RE: IR Extender... Revisited!

["KIFF, Graham, FM" <graham.kiff@xxxxxxx>]

Here's some information I got directly from Pace on the subject:

Hello
I am sorry but I do not know of a universal handset or remote extender that
will control your digital cable box due to a completely different system of
I.R. modulation being used by the Pace cable receiver handsets .

The system used was chosen by our customers ( the network providers ) and
is
a high speed system that gives some " future proofing "  of the
design . The
system is  designed for remote keyboard use ( Web browsing ) and to enable
multiple handset to be used " simultaneously " as required when
playing
games . This is because at some time in the near future the network
providers  will offer these services .

"Normal" handsets use a system of modulating (switching on and
off ) a
carrier signal . The normal frequency of the carrier being in the range of
35kHz to 60kHz..

The system used by Pace uses TWTV protocol which is based on the IRDA
standard that has been designed to enable computer peripherals to be linked
without cables . ( This is not surprising  as modern digital cable set top
boxes contain a powerful micro processing systems and the Pace boxes are
the
first to also provide an integrated  cable modem within the box.) The
handset data is transmitted as discrete pulses of IR - it is not carrier
based . The pulse rate is approximately 115kHz . The handsets have
identification keys / tabs that  enable the receiver to identify the
handset
. Each key sends a 7 byte package of data within 600uSec (  the same time
that it taken to send only 1 or 2 bits of information with the normal
system
) . This allows the data to be sent very quickly thus freeing time for a
second handset to jump in . The receiver software also adds a time stamp to
the data to enable the games programmes to decide which handset responded
first . The system and protocols used are covered by patents hel
d by TWO WAY TV LTD .

I hope this answers your query but should you have any further queries
please contact me again.

Regards
Craig Charlwood
Technical Support - Service
Pace Micro Technology plc www.pace.co.uk <http://www.pace.co.uk>


> If it is just the modulation frequency then I could probably build it
into
> the current PIC based model. Each transmitter unit would be selectable
for
> IRDA or normal IR via a jumper. The only other hurdle would be the
receiver
> unit. For IR they are nice off the shelf units.
>
> Does anyone know whether IRDA is simply a higher frequency and are
there
> receivers available off the shelf. Ideally these would output a
modulated
> signal i.e. no carrier just like the TSOP 1838's we all know and love
from
> the current IR units.
>
> Ideas folks
>
> Ian
>
> > -----Original Message-----
> > From: James Hoye [mailto:james.hoye@xxxxxxx]
> > Sent: 16 August 2001 14:54
> > To: ukha_d@xxxxxxx
> > Subject: RE: [ukha_d] IR Extender... Revisited!
> >
> >
> > > Stuart, I have exactly the same problem.  So if you get any
> > > information on this subject or anyone else has any ideas, I
will
> > > be eternally grateful!
> >
> > Perhaps Mr Bird would look at making an IrDA compatibile version
- is it
> > just the modulation frequency that's much higher, or is it a
completely
> > different protocol (ie. no carrier, PWM, PPM or any other acronym
you
care
> > to imagine).  Someone (Keith) is probably now going to tell me
> > that carrier
> > modulation is the same as PWM/PPM/whatever :)
> >
> > James H
> >
> >
> > For more information: <a
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>
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