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diff --git a/sdrgui/readme.md b/sdrgui/readme.md
index 1d8f2a790..02523a4e2 100644
--- a/sdrgui/readme.md
+++ b/sdrgui/readme.md
@@ -487,6 +487,10 @@ The server only sends data. Control including FFT details is done via the REST A
+3B.7. Spectrum markers dialog
+
+Opens the [spectrum markers dialog](spectrummarkers.md)
+
3C. Spectrum display control line 3
@@ -951,6 +955,10 @@ A status line is displayed at the left of the top margin. It displays the follow
+Note that spectrum markers appear only when spectrum display is active (shoes data)
+
+The spectrum markers can be set either with the mouse as explained next or with the [spectrum markers dialog](spectrummarkers.md) that can be opened with the markers button (3B.7).
+
Use Shift and mouse left click to set a new marker. There is a maximum of two markers with a different status:
- The first marker will display frequency (2) and power (1) or time (5) on the scale side of the view. Frequency units are the same as displayed in the frequency scale.
- The second marker will display frequency difference (3 or 6) and power difference (4) or time difference (7) from the first marker on the opposite side of the scales. Difference values may be suffixed with a multiplier character.
@@ -969,8 +977,6 @@ Values may be suffixed by a multiplier character:
Use mouse right click anywhere in the view to remove the last entered marker. Use shift and mouse right click to remove all markers.
-Any change in the spectrum settings is not reflected in the markers. You have to clear them and make a new measurement if any critical setting of the spectrum is changed.
-
Mouse scroll wheel
diff --git a/sdrgui/spectrummarkers.md b/sdrgui/spectrummarkers.md
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+++ b/sdrgui/spectrummarkers.md
@@ -0,0 +1,111 @@
+Spectrum markers management
+
+The spectrum markers are controlled with this dialog. Note that spectrum markers will effectively show on the spectrum display only when it is active (shows some data).
+
+General interface
+
+
+
+1. Sub-dialog selection
+
+The complete dialog is split into tabs:
+
+ - **Hist** for histogram (spectrum line) markers
+ - **Wat** for waterfall markers
+
+2. Markers set selection
+
+This lets you selects which markers are displayed
+
+ - **None**: no markers are displayed
+ - **Spec**: spectrum markers are displayed
+
+Histogram markers tab
+
+
+
+1. Marker frequency
+
+Use this frequency dial to set the marker frequency in Hz
+
+2. Center marker frequency
+
+Push this button to move the marker at the center of the spectrum
+
+3. Marker color
+
+The marker color is displayed here. You can click on the square to open a standard color selection dialog to select the marker color. Note that it selects the color of the text display of the marker the crosshairs remain in white color.
+
+4. Marker show
+
+Toggles marker display on the spectrum
+
+5. Marker selection
+
+Turn the dial button to select the marker being set up. The index of the marker appears at left.
+
+6. Swap marker with reference marker (index 0)
+
+Push this button to swap the current marker with marker at index 0. The marker at index 0 is the reference marker. Note that the colors are not swapped so that the marker color is associated to its index and not the marker itself.
+
+7. Add/Remove marker
+
+ - Press the "+" button to add a new marker with a maximum of 4 markers.
+ - Press the "-" button to remove the current marker. When reference marker (index 0) is removed the marker at index 1 if it exists replaces it and thus is made the reference marker.
+
+8. Power hold reset
+
+When the power max hold is selected (9) this button resets the max hold
+
+9. Marker type
+
+This combo lets you select the type of marker:
+
+ - **Man**: manual power set. The value is set with the next control (10)
+ - **Cur**: current power. The marker will move according to the current power at the marker frequency
+ - **Max**: max hold. The marker will move according to the maximum power at the marker frequency. Use button (8) to reset.
+
+10. Manual (fixed) power
+
+Use this slider to adjust the power position of the marker. The units are in dB irrespective of the linear or log set of the spectrum display.
+
+Waterfall markers tab
+
+
+
+1. Marker frequency
+
+Use this frequency dial to set the marker frequency in Hz
+
+2. Center marker frequency
+
+Push this button to move the marker at the center of the spectrum
+
+3. Marker color
+
+The marker color is displayed here. You can click on the square to open a standard color selection dialog to select the marker color. Note that it selects the color of the text display of the marker the crosshairs remain in white color.
+
+4. Marker show
+
+Toggles marker display on the spectrum
+
+5. Marker selection
+
+Turn the dial button to select the marker being set up. The index of the marker appears at left.
+
+6. Swap marker with reference marker (index 0)
+
+Push this button to swap the current marker with marker at index 0. The marker at index 0 is the reference marker. Note that the colors are not swapped so that the marker color is associated to its index and not the marker itself.
+
+7. Add/Remove marker
+
+ - Press the "+" button to add a new marker with a maximum of 4 markers.
+ - Press the "-" button to remove the current marker. When reference marker (index 0) is removed the marker at index 1 if it exists replaces it and thus is made the reference marker.
+
+8. Time mantissa
+
+The time mark of the marker is given in seconds by mantissa M and exponent E so that t(s) = M × 10E. This part controls the mantissa component M that appears on the left. The slider lets you control the decimal part from .000 to .999 and the dial button the integer part from 0 to 9.
+
+9. Time exponent
+
+This slider lets you control the exponent part E of the time mark so that t(s) = M × 10E. The value in exponential notation appears on the left.