Flwrap

Lets suppose you want to send a critical message that must be received exactly as it was sent, or maybe you want to send a data file where it's highly unlikely that even a trained operator could tell that there was an error in receiving the data. Or perhaps you need to broadcast a weather bulletin or situation report to multiple stations and allow each station to verify that the message was received exactly as it was sent.

Flwrap is an application that is designed to take care of each of these situations. Flwrap allows you to transmit a text message, image, or binary file to either single or multiple stations and allow each receiving station to verify that the transmission was received without error. In the discussion which follows the application name is Flwrap, the file encapsulation process is called wrap, wrapping and the encapsulated file is said to be wrapped.

The flwrap executable is a small desktop application that encapsulates a text file, an image file, or a binary file within a set of identifier blocks. These blocks include a 16 bit checksum that is used to test the encapsulated file for integrity.

Flwrap is designed to be used to best advantage with fldigi but can be used with any digital modem program. Fldigi can recognize an wrapped transmission in the Rx data stream and automatically save the file. Fldigi can process multiple wrapped files that are sent in rapid succession. Fldigi does this without operator intervention. The conversion of files to and from the wrapped format do still require an operator.

A text file is encapsulated without changes to the text. Images and other binary files are first converted to a base-64 format. The converted file is then encapsulated. The header blocks identify the type of file and whether or not it has been converted to base-64. Files with any of the following extensions will be treated as binary data files and converted to the base-64 format: jpg, jpeg, png, gif, bmp, ico, zip, gz, tgz, and bz2

Flwrap is simple and easy to use by means of drag and drop operation.