HackRF plugin: added two sampling rates above 4.8 MS/s

Readme.md

@@ -89,7 +89,7 @@ If you use your own location for libhackrf install directory you need to specify
 
 `-DLIBHACKRF_LIBRARIES=/opt/install/libhackrf/lib/libhackrf.so -DLIBHACKRF_INCLUDE_DIR=/opt/install/libhackrf/include`
 
-HackRF is better used with a sampling frequency over 8 MS/s. You can use the 9.6Ms/s setting that decimates nicely into integer kS/s sample rates. There are quite a few problems with narrowband work with this hardware. You may try various amplifiers settings to limit images and I/Q imbalance with varying success... The cheap RTL-SDR dongles usually do better.
+HackRF is better used with a sampling rate of 4.8 MS/s and above. The 2.4 and 3.2 MS/s rates are considered experimental and are way out of specs of the ADC. You may or may not achieve acceptable results depending on the unit. A too low sampling rate will typically create ghost signals (images) and/or raise the noise floor.
 
 <h2>RTL-SDR</h2>
 

plugins/samplesource/hackrf/hackrfgui.cpp

@@ -287,7 +287,7 @@ void HackRFGui::updateHardware()
 	m_updateTimer.stop();
 }
 
-unsigned int HackRFSampleRates::m_rates_k[] = {2400, 3200, 4800, 6400, 9600, 12800, 19200};
+unsigned int HackRFSampleRates::m_rates_k[] = {2400, 3200, 4800, 5600, 6400, 8000, 9600, 12800, 19200};
 
 unsigned int HackRFSampleRates::getRate(unsigned int rate_index)
 {

plugins/samplesource/hackrf/hackrfgui.h

@@ -89,7 +89,7 @@ class HackRFSampleRates {
 public:
 	static unsigned int getRate(unsigned int rate_index);
 	static unsigned int getRateIndex(unsigned int rate);
-	static const unsigned int m_nb_rates = 7;
+	static const unsigned int m_nb_rates = 9;
 	static unsigned int m_rates_k[m_nb_rates];
 };