National Instruments Corporation

Abhay Samant

Baijayanta Ray

Kunal Agarwal

Vrishti Agrawal

Sanjeev G Dhumawad

Sastry Vadlamani

Pramod Subramanyan

A system and method for determining the modulation type and constellation order of an input signal given that the modulation type and constellation order are known to belong to set of possible types/orders. A computer operates on samples of the input signal to compute signal features. The computer classifies the modulation type and the constellation order by comparing each feature to one or more corresponding threshold values. The results of the comparisons are used to determine the modulation type and constellation order of the input signal from the set of possible types/orders. The classification may be performed based on a decision tree, each leaf node of the decision tree corresponding to a type/order combination, and each non-leaf node corresponding to one or more of the comparisons. The set of possible types/order may include PSK with a number of different constellation orders and QAM with a number of different constellation orders.

Detecting the modulation type and/or constellation order of a PSK/QAM-modulated signal

A system and method for classifying an input signal suspected of being a wireless LAN signal. Bursts are isolated based on an analysis of an average power signal that is derived from the input signal. A correlation-based test is performed to determine if the input signal contains a Barker code typical of DSSS transmissions. Another correlation-based test is performed to determine of the input signal contains a long training sequence typical of OFDM transmissions. The results of the two tests are used to classify the input signal as being DSSS, OFDM or neither.

Classification of wireless LAN signals

A method for testing GPS receivers may read GPS files with data for a plurality of GPS satellites, and two or more GPS satellites may be selected from that data. The method may receive parameters for a GPS receiver to be tested. The method may generate two or more GPS signals for the two or more selected GPS satellites. The method may operate on the two or more GPS signals using the received parameters for the GPS receiver to generate two or more calculated GPS signals. These two or more calculated GPS signals may be re-sampled to a common rate. The two or more re-sampled GPS signals may be added together to create a composite GPS signal. The composite GPS signal may be generated using a hardware signal generator, where the composite GPS signal used to test the GPS receiver.

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Abhay Samant