Add frequency resolution computing

src/gpio.cpp

@@ -194,7 +194,7 @@ int clkgpio::ComputeBestLO(uint64_t Frequency,int Bandwidth)
       best_divider=0;
       for( divider=1;divider<4096;divider++)
       {
-        if( Frequency*divider <  600e6 ) continue; // widest accepted frequency range
+        if( Frequency*divider <  300e6 ) continue; // widest accepted frequency range
         if( Frequency*divider > 1500e6 ) break;
 
         max_int_multiplier=((int)((double)(Frequency+Bandwidth)*divider*xtal_freq_recip));
@@ -242,6 +242,22 @@ int clkgpio::ComputeBestLO(uint64_t Frequency,int Bandwidth)
     	}
 }
 
+double clkgpio::GetFrequencyResolution()
+{
+	double res=0;
+	if(ModulateFromMasterPLL)
+	{
+		res=XOSC_FREQUENCY/(double)(1<<20)/PllFixDivider;
+	}
+	else
+	{
+		double Freqresult=(double)Pllfrequency/(double)(CentralFrequency);
+		uint32_t FreqDivider=(uint32_t)Freqresult;
+		res=(Pllfrequency/(double)(FreqDivider+1)-Pllfrequency/(double)(FreqDivider))/4096.0;
+	}
+	return res;
+}
+
 int clkgpio::SetCenterFrequency(uint64_t Frequency,int Bandwidth)
 {
 	CentralFrequency=Frequency;

src/gpio.h

@@ -161,6 +161,7 @@ class clkgpio:public gpio
 	void SetPhase(bool inversed);
 	void SetAdvancedPllMode(bool Advanced);
 	int SetCenterFrequency(uint64_t Frequency,int Bandwidth);
+	double GetFrequencyResolution();
 	int ComputeBestLO(uint64_t Frequency,int Bandwidth);
 	int SetMasterMultFrac(uint32_t Mult,uint32_t Frac);
 	uint32_t GetMasterFrac(double Frequency);