Phil Allison wrote:

Michael Terrell wrote:
Phil Allison wrote:
Michael Terrell wrote:


Adjacent channel interference like that is caused by the IF bandwidth
and the skirt. The IF transformers aren't brick wall, the amplitude
drops away slowly outside the desired bandwidth.

** FM receivers have multiple stages of IF band limiting making the falloff very sharp outside the needed 200kHz.

That allows a local
station to be strong enough to cause problems.

** Nope - the FM detector ( ratio or quadrature) is also tuned to the centre of the IF strip and will not demodulate an out of band signal.


More Phil****, as always. It's a damned good thing you didn't design
and build deep space telemetry equipment.

** Desperate liars resort to abuse when they have no case.


DING! DING! DING! Whenever you have no clue you start your 'Angry
Dumbass Dance', and call people a liar. All you do is prove what a fool
you are.


Even business radios used
expensive crystal filters to reduce adjacent channel interference,

** Not one bit relevant to *wide band* FM broadcast receivers.


Only if you have the I.Q. of a rusty doorknob.


instead of 50 cent IF transformers.

** Which, when used in multiples, produce sharp roll ofsf at the skirts of the pass band.


Define sharp. If it is too sharp, it causes distortion in the
recovered signal. Each transformer has an insertion loss in the IF
stages. FM radios use just enough tuned circuits to get barely
acceptable performance. Even the cheap Murata ceramic filters have a
sloppy skirt. The only advantage is that they don't need aligned during
manufacturing.


Cram your bull**** and look at it on a network analyzer. Oh, that's
right. You have no real test equipment, just junk from a '70s TV shop.
You want to talk wideband? One of the Telemetry products we
manufactured had an IF range from 1 KHz to 20 MHz bandwidth at the -3 dB
points. They had to be aligned on a network analyzer, or with a
calibrated sweep generator to achieve the proper skirt.


Digitally tuned FM receivers can still receive an adjacent channel,

** More irrelevance, it matters not how the LO is tuned.

Sigh. More of your stupidity. Digital has no AFC, so it can't be
pulled off of center.


but more than a channel away it
becomes quite distorted.

** Tuned FM detectors are like that.

Go back to hacking old stereos.

** Go back to washing dunny floors, you pathetic ass.


Whatever the hell that crap means, but I guess that you've heard it
all your life from people around you. Read a damned book on receiver
design. Analog IF bandwidth is specified at the -3 dB points. That
wouldn't be possible without a skirt. Brick wall requires a FIR filter
or another digital filter that processes a digitized input. The design
I worked on digitized to 50 to 890 MHz range for a 70 MHz IF. That was
followed by a pair of FIR filters for the IF and another pair for the
output bandwidth.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.