JIQFile

Open a existing IQ File from file system, with random access. Internally the IQFile object has a "reader position" initialized to 0 on start. The file can then be processed :

• sequentially using getSamples(count) where the reader position will be updated
• randomly using getSampleRange( from, to ) where any section of the file can be read.

The reader position can be retrieved by getOffset() or changed by goto(offset).

• IQData blocks are timestamped based on the intial timestamp (first sample) and offset. You can set the intial timestamp with setStartTimestamp()
• Unless samples are extracted from a WAV file, the sampling rate is not knwon and must be provided via setSampleRate()

object IQFile {
        constructor IQFile();
        bool open( string filename );
        number getSampleCount();
        bool goto( offset );
        number getOffset();

        IQData getSamples( count );
        IQData getSampleRange( from, to );
        setCenterFreq( center_MHz );
        setSampleRate( sample_rate_hz );
        number getSampleRate();

        setStartTimestamp( t0_epoch );
    }

Constructor IQFile

.open( filename )

The extension is used to recognize the file type. The following extensions are valid :

• .CF32 or .FC32 or .IQ32 : Complex float single precision (8 bytes by sample, 4 for I, 4 for Q)
• .CS16 : Complex signed integer : 16 bits
• .CS8 : Complex signed integer: 8 bits
• .WAV : wave files, max two channels (float only)

Example:

var filename = "/home/me/sdrcode/data/airdata.wav"
var f = new IQFile();
if (f.open(filename) == false) {
    print('cannot open file ?');
    exit();
}

.getSampleCount()

Example:

var samples = f.getSampleCount();
print(' We have ' + samples + ' samples.');
print(' file duration is ' + samples * 1.0 / f.getSampleRate() + ' secs.');

.getSamples()

Reads a fixed number of samples from the current reading position, and shift the reading position.

Example:

for (; ;) {
    var IQ = f.getSamples(25000); 
    if( IQ.getLength() == 0 ) {
        break ;
    }
    ...
}