design report

You are asked to design (i.e. choose with justification the detailed design parameters for) a modem for a UHF radio system for use by a town’s fire service. The system is to be used to communicate between a hospital and an ambulance which can travel at speeds up to 130 km/h. Three types of data are to be communicated: (a) digitised ‘telephone quality’ voice, (b) data from a fire engine monitoring system (safety equipment, water levels, water pressure, etc) and (c) still pictures taken with a digital camera. The system should be capable of operating in both directions will use a handshaking protocol to enable the system to adapt to changing conditions in order to maximise data throughput. Each radio modem will operate on a frequency of around 2 GHz, a bandwidth of 10 kHz and with signal to noise ratios (measured within a 10 kHz bandwidth) exceeding 50 dB for about 15% of the time and exceeding 15 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 fire engine would be assigned its own 10 kHz radio channel so there is no need to consider how several fire engines would share bandwidth. There is also no need to consider propagation loss models. The on-board instruments produce data at a fixed rate of 100 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 electronic publications) and the internet to investigate the state-of-the-art in codecs for these two applications.