James B Blair

US Patent:

60914416, Jul 18, 2000

Filed:

Feb 10, 1998

Appl. No.:

9/021086

Inventors:

Saleh R. Al-Araji - Alpharetta GA
James F. Blair - Winder GA
Herman A. Kruse - Winder GA

Assignee:

Scientific-Atlanta, Inc. - Norcross GA

International Classification:

H04N 1700
H04N 514

US Classification:

348 6

Abstract:

A distribution amplifier (210) for a cable television system (100) includes an output gain stage section (215) for receiving an input signal from a cable head end section (105). The output gain stage section (215) includes multiple active amplifier circuits (225, 230) for amplifying the input signal to generate main and auxiliary outputs that are processed by a radio frequency (RF) detector (255) having at least a first detector circuit (300) for processing the main output to generate a first voltage and a second detector circuit (305) for processing the auxiliary output to generate a second voltage. Further included in the distribution amplifier (210) is a status monitor (260) coupled to the RF detector (255) for converting the first and second outputs to first and second digital values and transmitting the first and second digital values. In this manner, an indication of a system or amplifier malfunction can be provided. Other advantages of the RF detector (255) are that the main and auxiliary outputs can be either simultaneously or sequentially processed, as desired, to provide multiple indications of system problems and that the RF stages of the detector circuits (300,305) are connected in series to reduce current drain, thereby reducing power consumption.