US 6,307,896 B1Granted

Instrumentation receiver for digitally modulated radio frequency signals

AssigneeTektronix, Inc.

InventorsLinley F. Gumm, Jeffrey D. Earls

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Abstract

An instrumentation receiver suitable for receiving a digitally modulated radio frequency input signal having a pilot signal at the RF frequency and symbol data generated at a symbol frequency generates a digitally modulated intermediate frequency signal having the pilot signal at the intermediate frequency equal to an integer multiple of the digital data's symbol frequency where the integer multiple is equal to or greater than one. A reference signal having a frequency equal to an integer multiple of the symbol frequency where the integer multiple is equal to or greater than one mixes with the IF signal to generate a control signal for controlling a local oscillator that generates a local oscillator signal for mixing with the digitally modulated RF input signal for locking the pilot signal to the reference signal. The instrumentation receiver is usable in a measurement test set for characterizing and monitoring an 8-VSB digital television transmitter or other digitally moduated RF signal containing a pilot at the carrier frequency.

Claims12

Dependent claims

An instrumentation receiver for generating a digitally modulated intermediate frequency signal from a digitally modulated radio frequency input signal, the digitally modulated radio frequency input signal being modulated by digital data generated at a symbol frequency and having a pilot signal coherent with the radio frequency carrier, comprising:

a mixer having as inputs the digitally modulated radio frequency input signal and a local oscillator signal and having as an output the digitally modulated intermediate frequency signal;
a local oscillator having as an input a control signal and having as an output the local oscillator signal, the control signal adjusting the frequency of the local oscillator signal such that in the digitally modulated intermediate frequency signal the pilot signal is coherent with the intermediate frequency carrier signal and equal to an integer multiple of the symbol frequency where the integer multiple is equal to or greater than one;
and
a wide bandwidth low pass filter having as an input the digitally modulated intermediate frequency signal from the mixer and having as an output the digitally modulated intermediate frequency signal with mixer sum products and local oscillator feed through from the mixer removed.

1 more element

Dependencies are inferred from the claim text.