RC-5 36kHz carrier absent??

[AMitK]

We tried to decode RC-5 waveform from an RC5 remote on a DSO using a circuitry consisting of a photo transistor (TIL 78)amplifiers and comparators..it is a pretty neat and working circuit and we actually managed to see perfect 14-bit manchester pattern for various controls on the remote, as can be seen from picture 1-remote waveform.

But the problem is, where is 36 kHz carrier??? We are not using a TSOP IC, its a general phototransistor, so it should decode all the frequency components AS IT DID when we actually generated our own RC5 waveform using 8051 and 555. In the wave we generated and then decoded using the SAME circuitry, we could clearly see the 36kHz carrier inside the information bits, as in Picture 2-generated waveform.

we kept the same DSO controls in both the cases but actual RC5 remote is not showing the 36kHz carrier but the waveform we generated as per theory of RC-5 is showing the carrier on DSO using same receiver circuitry!! We are confused! Do actual RC-5 remotes use 36kHZ carrier?? Some one kindly help us...! (The low frequency wave in picture 1 is 50hz pickup.)

 

[FvM]

You may want to display the related transmitter LED voltage for reference. Most likely, your photodiode circuit is too slow to see the 36 kHz carrier.

 

[Pishty]

The carrier frequency of RC-5 is not exactely 35Khz.I'm also wondering if your receiver is equiped with IR filtering coat ,if it is, then try deconnecting the gnd pin from your receiver and measure the frequency of the signal that you receive when gnd pin is not connected.I also had a prject for an IR receiver and i don't really understand why you need the carrier signal.