There is provided an apparatus for determining a carrier-to-noise power density ratio (CN0) of a spread spectrum signal. The apparatus includes a signal power calculation unit and a conversion unit. The signal power calculation unit determines a signal power indicator indicative of a signal to noise ratio of the spread spectrum signal. The conversion unit is coupled to the signal power calculation unit and stores a lookup table representing a relationship between the signal power indicator and the carrier-to-noise power density ratio. The conversion unit is operable for converting the signal power indicator to the carrier-to-noise power density ratio according to the lookup table.