public override void ProcessWideBandData(ref byte[] EP4buf)
{
if (MainForm.doWideBand) // display wide band spectrum
{
// Read new buffer of full-bandwidth
int ret = libUSB_Interface.usb_bulk_read(hdev, 0x84, EP4buf, Form1.EP4BufSize, 100);
if (ret == Form1.EP4BufSize)
{
float scaleIn = (float)(1.0 / Math.Pow(2, 15));
float Sample, RealAverage;
RealAverage = 0.0f;
int i, k;
for (i = 0, k = 0; i < Form1.EP4BufSize; i += 2, ++k)
{
// use this rather than BitConverter.ToInt16()...since its faster and less CPU intensive
// without the '(short)' in there, the value doesn't get sign-extended!
// so what should be small negative values show up as (almost) positive values?
Sample = scaleIn * (float)(short)((EP4buf[i] << 8) | (EP4buf[i + 1]));
RealAverage += Sample;
SamplesReal[k] = Sample;
}
RealAverage /= (float)k;
for (i = 0; i < k; ++i)
{
SamplesReal[i] -= RealAverage; // Subtract average
SamplesImag[i] = SamplesReal[i]; // temporary -- soon will do digital down-conversion
// with sin & cos, so we'll actually have I & Q data to enter.
}
FullBandwidthSpectrum.Process(SamplesReal, SamplesImag, Form1.EP4BufSize / 2);
}
}
}
public override void ProcessWideBandData(ref byte[] EP4buf)
{
if (bWriteFullBandData && (fullBandData != null))
{
// Open the stream for writing.
try
{
// Add some information to the file.
// write a timestamp (8 bytes)
// the reverse action is done by:
// DateTime d = DateTime.FromBinary(BitConverter.ToInt64(b, 0))
// where 'b' is an array of bytes of length 8.
DateTime timestamp = DateTime.UtcNow;
byte[] time = BitConverter.GetBytes(timestamp.Ticks);
fullBandData.Write(time, 0, time.Length);
// write number of bytes that follow (using 4 bytes for the length)
// the reverse of this is: int length = Integer.FromBinary(DateTime d = DateTime.FromBinary(BitConverter.ToInt32(b, 0))
// where 'b' is an array of bytes of length 4.
byte[] length = BitConverter.GetBytes(EP4buf.Length);
fullBandData.Write(length, 0, length.Length);
// write the data
fullBandData.Write(EP4buf, 0, EP4buf.Length);
// how to decode the file:
// 1: read 8 bytes, and convert into a timestamp in UTC time
// 2: read 4 bytes, and convert into an integer, call this 'length'. This is the number of bytes to read next.
// 3: read 'length' bytes into a byte array.
// 4: process the resulting data, exactly as it is processed below in the 'if (MainForm.doWideBand)' clause.
}
catch (Exception ex)
{
// if it's an IO exception, then the folder where the file is stored MAY be used
// by other processes like an AntiVirus program scanning the file after it was closed,
// or a program like 'WD Sync', which shadows your files to to a network or USB drive,
// and may NOT use a shadow-copy mode that allows the file to be opened!
// Best to configure these tools to store the file somewhere else that IS NOT
// being managed by such programs
MessageBox.Show("Likely there is a process like AntiVirus or 'WD Sync' that is accessing the file, preventing further writes. Reconfigure your programs and/or don't save the data file where it will be scanned or copied", "Another program is interfering");
MainForm.disableDataLogging();
}
}
if (MainForm.doWideBand) // display wide band spectrum
{
// EP4 contains 4k x 16 bit raw ADC samples
// Actually it may contain 4 times that! (16k x 16 bit raw adc samples)
{
float scaleIn = (float)(1.0 / Math.Pow(2, 15));
float Sample, RealAverage;
RealAverage = 0.0f;
int numRawSamples = Form1.EP4BufSize;
int numSamples = numRawSamples / 2;
for (int i = 0, k = 0; i < numRawSamples; i += 2, ++k)
{
// use this rather than BitConverter.ToInt16()...since its faster and less CPU intensive
// without the '(short)' in there, the value doesn't get sign-extended!
// so what should be small negative values show up as (almost) positive values?
Sample = scaleIn * (float)(short)((EP4buf[i + 1] << 8) | (EP4buf[i]));
RealAverage += Sample;
SamplesReal[k] = Sample;
}
RealAverage /= (float)numSamples;
// normalize each real data value, based on the average of all samples,
// and copy the Real value to the Imaginary array.
for (int i = 0; i < numSamples; ++i)
{
SamplesReal[i] -= RealAverage; // Subtract average
// temporary fake Imaginary data -- soon will do digital down-conversion
// with sin & cos, so we'll actually have I & Q data to enter.
SamplesImag[i] = SamplesReal[i];
}
FullBandwidthSpectrum.Process(SamplesReal, SamplesImag, numSamples);
}
}
}
