBFE_OBC_ON.
Do I get you correctly? Because while I think it isn't wrong,
it contradicts what you say below:
*trying to understand what you mean*
Will try to take it in steps, because i am still answering the same
questions which were raised earlier.
sismis and stream_id are only used in backward compatible mode.
In the mis mode both hp and lp streams are received, whereas in sis mode
stream_id is used to select hp or lp stream.
I just read EN 302 307 annex F *again*, and it contains two
totally different BC modes (again, a lot of guesswork done
by me, please correct and/or amend):
- layered modulation: one DVB-S and one DVB-S2 signal are just mixed
together and broadcast on the same transponder
("asynchronously combined on the same radio-frequency channel");
i.e. a DVB-S receiver will just see a DVB-S signal (the DVB-S2
signal will appear as additonal noise); a DVB-S2 receiver will
just see a DVB-S2 signal; in our API one would select the
stream via DVBFE_DELSYS_DVBS vs. DVBFE_DELSYS_DVBS2
("this operational mode does not require any specific tool
in the DVB-S.2 specification")
remember the framing of DVB-S and DVB-S2 is totally differernt,
in DVB-S2 mode the demod will just not sync to a DVB-S signal
TR 102 376 says,
Layered Modulations,
where a DVB-S2 and a DVB-S signals are asynchronously combined on the
radio frequency channel (therefore this operational mode does not
require any specific tool in the DVB-S2 specification), the DVB-S signal
being transmitted at significantly higher power level than DVB-S2. Since
the resulting signal shows large envelope variations, it must be
transmitted on a quasi-linear transponder, far from saturation. As an
alternative, to better exploit the satellite power resources, HP and LP
signals can be independently transmitted on the uplink, and amplified
each by an independent satellite amplifier (HPA), driver near
saturation, the resulting signals are then combined on the down-link
channel.
"This requires the design and launch of new generation satellites"
NOTE: What i understand thus, So IOW, We do *not* have this backward
compatibility mode yet. We *might* have this compatibility in *future*
I hope, you agree. If so i can chop this thing off from the list for now.
Manu
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