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Mike:<br>
<br>
As far as any Mercury alias, the equation will be Alias = ABS(122.88
MHz - Fc)<br>
<br>
So, could be FM two-way radio at 122.88 + 28.xxx MHz, or FM
broadcast at 122.88 - 28.xxx MHz.<br>
But if not near-by and you have ALEX in line, then that is an
unlikely source.<br>
<br>
As far as the cross modulation, it sounds like you have one or both
Noise Blankers (NB or NB2)<br>
turned on. Turn off both noise blankers and try again.<br>
The current noise blankers in PowerSDR have a known behavior that
they produce<br>
cross modulation in the presence of a strong signal. Most noise
blankers will do this, because <br>
the noise blanker signal gate is behaving like a mixer.<br>
<br>
--- Graham / KE9H<br>
<br>
==<br>
<br>
On 9/26/2011 9:05 AM, Mike Stevenson wrote:
<blockquote cite="mid:C89825CBA56643FC8F48D6196279D034@MikePC"
type="cite">
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<div><font size="2" face="Arial">Hi Graham</font></div>
<div> </div>
<div><font size="2" face="Arial">FM broadcasts are in the 80 to
100 MHz band but not too strong here.</font></div>
<div><font size="2" face="Arial">My first reaction was a local FM
transmission from a taxis or other VHF user.</font></div>
<div><font size="2" face="Arial">Alex in or out makes little
difference and I have ferrites on coax cables.</font></div>
<div> </div>
<div><font size="2" face="Arial">The modulation that I can hear is
coming from stations in the 28.5 MHz band.</font></div>
<div><font size="2" face="Arial">I had the case of just two S7 to
S9 signals on the spectrum display, tune one in and could
detect the audio of the other. Also the audio (low level )
from the second station stopped when the second station
stopped transmitting. I could also see the DC spur being
modulated by the second station.</font></div>
<div> </div>
<div><font size="2" face="Arial">As I said I cannot hear any of
these effects with Bill's software but they may exist on the
DC spur 9khz away.</font></div>
<div> </div>
<div><font size="2" face="Arial">Having said all of this I am
having a great time on 10m using Pennywhistle driving a Expert
1K linear with 400watts output. My K3 gets little use.</font></div>
<div> </div>
<div><font size="2" face="Arial">This was for information and
HPsdr is still a great product and fun.</font></div>
<div><font size="2" face="Arial">Thanks again to all who have made
this possible.</font></div>
<div> </div>
<div><font size="2" face="Arial">Mike G8ALS.</font></div>
<blockquote style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT:
5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<div style="FONT: 10pt arial">----- Original Message ----- </div>
<div style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color:
black"><b>From:</b> <a moz-do-not-send="true"
title="KE9H@austin.rr.com" href="mailto:KE9H@austin.rr.com">Graham
/ KE9H</a> </div>
<div style="FONT: 10pt arial"><b>To:</b> <a
moz-do-not-send="true" title="mike.g8als@ntlworld.com"
href="mailto:mike.g8als@ntlworld.com">Mike Stevenson</a> </div>
<div style="FONT: 10pt arial"><b>Sent:</b> Monday, September 26,
2011 2:21 PM</div>
<div style="FONT: 10pt arial"><b>Subject:</b> Re: [hpsdr]
Mercury and 28Mhz receive</div>
<div><br>
</div>
What is the frequency of the FM broadcast station closest to
your QTH?<br>
--- Graham / KE9H<br>
<br>
==<br>
<br>
On 9/26/2011 4:25 AM, Mike Stevenson wrote:
<blockquote cite="mid:D01B48AFFDC7495CBB88D26A0ED4D13D@MikePC"
type="cite">
<pre wrap="">***** High Performance Software Defined Radio Discussion List *****
</pre>
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<div><font size="2" face="Arial">I have been spending quite a
lot of time operating on </font></div>
<div><font size="2" face="Arial">10m now is open again.</font></div>
<div><font size="2" face="Arial">There has always been a
higher level of spurious signals on this band than any
other even with Mercury input terminated directly in 50
ohms.</font></div>
<div> </div>
<div><font size="2" face="Arial">What I am now seeing using
Doug's, W5WC software with zero frequency IF is between
about 28.300 and 28.650 a spurious signal at 0Hz in the
receive pass band.</font></div>
<div><font size="2" face="Arial">Also I am hearing what sounds
like intermod produced by other signals in the display
pass band producing an audible output. I have see the
effect produce by signal of only S7. Also at the same time
I see the 0Hz spurious being modulated by the off
frequency S7 signal.</font></div>
<div><font size="2" face="Arial">The above applies to Doug's
software 1.19.3.4, 1.19.3.5 and 2.2.3.</font></div>
<div> </div>
<div><font size="2" face="Arial">Using Bill's KD5TFD</font> <font
size="2" face="Arial">software with 9Khz IF I see much the
same spurious on the spectrum display but 0Hz spurious is
offset by 9Khz and so far have not detected any unwanted
products in the audio output.</font></div>
<div> </div>
<div><font size="2" face="Arial">Current cards</font></div>
<div><font size="2" face="Arial">Mercury V2.9</font></div>
<div><font size="2" face="Arial">Pennylane V1.4</font></div>
<div><font size="2" face="Arial">Metis V1.4</font></div>
<div><font size="2" face="Arial">Excalibur</font></div>
<div><font size="2" face="Arial">Alex</font></div>
<div> </div>
<div><font size="2" face="Arial">Has anyone else seen this or
do I have a one off problem.</font></div>
<div> </div>
<div><font size="2" face="Arial">Mike G8ALS</font></div>
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