no at least not for cryptographic steganography i should say first that steganography is a much slipperier subject than cryptography it's harder to specify and analyze but a spread spectrum signal need not be any harder to detect than a narrow spectrum a signal that is transmitted at a very low bitrate may be difficult to detect but even this is not necessarily true in steganography the message is normally hidden inside another message the study of analog technical ways to transmit signals secretly is not really within the purview of steganography it includes tricks like line of sight infrared lasers transmissions as short high data rate bursts and other esoteric tricks jan utc