[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Discuss-gnuradio] spectral purity (or, weaver not ready for prime time)
From: |
Chuck Swiger |
Subject: |
[Discuss-gnuradio] spectral purity (or, weaver not ready for prime time) |
Date: |
Thu, 24 Feb 2005 09:02:11 -0500 |
Gang - Here's a disturbing display of the spectrum about my weaver generated
ssb signal - there were lumps where there shouldn't be so I turned up the
resolution:
http://webpages.charter.net/cswiger/weaver_spectrum.jpg
this is with the duc center freq at 3900e3, carrier freq at 27e3, and an
audio signal at 600hz, LSB.
You can see the main peak right where expected at 3926.4Khz, (3927e3-600),
but there's
other junk not far down - there's something at 3905.6, which would be a
3905 carrier USB,
another one at 3894.34 (likely 3895 LSB), 3873.6, which would be 3900e3 -
27e3 + 600, the
negative freq of the main signal (3873Khz, 600hz USB) - and a really
bizarre one out at 3958.3
that I can't explain at all - it's a little further out than 27e3 X 2, and
not reflected about 3900e3.
All of them can be heard in a nearby receiver.
So I'll have to track down their origin and fix (somehow) before jumping on
20meter psk31
anytime soon. A pure usrp tone doesn't have those issues - only my weaver
graph.
--Chuck
kb4new
- [Discuss-gnuradio] spectral purity (or, weaver not ready for prime time),
Chuck Swiger <=