Cospas-Sarsat is in the process of specifying a new, additional beacon modulation and message scheme based on spread-spectrum technology with quadrature phase-shift keying (QPSK). Presently beacons that will use this scheme are termed "second generation" beacons. This technology will allow the use of battery-saving lower-power transmissions, improve the accuracy of the determination of the beacon location by the Cospas-Sarsat System, and avoid the need for discrete channelization in the assigned 406.0 to 406.1 MHz band (e.g., avoiding the need for periodic closing and opening of channels by Cospas-Sarsat for use by beacon manufacturers based on narrowband channel loading). Second-generation beacons will have a longer transmission period of one second, with 250 transmitted bits, 202 of those being message bits. Additionally, the information sent in the message bits from one transmission to the next can be changed on a rotating transmission schedule ("rotating message fields") to allow significantly more information to be communicated over the course of a series of transmission bursts.