Simultaneous Transmission of Speech and Data Using Code-Breaking Techniques

There are numerous schemes 1,2 for analog scrambling of speech signals, but they all require a scrambling key. For example, we may sample the speech at a rate in excess of its Nyquist rate, parcel the samples into blocks, and rearrange the blocks prior to transmission. This rearrangement of the blocks breaks up the rhythm in the speech making it difficult for an eavesdropper to comprehend the conversation. The shuffling of the block positions is done under the auspices of the scrambling-key, and provided the receiver knows this key and, hence, the descrambling key, the blocks of speech can be correctly repositioned and made intelligible to the desired recipient. It is not our purpose to describe the numerous scrambling techniques, but rather to suggest a method whereby speech and data can be transmitted simultaneously over the channel by using scrambling 2081 strategies. The principle is very simple. The scrambling key becomes the data to be transmitted. The receiver adopts the role of codebreaker. Every time the receiver correctly guesses the key and breaks the code, it recovers both the speech and the data. For the scheme to have any significance, the receiver must break the code successfully at nearly every attempt. Therefore, we must select scrambling keys which are easy to break, and this means that we are not aiming for speech privacy (although a degree of privacy may be achieved as a byproduct). The scrambling process is, therefore, a catalyst which enables the data to be transmitted.