Description
In today’s world, we can find signals being transmitted on every portion of the frequency spectrum from a few Hertz up to several Giga Hertz. Frequencies of upwards of 60GHz are common today. Although it is now common to operate in ever higher frequencies, High Frequency (HF) frequencies (3 to 30 MHz) enjoyed huge popularity during the advent of early long-range communication work. Before satellites were invented, it was the only means of transmitting information at long distances wirelessly. Initial work in the defense industry gave fruit to Multitone modems which were then superseded by single tone modems for both data and voice communications at 2400bps, 9600bps and 19400bps. With the growing popularity of digital signal processing and software radio, these modems are now easily implemented. This thesis revisits Multitone modems, also known as parallel tone modems, which use 16 and 39 tones for data and voice respectively. A comparison with modern communication systems will be explored. A description of the Modem sections will be created using MATLAB. All information pertaining to the Multitone modem can be found in the public domain and fully declassified. Any detailed classified information is excluded from this thesis.
