Synchronized offset extraction in a data receiver
AssigneeMotorola, Inc.
InventorsDaniel A. Morera, David R. Petreye
Life of this patent
Estimating the term…
Abstract
A selective call receiver (106) receives a radio frequency signal having digital signals contained within symbols. The signal demodulated by the receiver (804) comprises a substantially constant DC offset voltage and an AC voltage (1810) indicative of the information contained within the symbols. A threshold level extraction circuit (808) which extracts the offset voltage is synchronously controlled (1840) providing for sampling of the received signal by the threshold level extraction circuit in substantially the center of each symbol.
Claims17
A selective call receiver comprising:
- receiving means for receiving and demodulating a radio frequency signal having digital information contained within symbols modulated thereon and for producing a received signal having a substantially constant DC offset voltage with an AC voltage representing the symbols combined therewith;
- determining means for determining the DC offset voltage;
- digitizing means for comparing the determined DC offset voltage with the received signal and for producing a digital signal indicative of the information contained within the symbols;
- synchronizing means for synchronizing to the symbols and for producing a synchronization signal in response thereto;
- decoding means for decoding the digital signal in response to the synchronization signal and for storing and alerting the reception of information directed to the selective call receiver;
- and
- control means responsive to the synchronization signal for enabling said determining means substantially in the center of each symbol.
A method of digitizing a received signal having a substantially constant offset signal and a symbol stream having a predetermined baud rate modulated thereon, said method comprising the steps of:
- enabling determination of the offset signal for a portion of each symbol in synchronization with the symbol stream;
- and
- disabling determination of the offset signal for a portion of each symbol exclusive of said step of enabling wherein said step of enabling occurs substantially during the center of each symbol, and wherein said step of disabling occurs substantially during transitions between symbols.
An apparatus for digitizing a received signal having a substantially constant offset signal and a symbol stream having a predetermined baud rate modulated thereon, said apparatus comprising:
- determining means for determining the magnitude of the offset signal;
- and
- control means for enabling said determining means for a portion of each symbol in synchronization with the symbol stream wherein said control means enables said determining means substantially during the center of each symbol, and disables said determining means substantially during transitions between symbols.
Dependencies are inferred from the claim text.