[. . . ] It operates on the carrier frequencies of 2. 3 and 2. 8 MHz for a high quality signal transmission. [. . . ] 502019 Technical Data Modulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FM, stereo Receiving frequencies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. 3/2. 8 MHz Frequency response (headphones). . . . . . . . . . . . . . . . . . . . . . . . . 50 ­ 16, 000 Hz Max. 125 dB (1 kHz) Nominal THD, total harmonic distortion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 1 % Signal-to-noise ratio. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . typ. A frequency range of 50 to 16, 000 kHz is covered by the stethoset receiver with a maximum sound pressure level of 125 dB at 1 kHz. The included rechargeable battery provides an operating time of 12 hours. The battery shall be Sennheiser BA 300, the stethoset receiver shall be Sennheiser HDI 1029-PLL 16-H. Product Variants RI 830 RI 830 S Cat. [. . . ] The battery shall be Sennheiser BA 300, the stethoset receiver shall be Sennheiser HDI 1029-PLL 16-H. Product Variants RI 830 RI 830 S Cat. [. . . ]