| 摘要 |
1,151,536. Diver's communication system. M. COPEL. 3 June, 1966 [4 June, 1965], No. 24903/66. Heading H4R. Speech signals from a diver operating in an ambient atmosphere of helium and/or high pressure are rendered more intelligible by selecting two or more separate frequency bands from the speech signal and moving them down in frequency so that they are closer together, but not overlapping. In the described embodiment, the bands selected are 850 to 1700 c.p.s. and 2400 to 5000 c.p.s. and they are modulated twice, first by a common frequency of 8000 c.p.s. and then the upper sidebands are modulated by frequencies of 8600 and 9000 c.p.s. respectively from which the lower sidebands of 250 to 1100 c.p.s. and 1400 to 4000 c.p.s. are selected, added together and reproduced. It is suggested that a lower frequency band may be transmitted unchanged. Circuits for a system in which speech signals from three divers may be treated by apparatus according to the invention in order to allow them to converse easily with one another or with a tender, are illustrated in Figs. 4a, 4b and 4c (not shown). |
