[vdr] Re: How to get IR at J2 working?

[Thomas Breuer <tb@tb-electronic.de>]

On 21/12/2002 11:12 Rene Bartsch wrote:

[RC5 remote carrier frequency]

> But all layouts use the TSOP1738. Can anyone enlighten this with a spec?

The official RC5 standard requires 36kHz carrier frequency. See page 2
of http://www.vishay.com/docs/fmod_data_formats.pdf

Of course it would be possible to use any other carrier frequency, this
is independent of the transmit protocol. Maybe there are remotes on the
market that do not fully comply to the standard and use a 38kHz carrier.
A simple measurement with an oscilloscope would verify this. So far I
haven't seen any with 38kHz.

According to the data sheets, the filter response of the TSOP1738 is
slightly wider compared for example to the SFH5110-38. The sensitivity
of the TSOP1738 will be reduced by 30%, while the SFH5110-38 will loose
50% at 36kHz. In practice, 30% less will hardly be noticed.

Thomas







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