Apparatus for encoding a plurality of received radio frequency (RF) analog signals. The apparatus includes a plurality of pseudo-noise (PN) encoders for performing analog signal spreading and down-conversion. Each PN encoder is configured to encode a respective received RF analog signal using a respective one of a plurality of mutually orthogonal PN complex codes and to output a respective PN-encoded analog signal. The apparatus also includes a PN complex code source configured to provide the mutually orthogonal PN complex codes to the plurality of PN encoders. The PN complex code source includes a code generator for generating multiple mutually orthogonal PN codes, and a complex modulator for modulating the mutually orthogonal PN codes.