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Lets say you want a receiver circuit to light up an LED when it receives a radio wave pulse.

How many periods must the emitted pulse last to generate enough electric current to be detectable and amplified by the receiver? Is one enough or do we need a hundred of them? What would the amplifier schematic look like?

PS: This is related to another question.

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    \$\begingroup\$ Depends on power, bandwidth, and discrimination required from other nearby interfering signals. \$\endgroup\$
    – user16324
    May 18, 2020 at 19:28
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    \$\begingroup\$ If you try to trigger on just one pulse, it will always be going off, because there is always some noise at every frequency. So a detectable pulse, louder than the surrounding noise, and for a certain duration are required to avoid "accidental" reception. Or other modulation schemes can be used, such as FSK. The full answer is a lot harder than it seems, covering the points Brian mentioned prior and more. If you don't want a degree in physics to understand how it works, ready-made RF boards are an easy solution. \$\endgroup\$
    – rdtsc
    May 18, 2020 at 19:39
  • \$\begingroup\$ With a strong enough signal, you can trigger on a tiny fraction of a pulse. \$\endgroup\$ May 18, 2020 at 20:14

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