Programmable telephone

Details Programmable telephone Programmable telephone

1991-12-05

1995-01-24

Dwyer, James L.

Telephonic communications

Substation or terminal circuitry

Conversion of signal form

379395, 379421, 379390, H04M 160

Patent

active

053848420

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to telephones. It relates particularly, but not exclusively, to test telephones.
2. Description of the Prior Art
A telephone that is to be manufactured for export to a number of countries must be adaptable to comply with the signalling and functional protocols used by the telephone exchanges of the various countries. Typically, a different protocol is required for each country. Techniques have been developed for adapting telephones to different systems. However, these techniques have involved long lead-times, high costs for each new protocol, and only limited scope for change once a protocol has been implemented.
Many telephones now are supplied with memory functions such as last number redial and storage of commonly used numbers. In known telephones, these functions have been implemented using volatile memory maintained by primary batteries, a small current drawn from the line, or secondary batteries and a small line current. Batteries are expensive and liable to cause data loss on discharge, and small line currents are undesirable and disallowed in some countries.
When a telephone is used in a high noise environment, hearing the received signal can be a problem: (a) because the ambient noise is heard in the receiver as side tone and (b) the noise break-through through the telephone handset and the user's skull and sinuses dominates the received signal.
If the gain of the receiver were increased with the microphone unmuted it would produce two problems: (a) amplifed side tone with no improvement in the signal to noise ratio; (b) the telephone would have a tendency to generate acoustic feedback.
Embodiments of the invention may enable one to ameliorate one or more of the above problems.


SUMMARY OF THE INVENTION

In one aspect, the present invention proposes a telephone incorporating an EEPROM memory (also written as E.sup.2 PROM memory) containing at least part of the firmware for implementing the signalling and functional protocol. The EEPROM is connected to a microcontroller which controls the operation of the component parts of the telephone. Preferably, more than one protocol is stored in the EEPROM memory during manufacture, any one of which is selectable without hardware re-configuration. Preferably part of the EEPROM memory is set aside for storage of information generated while the telephone is in service. Furthermore, the EEPROM memory may obtain all of its operating power for both memory entry and retrieval operations from the telephone line while off-hook. The EEPROM retains data when on-hook without any external or battery supply.
In another aspect the invention provides a telephone in which the problems caused by ambient noise are ameliorated, by providing a telephone having means whereby the gain of the receiver may be increased and the microphone simultaneously cut off. The desired signal is thereby boosted while the unwanted side tone is reduced or eliminated. Preferably, the degree of gain may be varied, possibly in a series of steps. This may be applicable to any telephone that may be used in a high noise environment or where extra gain is required for the hard of hearing in order to reduce side tone interference. A preferred telephone embodies both the first and second aspects, and both may then employ the EEPROM.


BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings wherein:
FIG. 1 shows a schematic diagram of a telephone which is an embodiment of the present invention;
FIG. 2 shows the data structure in the EEPROM shown in FIG. 1;
FIG. 3 shows an exemplary circuit structure for the rectifier and the sounder shown in FIG. 1;
FIG. 4 shows an exemplary circuit structure of the speech circuit shown in FIG. 1; and
FIG. 5 shows an exemplary circuit structure of the constant-current source, the power-up reset circuit, the microcontroller, the dialler circuit and the EEPROM shown in FIG. 1.


D

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