- #1
PhysEd
- 12
- 0
Hi guys, my first post on these forums.
I am learning electronics and am still very new to this all.
My current tinker project is to learn how regular tv remote controls work.
So far I have understood that the remote sends blinking IR pulses through an 940 nm LED.
The remote uses frequency modulation to help avoid noise and interference.
The remote uses some protocol depending on which brand it is.
And the receiver uses an IR photo transistor with some demodulation and then to some microchip to do the work.
I have hooked up a very simple circuit, which has a 5v power supply, a resistor and a photo transistor that goes to my oscilloscope.
When I use the remote control to press a key close to the phototransitor, I can see the transmission on my oscilloscope just fine and I have even decoded the protocol so I understand everything going on there.
But my question is this, why am I seeing the protocol data on my oscilloscope instead of the frequency modulated signal?
If it helps, I am using the samsung protocol / remote and according to their specs, the carrier frequency is 38.9 khz.
Thanks.
I am learning electronics and am still very new to this all.
My current tinker project is to learn how regular tv remote controls work.
So far I have understood that the remote sends blinking IR pulses through an 940 nm LED.
The remote uses frequency modulation to help avoid noise and interference.
The remote uses some protocol depending on which brand it is.
And the receiver uses an IR photo transistor with some demodulation and then to some microchip to do the work.
I have hooked up a very simple circuit, which has a 5v power supply, a resistor and a photo transistor that goes to my oscilloscope.
When I use the remote control to press a key close to the phototransitor, I can see the transmission on my oscilloscope just fine and I have even decoded the protocol so I understand everything going on there.
But my question is this, why am I seeing the protocol data on my oscilloscope instead of the frequency modulated signal?
If it helps, I am using the samsung protocol / remote and according to their specs, the carrier frequency is 38.9 khz.
Thanks.