Hi Stan,
Yes, the tone at 7.056 MHz (or what ever frequency you set in as the
fixed oscillator frequency) is always there. One of the software
guys who has worked on SDR-1000 software thinks something can be
done to reduce that large noise spike. The source for that tone when
no SoftRock is connected is still not well understood, at least not
by me. The thought is that the sound card adds more noise at near
zero frequency as well as 60 Hz noise pickup. I have notice when a
SSB signal spectrum was centered on that frequency, the SSB signal
was still quite readable. When the SoftRock is connected, then that
noise at 7.056 MHz also contains a LO signal.
The use of the XG1 is for S9 calibration at -73 dBm, receiver
sensitivity check and image null at (7.056 -7.04) above 7.056 MHz.
Hope this helps Stan
73,
Tony KB9YIG
--- In softrock40@..., "Stan Rife" <srife@s...> wrote:
Tony, one thing I noticed, when just playing around with the SDR
software, was the 600 Hz tone that comes from the soundcard (?) at
the 7.056
freq. after the Fixed HW oscilator is set up per the instructions.
This is,
of course, without the SoftRock hardware installed, as I do not
even have my
kit YET. (boo hoo).
Is this oscilator tone, at that freq., something that will
always be
there? I saw a procedure in the manual that said something about
going above
7.056, as much as the test oscilator is below 7.056 and adjusting
for a
null. I am not quite clear on all of this. I do have an XG-1, and
I assume
that is what this is refering to.
Stan Rife
W5EWA
Houston, TX
K2 S/N 4216
-----Original Message-----
From: softrock40@...
[mailto:softrock40@...] On
Behalf Of kb9yig
Sent: Saturday, September 17, 2005 9:28 PM
To: softrock40@...
Subject: [softrock40] Re: Interference from PC?
Hi Rein,
I have built about 25 of the v4.0 SoftRock40 receivers and find
the PC
noise does not cause much of a problem. When the receiver is
calibrated to S9, (-73 dBM, 50 uV RMS), the baseline is around -
135
dBm with 10-15 dB spikes riding on the baseline every 1 kHz or
so.
Also at the LO frequency, around 7.054-7.056 MHz there is a large
broad spike associated with the LO and the fact that the soundcard
contributes lots of noise near zero frequency.
I will be quite interested in the experience of SoftRock40
builders as
they finish their kits. If I can help with problems in getting
the
little receive running, I would be happy to do so.
73,
Tony KB9YIG
--- In softrock40@..., "observer35" <rein0zn@i...>
wrote:
Hi all,
Just new to the group.
Does anybody experience interference from the PC on 40 meters?
What about noise and garbage on the 5 V USB line?
73 Rein W6/PA0ZN
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