Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
2006-03-07
2006-03-07
Pezzlo, John (Department: 2662)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S514000, C370S523000
Reexamination Certificate
active
07010000
ABSTRACT:
The invention generally relates to a modem connected via a digital interface to a switched public telephone network and to a method for probing the line properties. The modem communicates with a second modem also connected via a digital interface to the same switched public telephone network. The public telephone network may incorporate voice compression devices (ADPCM G.726, G.723 etc.), digital pads (digital attenuators), robbed bit signalling and echo cancelling devices. The probing sequence of the invention uses large amplitude changes in a symbol sequence (each symbol having a duration of 125 μs). After that single amplitude change, the signal may return to the previous value or continue with the new amplitude value for a number of symbols. The number of symbols is selected to be larger than any expected impulse response of a digital impairment of the channel. The amplitude value change must be large enough to produce a sufficient result in the presence of digital pads with or without the presence of RBS.
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Infineon - Technologies AG
Pezzlo John
Tsegaye Saba
LandOfFree
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