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Antenna Calculator: fix out-of-range handling + add Comet W100RX (#3321)

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* Antenna Calculator: handle out-of-range frequencies

Fix an out-of-bounds read in update_result(): when the required
quarter-wave length was shorter than the fully-collapsed antenna, the
element interpolation indexed elements[-1]. Guard the frequency range and
report 'retracted' (above the fundamental range; a wideband RX whip still
receives here via harmonics) or 'fully ext.' (below range) instead of a
garbage element count.

* Add Comet W100RX to the sample WHIPCALC/ANTENNAS.TXT

Comet W100RX telescopic RX whip, segment lengths (mm) from the Comet
W100RX instruction sheet: 200/300/400/510/615/800/986.
This commit is contained in:
Mo
2026-09-16 18:30:36 +02:00
committed by GitHub
parent 60b5cc8832
commit 59fb74be1d
2 changed files with 22 additions and 1 deletions
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firmware/application/external/antenna_length/ui_whipcalc.cpp
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@@ -73,6 +73,26 @@ void WhipCalcView::update_result() {
uint8_t ant_count = 9; // Shown antennas counter
length *= 1000; // Get length in mm needed to extend the antenna
for (antenna_entry antenna : antenna_db) { // go thru all antennas available
if (antenna.elements.empty())
continue;
// Needed quarter-wave length is shorter than the fully-collapsed antenna:
// above its fundamental range. Report it as retracted (shortest setting);
// a wideband RX whip still receives here via harmonics, but this
// quarter-wave model cannot compute those positions. This also avoids an
// out-of-bounds read of elements[-1] in the interpolation below.
if (length < antenna.elements.front()) {
console.write(antenna.label + ": retracted\n");
continue;
}
// Needed length is longer than the fully-extended antenna: already maxed
// out, so the frequency is below this antenna's range.
if (length > antenna.elements.back()) {
console.write(antenna.label + ": fully ext.\n");
continue;
}
uint16_t element, refined_quarter = 0;
for (element = 0; element < antenna.elements.size(); element++) {
if (length == antenna.elements[element]) // Exact element in length