Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
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Mixer SSB and DSB conversion loss and NF - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: Mixer SSB and DSB conversion loss and NF
postPosted: Fri Dec 24, 2004 5:22 pm
I read in
an application note that there is a difference of 3dB between SSB noise
figure and conversion loss of a mixer to these paramaters in DSB (conversion
loss of SSB is 3dB higher than DSB).
If you input DSB (Dual Side
Band) signal with twice as power as SSB signal to a given mixer you
will obtain twice as power at the output as well. And if you input the
SSB signal to that mixer the ratio of power in the input and output
should remain the same (only with 3dB less in the aboslute values at
each port) - please correct me if I am wrong!
My question is
why is this difference?
Post subject: Mixer Noise Figure
Mon Dec 27, 2004 2:36 pm
The double side band has twice the
power level , therfore the signal to noise ratio at the output is 3dB
higher. In a SSB mixer, half the power is at the output, but the same
noise power. The signal to noise ratio is 3dB lower. Therefore, the
noise figure is 3dB higher.