Pulse or digital communications – Receivers – Automatic gain control
Reexamination Certificate
2006-05-16
2006-05-16
Chin, Stephen (Department: 2634)
Pulse or digital communications
Receivers
Automatic gain control
C375S316000, C455S136000, C455S138000, C455S234100, C455S239100, C455S245100, C455S247100
Reexamination Certificate
active
07046749
ABSTRACT:
An Automatic Gain Control (AGC) circuit as used in a digital receiver that utilizes a main loop filter that is of a relatively wide bandwidth. A pre-filter, wideband variance is determined from the input digital signal, and a post-filter, narrowband variance is also determined. The wideband and narrowband variances are then compared to determine if the wideband signal power indicates a variance level that is too great to permit normal loop operation. By reapplying this difference in the power levels to the filter output as needed, such as by a scaling operation, the loss in dynamic range is effectively recovered. In a preferred embodiment, an adjustable gain input amplifier feeds an intermediate frequency (IF) signal to an analog-to-digital converter (ADC). The digitized IF signal is then down-converted to a baseband frequency and subjected to digital filtering. A narrowband sample variance (PN) of the digitally filtered (narrowband) data is then determined. A wideband sample variance (PW) is also taken from the raw ADC output data over the same period as the time period used for PN. In the presence of out-of-band signal components, PWwill be quite different from PN. This difference indicates a desired proportional difference in a control voltage or a gain backoff amount.
REFERENCES:
patent: 5175883 (1992-12-01), Ueno
patent: 5469115 (1995-11-01), Peterzell et al.
patent: 5640385 (1997-06-01), Long et al.
patent: 6178211 (2001-01-01), Whikehart et al.
patent: 6556636 (2003-04-01), Takagi
patent: 6650878 (2003-11-01), Abe et al.
patent: 6658069 (2003-12-01), Imura
patent: 6731703 (2004-05-01), Kurihara
patent: WO 96/10298 (1996-04-01), None
patent: WO 00/18023 (2000-03-01), None
Haenggi Stefan
Keel, Jr. Alton S.
Takatz Mark J.
Chin Stephen
Hamilton Brook Smith & Reynolds P.C.
IPR Licensing Inc.
Wang Ted M.
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