Pilot recovery and polarity detection system
AssigneeZenith Electronics Corporation
InventorGary J. Sgrignoli
Life of this patent
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Abstract
A polarity detection circuit for an FPLL demodulated signal including a small DC pilot recovers the DC pilot by determining the DC levels of the demodulated output signals both with and without the DC pilot. A zero carrier condition is created for determining the DC level of the output signal without the DC pilot. The two DC levels are subtracted and limited and the polarity of the recovered DC pilot is used to control the operation of a polarity inverter to assure that the output signal has a desired polarity.
Claims20
A method of processing an FPLL demodulated signal including a DC pilot comprising:
- determining the DC level of the FPLL demodulated output signal with the pilot;
- determining the DC level of the FPLL demodulated output signal without the pilot;
- and
- subtracting the two determined DC levels to recover the pilot.
A method of processing an FPLL demodulated signal including a DC pilot comprising:
- integrating the FPLL demodulated output signal to determine its DC level with the DC pilot;
- integrating the FPLL demodulated output signal under a zero carrier condition to determine its DC level without the DC pilot;
- and
- subtracting the two determined DC levels to recover the magnitude and the polarity of the DC pilot.
A method of detecting the polarity of lock in an FPLL demodulated signal including a DC pilot comprising:
- A/D converting the demodulated signal;
- determining the DC level of the FPLL demodulated output signal with the DC pilot;
- determining the DC level of the FPLL demodulated output signal without the DC pilot;
- and
- subtracting the two determined DC levels to find the polarity of the DC pilot.
A method of providing a given polarity FPLL demodulated output signal that includes a DC pilot comprising:
- A/D converting the output signal;
- integrating the output signal under a zero carrier condition to determine its DC level without the DC pilot;
- integrating the output signal to determine its DC level with the DC pilot;
- subtracting the determined DC levels to find the polarity of the DC pilot;
- and
- producing a change in the polarity of the demodulated output signal, if required, based upon the polarity of the DC pilot.
A receiver for receiving a signal including a pilot in the form of a DC offset comprising:
- FPLL demodulator means for producing a demodulated output signal with a DC pilot;
- means for determining the DC levels of said output signal with said DC pilot and without said DC pilot;
- and
- means for subtracting said two determined DC levels to recover said DC pilot.
A receiver for receiving an RF signal including a pilot in the form of a DC offset comprising:
- FPLL demodulator means for producing an output signal including a DC pilot from said RF signal;
- A/D converter means for converting said output signal to digital form;
- polarity inverting means for changing the polarity of said output signal;
- integrator means for determining a first DC level of said output signal including said DC pilot and a second DC level of said output signal excluding said DC pilot;
- gate means for establishing a zero RF carrier condition and for operating said integrator means to determine said first and second DC levels;
- means for determining the polarity of said DC pilot by subtracting said first and second DC levels;
- and
- polarity selection means for operating said polarity inverting means, as required, to assure a given polarity of said output signal in response to the polarity of said DC pilot.
Dependencies are inferred from the claim text.