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P-Q
PDC
Personal Digital Communications. A digital cellular standard presently being
used in Japan. To avoid the previous problem of lack of compatibility between
the differing types of earlier analog mobile phones in Japan (i.e. NTT type and
US developed TACS type), digital mobile phones have been standardised
under PDC. In the case of the PDC standard, primarily six channel TDMA
(Time Division Multiple Access) technology is applied. PDC, however, is a
standard unique to Japan which renders such phone units incompatible with
devices which adopt the more worldwide prevalent GSM standard.
Nevertheless, digitalisation under the standard enables ever smaller and lighter
mobile phones which in turn has spurred market expansion. As a result, over
930/0 of all mobile phones in Japan are now digital.
PHS
Personal Handyphone System. A digitalised evolution of the earlier analog
cordless phone concept which enables outdoor use as well. PHS incorporates
a unique Japanese standard which melds the advantages of the European
DECT and CT2. The system operates in the 1.9 GHz band.
PSTN
Public Switched Telephone Network. Switch-connected type
telecommunications circuitry provided by communication service operators. In
a narrow sense, it implies a subscriber telephone network. In a broader sense,
it is a concept which includes data communication as typified by the packet-
switched network (also referred to as PSDN). ISDN is sometimes included
within this definition. By connecting a computer or other type of terminal, a
user can communicate with multiple parties. PSTN services are broadly
categorised into four types, i.e. telephony, telegraphy, packet-switched (data
type) and circuit-switched (for data use).
QCIF
Quarter CIF (1/4C1 F). QCIF is as video image format which employs 176
horizontal pixels and 144 vertical lines. Although resolution is courser than
CIF, QCIF consumes less memory while still achieving an acceptable level of
clarity on small displays such as those incorporated in mobile phones.
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