Adds airspy USB tuner support and updates the spectral display

component.

-Airspy supported with 10 and 2.5 MSps sample rates.  Additional
decimation may be added later.

-Spectral display updated to include smoothing and filtering options.

Note: the decimated output of a tuner channel from the airspy is
48,076.9 samples per second, versus the normal 48 kHz decimated rate.
This is 1.0015 times the normal rate and doesn't appear to impact the
decoders or audio processing.  Therefore, no fractional resampling has
been added.

src/util/Oscillator.java

@@ -1,108 +0,0 @@
-/*******************************************************************************
- *     SDR Trunk 
- *     Copyright (C) 2014 Dennis Sheirer
- * 
- *     This program is free software: you can redistribute it and/or modify
- *     it under the terms of the GNU General Public License as published by
- *     the Free Software Foundation, either version 3 of the License, or
- *     (at your option) any later version.
- * 
- *     This program is distributed in the hope that it will be useful,
- *     but WITHOUT ANY WARRANTY; without even the implied warranty of
- *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *     GNU General Public License for more details.
- * 
- *     You should have received a copy of the GNU General Public License
- *     along with this program.  If not, see <http://www.gnu.org/licenses/>
- ******************************************************************************/
-package util;
-
-import sample.complex.Complex;
-
-public class Oscillator
-{
-	private double mFrequency;
-	private double mSampleRate;
-
-	private Complex mAnglePerSample;
-	private Complex mCurrentAngle = new Complex( 0.0f, -1.0f );
-
-	/**
-	 * Oscillator produces complex or float samples corresponding to a sine wave 
-	 * oscillating at the specified frequency and sample rate
-	 * 
-	 * @param frequency - positive or negative frequency in hertz
-	 * @param sampleRate - in hertz
-	 */
-	public Oscillator( long frequency, int sampleRate )
-	{
-		mSampleRate = (double)sampleRate;
-		mFrequency = (double)frequency;
-		
-		update();
-	}
-	
-	/**
-	 * Updates the internal values after a frequency or sample rate change
-	 */
-	private void update()
-	{
-		float anglePerSample = 
-				(float)( 2.0d * Math.PI * mFrequency / mSampleRate );
-
-		mAnglePerSample = Complex.fromAngle( anglePerSample );
-	}
-
-	/**
-	 * Sets or changes the frequency of this oscillator
-	 */
-	public void setFrequency( long frequency )
-	{
-		mFrequency = (double)frequency;
-		update();
-	}
-
-	/**
-	 * Sets or changes the sample rate of this oscillator
-	 */
-	public void setSampleRate( int sampleRate )
-	{
-		mSampleRate = (double)sampleRate;
-		update();
-	}
-
-	/**
-	 * Steps the current angle by the angle per sample amount
-	 */
-	public void rotate()
-	{
-		mCurrentAngle.multiply( mAnglePerSample );
-		mCurrentAngle.fastNormalize();
-	}
-
-	public float inphase()
-	{
-		return mCurrentAngle.inphase();
-	}
-	
-	public float quadrature()
-	{
-		return mCurrentAngle.quadrature();
-	}
-	
-	/**
-	 * Get next complex sample
-	 */
-	public Complex getComplex()
-	{
-		return mCurrentAngle.copy();
-	}
-
-	/**
-	 * Get the next float sample
-	 */
-	public float getFloat()
-	{
-		return mCurrentAngle.real();
-	}
-}