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Re-programming Audio Files in a FatLady™ USB Car Horn

The FatLady™ USB Car Horn has a USB cable extending from the back of the unit and should have a plastic cover attached that is taped to the connector to protect the USB connector from dirt and moisture. The USB cable can be connected to any PC, Mac, Linux, Android OTG or other host computer system that supports USB Mass Storage Device (MSD) with a FAT file system.The audio is stored in files in the horn.  All of the audio files are stored with a ‘.RAW’ file extension.  The audio files are 8-bit unsigned PCM audio, 16khz sample rate, 1 channel (mono) with no header.

The horn can contain up to 5 files that the horn will play:

  1. START.RAW – The startup sound when power is first applied.
  2. A.RAW –           Song / Sound played when button “A” on remote is pressed.
  3. B.RAW –           Song / Sound played when button “B” on remote is pressed.
  4. C.RAW –           Song / Sound played when button “C” on remote is pressed.
  5. D.RAW –           Song / Sound played when button “D” on remote is pressed.

If START.RAW is not present in the horn, the horn will not play any startup sound.

If any of the A.RAW – D.RAW are not present in the horn, the horn will make a beep sound if the user presses the corresponding button on the remote.

COPY THE FILES FROM THE HORN TO YOUR COMPUTER FIRST!  Then you’ll have a backup of all the original files, just in case things don’t go quite right.

Preparing audio files for the horn:

There are several different ways to convert audio to the correct file format for the horn.  One of the easiest is to use the open-source program AUDACITY (  The program is available for Windows, Mac and Linux.

We are in the process of making an easy tool to use on our website to create .RAW audio files from many other common audio file formats.  For now, Audacity is the easiest tool to use.

Download the Audacity install files from the link above, install on your desktop computer and then run Audacity.  Once you are in Audacity, perform these steps to prepare each audio file for the horn:

  1. Use “File->Open” to open the original audio file.
  2. Use the Audacity editor to edit the audio to the correct length. The horn can store up to 4MB of files, which is approximately 4 minutes of audio.  The typical sequence is to delete any silence or unwanted audio at the beginning of the file, then go to the time corresponding to the length you want the file to be and then delete the audio from that point to the end of the audio file.
  3. Change the Project Rate to 16000:
  4. Convert stereo to mono: “Tracks->Stereo Track to Mono”.
  5. Resample audio to 16khz:
    1. “Tracks->Resample…”
    2. Enter “16000” for “New sample rate (Hz):”.
    3. Click the “OK” button.
  6. Export the RAW audio file:
    1. “File->Export Audio…”.
    2. Select the location on your computer to store the audio file and enter the name of the audio file to save.
    3. Select “Save as type” of “Other uncompressed files”.
    4. Click “Options” button in lower right corner of dialog box.
    5. Select “Header” of “RAW (header-less)”.
    6. Select “Encoding” of “Unsigned 8 bit PCM”
    7. Click “OK” button to accept and close “Options” dialog box.
    8. Click “Save” button to Save the RAW audio file to your computer
  7. Repeat this process from step 1 for all audio files that you want to prepare for the horn.

Copying RAW audio files to the horn:

  1. Plug the horn USB connector into one of your computers USB jacks or USB hub.
  2. Open file explorer (on Windows, press Windows key + “e”).
  3. Navigate to the disc drive that is your horn. This will be differ on various computers depending on your computers configuration and operating system.  On a Windows system, the USB horn will often show up as drive D or E.
  4. You should see the five file name listed above: “START.RAW”, “A.RAW”, etc. The case of the file names may be different (upper / lower case), but the case doesn’t matter.
  5. Copy ALL of the files off the horn and save them into a safe location on your computer. You might want to rename the files to what they actually contain.  “B.RAW” is often the National Anthem, etc.
  6. Delete any of the files on the horn that you intend to replace. If you want to replace the audio file for the “A” button, delete “A.RAW”.
  7. Copy the prepared RAW audio file to the horn and rename it to the appropriate file name to correspond to the function that you want that audio file to be used for. For example, if you want it to play when you press the “A” button on the remote, name the file “A.RAW”.
  8. Repeat from step 6 for all files that you want to update on the horn.
  9. Once you have copied all of the files to the horn, it is advised that you perform the correct media removal process for your particular system. On Windows, this ejecting the USB drive or doing the Safe Removal process.
  10. Apply +12VDC power to the horn and you should hear the startup sound if there is a “START.RAW” file in the horn. Try each of the four buttons on the remote (A, B, C, D) to confirm the audio files that you copied to the horn are working correctly.
  11. Be sure to re-attach the USB cover and black electrical tape to protect the USB from dirt and moisture contamination.

What to do if copying the files to the horn isn’t working:

  1. Re-format the USB Horn drive!  The memory device used in the horn isn’t setup for repeatedly copying and changing files on the horn and can become corrupt after multiple file changes.  If things just don’t seem right with the horn’s file system, just re-format the horn to FAT file system, then copy all the files to the horn.


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