| 摘要 |
<p>A triphonic sound system in which three independent stereophonically related audio frequency source signals L, R and C are combined to derived three other audio frequency signals M, S and T which respectively comprise (L+1.4C+R), (L-R) and (-1.4C). In a preferred transmitter embodiment, useful in television broadcasting, the audio signals S and T modulate (14, 16) two quadrature-related sub- carriers of the same frequency to develop two double-sideband, suppressed-carrier signals, the frequency of the subcarriers being sufficiently high as to assure a frequency gap between the lower sidebands of the modulated subcarrier signals and the audio frequency signal (L+1.4C+R). The aforementioned signals, and a pilot signal having a frequency which lies within the frequency gap, are combined (12) and frequency-modulated onto a high frequency carrier for the purpose of transmitting the same to one or more remote receivers. The receiver (Figure 6) is operative in response to reception of the high frequency carrier to reproduce each of the audio frequency source signals L, R and C, and includes means (20) for reproducing conventional monophonic and two-channel broadcasts. <IMAGE></p> |
