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<tt>Doug,<br>
<br>
(1) In Setup, PowerSDR has a calibration capability. You tell it
the frequency and power level. It observes the signal with
Mercury's input attenuator both in and out, and stores the
appropriate calibration factors. Kiss Konsole uses fixed
approximate calibration factors.<br>
<br>
(2) ep6 data is derived from the raw ADC samples through digital
downconversion, low-pass filtering and sample rate reduction
(decimation). The noise floor is reduced as the final sample rate
is decreased. The relationship between the ADC samples and the
final 24-bit I & Q values is variable only in the selection of
digital down-conversion frequency and decimation factor. The
values are 2s complement binary. The low-pass filtering and
decimation process (two CIC sections, followed by a FIR filter)
result in the additional bits. I'm not sure what the maximum and
minimum values are.<br>
<br>
(3) ep4 data is simply a snapshot of a group of 16384 contiguous
raw ADC samples, taken at a rate of 122.88 M samples per second.
(Older firmware produced blocks of 4096 samples.) The values are
2s complement (signed) binary, so they have a range of -32768 to
+32767.<br>
<br>
(4) Unless you have a narrow-band antenna or a high-pass filter in
the antenna feed, I'd expect very large broadcast-band
signals--their transmitters are generally much more powerful than
ham transmitters, their antennas are huge, and they may be located
very close to you!<br>
<br>
(5) I'm surprised that ep4 packets continue to be sent when the
wideband data is "turned off". I'll take a look. If it's true,
sounds like a firmware bug.<br>
<br>
73,<br>
Dave<br>
WA8YWQ<br>
</tt> <br>
<br>
<br>
On 9/27/2012 4:08 PM, Doug Adams wrote:
<blockquote cite="mid:C8C44B50-51CD-4144-8DDF-4744C7ED0851@me.com"
type="cite">
<pre wrap="">***** High Performance Software Defined Radio Discussion List *****
</pre>
<br>
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<meta http-equiv="Content-Type" content="text/html;
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<div>I have a few questions concerning Mercury:</div>
<div><br>
</div>
<div>
<ul class="MailOutline">
<li>Is there any easy way, without a lot of test equipment to
determine where the noise floor should be positioned on the
Panadapter display All of the software available provides a
"calibration" adjustment, how do you determine where to set
that adjustment?</li>
<li>Normal receiver data (i.e. ep6 data):</li>
<ul>
<li>What will be the expected range of values? I can see
that it is made up of 24-bit samples. Is the data in some
fixed relationship to the input signal, i.e. a specific
input values generates a specific data value or is it
somehow variable?</li>
</ul>
<li>Wide Bandscope data from Mercury (i.e. ep4 data):</li>
<ul>
<li>How is the Wide Bandscope data generated, I'm assuming
that it is a decimated version of the Normal receiver
data.</li>
<li>What will be the expected range of values? I can see
that it is made up of 16-bit samples. Is the data in some
fixed relationship to the input signal, i.e. a specific
input values generates a specific data value or is it
somehow variable? When I look at the frequency-domain
signal on my bandscope, it seems that the broadcast band
stuff is huge but most of the signals at higher
frequencies are at much lower levels.</li>
<li>It appears that when you tell Mercury not to send
bandscope data (in the StartStop Packet, 0x01 vs 0x03) I
still see incoming ep4 packets but the data in them is a
fixed value. Is that correct or am I doing something
wrong? </li>
</ul>
</ul>
</div>
<div><br>
</div>
I've been following this list for some time and have found it very
helpful for learning more about openHPSDR. Thanks for all the good
information.
<div><br>
<div apple-content-edited="true">
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<div>
<div>Doug Adams - K3TZR</div>
<div><a moz-do-not-send="true"
href="mailto:douglas.adams@me.com">douglas.adams@me.com</a></div>
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Clear Stream Technologies</pre>
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