# US 5,353,341 A · Cordless telephone arranged for operation in a frequency hopping system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,353,341 A - Document ID: US5353341A - Status: Granted - Kind: A - Application number: 07/779,754 - Filed: 1991-10-21 - Granted: 1994-10-04 - Earliest claimed: 1991-10-21 - Assignees: AT&T Bell Laboratories - Inventors: Mark E. Gillis; Kenneth W. Leland; William J. Nealon; Hon Yu - Web page: https://patentgrep.com/patent/US5353341A ## CPC - H04B 1/7156: Arrangements for sequence synchronisation - H04M 1/72511: Searching for available channels - H04B 2001/71563: {Acquisition} - H04M 1/727: Identification code transfer arrangements - Y02D 30/70: in wireless communication networks - H04B: TRANSMISSION - H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract A cordless telephone arranged for operation in a frequency hopping system conserves battery power in a handset unit when this unit is located remote from an associated base unit and in a standby state. While in this standby state, the handset unit resides in a low power monitoring mode and monitors a channel pseudo-randomly selected from a plurality of available channels in the frequency hopping band for receipt of an initialization signal from the associated base unit. The base unit similarly monitors this selected one of the channels for receipt of this initialization signal from the handset unit. Should ongoing communications between the base unit and the handset unit be inadvertently interrupted, the cordless telephone quickly re-establishes communications in the frequency hopping system through an initialization process executed by both the handset unit and the base unit. ## Claims ### Claim 1 An arrangement for providing communications between a base unit and a handset unit in a cordless telephone employed in a frequency hopping system, the base unit including a first transmitter and a first receiver and the handset unit including a second transmitter and a second receiver for respectively transmitting to the first receiver and receiving from the first transmitter in the base unit over any one of a plurality of communication channels, the arrangement comprising: means for deactivating the second transmitter and the second receiver while the handset unit is located remote from the base unit and in a standby state; means for selecting one from a plurality of available channels in a frequency hopping band for initiating communications between the base unit and the handset unit while the handset unit is in the standby state; and means for communicating a start time over the selected one of the plurality of channels for the base unit and the handset unit to begin a frequency hopping cycle, the start time communicating means including means for generating in the base unit a series of data messages and for providing these data messages to the handset unit, the handset unit comprising means for acknowledging receipt of the data messages, the data messages being indicative of the start time for the base unit and the handset unit to begin the frequency hopping cycle, the data messages linearly decreasing in value with time to a predetermined value at which the base unit and handset unit begin the frequency hopping cycle. ### Claim 2 A method of initiating communications between a base unit and a handset unit of a cordless telephone employed in a frequency hopping system, the base unit including a first transmitter and a first receiver and the handset unit including a second transmitter and a second receiver for respectively transmitting to the first receiver and receiving from the first transmitter in the base unit over any one of a plurality of communication channels, the method comprising the steps of: selecting one from a plurality of available channels in a frequency hopping band for initiating communications between the base unit and the handset unit; configuring the second receiver for monitoring the selected one of the channels; transmitting an initialization synchronization pattern by the base unit over the selected channel and receiving this pattern by the handset unit over the selected channel; and communicating a start time over the selected one of the plurality of available channels for the base unit and the handset unit to begin a frequency hopping cycle, the communicating step including the steps of generating a series of data messages by the base unit, transmitting the data messages to the handset unit, and acknowledging to the base unit receipt of the data messages by the handset unit, the data messages being arranged for linearly decreasing in value with time and decreasing to a predetermined value at which the handset unit and base unit begin the frequency hopping cycle. ### Claim 3 (depends on 2) The method of claim 2 wherein the channel selected from one of the plurality of available channels is one in a group of channels selected by a pseudo-random sequence. ### Claim 4 An arrangement for providing communications between a base unit and a handset unit in a cordless telephone employed in a frequency hopping system, the base unit including a first transmitter and a first receiver and the handset unit including a second transmitter and a second receiver for respectively transmitting to the first receiver and receiving from the first transmitter in the base unit over any one of a plurality of communication channels, the arrangement comprising: means for selecting one from a plurality of available channels in a frequency hopping band for initiating communications between the base unit and the handset unit; means for configuring both the first receiver and the second receiver for monitoring the selected one of the channels; and means for communicating a start time over the selected one of the channels for the base unit and the handset unit to begin a frequency hopping cycle, the start time communicating means including means for generating in the base unit a series of data messages and for providing these data messages to the handset unit, the handset unit comprising means for acknowledging receipt of the data messages, the data messages being indicative of the start time for the base unit and the handset unit to begin the frequency hopping cycle, the data messages linearly decreasing in value with time to a predetermined value at which the base unit and handset unit begin the frequency hopping cycle. ### Claim 5 (depends on 4) The arrangement of claim 4 wherein the channel selected from one of the plurality of available channels is one in a group of channels selected by a pseudo-random sequence. ### Claim 6 (depends on 5) The arrangement of claim 5 wherein the group of channels includes a first set of channels for initiating communications and a second set of channels for maintaining ongoing communications between the handset unit and the base unit. ### Claim 7 In a cordless telephone, a handset unit arranged for communicating with a base unit in a frequency hopping system, the handset unit including a first transmitter and a first receiver for respectively transmitting to a second receiver and receiving from a second transmitter in the base unit over any one of a plurality of communication channels, the handset unit comprising: means for selecting one from a plurality of available channels in a frequency hopping band for initiating communications with the base unit means for configuring the first receiver for monitoring the selected one of the channels; and means for receiving a series of data messages from the base unit, the data messages being indicative of the start time for the base unit and the handset unit to begin the frequency hopping cycle, the data messages linearly decreasing in value with time to a predetermined value at which the base unit and handset unit begin the frequency hopping cycle. ### Claim 8 (depends on 7) The handset unit of claim 7 wherein the channel selected from the plurality of available channels is one in a group of channels selected by a pseudo-random sequence. ### Claim 9 (depends on 8) The handset unit of claim 8 wherein the group of channels includes a first set of channels for initiating communications with the base unit and a second set of channels for maintaining ongoing communications with the base unit. ### Claim 10 In a cordless telephone, a base unit arranged for communicating with a handset unit in a frequency hopping system, the base unit including a first transmitter and a first receiver for respectively transmitting to a second receiver and receiving from a second transmitter in the handset unit over any one of a plurality of communication channels, the base unit comprising: means for selecting one from a plurality of available channels in a frequency hopping band for initiating communications with the handset unit; means for communicating a start time over the selected one of the plurality of channels for the base unit and the handset unit to begin a frequency hopping cycle; and means for generating a series of data messages and for providing these data messages to the handset unit, the data messages being indicative of the start time for the base unit and the handset unit to begin the frequency hopping cycle, the data messages linearly decreasing in value with time to a predetermined value at which the base unit and handset unit begin the frequency hopping cycle. ### Claim 11 (depends on 10) The base unit of claim 10 wherein the channel selected from the plurality of available channels is one in a group of channels selected by a pseudo-random sequence. ### Claim 12 A method of communicating for a cordless telephone having a base unit and a handset unit employed in a frequency hopping system, the base unit including a first transmitter and a first receiver and the handset unit including a second transmitter and a second receiver for respectively transmitting to the first receiver and receiving from the first transmitter in the base unit over any one of a plurality of communication channels, the method comprising the steps of: selecting any one from a plurality of available channels in a frequency hopping band for initializing the handset unit and base unit on said selected channel while the handset unit is mated with the base unit, the selected channel being used for initiating communications between the base unit and the handset unit while the handset unit is located remote from the base unit and in a standby state; configuring both the first receiver and the second receiver while the handset unit is mated with the base unit, the first receiver and the second receiver monitoring the selected one of the channels while the handset unit is in the standby state; deactivating the second transmitter and reducing the on-time state of the second receiver while the handset unit is located remote from the base unit and is in the standby state; and transmitting an initialization synchronization pattern by the base unit over the selected channel and receiving this initialization synchronization pattern by the handset unit over the selected channel while the handset unit is located remote from the base unit, the initialization synchronization pattern including phase aligning signals and a security code signal, said phase aligning signals including a dotting sequence signal and a barker code signal for synchronizing the second receiver with the first transmitter. ### Claim 13 (depends on 12) The method of claim 12 wherein the channel selected from one of the plurality of available channels is one in a group of channels selected by a pseudo-random sequence. ### Claim 14 (depends on 13) The method of claim 13 wherein the group of channels includes a first set of channels for initiating communications and a second set of channels for maintaining ongoing communications between the handset unit and the base unit. ### Claim 15 (depends on 14) The method of claim 14 wherein the channel selected from one of the plurality of available channels for initiating communications comprises the first selected one of the first set of channels.