Mobile speech level reduction circuit responsive to base transmitted signal
First Claim
1. A digital mobile radiotelephone unit for communicating with a base station having a hybrid unit connected between a two-wire circuit and a four-wire circuit, and an echo canceler for canceling an echo of an analog speech signal leaked through the hybrid unit, comprising:
- means for establishing a downlink channel with the base station for receiving a base-to-mobile coded speech signal;
a speech coding circuit for encoding a mobile-to-base speech signal into a coded speech signal;
means for establishing an uplink channel with the base station for transmitting the mobile-to-base coded speech signal on the uplink channel;
a speech decoding circuit for decoding the received base-to-mobile encoded speech signal into a decoded speech signal;
means for comparing the mobile-to-base coded speech signal with the received base-to-mobile coded speech signal and determining a difference in magnitude therebetween when the magnitude of the mobile-to-base coded speech signal is higher than the magnitude of the received base-to-mobile coded speech signal; and
means for reducing the magnitude of the coded mobile-to-base speech signal by an amount corresponding to the difference detected by the comparing means.
1 Assignment
0 Petitions
Accused Products
Abstract
In a mobile radio communication system where a base station is connected to a public switched telephone network, a hybrid unit and an echo canceler are provided in the base station. A mobile radiotelephone unit receives a base-to-mobile coded speech signal from the base station on a downlink channel and transmits a mobile-to-base coded speech signal on an uplink channel. In order to avoid the interruption of a base-to-mobile speech signal at the echo canceler which would occur as a result of a delayed, high-amplitude mobile-to-base analog speech signal, the mobile unit compares the energy parameter of the mobile-to-base coded speech signal and the energy parameter of the base-to-mobile coded speech signal, determines the difference therebetween when the former is higher than the latter, and reduces the energy parameter of the mobile-to-base speech signal by an amount corresponding to the difference.
45 Citations
11 Claims
-
1. A digital mobile radiotelephone unit for communicating with a base station having a hybrid unit connected between a two-wire circuit and a four-wire circuit, and an echo canceler for canceling an echo of an analog speech signal leaked through the hybrid unit, comprising:
-
means for establishing a downlink channel with the base station for receiving a base-to-mobile coded speech signal; a speech coding circuit for encoding a mobile-to-base speech signal into a coded speech signal; means for establishing an uplink channel with the base station for transmitting the mobile-to-base coded speech signal on the uplink channel; a speech decoding circuit for decoding the received base-to-mobile encoded speech signal into a decoded speech signal; means for comparing the mobile-to-base coded speech signal with the received base-to-mobile coded speech signal and determining a difference in magnitude therebetween when the magnitude of the mobile-to-base coded speech signal is higher than the magnitude of the received base-to-mobile coded speech signal; and means for reducing the magnitude of the coded mobile-to-base speech signal by an amount corresponding to the difference detected by the comparing means.
-
-
2. A digital mobile radiotelephone unit for communicating with a base station having a hybrid unit connected between a two-wire circuit and a four-wire circuit, and an echo canceler for canceling an echo of an analog speech signal leaked through the hybrid unit, comprising:
-
means for establishing a downlink channel with the base station for receiving a base-to-mobile encoded speech signal which is represented by speech parameters and an energy parameter; a speech coding circuit for encoding a mobile-to-base analog speech signal into speech parameters and an energy parameter; means for establishing an uplink channel with the base station for transmitting the encoded mobile-to-base speech signal on the uplink channel; means for comparing the energy parameter of the mobile-to-base. speech signal with an energy parameter of the received base-to-mobile encoded speech signal and determining a difference in magnitude between the energy parameters of the mobile-to-base signal and the base-to-mobile signal when the magnitude of the energy parameter signal of the mobile-to-base speech signal is higher than the magnitude of the energy parameter signal of the received base-to-mobile signal; means for reducing the magnitude of the energy parameter of the mobile-to-base speech signal by an amount corresponding to the difference detected by the comparing means; and a speech decoding circuit for decoding the received base-to-mobile encoded speech signal into a decoded speech signal. - View Dependent Claims (3)
-
-
4. A digital mobile radiotelephone unit for communicating with a base station, comprising:
-
a speech coding circuit for encoding a mobile-to-base speech signal into a coded mobile-to-base speech signal; means for comparing the mobile-to-base coded speech signal with a received base-to-mobile coded speech signal and determining a difference in magnitude therebetween when the magnitude of the mobile-to-base coded speech signal is higher than the magnitude of the received base-to-mobile coded speech signal; and means for reducing the magnitude of the coded mobile-to-base speech signal by an amount corresponding to the difference detected by the comparing means. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
-
Specification