some fixes and improvements

python_app/gui/controllers/sections/processing_section.py

@@ -403,6 +403,22 @@ def build_processing_group(owner) -> QGroupBox:
     owner._legacy_gpr_look_angle_deg.setSingleStep(0.1)
     owner._legacy_gpr_look_angle_deg.setValue(float(legacy_gpr_defaults.look_angle_deg))
 
+    # Intra-sweep phase compensation toggle. When checked, S21 phase is
+    # corrected per frequency point before the IFFT so the radar's motion
+    # during one sweep is removed at the spectrum stage. Only matters when
+    # speed != 0; otherwise has no effect by construction.
+    owner._legacy_gpr_apply_freq_phase_correction = QCheckBox("Apply intra-sweep phase correction")
+    owner._legacy_gpr_apply_freq_phase_correction.setChecked(
+        bool(legacy_gpr_defaults.apply_freq_phase_correction)
+    )
+
+    # Anchor point for the motion model's per-event `dt_ref`. `frame_center`
+    # spreads motion symmetrically around the frame midpoint; `first_tx_event`
+    # accumulates it forward from the first event center.
+    owner._legacy_gpr_reference_mode = QComboBox()
+    owner._legacy_gpr_reference_mode.addItems(["frame_center", "first_tx_event"])
+    owner._set_combo_current_text(owner._legacy_gpr_reference_mode, legacy_gpr_defaults.reference_mode)
+
     owner._legacy_gpr_background_subtract_enabled = QCheckBox("Subtract mean of previous collections")
     owner._legacy_gpr_background_subtract_enabled.setChecked(bool(legacy_gpr_defaults.background_subtract_enabled))
 
@@ -460,6 +476,8 @@ def build_processing_group(owner) -> QGroupBox:
             ("Start MHz", owner._legacy_gpr_start_freq_mhz),
             ("Stop MHz", owner._legacy_gpr_stop_freq_mhz),
             ("Look angle deg", owner._legacy_gpr_look_angle_deg),
+            ("Reference mode", owner._legacy_gpr_reference_mode),
+            owner._legacy_gpr_apply_freq_phase_correction,
             ("Visible X min m", owner._legacy_gpr_visible_x_min_m),
             ("Visible X max m", owner._legacy_gpr_visible_x_max_m),
             ("Visible Z min m", owner._legacy_gpr_visible_z_min_m),
@@ -526,6 +544,8 @@ def build_processing_group(owner) -> QGroupBox:
         owner._on_legacy_gpr_ignore_socket_speed_toggled
     )
     owner._legacy_gpr_look_angle_deg.valueChanged.connect(owner._on_processing_live_settings_changed)
+    owner._legacy_gpr_apply_freq_phase_correction.toggled.connect(owner._on_processing_live_settings_changed)
+    owner._legacy_gpr_reference_mode.currentTextChanged.connect(owner._on_processing_live_settings_changed)
     owner._legacy_gpr_background_subtract_enabled.toggled.connect(owner._on_processing_live_settings_changed)
     owner._legacy_gpr_background_mean_count.valueChanged.connect(owner._on_processing_live_settings_changed)
     owner._legacy_gpr_render_mode.currentTextChanged.connect(owner._on_gpr_visual_settings_changed)