What is COFDM?
CODFM is an acronym that refers to coded orthogonal frequency-division multiplexing. Ina broad sense, it is modulation scheme that splits a single digital signal to over a thousand signal carriers at the same time. The signals are referred to as orthogonal due to the fact that they are sent at right angles to each other. This is very crucial in ensuring that at no point do they interfere with one another. COFDM is particularly ideal for the conditions that avail in terrestrial broadcasting channels. To put it in other words, the concept of COFDM enables the functioning of single frequency networks where a number of transmitters send an identical signal on the same frequency with the result being an â€˜artificial multipathâ€™ to be able to obtain the special performance characteristics offered by COFDM, there needs to be a deliberate selection of parameters and special attention needs to be thrust on the method of application of the forward errorcorrection coding.
This new form of modulation has enjoyed application in DAB and DVB-T broadcasting. DAB is an improvement on AM and FM that paid special attention to the problem of multipath reception of a time varying nature that avails when it comes to getting reception in moving cars. On the other hand, DVB-T has a higher capacity than that of DAB. It keeps focus on mobile reception and builds on multi-path tolerance.
The successful application of COFDM has been largely due to its orthogonal nature, the inclusion of a guard interval and the use of the concepts interleaving, error coding and channel-state information. Orthogonal frequency division multiplexing is currently the modulation of choice for all existing and new wireless technologies. Its spectral efficiency is unparalleled in the way it maintains data quality and signal unlike in the UHF and microwave domain where such problems run riot. The applications of this technology have gone further than DVB-T and DAB and now include HD Radio in the US, DVB-H, wireless LANâ€™s, the wideband wireless metro are network technology (MAN), the high speed short range Ultra-Wide Band (UWB), 4G cellular technology among many others. The first successful uses of OFDM were in the telephone line connected data modem. VDSL and ADSL also use discrete multi-tone which is a type of OFDM. Other classified uses exist in the satellite and military worlds far from the public glare. There are companies online that are providing security, surveillance and broadcasting solutions based on this technology. More information on what is COFDM can be obtained online where you will find tutorials that give you a precise introduction to the technology.