I have just received a reply from a very helpful engineer at Pace, and unfortunately it is not what we wanted to hear. He has given his permission to post his reply here:
Hi Teresa ,
May I introduce myself - I am Vic Fielding one of the senior
design engineers a Pace . I have been responsible , amongst other things ,
for the Handset / I.R. receiver side of our digital cable set top boxes .
I feel that you will not be able to use your handset to control
cable box due to a completely different system of I.R. modulation being used
by the Pace cable receiver handsets . It is akin to asking a FM radio to
receive AM signals .
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 . Each data bit sent requires typically 20 to 30 pulses of
this carrier . Data bits are separated in time equivalent to 60 to 100
pulses of the carrier . Each key sends 16/18 data bits and if the key is
held down this sequence is repeated 8/10 times a sec .
The system used by Pace 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
aprox. 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 the 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 held by TWO WAY TV LTD .
I hope this information has been of some use to you however in the
final analysis you will have to go back to 2 handsets - sorry !
For more information on the IRDA system visit
WWW.irda.org
If you require any further clarifications do not hesitate to contact
me directly .
Best Regards
Vic
Vic Fielding
Pace Micro Technology Plc. Victoria Road Saltaire
Shipley BD18 3LF UK
E-mail: [email protected] <mailto:[email protected]>
Tel: Direct line 44(0)1274 537267 Fax:44(0)1274
538029
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It's a real shame, but at least we can stop trying to get the damned thing to work.
Teresa
