Technologies are generally described for cognitive radio spectrum sensing via Code Division Multiple Access (CDMA) receiver coding. A CDMA module in the front-end of a cognitive radio system may be used to sense spectrum. When the system is not decoding or transmitting signals, a modified CDMA receiver coding may replace a pseudorandom code used in decoding with relatively pure, non-random detection frequency to scan for energy from primary users of the spectrum. Multiplication of the received signal by spectrally pure codes in place of the CDMA code renders the CDMA processor effectively a scanning spectrum analyzer and may detect energy at multiple frequencies. The allocation of sub-bands and/or timing may be adjusted to account for the detected energy.