| 摘要 |
Use of a single high-power amplifier, for common amplification of adjacentband television signals, is not only possible, but practical and economical. Such adjacent-band signals can include analog-format signals such NTSC signals, and digitalformat signals such as DTV signals, in all combinations (NTSC/DTV, DTV/NTSC, NTSC/NTSC and DTV/DTV). The amplifier preferably includes a tetrode-class tube (such as a diacrode) and a properly-chosen cavity resonator. Circuits provide analog-format (e.g., NTSC) and digital-format (e.g., DTV) signals under control of a common frequency reference. The amplifier input receives a signal from a device that cleanly and linearly combines the NTSC and DTV signals at broadcast frequency, and amplifies the combined signal for transmission through a single, common antenna. Thus, not only may a single antenna be used for transmission of adjacent-band analog-format and digital-format signals, but interference between the transmitted analog-format and digital-format signal components is avoided by virtue of the substantial linearity of the combiner and amplifier components.
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