Method and apparatus for generating reference transmission signal for use in testing communications receivers
View Patent ↗A method and apparatus for generating a reference transmission signal for use in testing a communications system. A data packet transmission signal containing a plurality of reference data is captured and digitized, following which reference data is retrieved. The retrieved data is used to modulate a carrier signal to produce a digital transmission signal, which is stored for later use, such that impairments in a signal from a traditional trusted unit are substantially removed, thereby minimizing uncertainty during later testing using such signal.
1. A method for generating a reference transmission signal for use in testing a communications system, comprising:
capturing a data packet transmission signal containing a plurality of reference data;
digitizing said data packet transmission signal;
retrieving at least a selected portion of said plurality of reference data from said digitized data packet transmission signal to produce a plurality of retrieved data;
modulating a carrier signal with said plurality of retrieved data to produce a digital transmission signal;
storing said digital transmission signal following said modulating of said carrier signal and prior to a use of said digital transmission signal in producing said reference transmission signal for transmission and demodulation;
retrieving said stored digital transmission signal; and
quadrature frequency up-converting said retrieved digital transmission signal to produce said reference transmission signal.
2. The method of claim 1 , wherein said capturing a data packet transmission signal containing a plurality of reference data comprises receiving said data packet transmission signal as an analog signal.
3. The method of claim 1 , wherein said capturing a data packet transmission signal containing a plurality of reference data comprises receiving said data packet transmission signal as a wireless signal.
4. The method of claim 1 , wherein said capturing a data packet transmission signal containing a plurality of reference data comprises receiving said data packet transmission signal as a wired signal.
5. The method of claim 1 , wherein said retrieving at least a selected portion of said plurality of reference data from said digitized data packet transmission signal to produce a plurality of retrieved data comprises demodulating at least a selected portion of said digitized data packet transmission signal to produce a plurality of demodulated data.
6. The method of claim 1 , wherein said retrieving at least a selected portion of said plurality of reference data from said digitized data packet transmission signal to produce a plurality of retrieved data comprises decoding at least a selected portion of said digitized data packet transmission signal to produce a plurality of decoded data.
7. The method of claim 1 , wherein said modulating a carrier signal with said plurality of retrieved data to produce a digital transmission signal comprises encoding said carrier signal with said plurality of retrieved data.
8. The method of claim 1 , wherein said storing said digital transmission signal comprises storing said digital transmission signal in memory.
9. The method of claim 1 , further comprising modifying one or more selected bits of said plurality of retrieved data prior to said modulating a carrier signal with said plurality of retrieved data to produce said digital transmission signal.
10. An apparatus including circuitry for generating a reference transmission signal for use in testing a communications system, comprising:
signal capture means for capturing a data packet transmission signal containing a plurality of reference data;
digitizer means for digitizing said data packet transmission signal;
first data retrieval means for retrieving at least a selected portion of said plurality of reference data from said digitized data packet transmission signal to produce a plurality of retrieved data;
signal modulator means for modulating a carrier signal with said plurality of retrieved data to produce a digital transmission signal;
storage means for storing said digital transmission signal following said modulating of said carrier signal and prior to a use of said digital transmission signal in producing said reference transmission signal for transmission and demodulation;
second data retrieval means for retrieving said stored digital transmission signal; and
frequency conversion means for quadrature frequency up-converting said retrieved digital transmission signal to produce said reference transmission signal.
11. The apparatus of claim 10 , further comprising data modifier means for modifying one or more selected bits of said plurality of retrieved data prior to said modulation of a carrier signal with said plurality of retrieved data to produce a digital transmission signal.