Telecommunications – Radiotelephone system – Including private cordless extension system
Reexamination Certificate
1997-03-27
2001-04-03
Nguyen, Lee (Department: 2746)
Telecommunications
Radiotelephone system
Including private cordless extension system
C455S062000, C455S450000, C455S465000, C455S513000
Reexamination Certificate
active
06212396
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to cordless telephones, and more particularly, to providing a telephone with an initial set of communications parameters at the time of manufacture and for providing provisions for changing communications parameters when the cordless telephone is placed in service or is already in service.
Cordless telephones normally include a base station and a handset which communicate over a radio frequency communications channel. Federal regulations provide for such communications to be carried out on any of a set of predefined channels. There are different bands of channels available for cordless telephone use. A band known as the CTO band includes 25 channel pairs, designated channels 1-25. Of these, only channels 16-25 can be used without first monitoring to check whether the channel is occupied. Most 25-channel CTO cordless telephones therefore start their communications on one of the channel pairs. In addition, cordless telephone manufacturers have implemented a security code feature in which a security code is included in transmissions between the base station and the handset to distinguish one call from another on the same communications channel. The communications channel and security code will hereinafter be referred to as communication parameters.
In addition to the aforementioned communication parameters, some applications of cordless telephones are preferably provided with brand line prompt information so that a user can observe on a display on the telephone, a prompt, indicative of the service provider and the like.
Normally, cordless telephones are manufactured with preprogrammed communications default parameters including initial channel selections. However, in order for a base and a handset to communicate with each other, they both must be programmed to communicate on the same channel. This requires that the base be matched to the handset at the time of shipping to ensure both are programmed appropriately. This increases the cost of production and forces the user to purchase a new base and a new handset in the event that one or the other must be replaced.
Another problem which occurs in cordless telephones is interference due to neighbouring telephones or other radio frequency equipment. When such interference occurs on a given channel, it is desirable to change the programming in the base and handset to cause the base and handset to communicate on a different channel.
It would be desirable if a base/handset pair could automatically locate a channel with a minimum amount of background noise and automatically program the base and handset to communicate on such channel.
BRIEF SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, there is provided a base apparatus of a cordless telephone. The base apparatus is operable to communicate with a handset of the cordless telephone on at least one communications channel within a channel set. The base apparatus includes a receiver for receiving signals from the handset and a transmitter for transmitting signals from the base to the handset. The base apparatus further includes a base working channel transmit buffer for storing a transmit channel indicator defining a channel on which the transmitter transmits signals. It further includes a base processor in communication with the receiver, the transmitter and the base working channel transmit buffer. The base processor is programmed to i) produce a first new channel message including a preferred channel identifier, ii)direct the transmitter to transmit the first new channel message in the signals transmitted from the base to the handset, on a channel defined by the contents of the base working channel transmit buffer, iii) successively load the base working channel transmit buffer with channel indicators corresponding to different channels within the channel set such that the first new channel message is successively transmitted on different channels, iv) receive an acknowledgment signal from the receiver when an acknowledgment signal is received from the handset and v) in response to the acknowledgement signal from the receiver, maintain in the base working channel transmit buffer a channel indicator associated with a last channel on which the message was transmitted immediately before the acknowledgment signal was received such that further communications between the base and the handset are conducted on the last channel.
Preferably, the base apparatus has a connector for supplying a charge current to the handset and includes a current sensor for measuring the charge current and for providing to the base processor a current detect signal which is rendered active when charge current exceeds a predefined value.
Preferably, the base processor is programmed to perform the step of successively loading the base working channel transmit buffer when the current detect signal is active.
Preferably, the base apparatus includes non-volatile memory for storing the preferred channel identifier.
Preferably, the base apparatus includes a power-up detection circuit for detecting and indicating to the base processor a power-up condition of the base.
Preferably, the base apparatus includes a base working channel receive buffer and preferably the base processor is programmed to copy the preferred channel identifier from the non-volatile memory to the base working channel transmit buffer and the base working channel receive buffer in response to the power-up condition.
Preferably, the base processor is programmed to transmit to the handset a prompt message including a prompt code associated with a prompt to be displayed on the handset for viewing by the user.
Preferably, the apparatus includes non-volatile memory for storing the prompt code.
Preferably, the base processor is programmed to direct the transmitter to transmit a wake-up message to the handset on a communications channel identified by the preferred channel identifier, prior to transmitting the first new channel message and is programmed to wait for a wake-up message acknowledgement signal from the handset and in response to the wake-up message acknowledgement signal, to maintain in the base working channel transmit buffer the transmit channel indicator identifying the channel on which the wake-up message was transmitted to the handset.
Preferably, the base receiver is operable to measure noise on at least some channels of the channel set and to provide to the base processor an indication of measured noise on each channel and preferably the base processor is programmed to receive the indication of measured noise on each channel and to identify the channel having the least measured noise.
Preferably, the base processor is programmed to direct the transmitter to transmit a second new channel message from the base to the handset, the second new channel message including a second new channel identifier identifying the channel with the least measured noise, such that further communications between the base and the handset are conducted on the channel with the least measured noise.
In accordance with another aspect of the invention, there is provided a handset apparatus operable to communicate with a base on at least one communications channel within a channel set. The handset apparatus includes a receiver for receiving signals from the base, a transmitter for transmitting signals to the base, and a handset working channel receive buffer for storing a receive channel indicator defining a channel on which the receiver receives signals. The handset further includes a handset processor in communication with the receiver, the transmitter and the handset working channel receive buffer. The handset processor is programmed to direct the receiver to receive a first new channel message including a preferred channel identifier, on at least one channel in the channel set and to direct the receiver to conduct subsequent communications with the base on a channel identified by the preferred channel identifier.
Preferably, the handset processor is further programmed to direct the transmitter to
Bleile Leonard George
Brown Paul Richard
Cobrin & Gittes
Nguyen Lee
Nortel Networks Limited
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