mstechca
New Member
I have found the following information from google groups on Superregen receivers:
Now look at this part:
is the "highest modulation component" equal to the highest frequency that can be heard? and if so, why 40 to 100Khz instead of just 40Khz?
Also, what is the "highest modulation component" for TV signals?
Believe it or not, you can build an FM receiver with only one active
device: the circuit
is called a "superregenerative detector". The active device (tube or
transistor)
oscillates at two frequencies: the signal frequency (e.g., 88 to 108 MHz)
and a lower
frequency called the "quench" frequency. Generally, the quench frequency
is twice
the highest modulation component in the signal frequency (say, 40 to 100
KHz for FM
broadcast reception).
You can build the circuit with one active device (called a self-quenched
detector) or
two (one device oscillates at the signal freqnency and the other at the
quench frequency.
The quench frequency modulates the signal-frequency oscillations,
suppressing
signal-frequency oscillations in one state and allowing the oscillator to
fully oscillate another, second state. In between the two states, the
signal-frequency
oscillator balances on the verge of oscillation, and incoming signals (or
random
noise) pushes the circuit into oscillation.
Thus, the superregen is capable of large amounts of gain, but the
signal-freqency
oscillation gets reradiated from the detector, making the circuit
unpopular with
onther sensitive receivers using that portion of the radio spectrum. You
can
add an RF amplifier stage, but then you're up to two or three active
devices.
Now look at this part:
Generally, the quench frequency
is twice
the highest modulation component in the signal frequency (say, 40 to 100
KHz for FM
broadcast reception).
is the "highest modulation component" equal to the highest frequency that can be heard? and if so, why 40 to 100Khz instead of just 40Khz?
Also, what is the "highest modulation component" for TV signals?