public void AnalyzeSignal_KnownSignal_ReturnsExpectedValues()
{
var audioStream = new MemoryStream();
var audioGenerator = new AudioGenerator(audioStream);
var fskAudioGenerator = new FskAudioGenerator(audioGenerator);
fskAudioGenerator.GenerateAudio(_binaryFskAnalyzerSettings.BaudRate,
_binaryFskAnalyzerSettings.SpaceFrequency, _binaryFskAnalyzerSettings.MarkFrequency,
_bitManipulator.StringToBits(Resources.LoremIpsumTestString));
var audioAnalyzer = new AudioAnalyzer(audioStream, audioGenerator);
var binaryFskAnalyzer = (IBinaryFskAnalyzer) new BinaryFskAnalyzer(audioAnalyzer, new ZeroCrossingsFrequencyDetector(), _binaryFskAnalyzerSettings);
var results = binaryFskAnalyzer.AnalyzeSignal();
var result = binaryFskAnalyzer.AnalyzeSignal();
var bits = new List <bool>();
foreach (var frame in result.AnalysisFrames)
{
if (frame.Bit.HasValue == true)
{
bits.Add(frame.Bit.Value);
}
}
var ascii = BitManipulator.BitsToString(bits);
Assert.AreEqual(Resources.LoremIpsumTestString, ascii);
}
public AnalysisResult AnalyzeSignal(string testString = null)
{
var baudRateIncrementMicroseconds = 1.0 / _settings.BaudRate * Math.Pow(10, 6);
var windowPositionEndMicroseconds = _audioAnalyzer.FileLengthInMicroseconds;
var frequencyDifferences = new List <int>();
int numberOfZeroFrequencies = 0;
var analysisFrames = new List <AnalysisFrame>();
var i = 0;
for (var currentWindowPositionMicroseconds = 0.0; currentWindowPositionMicroseconds < windowPositionEndMicroseconds; currentWindowPositionMicroseconds += baudRateIncrementMicroseconds)
{
// Debug.WriteLine($"Current pos: {currentWindowPositionMicroseconds:N1}, increment: {baudRateIncrementMicroseconds:N1}, end: {windowPositionEndMicroseconds :N1}");
i++;
var samplingResult = _audioAnalyzer.GetSamples(currentWindowPositionMicroseconds, currentWindowPositionMicroseconds + baudRateIncrementMicroseconds);
// TODO: How to set this threshold?
var targetNumberOfSamples = _audioAnalyzer.SampleRate / Math.Pow(10, 6) * baudRateIncrementMicroseconds;
var sampleThreshold = 0.9;
if (samplingResult.Samples.Count() < (targetNumberOfSamples * sampleThreshold))
{
continue;
}
var frequency = _frequencyDetector.DetectFrequency(samplingResult.Samples);
var frequencyDifference = FrequencyDifference(frequency, _settings.SpaceFrequency, _settings.MarkFrequency);
var markOrSpace = MarkOrSpace(frequency, _settings.SpaceFrequency, _settings.MarkFrequency);
if (frequency <= 0)
{
numberOfZeroFrequencies++;
}
if (frequencyDifference > _settings.FrequencyDeviationTolerance)
{
Debug.WriteLine($"WARN: @ {currentWindowPositionMicroseconds / Math.Pow(10, 6):N3} seconds (Baud rate {_settings.BaudRate}) [{i}] outside of tolerance (frequency {frequency} Hz, difference {frequencyDifference} Hz, tolerance {_settings.FrequencyDeviationTolerance} Hz)");
frequencyDifferences.Add(frequencyDifference);
}
// Debug.WriteLine($"[{currentWindowStart:N3} us to {currentWindowStart + currentWindowLength:N3} us ({(currentWindowStart + currentWindowLength) - currentWindowStart:N3} us)] {frequency:N0} Hz average (+/- {frequencyDifference:N0} Hz) [Want {_settings.MarkFrequency:N0} Hz / {_settings.SpaceFrequency:N0} Hz] -> bit {bits.Count}: {markOrSpace}");
analysisFrames.Add(
new AnalysisFrame
{
Bit = (frequency > 0 && frequencyDifference <= _settings.FrequencyDeviationTolerance) ? (markOrSpace == 0 ? false : true) : (bool?)null,
Frequency = frequency,
DecodeFailure = frequency > _settings.FrequencyDeviationTolerance ? true : false,
DifferenceFromExpectedFrequencies = frequencyDifference,
TimeOffsetMicroseconds = currentWindowPositionMicroseconds
}
);
}
var analysisResult = new AnalysisResult
{
AnalysisFrames = analysisFrames,
NumberOfFrequencyDifferences = frequencyDifferences.Count(),
NumberOfZeroFrequencies = numberOfZeroFrequencies,
MinimumFrequencyDifference = frequencyDifferences.Count() > 0 ? frequencyDifferences.Min() : 0,
MaximumFrequencyDifference = frequencyDifferences.Count() > 0 ? frequencyDifferences.Max() : 0,
AverageFrequencyDifference = frequencyDifferences.Count() > 0 ? frequencyDifferences.Average() : 0
};
bool? match = null;
string resultingString = null;
if (testString != null)
{
var bits = new List <bool>();
analysisFrames.Where(x => x.Bit.HasValue == true).Select(x => x).ForEach(x => bits.Add(x.Bit.Value));
resultingString = BitManipulator.BitsToString(bits);
match = false;
if (resultingString == testString)
{
match = true;
}
}
// Debug.WriteLine($"Boost freq.: {_audioAnalyzer.BoostFrequencyAmount} Hz, avg. freq. diff.: {averageFrequencyDifference}, # missed freqs.: {missedFrequencies}");
AnalysisComplete((int)_settings.BaudRate, _audioAnalyzer.BoostFrequencyAmount, analysisResult, resultingString, match);
return(analysisResult);
}