| 单词 | PWT-E (Personal Wireless Telecommunications-Enhanced) |
| 释义 | PWT-E (Personal Wireless Telecommunications-Enhanced) A U.S. standard for digital cordless telephony, based on the pan-European Digital Enhanced Cordless Telecommunications (DECT) standard and essentially an enhancement of PWT. PTW-E extends PWT into the licensed bands of 1850–1910 MHz and 1930–1990 MHz, and tightens the channel separation to 1 MHz. See also channel, cordless telephone, DECT, digital, and PWT. P × 64 (P times 64) An ITU-T videoconferencing specification more correctly known as H.320 and sometimes referred to as H.261, which actually specifies the video encoding technique. Designed for videoconferencing applications, P × 64 supports p channels of 64 kbps, up to a maximum of 30 channels, which is equivalent to E-1. P × 64 video formats include Common Intermediate Format (CIF), which is optional, and Quarter-CIF (QCIF), which is mandatory in compliant codecs. H.261 CIF supports 352 × 288 = 101,376 pixels per frame and 30 frames per second (fps), although lower frame rates also are supported. QCIF supports 176 × 144 = 25,344 pixels per frame, exactly 1⁄4 the resolution of CIF. See also CIF, codec, encode, frame, frame rate, fps, H.261, H.320, ITU-T, pixel, video, videoconference, and QCIF. |
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