Airband VOR receiver and trasmitter (#3244)

* First test

* Reorder includes for consistency and fix string dereference in VorCdiIndicator

* Add memory section and linker script entry for vor_rx application

* Testing VOR TX

* Moving VOR TX to SD

* Code refactoring to align with guidelines

* Add TODO comment to verify radial sign convention in vor_tx_config

* Remove unnecessary set_dirty() calls in VorRxView methods

* Update Course Deviation Indicator label and adjust UI element positions

* Update VorTxView to run prepared image from memory map

* Update build condition in nightly release workflow to include workflow_dispatch event

* Reverting action changes

* Adjust Course Deviation Indicator layout and refine painting logic

* Refactor VorRxView UI elements for improved layout and clarity

* Add calibration field and update radial calculation logic in VorRxView

* Enhance VOR processing: add renormalization to phase oscillator, improve signal handling, and update configuration parameters

* Implement radial smoothing and TO/FROM state handling in VorRxView; update VOR processing logic

* Setting comments inline

* Refactor VorCdiIndicator and VorRxView: change normalize_signed_degrees to use int32_t, update radial smoothing to use fixed point arithmetic to reduce flash usage

* Update external app address end to 0xAE0B0000

* Update set_vor_tx_config to include enabled parameter for consistency

* Refactor VorRx to omit decim_2 stage and update comments for clarity on VOR processing

* Add RSSI, Channel, and Audio fields to VorRxView to mimic existing apps

* Refactor VorRxView labels and status messages

* Update VorRxView calibration field range to allow full circle input

* Completing Ident transmission logic

* Fixing TX gain and moving log label

* Refactor VOR phase calculations and update radial offset handling for accurate bearing representation

* Add low-pass filters to strip 9960 Hz subcarrier from audio output

firmware/common/dsp_iir_config.hpp

@@ -119,4 +119,12 @@ constexpr iir_biquad_config_t apt_audio_12k_lpf_2000hz_config{
     {0.15505103f, 0.31010205f, 0.15505103f},
     {1.00000000f, -0.6202041f, 0.24040821f}};
 
+// scipy.signal.butter(2, 3200 / 24000.0, 'low', analog=False)
+// VOR RX audio low-pass. Removes the 9960 Hz FM subcarrier (the annoying
+// high-pitch whine) while passing voice and the 1020 Hz ident tone. Cascade
+// two of these sections for a 4th-order roll-off (~44 dB at 9960 Hz).
+constexpr iir_biquad_config_t audio_48k_lpf_3200hz_config{
+    {0.03357181f, 0.06714362f, 0.03357181f},
+    {1.00000000f, -1.41898265f, 0.55326989f}};
+
 #endif /*__DSP_IIR_CONFIG_H__*/

firmware/common/message.hpp

@@ -162,6 +162,9 @@ class Message {
         ToneDetectConfig = 104,
         FlexTosend = 105,
         EPIRBRXConfig = 106,
+        VorRxConfigure = 107,
+        VorRxStatusData = 108,
+        VorTxConfigure = 109,
         MAX
     };
 
@@ -1899,6 +1902,68 @@ class ToneDetectConfigureMessage : public Message {
     uint32_t ctcss_freq_x10{0};  // CTCSS frequency × 10 (e.g. 1000 = 100.0 Hz); 0 = None
 };
 
+class VorRxConfigureMessage : public Message {
+   public:
+    constexpr VorRxConfigureMessage(bool enabled = true)
+        : Message{ID::VorRxConfigure},
+          enabled{enabled} {
+    }
+
+    bool enabled{true};
+};
+
+class VorRxStatusDataMessage : public Message {
+   public:
+    constexpr VorRxStatusDataMessage(
+        uint16_t phase_deg = 0,
+        uint16_t radial_deg = 0,
+        uint16_t reference_level = 0,
+        uint16_t variable_level = 0,
+        uint8_t quality = 0,
+        bool valid = false,
+        bool to_from = false)
+        : Message{ID::VorRxStatusData},
+          phase_deg{phase_deg},
+          radial_deg{radial_deg},
+          reference_level{reference_level},
+          variable_level{variable_level},
+          quality{quality},
+          valid{valid},
+          to_from{to_from} {
+    }
+
+    uint16_t phase_deg{0};
+    uint16_t radial_deg{0};
+    uint16_t reference_level{0};
+    uint16_t variable_level{0};
+    uint8_t quality{0};
+    bool valid{false};
+    bool to_from{false};
+};
+
+class VorTxConfigureMessage : public Message {
+   public:
+    VorTxConfigureMessage(
+        uint16_t radial_deg = 0,
+        bool ident_enabled = true,
+        const char* ident = "",
+        bool enabled = true)
+        : Message{ID::VorTxConfigure},
+          radial_deg{radial_deg},
+          ident_enabled{ident_enabled},
+          enabled{enabled} {
+        size_t i = 0;
+        for (; ident && ident[i] && i < sizeof(ident_text) - 1; ++i)
+            ident_text[i] = ident[i];
+        ident_text[i] = '\0';
+    }
+
+    uint16_t radial_deg{0};
+    bool ident_enabled{true};
+    bool enabled{true};
+    char ident_text[8]{};  // CW identifier, null-terminated (max 7 chars)
+};
+
 class FlexTosendMessage : public Message {
    public:
     constexpr FlexTosendMessage(

firmware/common/spi_image.hpp

@@ -129,6 +129,8 @@ constexpr image_tag_t image_tag_noaaapt_rx{'P', 'N', 'O', 'A'};
 constexpr image_tag_t image_tag_sstv_rx{'P', 'S', 'R', 'X'};
 constexpr image_tag_t image_tag_morse{'P', 'M', 'R', 'S'};
 constexpr image_tag_t image_tag_morsetx{'P', 'M', 'R', 'T'};
+constexpr image_tag_t image_tag_vor_tx{'P', 'V', 'T', 'X'};
+constexpr image_tag_t image_tag_vor_rx{'P', 'V', 'R', 'X'};
 constexpr image_tag_t image_tag_rttyrx{'P', 'R', 'T', 'R'};
 constexpr image_tag_t image_tag_rttytx{'P', 'R', 'T', 'T'};
 constexpr image_tag_t image_tag_tonedetect{'P', 'T', 'N', 'E'};