 Single VS dual heterodyne receiver results.
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ShawnLG
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Sun Aug 05 2007, 06:34AM
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Registered Member #286
Joined: Mon Mar 06 2006, 04:52AM
Location:
Posts: 399
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I have finished my dual heterodyne reciever. I was told that a second IF with a narrow filter can help improve the signal to noize ratio. I did not notice much difference in the signal to noize ratio. You can see the narrow bandwidth filter at work from the noize lump in spectran.
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Sulaiman
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Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
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I assume the spectran results are with no aerial?
Every extra stage of electronics will increase the noise of the receiver
The important thing is, does it improve the received signal to noise ratio by reduciing received noise?
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ShawnLG
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Registered Member #286
Joined: Mon Mar 06 2006, 04:52AM
Location:
Posts: 399
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"I assume the spectran results are with no aerial?"
I did use an aerial. Why would you think otherwize? I use a small RF oscillator as the RF test source.
"The important thing is, does it improve the received signal to noise ratio by reduciing received noise?" Not really. It only attenuated outer sidebands of the 455khz filter. This is only good for recieving weak CW when there is a very strong carrier near by.
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