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<div class="moz-cite-prefix"><big><big><br>
Bill,</big></big><big><big> Some schooling......<br>
<br>
</big></big><big><big>It looks like your method to measured the
frequency was by using the time interval between peaks and
calculating the reciprocal of 8 milliseconds. = 125 cycles.<br>
<br>
Isn't the repeater CTCSS frequency at 127.5 cycles ? (which
would be 7.9921 Milliseconds)<br>
<br>
You measured 8 milliseconds, you could easily have had a
possible measuring error of 8 <b>micro</b>seconds ? <br>
<br>
I generally teach that Measuring time intervals on a scope by
time between peaks is not good practice because the rate of
change of the sine wave at the peaks is very small. (actually
you are looking for a time period where there is no change
(Zero) and I don't think mathematically you can do that.)<br>
<br>
Normal procedure would be to expand the scope time base out to
display a single cycle and <b><i>measure the time between
zero crossings</i></b>, where the rate of change is at
maximum and better defined. <br>
<br>
Just a logical question..<br>
'<br>
Don Ki4EFL <br>
<br>
</big></big><br>
On 12/03/2014 05:06 AM, 'Bill' <a class="moz-txt-link-abbreviated" href="mailto:billkodak@verizon.net">billkodak@verizon.net</a> [LakelandARC]
wrote:<br>
</div>
<blockquote cite="mid:41CACC22AE1D44A1B0E6EF49FF6B9E48@BillDell"
type="cite"> <span style="display:none"> </span>
<div id="fromDMARC" style="margin-top: 10px;">
<p>
</p>
<div><font face="Arial">Got your call, but it was too late.
Things were a bit hectic last evening. </font></div>
<div> </div>
<div><font face="Arial">I am still trying to make sense out
of the repeater project. </font></div>
<ol>
<li><font face="Arial">That hum is not related to the
wallwart. It is still there after I replaced it with
batteries. </font></li>
<li><font face="Arial">I discovered another oddity. If I
transmit near the recording radio using another HT,
my voice gets blanked out. However, if I move to
another room, my voice gets recorded. </font></li>
<li><font face="Arial">I measure the hum at 125 HZ. This
is probably measurement error, with the real frequency
being 120 Hz.</font></li>
</ol>
<div> </div>
<div><font face="Arial">See below, Audacity output. Period
is 8 milliseconds.</font></div>
<div> </div>
<div><br>
</div>
<br>
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<a class="moz-txt-link-rfc2396E" href="mailto:billkodak@verizon.net"><billkodak@verizon.net></a>
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