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DATV demod: adapted CNR estimation to a bandwidth always twice the symbol rate

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This commit is contained in:
f4exb 2023-04-01 11:53:44 +02:00
parent b4a1680d54
commit 9f71f4d402
3 changed files with 8 additions and 2 deletions
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6
plugins/channelrx/demoddatv/datvdemodgui.ui
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@ -1056,6 +1056,9 @@
<height>0</height>
</size>
</property>
<property name="toolTip">
<string>MER estimation value (dB)</string>
</property>
<property name="text">
<string>00.0</string>
</property>
@ -1116,6 +1119,9 @@
<height>0</height>
</size>
</property>
<property name="toolTip">
<string>CNR estimation value (dB)</string>
</property>
<property name="text">
<string>00.0</string>
</property>

2
plugins/channelrx/demoddatv/leansdr/sdr.h
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@ -1998,7 +1998,7 @@ struct cnr_fft : runnable
float n2 = (avgslots(icf - nstop, icf - nstart) +
avgslots(icf + nstart, icf + nstop)) / 2;
#elif LEANDVB_SDR_CNR_METHOD == 2
int bw = bandwidth * 0.75 * fft.size();
int bw = bandwidth * 0.6 * fft.size();
float c2plusn2 = 0;
float n2 = 0;
minmax(icf - bw, icf + bw, n2, c2plusn2);

2
plugins/channelrx/demoddatv/readme.md
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@ -48,7 +48,7 @@ This gauge gives the MER estimation. The averaged value appears on the right.
<h4>B.4: CNR estimation</h4>
This gauge gives the CNR estimation. The averaged value appears on the right.
This gauge gives the CNR estimation. The averaged value appears on the right. Estimation is made comparing spectrum power in the center of the passband compared to the sides. The passband is the one presented to the demodulator and is always twice the symbol rate. the "center" is estimated at 60% of the full passband. Note that the RF filter comes before that and may change the aspect of the spectrum thus the best estimation is obtained when the RF filter width is close to twice the symbol rate and the surroundings are quiet.
<h4>B.5: Output transport stream to UDP</h4>