Signals

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lecto

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Could d.c be counted as a signal? I'm new at electronics and I have this question in front of me, Which one of the following signals is in common use in electronics.
1)Continuous d.c ,2) Frequency modulated ,3)Constant amplitude a.c, 4)Interrupted a.c , I strongly suspect the last two cannot be the answer, but I'm getting mix up with the first two though.
 

hi,
Noun1.**broken link removed**electronic signal - a signal generated by electronic means

FM is just a 'description' of a type of signal....
 
If a signal is defined as transmitting information, then continuous DC and constant amplitude AC are not signals. The other two are signals by this definition.
 
(3) is tough. It can transmit frequency info. Two such signals can transmit phase. In context, I'd have to say it isn't. I would argue and might win, but its probably not the expected answer. Bad question.
 
This is a ridiculous question.



Sorry there is no easy answer.

JimB
 
yep. Ridiculus question.

Continuous DC - one has to assume it never goes off.
Frequency modulated - Definately conveys info
Constant amplitude AC - One again assumes it never goes off. Frequency info in conveyed.
Interrupted AC - again, one has to assume it never goes completely off. I'm not even sure what interrupted AC is. Switched AC? A pulsating siren.
 
You can interrupt an AC carrier (turn on and off) with PWM to transmit a signal.
 
signal means time varying quantity that is use for information, so according to that any electrical quantity that uses frequency could b a signal. but we cant say a continuous dc quantity as a signal and if the dc is in pulse form that may b a signal.
 
Time varying - A DC power switch. In the limit, I could argue that there is no such thing as "continuous DC" in real life.
 
KeepItSimpleStupid said:
Time varying - A DC power switch. In the limit, I could argue that there is no such thing as "continuous DC" in real life.
Click to expand...
Quite correct, it just depends on how long you want to sit watching it!

Consider an emergency shutdown switch in a chemical plant, in normal operation the switch is closed, it will only ever be opened for periodic testing to verify that the circuit works, or if it fails to the open state or if someone pushes it in a real emergency.
Assuming that it does not fail and there is no emergency, it may only be tested every six months.
That sounds near to "continuous DC" to me.

However starting at the "big bang" and running through to the end of the universe, that switch was only closed for a very short transient in time.

JimB
 
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