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Fix fractional calculation for frequencies close to integer multiples

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This commit is contained in:
Jan Käberich 2021-11-13 19:32:58 +01:00
parent b3cc97c0c9
commit e0c9f4dcee
2 changed files with 12 additions and 2 deletions
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8
Software/VNA_embedded/Application/Drivers/max2871.cpp
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@ -190,6 +190,14 @@ bool MAX2871::SetFrequency(uint64_t f) {
auto approx = Algorithm::BestRationalApproximation(fraction, 4095); auto approx = Algorithm::BestRationalApproximation(fraction, 4095);
if (approx.denom == approx.num) {
// got an impossible result due to floating point limitations(?)
// Set fractional part to zero, increase integer part instead
approx.num = 0;
approx.denom = 2;
N++;
}
if(approx.denom == 1) { if(approx.denom == 1) {
// M value must be at least 2 // M value must be at least 2
approx.denom = 2; approx.denom = 2;

6
Software/VNA_embedded/Application/VNA.cpp
View File

@ -180,9 +180,11 @@ bool VNA::Setup(Protocol::SweepSettings s) {
// Configure LO2 for the changed IF1. This is not necessary right now but it will generate // Configure LO2 for the changed IF1. This is not necessary right now but it will generate
// the correct clock settings // the correct clock settings
last_LO2 = actualFirstIF - HW::IF2; last_LO2 = actualFirstIF - HW::IF2;
LOG_INFO("Changing 2.LO to %lu at point %lu (%lu%06luHz) to reach correct 2.IF frequency", LOG_INFO("Changing 2.LO to %lu at point %lu (%lu%06luHz) to reach correct 2.IF frequency (1.LO: %lu%06luHz, 1.IF: %lu%06luHz)",
last_LO2, i, (uint32_t ) (freq / 1000000), last_LO2, i, (uint32_t ) (freq / 1000000),
(uint32_t ) (freq % 1000000)); (uint32_t ) (freq % 1000000), (uint32_t ) (actualLO1 / 1000000),
(uint32_t ) (actualLO1 % 1000000), (uint32_t ) (actualFirstIF / 1000000),
(uint32_t ) (actualFirstIF % 1000000));
} else { } else {
// last entry in IF table, revert LO2 to default // last entry in IF table, revert LO2 to default
last_LO2 = HW::IF1 - HW::IF2; last_LO2 = HW::IF1 - HW::IF2;