Design of a modem for a UHF radio system for use by a rescue helipcopter service.

Design (i.e. choose with justification the main design parameters that can be developed subsequently into a full implementation) of a modem for a UHF radio system for use by a rescue helicopter service. The system is to be used to communicate between a central control station and a helicopter which can travel at speeds up to 200 km/h. Three types of data are to be communicated: (a) digitised ‘telephone quality’ voice, (b) data from onboard instruments and (c) still pictures taken with a digital camera. The system should be capable of operating in both directions and the use of a handshaking protocol to enable the system to adapt to changing conditions in order to maximise data throughput is possible. Each radio modem will operate on a frequency of around 2 GHz, a bandwidth of up to 10 kHz and with signal to noise ratios (measured within a 10 kHz bandwidth) exceeding 50 dB for about 20% of the time and exceeding 20 dB for 50% of the time. Fading and increased distances at the limits of the service area will, of course, mean that the SNR often will be considerably lower than this figure and appropriate methods of coping with the degradation in SNR will need to be included in your design study. Each helicopter would be assigned its own radio channel. The onboard instruments produce data at a fixed rate of 200 bits per second, and it is essential that communication from these devices is maintained at all times. In order to minimise the overall data transmission requirements, you should include codecs for both the voice and picture messages. Use the library (including the Web of Knowledge database) and possibly the internet to investigate the state-of-the-art in codecs for these two applications. In making decisions about various parts of the system, you should consider a range (i.e. more than one) possible solutions and you must justify why your final choice it best. It is not sufficient to find the first possibility and to simply use that. You should support your decisions with appropriate calculations and, if you think it appropriate, support your design choices with appropriate simulations using the MATLAB blocksets. However, it is not necessary to construct the design in Matlab.