"Jeff Liebermann"


Yes, but it's not obvious or really TRF. The reason superheterodyne
receivers were invented was that decent narrow band LC or crystal IF
bandpass filters were not tuneable and didn't work well at higher RF
frequencies.

** Total hogwash.

That has got nothing to do with the invention and wide adoption of superhet
radios.


These daze, dramatically improved semiconductor technology has
produced chips that work at almost any useful RF frequency. No more
need to downconvert when the IF filtering is done by a DSP (digital
signal processor). Instead of TRF, it's now called "direct
conversion".

** TRF and "direct conversion" are separate techniques.


There's no local oscillator, no mixer, for fixed IF
filter, and probably no LC devices anywhere. Just a ceramic bandpass
filter (or duplexer) some gain, an A/D converter, and a DSP for
demodulation. Most GPS, Wi-Fi, and cellular chipsets work this way.


http://en.wikipedia.org/wiki/Direct-conversion_receiver


** How hysterically funny.

The bull****ting fool has posted a Wiki link that completely contradicts his
fabricated thesis.

" In telecommunication, a direct-conversion receiver (DCR), also known as
homodyne, synchrodyne, or zero-IF receiver, is a radio receiver design that
demodulates the incoming signal by mixing it with a local oscillator signal
synchronized in frequency to the carrier of the wanted signal. "




...... Phil