|DATE:||Tuesday, September 13, 2005
26905 W. 11 Mile Road
COFDM in ENG Transmissions:
New Problems, New Solutions
What is COFDM? How do you manage it, control it, and deal with it? The transition to digital ENG necessitates changes not only to transmit and receive hardware, but also to the tools and methods utilized to monitor and maintain signal quality. Historically, the TV/monitor approach has been the industry-standard for analog transmissions; the remote spectrum analyzer will become the new standard for monitoring and control in the digital domain.
While COFDM is designed to work well in multi-path environments, interference can affect signal levels. COFDM signals are susceptible to the "Cliff Effect" and to over-saturation; both result in the failure of the receive chain to produce a useable signal. The "Cliff Effect" refers the drop off in reception resulting from marginal signal levels. When analog signals degrade, the picture quality degrades with an increase of sparkles or snow. However, digital signals lack the corresponding degradation of picture quality; when the signal drops below the minimum threshold, the digital picture simply and abruptly disappears. Conversely, over-saturation occurs when the signal level exceeds the maximum threshold. This causes excessive inter-modulation or side band regrowth, preventing the receive chain from decoding the signal. In either situation, the picture quality does not give any indication of the proximity of the signal to the relative threshold until it's too late.
Tish Boyles is the Sales Manager for Morrow Technologies and has been in the Technology field for over 6 years. She worked with Allied Telesyn for a number of years in the networking market. She now is with Morrow Technologies in the test & measurement field. She has a degree in business with a focus on technology.
Managers' Dinner is at 5:30 PM at Steak & Ale, 27590 Orchard Lake Road (at 12 Mile), Farmington Hills. (248) 476-8440