SdrDx Documentation -- Native Recording (page 44)

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5.23 - Native Recording

5.23.1 - System Requirements and Limitations

Please be aware that these functions take significant CPU power as well as require a fast storage device. Some machines may not be able to record. If you have problems, try a lower SDR bandwidth (e.g. 50 KHz) as this will reduce the data rate, and so the demands upon your computer's filesystem and CPU.

The maximum size of the file recorded in megabytes, and the directory where SdrDx looks for, and saves, recordings, can be set by right clicking on the o (record) control. If the recorded file size exceeds that size, the file will be closed and another one opened. The default max file size is 500 MB.

5.23.2 - Setting up to Record

First, set the SDR to the bandwidth you intend to record. Then, with Run on, press the o or "record" button, and record for the period of time you wish. Be aware that this uses up disk space extremely quickly. If you run out of disk space, the recording will stop automatically and you'll be left to move or delete the recording. To stop recording, just press o again.

5.23.3 - While Recording

The size of the file currently being recorded is indicated in two ways. First, in the topmost info black at the end, where the size is indicated as "X.XX GB"; second, in the scrub bar, which shows progress towards the maximum set file size.

During Record, the center frequency is locked.

Caution: The wider the SDR bandwidth is (e.g., 50, 100, 500 KHz), the more disk space the recording will take.

5.23.4 - Record File Format

If you're interested in reading files saved by SdrDx, here is a description of the files it creates:

Wave Header: ------------ signed byte (4) - 4 ASCII characters = "RIFF" unsigned 32bit (1) - file length signed byte (8) - 8 ASCII characters = "WAVEfmt " unsigned 32bit (1) - format length unsigned 16bit (1) - format tag unsigned 16bit (1) - number of channels unsigned 32bit (1) - samples per second unsigned 32bit (1) - Average bytes per second unsigned 16bit (1) - block align unsigned 16bit (1) - bits per sample = 16 signed byte (4) - 4 ASCII characters = "DATA" unsigned 32bit (1) - data size Interstitial Padding -------------------- signed 8bit (2) - content not used Auxiliary Information --------------------- unsigned 16bit (1) - start year unsigned 16bit (1) - start month unsigned 16bit (1) - start day of week unsigned 16bit (1) - start day of month unsigned 16bit (1) - start hour unsigned 16bit (1) - start minute unsigned 16bit (1) - start second unsigned 16bit (1) - start millisecond unsigned 16bit (1) - stop year unsigned 16bit (1) - stop month unsigned 16bit (1) - stop day of week unsigned 16bit (1) - stop day of month unsigned 16bit (1) - stop hour unsigned 16bit (1) - stop minute unsigned 16bit (1) - stop second unsigned 16bit (1) - stop millisecond unsigned 32bit (1) - Center Frequency unsigned 32bit (1) - A/D Frequency unsigned 32bit (1) - IF Frequency unsigned 32bit (1) - Bandwidth unsigned 32bit (1) - I/Q Offset unsigned 32bit (1) - dB Offset unsigned 32bit (1) - Maximum Value unsigned 32bit (1) - unused unsigned 32bit (1) - unused signed 16bit (n) - where n is the number of samples

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