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Generating Audio Stream Files for DAB/DAB+

N7611B DAB/DAB+ sources can support both BER and audio test. For audio test, audio stream file will be used as payload. Different audio encoding and stream formats are used by DAB and DAB+. N7611B provides demo files respectively. And your own audio streams can also be served as input for DAB or DAB+ signal generations.

In the DAB system, MPEG-2 audio encoding scheme is used. For DAB+, AAC+ audio encoding scheme is used and the data is packed into ETI stream. Accordingly, in N7611B Signal Studio, mp2 audio steam is required for DAB as payload for audio test and ETI steam with AAC+ encoded audio data is required for DAB+.

In this section, the process of converting WAV files to DAB and DAB+ audio stream is introduced using some tools. You can find the WAV audio files very easily, for example file1.wav.

Step 1: Use SOX.exe to do re-sampling because DAB has requirements on sampling rate (48 kHz or 24 kHz).  

Command: sox file1.wav -r 48000 file2.wav (file2.wav: generated new file)             

Step 2: Use toolame.exe to convert the file2.wav to mp2 file.

Command: toolame -s 48 -e -b 160 -D 4 file2.wav file2.mp2 (file2.mp2: generated new file)            

Step 3: Optional, add PAD by running MP2FileModifyPADs.exe. Then you can use the mp2 file in signal Studio for DAB test.

Step 4: To generate DAB+ audio stream, send the mp2 file to http://mmbtools.crc.ca/content/view/26/50/. After receiving the .eti file from the website, run ETI_FileExtractor.exe, and you will get another four files. Use ficdec.exe to analyze the *'FIC file, and find the steam file with the same data rate as you want. Then this stream file is the right one, which you can use in N7611B for DAB+ test.