Re: receiving a carrier



On Dec 21, 5:31 am, "jhon1" <aomarena...@xxxxxxxxx> wrote:
Hello All.
I am a beginner, all I need is to build a transmitter that only
transmits a carrier without any modulation and be able to receive this
carrier at the second location.
unfortunaitly, most receiver circuits that are available over the
internet use a different techniques such as superhet, which is not
suitable for my application, I need to receive the carrier only with
the same frquency as I sent it.
please try to help me.
thanks

Google "superregen" or "super regenerative receiver" and other
variants.Super-regenerative receivers are popular in applications such
as garage door remote, car alarm systems and wireless door chimes. They
are ideal where information rate and cost are low.

If you want to design your own, let me know; however, it may be
challenging for a beginner. There are some examples on the web, as well
as some commercially available units.

Super-regenerative receivers are used often at 210, 280, 312, 315, 390,
418, 434 MHz. I have also seen applications at 2441 and higher.

This type of receiver works like this: An RF amplifier with positive
feedback (at inteded receive frequency) is allowed to go in and out of
oscillation at a rate called the quench frequency. Sometimes the quench
is forced externally, and sometimes a single transistor is biased and
configured such that the RF transistor serves also as the quench
oscillator (self quenching).

If you do it right, you can build a single-transistor receiver for a
few pennies. Sensitivity is about 10uV with 75 ohm input. YMMV. In
commercial applications, the challenging part of the design is meeting
regulatory agency approvals, especially passing the "unintentional
radiator" criteria.

Frank Raffaeli
http://www.aomwireless.com/

.

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