just wondering if anyone knows of any good tutorials on this subject or if anyone could give me some help trying to understand this topic a little better?
Basically what i am trying to find out is, how is "data" transfered across a frequency?
does data travel across an existing frequency or does the frequency only exist when there is data to be sent?
Example: I set up a IR transmitter @ 38KHz and sent that signal to a receiver with a LED on the output!(the LED just stays lit because the signal is so fast) would i be right in saying that there was no "data" sent to the receiver, just a 38KHz signal?
And when i use a TV remote @ 38KHz the LED flashes on and off very fast! would this indicate that "data" is been sent?
I know that "data" is 1'ns(high) and 0's(low) but isn't the frequency also 1'ns and 0's, how can you send "data" along a frequency if they both have 1'ns and 0's?
sorry there is so many questions its just i cant work it all out without some sort of human interaction!
Basically it's the variation in the frequency, pulse width, or amplitude of the sent wave that carries the data. As you thought, a steady frequency carries no information. Some transmission schemes send a steady frequency (carrier) even when no information is being sent. This is typical of standard AM and FM radio signals. Others, such as most IR remotes, send a signal only when data is being sent.
Basically it's the variation in the frequency, pulse width, or amplitude of the sent wave that carries the data. As you thought, a steady frequency carries no information. Some transmission schemes send a steady frequency (carrier) even when no information is being sent. This is typical of standard AM and FM radio signals. Others, such as most IR remotes, send a signal only when data is being sent.
So in the IR situation, if i was to send a code of data eg: 1011001, how does it send the two 1ns and two 0's that are right next to each other without sending a 0 in between them?
Does the code of data do the "101" part and then turn off and then turn back on again and do the "10" and then off and on and then do the "01" very fast?
So 101 (then no signal) 10 (then no signal) 01 then code done, repeat
101 10 01 101 10 01 101 10 01 and so on as the button is held down?
sorry if it isn't clear to understand, i don't know of any other way to explain what i am thinking.
A "1" is transmitted when the LED is switched on and off for 1.2mS at a 38kHz rate. A logic 0 is transmitted when the LED is switched on and off for 0.6mS at a 38kHz rate. There is a dead time between bits of 0.6mS, when the LED is off. This graph is on the page you bookmarked, but you apparently didn't understand it.
A "1" is transmitted when the LED is switched on and off for 1.2mS at a 38kHz rate. A logic 0 is transmitted when the LED is switched on and off for 0.6mS at a 38kHz rate. There is a dead time between bits of 0.6mS, when the LED is off. This graph is on the page you bookmarked, but you apparently didn't understand it.
I thought that a "1" was voltage high for 1.2ms, and a "0" was voltage high for 0.6ms followed by a delay(no voltage) of 0.6ms representing the "0", and all the other delays(no voltage)of 0.6ms in between the "1ns" were to supply a gap of no voltage so another "1" can follow?
I thought that a "1" was voltage high for 1.2ms, and a "0" was voltage high for 0.6ms followed by a delay(no voltage) of 0.6ms representing the "0", and all the other delays(no voltage)of 0.6ms in between the "1ns" were to supply a gap of no voltage so another "1" can follow?
I apologize. I got the times vs logic levels reversed. I will go back and edit my post. I think you have the idea. It should help you to realize that a logic 1 is not always a high voltage.
I apologize. I got the times vs logic levels reversed. I will go back and edit my post. I think you have the idea. It should help you to realize that a logic 1 is not always a high voltage.