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Allow different source PLL power per sweep point, add power range to sweep

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This commit is contained in:
Jan Käberich 2021-07-09 19:34:53 +02:00
parent 6490d6fd14
commit 7bc18881a5
10 changed files with 96 additions and 389 deletions
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62
Software/VNA_embedded/Application/VNA.cpp
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@ -23,7 +23,7 @@ static uint16_t pointCnt;
static bool excitingPort1;
static Protocol::Datapoint data;
static bool active = false;
static bool sourceHighPower;
static Si5351C::DriveStrength fixedPowerLowband;
static bool adcShifted;
static uint32_t actualBandwidth;
@ -76,26 +76,24 @@ bool VNA::Setup(Protocol::SweepSettings s) {
// has to be one less than actual number of samples
FPGA::SetSamplesPerPoint(samplesPerPoint);
// Set level (not very accurate)
int16_t cdbm = s.cdbm_excitation;
if(cdbm > -1000) {
// use higher source power (approx 0dbm with no attenuation)
sourceHighPower = true;
Source.SetPowerOutA(MAX2871::Power::p5dbm, true);
} else {
// use lower source power (approx -10dbm with no attenuation)
sourceHighPower = false;
Source.SetPowerOutA(MAX2871::Power::n4dbm, true);
cdbm += 1000;
}
uint8_t attenuator;
if(cdbm >= 0) {
attenuator = 0;
} else if (cdbm <= -3175){
attenuator = 127;
} else {
attenuator = (-cdbm) / 25;
// Start with average level
auto cdbm = (s.cdbm_excitation_start + s.cdbm_excitation_stop) / 2;
// correct for port 1, assumes port 2 is identical
auto centerFreq = (s.f_start + s.f_stop) / 2;
// force calculation of amplitude setting for PLL, even with lower frequencies
if(centerFreq < HW::BandSwitchFrequency) {
centerFreq = HW::BandSwitchFrequency;
}
auto amplitude = HW::GetAmplitudeSettings(cdbm, centerFreq, true, false);
uint8_t fixedAttenuatorHighband = amplitude.attenuator;
Source.SetPowerOutA(amplitude.highBandPower, true);
// amplitude calculation for lowband
amplitude = HW::GetAmplitudeSettings(cdbm, HW::BandSwitchFrequency / 2, true, false);
uint8_t fixedAttenuatorLowband = amplitude.attenuator;
fixedPowerLowband = amplitude.lowBandPower;
FPGA::WriteMAX2871Default(Source.GetRegisters());
uint32_t last_LO2 = HW::IF1 - HW::IF2;
@ -117,6 +115,7 @@ bool VNA::Setup(Protocol::SweepSettings s) {
for (uint16_t i = 0; i < points; i++) {
bool harmonic_mixing = false;
uint64_t freq = s.f_start + (s.f_stop - s.f_start) * i / (points - 1);
int16_t power = s.cdbm_excitation_start + (s.cdbm_excitation_stop - s.cdbm_excitation_start) * i / (points - 1);
freq = Cal::FrequencyCorrectionToDevice(freq);
if(freq > 6000000000ULL) {
@ -206,6 +205,16 @@ bool VNA::Setup(Protocol::SweepSettings s) {
pointsWithoutHalt = 0;
}
uint8_t attenuator = freq >= HW::BandSwitchFrequency ? fixedAttenuatorHighband : fixedAttenuatorLowband;
if(!s.fixedPowerSetting) {
// adapt power level throughout the sweep
amplitude = HW::GetAmplitudeSettings(power, freq, true, false);
if(freq >= HW::BandSwitchFrequency) {
Source.SetPowerOutA(amplitude.highBandPower, true);
}
attenuator = amplitude.attenuator;
}
FPGA::WriteSweepConfig(i, lowband, Source.GetRegisters(),
LO1.GetRegisters(), attenuator, freq, FPGA::SettlingTime::us20,
FPGA::Samples::SPPRegister, needs_halt);
@ -331,11 +340,20 @@ void VNA::SweepHalted() {
uint64_t frequency = settings.f_start
+ (settings.f_stop - settings.f_start) * pointCnt
/ (settings.points - 1);
int16_t power = settings.cdbm_excitation_start
+ (settings.cdbm_excitation_stop - settings.cdbm_excitation_start)
* pointCnt / (settings.points - 1);
bool adcShiftRequired = false;
if (frequency < HW::BandSwitchFrequency) {
auto driveStrength = fixedPowerLowband;
if(!settings.fixedPowerSetting) {
auto amplitude = HW::GetAmplitudeSettings(power, frequency, true, false);
// attenuator value has already been set in sweep setup
driveStrength = amplitude.lowBandPower;
}
// need the Si5351 as Source
Si5351.SetCLK(SiChannel::LowbandSource, frequency, Si5351C::PLL::B,
sourceHighPower ? Si5351C::DriveStrength::mA8 : Si5351C::DriveStrength::mA4);
Si5351.SetCLK(SiChannel::LowbandSource, frequency, Si5351C::PLL::B, driveStrength);
if (pointCnt == 0) {
// First point in sweep, enable CLK
Si5351.Enable(SiChannel::LowbandSource);