Full spectrum bat detectors continuously record all frequencies and retain details of the call structure, making them an excellent choice for detailed call analysis with bioacoustics software. They require a lot of power but when used with an external power source can be left in the field for weeks or months at a time. Passive full spectrum recorders are designed to be left in the field for unattended monitoring and have superior weatherproofing. Many of the passive full spectrum recorders can be programmed with advanced recording schedules based on sunrise and sunset times.