H - Electricity – 04 – B
Patent
H - Electricity
04
B
H04B 7/005 (2006.01)
Patent
CA 2265667
There is provided a method for detecting TTY/TDD signals at an encoder, and for bypassing a speech coder if these signals are detected. The bitstream contains information about the TTY/TDD characters being transmitted. At the decoder, TTY/TDD tones are regenerated based on the received bitstream. An input signal is preferably high-pass filtered and is first processed by the TTY detector. If a TTY start bit is detected, the TTY encoder is used and at least one TTY character is encoded. The start bit detection is performed for each new TTY character. To ensure correct initialization of the speech coder after the transmission in text telephone mode, the memories of the speech coder are systematically reset to their initial states. This is important in particular when using VCO/HCO (Voice Carry Over/Hearing Carry Over) capability. If a TTY signal is not detected, the speech coder is used. At the decoder, the information regarding the nature of the signal must be available (speech or TTY). If a TTY signal is present, the TTY decoder is used, and a clean TTY signal is outputted (at nominal frequencies and with nominal character rate). Otherwise, the speech decoder is used. The output signal is preferably high-pass filtered. A concealment procedure is also included to ensure correct decoding of TTY/TDD signals even at high percentages of frame erasures and bit errors.
L'invention se rapporte à un procédé et un appareil permettant la commande de puissance, qui peut être utilisé dans un système de communications mobile ayant au moins une station mobile (12), laquelle est en communication avec au moins une station de base (16) par le biais de voies d'aller et de retour, et une unité (14) de contrôle des stations de base couplée à la station de base (16). La station mobile (12) envoie des messages de qualité ou d'erreur de trame indiquant une qualité de la voie d'aller reçue de la station de base (16). La station de base (16) reçoit ces messages et les achemine vers l'unité (14) de contrôle. En réponse à ces messages, la station de base détermine un niveau de puissance de transmission des signaux émis vers la station mobile (12). En réponse auxdits messages, l'unité (14) de contrôle détermine un niveau de puissance de transmission correct des signaux émis à partir de la station de base vers la station mobile (12) et envoie des signaux de commande indiquant le niveau de puissance à la station de base (16). La station de base (16) ajuste ensuite la puissance de ses signaux de transmission de voie d'aller envoyés à la station mobile (12) en réponse à ces signaux de commande provenant de l'unité de contrôle (14).
Qualcomm Incorporated
Smart & Biggar
LandOfFree
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