Curt,
Would you not agree that a 3rd Order dynamic range test performed with both
test tones placed outside of the IF filter's passband ,with a product in the
passband, does not provide a complete measure of a receiver's odd order IMD
performance but only that of its front end? A receiver with a "weak" cascade
following the IF filter might appear to be be a good performer based on
tests done this way, but will probably fall apart when two or more strong
signals enter the IF filter's passband. During the development of high
performance receivers common practice in my experience was to employ
multiple signal tests, two tones in the IF passband and one or two placed on
the skirts. I am aware of suggestions that have been made during the past
years regarding these test procedures used to evaluate amateur receivers,
likewise to restore proper useage of the term MDS which is another story :-)
73,
Geoff
GM4ESD
Curt Milton <[EMAIL PROTECTED]> wrote:
Mike
for two tone dynamic range testing, both signals are
located intentionally outside the detection passband
(narrowest filter) of the receiver, and the receiver
is tuned so that one of the third order intermods is
within the passband.
you may find that this is a useful reference:
http://www.arrl.org/tis/info/pdf/109435.pdf
when the measurement is bounded by phase noise, it
means that instead of introducing a distortion product
or reducing the level of a weak signal, instead the
phase noise introduced by the receiver itself
(generally the local oscillators) has degraded
detection of the weak signal.
otherwise, you seem to be on the right track with your
understanding.
73, curt
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