M3 step 5: Sweep, the band's signal strength as bars and a waterfall

Tab in the LoRa Scanner sweeps 863-870 MHz in 100 kHz steps (the
strongest of three RSSI readings at each, at 125 kHz), shown as bars with
peak hold over a waterfall, the Sniffer's frequency marked (Q98). The
Sweep pauses the Sniffer and keeps its packets; Tab resumes it (Q99).
Status Bar: SW. The floor, top and peaks are host-tested; `lora sweep
on|off|dump` prints them on the console.

At the desk: about 607 ms a pass, a flat floor at -100 to -102 dBm
(15 dB above the chip's own) and a steady carrier at 863.2 MHz.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

test/test_sweep/test_sweep.cpp

@@ -0,0 +1,74 @@
+#include <unity.h>
+
+#include <vector>
+
+#include "sweep_view.h"
+
+using namespace roro::lora;
+
+void setUp() {}
+void tearDown() {}
+
+// 863.0 to 870.0 MHz in 100 kHz steps: 71 readings.
+static std::vector<int8_t> band(int8_t floor) { return std::vector<int8_t>(71, floor); }
+
+void test_floor_is_the_median() {
+    auto b = band(-95);
+    b[10] = -60;  // a few strong steps don't move the median
+    b[11] = -62;
+    b[50] = -70;
+    SweepStats s = summarize(b.data(), b.size(), 863000000, 100000);
+    TEST_ASSERT_EQUAL_INT(-95, s.floor);
+    TEST_ASSERT_EQUAL_INT(-60, s.top);
+}
+
+void test_peaks_strongest_first_and_merged() {
+    auto b = band(-95);
+    b[11] = -70;  // 864.1 MHz, with shoulders: one peak, not three
+    b[10] = -75;
+    b[12] = -78;
+    b[65] = -55;  // 869.5 MHz
+    b[30] = -90;  // only 5 dB above the floor: not a peak
+    SweepStats s = summarize(b.data(), b.size(), 863000000, 100000);
+    TEST_ASSERT_EQUAL_size_t(2, s.peaks.size());
+    TEST_ASSERT_EQUAL_UINT32(869500000u, s.peaks[0].hz);
+    TEST_ASSERT_EQUAL_INT(-55, s.peaks[0].dbm);
+    TEST_ASSERT_EQUAL_UINT32(864100000u, s.peaks[1].hz);
+}
+
+void test_at_most_three_peaks() {
+    auto b = band(-100);
+    for (int i = 5; i < 70; i += 10) b[i] = static_cast<int8_t>(-80 + i / 10);
+    SweepStats s = summarize(b.data(), b.size(), 863000000, 100000);
+    TEST_ASSERT_EQUAL_size_t(3, s.peaks.size());
+    TEST_ASSERT_EQUAL_INT(-74, s.peaks[0].dbm);  // the strongest three
+}
+
+void test_flat_band_has_no_peaks() {
+    auto b = band(-88);
+    SweepStats s = summarize(b.data(), b.size(), 863000000, 100000);
+    TEST_ASSERT_EQUAL_size_t(0, s.peaks.size());
+    TEST_ASSERT_EQUAL_INT(-88, s.floor);
+}
+
+// The waterfall's scale: dark at the bottom, through blue and green to red at the top.
+void test_heat_scale() {
+    TEST_ASSERT_EQUAL_UINT8(0, heatLevel(-130, -120, -60));
+    TEST_ASSERT_EQUAL_UINT8(0, heatLevel(-120, -120, -60));
+    TEST_ASSERT_EQUAL_UINT8(255, heatLevel(-60, -120, -60));
+    TEST_ASSERT_EQUAL_UINT8(255, heatLevel(-20, -120, -60));
+    TEST_ASSERT_EQUAL_UINT8(128, heatLevel(-90, -120, -60));
+    TEST_ASSERT_TRUE(heatColor(0) != heatColor(255));
+    TEST_ASSERT_EQUAL_HEX16(0x0000, heatColor(0));  // black
+    TEST_ASSERT_EQUAL_HEX16(0xF800, heatColor(255));  // red
+}
+
+int main() {
+    UNITY_BEGIN();
+    RUN_TEST(test_floor_is_the_median);
+    RUN_TEST(test_peaks_strongest_first_and_merged);
+    RUN_TEST(test_at_most_three_peaks);
+    RUN_TEST(test_flat_band_has_no_peaks);
+    RUN_TEST(test_heat_scale);
+    return UNITY_END();
+}