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@ -419,6 +419,7 @@ span.mainfunction {color: #993300; font-weight: bolder}
{"type":"radioCESSBtransmit_F32","data":{"defaults":{"name":{"value":"new"}},"shortName":"CESSB_Mod","inputs":"1","output":"0","category":"radio-function","color":"#E6E0F8","icon":"arrow-in.png","outputs":"2"}},
{"type":"radioCESSB_Z_transmit_F32","data":{"defaults":{"name":{"value":"new"}},"shortName":"CESSB_Z_Mod","inputs":"1","output":"0","category":"radio-function","color":"#E6E0F8","icon":"arrow-in.png","outputs":"2"}},
{"type":"RadioFMDiscriminator_F32","data":{"defaults":{"name":{"value":"new"}},"shortName":"FMDiscrim","inputs":"1","output":"0","category":"radio-function","color":"#E6E0F8","icon":"arrow-in.png","outputs":"2"}},
@ -3538,6 +3539,11 @@ The actual packets are taken
that include file has information relating to this Teensy Audio implementation, as well.
</p>
<p>This class may not be suitable for directly driving external I-Q hardware
mixers. The limited LO-RF isolation of those mixers can introduce a midband tone
that will be transmitted. To work around this problem, use the companion
class radioCESSB_Z_transmit_F32 that uses the phasing method of SSB generation.</p>
<p>The first activity for CESSB is to limit or clip the amplitude of the SSB signal. Internally
this always occurs when the envelope of the SSB signal exceeds 1.0. This is all done
with floating point arithmetic so values may exceed 1.0. The input level where this occurs
@ -3564,7 +3570,150 @@ The actual packets are taken
to a communications bandwidth of around 2700 Hz.</p>
</script>
<script type="text/x-red" data-template-name="radioBFSKModulator_F32">
<script type="text/x-red" data-template-name="radioCESSBtransmit_F32">
<div class="form-row">
<label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
<input type="text" id="node-input-name" placeholder="Name">
</div>
</script>
<script type="text/x-red" data-help-name="radioCESSB_Z_transmit_F32">
<!-- ============ radioCESSB_Z_transmit_F32 ========= -->
<h3>Summary</h3>
<div class=tooltipinfo>
<p>Converts audio into SSB and then applies Dave Hershberger, W9GR,
CESSB controlled clipping and
filtering. This prevents the SSB peaks from exceeding a maximum level.
This increases the peak limited average power by 3 or more dB. The output
can be up converted by a RadioIQMixer_F32 object or sent via DAC's as
I-Q baseband, ready for quadrature mixer transmit.
</p>
</div>
<h3>Audio Connections</h3>
<table class=doc align=center cellpadding=3>
<tr class=top><th>Port</th><th>Purpose</th></tr>
<tr class=odd><td align=center>In 0</td><td>Input Audio Signal</td></tr>
<tr class=odd><td align=center>Out 0</td><td>Baseband SSB I Signal</td></tr>
<tr class=odd><td align=center>Out 1</td><td>Baseband SSB Q Signal</td></tr>
</table>
<h3>Functions</h3>
<p class=func><span class=keyword>setSampleRate_Hz</span>
(<strong>float32_t</strong> fs_Hz bitRate);</p>
<p class=desc>Specifically, this sets the sample rate, in samples per second,
that is used by CESSB. It also sets other parameters, such as
decimation ratios and filter cutoff frequencies. Thus this function
is <strong>required.</strong> At this time, the design is centered
on 48000 sps, but can be used with other close values such as
44100 or 50000. The plan is to eventually support 96000 sps if users
are needing it. There is no default value and the CESSB objects will not run if
this function is not called.</p>
<p class=func><span class=keyword>getLevels</span>(<strong>int</strong> what);</p>
<p class=desc>Returns a pointer to a structure of type levels. This allows
knowledge of the average and peak levels at both the input and output sides
of the SSB clipper and overshoot compensator. If what==0 the pointer is returned
but no updating is done. That is used to setup the process before data is
available. If what != 0, the contents of the structure are updated and measuring
is reset. The function levelDataCount() below can be used to set the time
between updates. The stucture is part of the object and is defined as:
<pre>
struct levels {
float32_t pwr0; // Average power at input
float32_t peak0; // Peak voltage at input
float32_t pwr1; // Average power at output
float32_t peak1; // Peak voltage at output
uint32_t countP; // Number of averaged samples for pwr0.
};
</pre></p>
<p class=func><span class=keyword>levelDataCount</span>();</p>
<p class=desc>Returns an uint32_t with the number of averaged samples
of the input power. See getLevels() above. The number of output
samples may differ by an integer factor because of decimation inside
the object.</p>
<p class=func><span class=keyword>setGains</span>(
<strong>float32_t</strong> gainIn,
<strong>float32_t</strong> gainCompensate,
<strong>float32_t</strong> gainOut);</p>
<p class=desc> These are the controls for the CESSB class. gainIn sets
the amount of clipping by setting the input level to the clipper.
gainCompensate sets the amount of correction applied to prevent
overshoot. A value of 1.4 is normally used. gainOut is
for convenience and sets the drive level to the next block. </p>
<p class=func><span class=keyword>setSideband</span>(<strong>bool</strong> sbReverse);</p>
<p class=desc>The LSB/USB selection depends on the processing of the
IQ outputs of this class. But, what we can do here is to reverse the
selection by reversing the phase of the Q signal. </p>
<p class=func><span class=keyword>setIQCorrections</span>
(<strong>bool</strong> useIQCorrection, <strong>float32_t</strong> gainI,
<strong>float32_t</strong> crossIQ,<strong>float32_t</strong> crossQI);</p>
<p class=desc>This allows small corrections at the output end of the
CESSB object, to patch up hardware flaws. The variable useIQCorrection should be
<strong>true</strong> to use the corrections. gainI corrects for gain errors between
the I and Q channels and should be close to 1.0.
The variables, crossIQ and crossQI correct for phase errors and should
be close to 0.0. There is interaction between the 3 variables, but
converging adjustment to null the unwanted sideband is doable. Either crossIQ or crossQI
should end up as 0.0. If use IQCorrection is false, there is no processor
load for corrections.</p>
<h3>Examples</h3>
<p class=exam>File &gt; Examples &gt; OpenAudio_ArduinoLibrary &gt; CESSB_ZeroIF
</p>
<h3>Notes</h3>
<p>The technical description, implementation and test results are in references
listed in the include file for this class,
<a href="https://github.com/chipaudette/OpenAudio_ArduinoLibrary/blob/master/radioCESSBtransmit_F32.h"
target="_blank">available from Github</a>
These should be used to understand the details of CESSB. The notes at the top of
that include file has information relating to this Teensy Audio implementation, as well.
</p>
<p>The first activity for CESSB is to limit or clip the amplitude of the SSB signal. Internally
this always occurs when the envelope of the SSB signal exceeds 1.0. This is all done
with floating point arithmetic so values may exceed 1.0. The input level where this occurs
depends on the setting for gainIn, described above. The maximum level seen ahead of the clipper
is measured by getLevels() as described above. One way to control the input to the CESSB block
is with
<a href="http://www.janbob.com/electron/OpenAudio_Design_Tool/index.html?info=AudioEffectCompressor2_F32"
target="_blank">Compressor2 Library block.</a> Note that Compressor2
is not a clipper, but is rather an automatic gain control that uses look-ahead
processing to allow gradual gain changes.
</p>
<p>The output of the CESSB processing is the in-phase and quadratuere components
(I-Q) of the SSB signal that has the suppressed carrier at zero frequency.
This can be translated to higher frequencies, either by a RadioIQMixer_F32
object, or by feeding through a pair of DAC's to quadrature hardware mixers. This
produces either an Upper Sideband (USB) or a Lower Sideband (LSB) signal. The sideband
can be selected in various ways, including the function for this class, setSideband()
described above.</p>
<p>Note the companion class, RadioCESSBtransmit_F32, that uses the Weaver-method
as is done used
in the referenced Hershberger documents. The performance of the two classes is
very similar. This version removes concerns about mid-band spurious tone generation
when used with hardware mixers.</p>
<p>CESSB as implemented here is intended for voice input, and also filters the voice
to a communications bandwidth of around 2800 Hz.</p>
<p>The Hilbert filter used with this class will provide high opposite
sideband rejection down to about 150 Hz. It is using 201 coefficients at a sample
rate of 12000. Still, for some situations it may be desireable to use an IIR
high pass filter on the input audio.</p>
</script>
<script type="text/x-red" data-template-name="radioCESSB_Z_transmit_F32">
<div class="form-row">
<label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
<input type="text" id="node-input-name" placeholder="Name">

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