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diff --git a/plugins/samplesource/testsource/readme.md b/plugins/samplesource/testsource/readme.md
index 3d31d8a50..b357c6f16 100644
--- a/plugins/samplesource/testsource/readme.md
+++ b/plugins/samplesource/testsource/readme.md
@@ -36,22 +36,25 @@ Record baseband I/Q stream toggle button
Baseband I/Q sample rate in kS/s. This is the device to host sample rate (3) divided by the decimation factor (4).
-2: Auto correction options
+2: Various options
-These buttons control the local DSP auto correction options:
+
+2.1: Auto corrections
+
+This combo box control the local DSP auto correction options:
+
+ - **None**: no correction
- **DC**: auto remove DC component
- - **IQ**: auto make I/Q balance. The DC correction must be enabled for this to be effective.
+ - **DC+IQ**: auto remove DC component and correct I/Q balance.
-3: Carrier shift from center frequency
-
-Use this control to set the offset of the carrier from the center frequency of reception.
-
-4: Decimation factor
+2.2: Decimation factor
The I/Q stream from the generator is doensampled by a power of two before being sent to the passband. Possible values are increasing powers of two: 1 (no decimation), 2, 4, 8, 16, 32. This exercises the decimation chain.
-5: Baseband center frequency position relative the center frequency
+This exercises the decimation chain.
+
+2.3: Baseband center frequency position relative the center frequency
Possible values are:
@@ -59,44 +62,60 @@ Possible values are:
- **Inf**: the decimation operation takes place around the center of the lower half of the BladeRF Rx passband.
- **Sup**: the decimation operation takes place around the center of the upper half of the BladeRF Rx passband.
-This exercises the decimation chain.
-
-6: Sample rate
-
-This controls the generator sample rate in samples per second.
-
-7: Sample size
+2.4: Sample size
This is the sample size in number of bits. It corresponds to the actual sample size used by the devices supported:
- **8**: RTL-SDR, HackRF
- **12**: Airspy, BladeRF, LimeSDR, PlutoSDR, SDRplay
- **16**: Airspy HF+, FCD Pro, FCD Pro+
-
-8: Amplitude coarse control
-This slider controls the number of amplitude bits by steps of 100 bits.
-
-9: Number of amplitude bits
+3: Sample rate
-This is the signal peak amplitude in number of bits
+This controls the generator sample rate in samples per second.
+
+4: Modulation
+
+ - **No**: No modulation
+ - **AM**: Amplitude modulation (AM)
+ - **FM**: Frequency modulation (FM)
+
+5: Modulating tone frequency
+
+This controls the modulating tone frequency in kHz in 10 Hz steps.
+
+6: Carrier shift from center frequency
+
+Use this control to set the offset of the carrier from the center frequency of reception.
+
+7: AM modulation factor
+
+This controls the AM modulation factor from 0 to 99%
+
+8: FM deviation
+
+This controls the frequency modulation deviation in kHz in 100 Hz steps. It cannot exceed the sample rate.
+
+9: Amplitude coarse control
+
+This slider controls the number of amplitude bits by steps of 100 bits. The total number of amplitude bits appear on the right.
10: Amplitude fine control
-This slider controls the number of amplitude bits by steps of 1 bit.
+This slider controls the number of amplitude bits by steps of 1 bit. The signal power in dB relative to the maximum power (full bit range) appear on the right.
-11: Signal power
-
-This is the signal power in dB relative to the maximum power (full bit range).
-
-12: DC bias
+11: DC bias
Use this slider to give a DC component in percentage of maximum amplitude.
-13: I bias
+12: I bias
Use this slider to give an in-phase (I) bias in percentage of maximum amplitude.
-14: Q bias
+13: Q bias
-Use this slider to give an quadrature-phase (Q) bias in percentage of maximum amplitude.
\ No newline at end of file
+Use this slider to give an quadrature-phase (Q) bias in percentage of maximum amplitude.
+
+14: Phase imbalance
+
+Use this slider to introduce a phase imbalance in percentage of full period (continuous wave) or percentage of I signal injected in Q (AM, FM).