Walsh code


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Walsh code

Also known as "Walsh-Hadamard code," it is an algorithm that generates statistically unique sets of numbers for use in encryption and cellular communications. Known as "pseudo-random noise codes," Walsh codes are used in direct sequence spread spectrum (DSSS) systems such as Qualcomm's CDMA. They are also used in frequency hopping spread spectrum (FHSS) systems to select the target frequency for the next hop. See CDMA.

Walsh Code Algorithm

          (a', b') = (a+b, a-b)
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It is capable of lightning-fast scans in multiple frequency bands, with multiple technologies, doing PN and Walsh Code, CPICH, DVCC, and BSIC decoding simultaneously.
As with previous designs, CDMA mode delivers Ec/Io, Ec/Ep, PN offset, delay, spread, individual Walsh code measurement, technology indication (1X, EVDO), All PN scan as well as an automated Top PN scan.
The scanner module operates in the CDMA450 Block A band (452-458MHz) and supports RSSI, Ec/Io, Ec/Ep, chip delay, chip spread, individual Walsh code measurement, 'All PN' scan as well as an automated Top PN scan.
Automated CDMA features available on the NetTek field tool include code domain power in Walsh Code and Bit-Reversed formats; codogram to identify code power variations over time; pilot power to accurately measure pilot power even when traffic channels are present; and signal quality tests for Rho, Tau, Error Vector Magnitude (EVM), PN Offset, and Carrier Feedthrough.