GB2457492A

GB2457492A - TETRA Modem Adapter converts USB signals for transmission over Peripheral Equipment Interface RS-232 connection

Info

Publication number: GB2457492A
Application number: GB0802838A
Authority: GB
Inventors: Andy Collier; Rob Lovelace
Original assignee: TETRATAB Ltd
Current assignee: TETRATAB Ltd
Priority date: 2008-02-15
Filing date: 2008-02-15
Publication date: 2009-08-19
Also published as: GB0802838D0; WO2009101189A1

Abstract

An adapter 1 for use with a TETRA modem over a Peripheral Equipment Interface (PEI) link 3 can be connected to a computer motherboard using USB 7, RS-232 9 and special control 10 links. The PEI interface is based on RS-232 and a USB to RS-232 converter 8 is provided. The control and RS-232 links are connected directly to the PEI link, bypassing the USB to RS-232 converter. The adapter draws power from the computer's power supply via connector 11 and regulates it 12/13 to provide appropriate voltages on signal lines. The invention allows TETRA modems to be connected to computers without the need to re-engineer the computer.

Description

Data Transfer Apparatus This invention relates to apparatus, such as a modem, for transferring data between a host device and an external port, each of which is configured to operate in accordance with different data protocols.

Terrestrial trunked radio (TETRA) systems are widely used by government agencies and emergency services such as police, fire and ambulance services, and comprise a network of two-way transceivers, commonly known as "walkie-talkies", used for voice and data communications either on a one-to-one basis or within a group, or within a cellular network. The advantages over other mobile telephone systems include robust multi-mode operation that ensures speed and reliability of communication, high level of communications security, and longer range operation. In order that the benefits of TETRA communications can be utilised by a portable computer device, such as a laptop PC, it is known to provide a TETRA modem that is integrated with the motherboard of the computer. However, this arrangement requires that each different computer model needs to be re-engineered to incorporate a TETRA modem.

An object of the invention is to provide an improved way of providing a TETRA modem connection for a computer.

According to the invention, a data modem adapter is provided comprising a first port configured according to a first data communications protocol for connection to a data modem, a second port configured according to a second data communications protocol for connection to a computer, a signal converter connected between the first and second ports and adapted to convert signals between the first and second communications protocols, a power input connector for connection to a power supply of the computer, and a power converter adapted to convert power from the power supply of the computer to a power supply suitable for powering the adapter.

In use, the adapter can be readily installed in a standard computer with an interconnection via the second port for data transfer according to the second protocol, and a power connection from the computer via the power input.

The adapter preferably includes a first set of terminals which are connected to the first port to provide modem control inputs in accordance with the first protocol, and which are adapted to be connected to control outputs of the computer so that the computer can control the modem.

Furthermore, the adapter preferably includes a second set of terminals which are connected to the first port to provide modem data connections in accordance with the first protocol, and which are adapted to be connected to data connections of the computer configured in accordance with the first protocol so that the computer can output data signals to the modem directly if protocol conversion is not required.

The adapter may also include a voltage controller to adjust the voltage level of the signals applied to the first port so that they meet the requirements of the first protocol.

It will be appreciated that an adapter according to the invention can be readily installed in a standard computer without having to re-engineer the motherboard of the computer, and it provides a standard interface for connection to a TETRA modem. The adapter preferably takes the form of an interface board which can be readily mounted on the motherboard of the computer. In the particular example of a TETRA modem, the first protocol might be based on the RS232 communications protocol and the connection to the computer may be a USI3 connection. The signal converter converts signals from the USB to the RS232 protocol for output to the TETRA modem following any further matching of these signals to the TETRA modem communications protocol. The power converter is adjusted in accordance with the input power supply available from the computer so as to generate an appropriate power supply for the adaptor. Furthermore, any modem input controls from the computer are mapped appropriately onto the first set of terminals in the adapter for connection to the TETRA modem. Therefore, in installing the adapter in a standard computer there is a set-up procedure to be followed, but this is non-intrusive and can be readily implemented.

The invention is equally applicable to modems operating according to other communication protocols and for use in other computer devices besides a laptop.

The invention will now be described by way of example or reference the accompanying drawings in which: Figure 1 is a schematic drawing of a adapter according to the invention in the form on an interface board connected between a TETRA data modem and a motherboard of a computer, and Figure 2 is a schematic drawing of the layout of the components on the interface board of Figure 1.

The adapter illustrated comprises an integrated circuit board I suitable for fitting to the motherboard 2 of a laptop computer so as to form a communications interface between the computer and a modem communications port 3 which is mounted on the adapter and is configured for connection via a cable 4 to a TETRA data modem 5.

The componentry of the adapter I is shown in Figure 2 and comprises a PE! (Peripheral Equipment Interface) connection 6 which incorporates the modem port 3 to provide a connection over the cable 4 with the modem 5. The data communications protocol employed over the connection 4 is based on the RS232 standard.

The adapter 1 also has a USB communications port 7 for connection to a USB connection from the computer. A signal converter module 8 is mounted on the board I and connected between the USB port 7 and the PEI connector 6, and is adapted so as to convert data signals between the USB protocol and RS232 protocol of the modem 5 in transferring signals between the USB port 7 and the modem port 3.

The adapter I also has a set of RS232 terminals 9 which are connected to the PEI connector 6 so as to provide an alternative data communications connection to the modem over the port 3 and cable 4. Therefore RS232 connections from the computer can be connected directly to the terminals, by-passing the protocol converter 8.

A second set of terminals 10 is also provided on the adapter I which are connected to the PEt connector 6 and are configured to carry control signals between the computer and the modem 5 over the cable 4.

The adapter is powered from a suitable point in the circuitry the computer via a power Input connection 11 but the input power has to be converted to meet the voltage requirements of the adapter componentry, and therefore a voltage converter 12 is provided for this purpose. The voltage converter 12 is adjustable to accommodate different power inputs available in different computer models. Also, the adapter is provided with a voltage adjuster module 13 which serves to adjust the voltage level of the RS232 signals in the PEI so that these are matched to the particular RS232 protocol of the modem 5.

Switching ON and OFF of the adapter 1 is controlled by a power switch 14, which enables status switching of the modem from live to program mode. The switch 14 may be operated by the computer or may be manually operable by a user of the computer via a virtual switch.

Claims

Claims I. A data modem adapter comprising a first port configured according to a first data communications protocol for connection to a data modem, a second port configured according to a second data communications protocol for connection to a computer, a signal converter connected between the first and second ports and adapted to convert signals between the first and second communications protocols, a power Input connector for connection to a power supply of the computer, and a power converter adapted to convert power from the power supply of the computer to a power supply suitable for powering the adapter.
2 The adapter as claimed in claim 1 including a first set of terminals which are connected to the first port to provide modem control inputs in accordance with the first protocol, and which are adapted to be connected to control outputs of the computer so that the computer can control the modem.
3. The adapter as claimed in claim 1 or 2 including a second set of terminals which are connected to the first port to provide modem data connections in accordance with the first protocol, and which are adapted to be connected to data connections of the computer configured in accordance with the first protocol so that the computer can output data signals to the modem directly if protocol conversion is not required.
4. The adapter as claimed in any of the preceding claims including a voltage controller to adjust the voltage level of the signals applied to the first port so that they meet the requirements of the first protocol.
5. A data modem adapter substantially as herein described with reference to the accompanying drawings.