Out-of-range warning system for cordless telephone

• US 5,373,548 A
• Filed: 04/08/1994
• Issued: 12/13/1994
• Est. Priority Date: 01/04/1991
• Status: Expired due to Fees

• Current Assignee: Thomson Consumer Electronics Incorporated (Vantiva SA)
• Original Assignee: Thomson Consumer Electronics Incorporated (Vantiva SA)
• Inventors: McCarthy, Dennis R.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US08/225,368
• Time in Patent Office: 249 Days
• Field of Search: 370/95.1, 379/56, 379/58, 379/61, 379/62, 379/63, 379/88, 379/356, 379/355, 455/33.1, 455/33.2, 455/34.1, 455/67
• US Class Current: 455/462
• CPC Class Codes: H04B 17/23 Indication means, e.g. displays, alarms, audible means
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04M 1/72502 with one base station connected to a single line
• CPC Class Codes: H04M 1/72516 with means for out-of-range alerting

Abstract

The present invention relates to a cordless telephone unit having a handset and a base unit. The signal strength of a handset which is received by the base unit is examined to determine whether or not the handset is beyond a predetermined range from the base unit. If such determination of out-of-range is made, a warning signal is transmitted from the base unit to the handset and if the handset is not brought within range within a predetermined number of warning signals, a hang up is initiated wherein the handset is placed in an "on" hook condition and the captured telephone line is released.

Claims

1. A cordless telephone unit having a handset unit and a base unit, the base unit being connectable to a telephone network and having actuatable means for seizing and releasing a telephone line of said telephone network, the handset unit having means for providing dialing and data signals to said telephone network, comprising:

duplex RF communications means between the handset and the base unit, said communications means including a base transmitter means and a base receiver means disposed in the base unit and a handset transmitter means and a handset receiver means disposed in the handset, said duplex RF communications including a carrier signal which is FM modulated with a first percentage of deviation,

signal strength determination means disposed in the base unit for determining the strength of the signal received by the base receiver means from the handset transmitter means,

range determination means disposed in the base unit for determining from the signal strength determination means whether the handset is at an out-of-range distance from the base unit,

warning means disposed in the base unit for transmitting a plurality of warning signals from the base unit to the handset when it is determined by the range determination means that the handset is at an out-of-range distance from the base unit, said warning signals FM modulating the carrier signal at a second percentage of deviation which is greater than the first percentage of deviation in order to provide, a warning signal at the handset at an out-of-range distance, and

means disposed in the base unit for putting the cordless telephone unit in an "on" hook status after a predetermined number of warning signals are transmitted.

2. A cordless telephone unit having a handset unit and a base unit, the base unit being connectable to a telephone network and having actuatable means for seizing and releasing a telephone line of said telephone network, the handset unit having means for providing dialing and data signals to said telephone network, comprising:

duplex RF communications means between the handset and the base unit, said communications means including a base transmitter means and a base receiver means disposed in the base unit and a handset transmitter means and a handset receiver means disposed in the handset, said duplex RF communications including a carrier signal which is FM modulated with a first percentage of deviation,

signal strength determination means disposed in the base unit for determining the strength of the signal received by the base receiver means from the handset transmitter means,

range determination means disposed in the base unit for determining from the signal strength determination means whether the handset is beyond a predetermined range from the base unit,

warning means disposed in the base unit for transmitting a plurality of warning signals from the base unit to the handset when it is determined by the range determination means that the handset is beyond the predetermined range, the warning means comprising a tone of predetermined duration that is modulated directly on the RF carrier overriding the normally transmitted signal, said warning tones FM modulating the carrier signal at a second percentage of deviation which is greater than the first percentage of deviation in order to provide a warning tone at the handset at a distance further than the predetermined range, and

means disposed in the base unit for putting the cordless telephone unit in an "on" hook status after a predetermined number of warning signals are transmitted.

3. A cordless telephone unit having a handset unit and a base unit the base unit being connectable to a telephone network and having actuatable means for seizing and releasing a telephone line of said telephone network, the handset unit having means for providing dialing and data signals to said telephone network, comprising:

duplex RF communications means between the handset and the base unit, said communications means including a base transmitter means and a base receiver means disposed in the base unit and a handset transmitter means and a handset receiver means disposed in the handset, said duplex RF communications including a carrier signal which is FM modulated with a first percentage of deviation,

signal strength determination means disposed in the base unit for determining the strength of the signal received by the base receiver means from the handset transmitter means,

range determination means disposed in the base unit for determining from the signal strength determination means whether the handset is at an out-of-range distance from the base unit,

warning means disposed in the base unit for transmitting a plurality of warning signals from the base unit to the handset when it is determined by the range determination means that the handset is at an out-of-range distance from the base unit, the warning means comprising means for transmitting the warning signals so that they are receivable by the handset even if the handset is at an out-of-range distance from the base unit, the warning signals comprising a tone of predetermined duration that is modulated directly on the RF carrier overriding the normally transmitted signal so that it can be heard at an out-of-range distance, said warning tone FM modulating the carrier signal at a second percentage of deviation which is greater than the first percentage of deviation in order to provide a warning tone at the handset at an out-of-range distance, and

means disposed in the base unit for putting the cordless telephone unit in an "on" hook status after a predetermined number of warning signals are transmitted.