GB2529417A

GB2529417A - Communications device

Info

Publication number: GB2529417A
Application number: GB1414664.1A
Authority: GB
Inventors: Simon Davies
Original assignee: SPECTRA GROUP UK Ltd
Current assignee: SPECTRA GROUP UK Ltd
Priority date: 2014-08-19
Filing date: 2014-08-19
Publication date: 2016-02-24
Anticipated expiration: 2034-08-19
Also published as: GB201414664D0; GB2529417B

Abstract

This application relates to a frequency conversion device 14 which includes a first connector 52 for connecting to a conventional terrestrial radio transceiver 10, and a second connector 36 for connecting to a satellite antenna 16. The radio transceiver preferably operates at UHF or VHF frequencies, and the satellite antenna preferably operates in the L-band. The frequency conversion device performs UHF/VHF to L-band upconversion to enable signals from the radio transceiver to be transmitted to a satellite, and performs L-band to UHF/VHF downconversion to enable signals from a satellite to be received at the radio transceiver. The frequency conversion device contains a frequency converter 40 which switches between transmit and receive modes. The frequency converter by default operates in a receive mode, unless the frequency conversion device detects 42 a transmit signal from the radio transceiver, in which case it operates in a transmit mode. The frequency conversion device may monitor temperature or antenna current or voltage, and activate a warning if one of these parameters falls outside a predetermined range.

Description

COMMUNICATIONS DEVICE

This invention relates to a communications device, and in particular to a communications device intended for use in conjunction with conventional radio transmitter/receiver equipment.

S

There are many situations in which there is a need to allow personnel in a range of locations to communicate with one another. The communications may take the form of, for example, voice and/or data communications. Where the personnel are reasonably closely located to one another, for example within a distance of, say, several tens of kilometres of one another, and so can be regarded as being in or near line of sight of one another, then one way in which they may communicate with one another involves the use of, for example, VHF or UHF radio communications equipment. Depending upon the nature and sensitivity of the information to be transmitted using the equipment, the equipment may incorporate appropriate encryption means so as to allow encryption of signals before transmission and to allow decryption of received signals.

Whilst such techniques operate well where the personnel who need to communicate with one another are located relatively close to one another, the techniques are of limited application where the personnel are spaced apart over a significant area. For example, if personnel on the ground are required to be in communication with a control centre located at a considerable distance from the personnel) possibly in a different country or a different continent) then relying upon VHF or UHF radio transmissions to provide communication between the personnel and the control centre is inappropriate as the radio transmissions are not able to propagate over a sufficiently large distance to permit effective communication.

To permit communications over greater distances, it is known to make use of satellite communications technology. However, the availability of such satellite communications both in terms of suitable equipment and in terms of availability of transmission bands is limited, and so tends to be costly. Consequently, it tends to be made available only to a small number of high priority radio users using specifically designed equipment to permit such communication.

Furthermore, the ability to provide personnel on the move with satellite based communications technologies is very limited.

It is an object of the invention to provide a communications device whereby at least some of S the disadvantages outlined hereinbefore are overcome or are of reduced impact.

According to the present invention there is provided a communications device comprising a first connection means for connection to a radio communications device, a second connection means for connection to a satellite communications antenna, frequency conversion means for converting signals received from the first connection means to a frequency required for use by the satellite communications antenna connected, in use, to the second connection means, and for converting signals received from the second connection means to a frequency required for use by the radio communications device connected, in use, to the first connection means, and a control unit operable to control the operation of the frequency conversion means, wherein the control unit is operable to detect whether or not a transmission is being received by the first connection means from the radio communications device and, where such a transmission is being received to place the frequency conversion means into a transmit mode in which it controls the frequency conversion means to convert the received transmission to the frequency suitable for use by the satellite communications transmitter, and where such a transmission is not being received by the first connection means places the frequency conversion means into a receive mode in which it controls the frequency conversion means to convert signals received at the second connection means to the frequency suitable for use by the radio communications device.

The use of such an arrangement is advantageous in that it allows personnel to use their existing radio communications device in substantially the usual manner, but the transmissions therefrom are automatically converted to a frequency suitable for use in satellite communications, for transmission using the satellite communications antenna, and that signals received using the satellite communications antenna are automatically converted to a frequency suitable for use by the radio communications device for output to the personnel in the usual manner. Any required encryption or encoding of transmissions can be undertaken by the radio communications device in the usual manner. Accordingly, no loss in transmission security arises through the use of the communications device of the invention. As the signals are transmitted by satellite, it will be appreciated that the distances over which the signals are transmitted may be significantly increased. Where only a single satellite is involved and so the S signals are re-transmitted by the satellite for reception by an antenna within the footprint of the single transmitter, beyond line of sight transmissions are possible. If morethan one satellite is included in the transmission path then potentially communications may be enabled between any two locations on the planet.

The satellite antenna is conveniently an L-band satellite antenna.

Preferably, the control unit is operable to introduce a switching delay when the frequency conversion means is switched between its transmit and receive modes. The switching delay may be of the order of 100-200ms in duration.

The device conveniently further comprises a power supply operable to power the control unit and the frequency converter. It may also supply power to the antenna as required. The power supply maybe integrated into the communications device, or may be located externally thereof.

The communications device may include a temperature sensor and the control unit may be operable to activate a warning in the event that the sensed temperature falls outside of a predetermined range. The warning is conveniently arranged to be activated in the event that the temperature of the device, or a part thereof) falls outside of the range of -30 to SOT. If the warning has been activated, it conveniently remains activated until the temperature falls within a normal working range, for example within the range of -26 to 58°C. when the alarm is activated, at least some of the operations of the device may be interrupted to assist in bringing the temperature back to within the normal operating range.

The device may further include diagnostic means monitoring a transmission path current, an antenna voltage and/or an antenna current, and operable to activate a warning in the event that one or more of these parameters falls outside of a predetermined range. The predetermined ranges for these parameters may depend upon whether the device is in its S transmit mode or its receive mode at any given time. Depending upon the nature of the warning, certain functions of the communications device may also be interrupted.

The invention further relates to a communications system comprising a radio communications device, a satellite communications antenna and a communications device as described hereinbefore, the radio communications device having an output connected to the first connection means of the communications device and the satellite communications antenna having an output connected to the second connection means of the communications device.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of a communications system incorporating a communications device in accordance with one embodiment of the invention; and Figure 2 is a diagrammatic representation of the communications device of Figure 1.

Referring to the accompanying drawings) a communications system in accordance with one embodiment of the invention is illustrated. The communications system comprises conventional UHF radio communications device 10 (referred to hereafter as a radio device), the output 12 from which is supplied to a communications device 14 described in further detail below for conversion to a frequency, for example in the range of ito 2 GHz, for transmission by a satellite antenna 16, preferably an L-band satellite antenna. A power supply unit 18 is provided to supply electrical power to the communications device 16 (and potentially to other parts of the communications system, if required, as denoted by line 18a). The satellite antenna 16 communicates via a satellite link 20 with the antenna 22 of another, similar communications system including a communications device 24, a power supply 26 and a radio device 28.

In use, where personnel controlling the radio device 10 wish to make a transmission, for S example a voice or data transmission) they operate the radio device 10 in the usual manner. If the transmission is to be encoded or encrypted, then the radio device 10 will encode or encrypt the transmission as usual before the transmission is transmitted to the communications device 14. The communications device 14, upon receipt of the transmission, modifies the frequency thereof to a frequency suitable for use by the satellite antenna 16 for transmission thereby, via the satellite communications link 20 to the antenna 22. The received signal is passed to the communications device 24, whereon the frequency is converted to a frequency suitable for use by the radio device 28 for output thereby. It will be appreciated that if the original signal was encoded or encrypted by the radio device 10, then the radio device 28 will be operable to decode or decrypt the received transmission.

Whilst the system illustrated makes use of a single satellite in the satellite communications link 20, it will be understood that this need not be the case, and that more than one satellite may be included in the link 20. Accordingly, the transmissions may be between locations that are close to one another, or between locations that are spaced apart from one another potentially by very significant, beyond line of sight distances. As the system makes use of the encryption or encoding techniques already present within the radio device, use of the system does not reduce the transmission security. Whilst Figure 1 illustrates hand held radio devices, it will be appreciated that the system may be used with equipment mounted to vehicles, for example to motorised personnel carriers or the like, or to aircraft, or may be located in fixed locations.

Furthermore, whilst described in relation to a UHF radio device 10, it will be appreciated that the invention is also applicable to systems using VHF radio devices.

Turning to Figure 2, the communications device 14 comprises a housing 30 upon which is mounted a first connector 32 whereby a cable 34 carrying the output from the radio device 10 is connected, in use, to the communications device 14. Likewise, the housing 30 is provided with a second connector 36 whereby a cable 38 providing a connection between the communications device 14 and the satellite antenna 16 maybe connected, in use, to the housing 30.

Within the housing 30, and connected to the first and second connectors 32, 36, is provided a S frequency converter 40 operable to convert signals between the frequencies used by the radio device 10 and the satellite transmitter 16. The operation of the frequency converter 40 is controlled by a control unit 42. The control unit 42 and frequency converter 40 are powered by the power supply unit 18, which may be located externally of the housing 30 or may be incorporated therein. Where the communications system is a portable system intended for use by personnel on the move, then the power supply 18 may take the form of a battery located within a backpack also containing the communications device 10 and to which the satellite antenna 1 is mounted. Where vehicle mounted, then a power supply built in to the vehicle may be used to supply power to the communications system.

The control unit 42 is arranged to monitor, via line 44 in the diagrammatic representation of Figure 2, the output from the radio device 10 to ascertain whether a signal is being transmitted thereby. This is achieved by monitoring the applied input power. If the input power is below 5dB, then the radio device 10 is not being used to transmit a signal. If it is greater than 15dB, then a signal is being transmitted. At levels above 37dB then it is assumed that a system overload is being experienced. If it is determined that a signal is being transmitted, then the control unit 42 is operable to send a control signal via a control line 46 to the frequency converter 40 to place the frequency converter 40 into a transmit mode in which the frequency converter 40 takes the signal from the first connector 32 and converts it to a frequency suitable for use by the satellite antenna 16, outputting the frequency converted signal to the second connector 36 for onward transmission via the satellite communications link 20 to a remote location.

If, on the other hand, it is determined that no signal is being output from the radio device 10, then the control unit 42 operates so as to place the frequency converter 40 into a receive mode in which it takes the signal from the second connector 36 and converts it to a frequency suitable for use by the radio equipment 10, outputting the frequency converted signal to the first connector 32.

If an overload condition is sensed then both the transmit mode and the receive mode are S disabled until the input power returns to a level below 37dB.

In normal use, when the frequency converter 40 is placed into the transmit mode, a 5V antenna voltage is applied to the satellite antenna 16. Upon switching to the receive mode, the 5V antenna voltage is removed. A timer 42a forming part of the control unit 42 is then used to apply a 100-ZOOms delay interval, and after the delay interval has expired a 5V receive path voltage is applied. When switching from the receive mode to the transmit mode, as a first stage the receive path voltage is removed, then a 100-200ms delay interval is employed, and subsequently a 5V antenna voltage is applied. It will be appreciated that the 100-200ms delay is important forthe proper and correct functioning of the frequency converter40 and associated diagnostic checks described below. A similar routine is followed if the frequency converter 40 is being reactivated after an overload condition having been experienced.

To ensure that the communications device 14 is operating correctly, a number of diagnostics checks are conveniently undertaken continuously or periodically during the operation thereof.

By way of example, as the frequency converter 40 and control unit 42 will typically produce significant quantities of heat, and the correct and reliable operation of the device 14 is, at least to some extent, dependent upon the temperature of the device 14 remaining within a normal operating range, the communications device 14 conveniently incorporates a temperature sensor 48, the output of which is supplied to the control unit 42. If the sensed temperature falls within an acceptable range of, say, -30 to 80°C then no action is taken by the control unit 42.

However, if the sensed temperature falls outside of this range, the control unit 42 activates a warning device 50. The warning device 50 conveniently includes a series of LEDs or the like, one or more of which may be illuminated to indicate that the sensed temperature is outside of the acceptable range. However, other forms of warning device may be used. In addition, in order to safeguard the continued operation of the communications device 14 once the temperature has returned to an acceptable temperature, and to hasten the return of the temperature to the acceptable level, if the temperature exceeds the upper end of the range then the control unit 42 may operate to disable the antenna and receive path voltages, and thereby prevent the use of the device 14 in the transmission or reception of signals. The generation of heat is thus reduced, assisting in allowing the temperature to drop to an acceptable level.

Once it is sensed that the temperature has returned to an acceptable level, the antenna and receive path voltages may be reapplied, as appropriate, to allow continued use of the communications device 14, and the warning deactivated. The acceptable level for recommencing use of the device 14 and for deactivation of the warning need not be the same as that used to trigger the warning. By way of example, the acceptable range for reactivation of the device 14 may be -26 to 58°C.

Where the communications device 10 is to be vehicle mounted, then it may be possible to enhance cooling by mounting the housing 30 directly to part of the bodywork or the like of the vehicle such that the bodywork or the like can be used as a heat sink, assisting in cooling of the device. Where the device is to be used in a fixed location, then appropriate cooling means, for example a fan or the like may be employed to assist in cooling of the communications device 14. Where the communications device 14 is to be backpack located, then the additional weight and power requirements associated with providing a fan may not be acceptable, in which case the housing 30 is conveniently provided with cooling apertures to assist in allowing airflow through the communications device 14, aiding cooling, and the communications device 14 is conveniently positioned so as to assist with cooling.

A further diagnostic check which may be undertaken is to monitor the antenna voltage and current, for example using sensor line 52. An analogue to digital convertor may be employed to convert the analogue sensed signals to digital signals suitable for use by the control unit 42.

If the instantaneous antenna voltage is lower than OV or higher than 36V, then the warning device 50 is activated to output an antenna voltage warning. If the instantaneous antenna current is higher than 1.3A or, where the device is operating in the receive mode, the antenna current exceeds 3SmA for longer than lOOms or, where the device is operating in the transmit mode, the antenna current exceeds 500mA for longer than lOOms, then a high antenna current warning is output. Also, where the device is operating in the receive mode and the current is lower than lOmA or, where the device is operating in the transmit mode and the current is lower than lOOmA, a low antenna current warning is output.

If a high antenna current warning is generated, then the control unit 42 may place the communications device into the receive mode, allowing the continued reception of signals but inhibiting the transmission of signals.

Another diagnostic check involves monitoring the transmit path current, or example using sensor line 54. An analogue to digital converter may be employed to convert the measured analogue current signal to a digital signal for use by the control unit 42. where the device is in the transmit mode and the transmit path current is greater than 5lOmA, then an appropriate warning is output by the warning device 50. If, whilst in the transmit mode, the transmit path current drops below 3SOmA, then a low transmit path current warning may be output. In either case, the device may be placed into the receive mode, allowing the continued reception of signals but not permitting the transmission of signals.

The current and voltage diagnostic checks are preferably disabled during switching between the transmit and receive modes, and for a short time thereafter, in order to reduce the generation of spurious warnings.

A further diagnostic check involves monitoring the output of the power supply unit 18, generating a warning in the event that the output voltage of the power supply unit falls outside of a predetermined range, for example of 6.2 to 7.35V.

The use of the invention allows signals to be transmitted over long, beyond line of sight distances. The radio equipment 10 used by personnel may be standard equipment with which the personnel are familiar. There is no need to incur the expense of replacing existing equipment, nor for personnel to undergo significant training in order to use the invention.

It will be appreciated that whilst the description hereinbefore is of one embodiment of the invention, a number of modifications and alterations may be made thereto without departing from the scope of the invention.

S

Claims

CLAIMS: 1. A communications device comprising a first connection means for connection to a radio communications device, a second connection means for connection to a satellite S communications antenna, frequency conversion means for converting signals received from the first connection means to a frequency required for use by the satellite communications antenna connected, in use, to the second connection means, and for converting signals received from the second connection means to a frequency required for use by the radio communications device connected, in use, to the first connection means, and a control unit operable to control the operation of the frequency conversion means, wherein the control unit is operable to detect whether or not a transmission is being received by the first connection means from the radio communications device and, where such a transmission is being received to place the frequency conversion means into a transmit mode in which it controls the frequency conversion means to convert the received transmission to the frequency suitable for use by the satellite communications transmitter, and where such a transmission is not being received by the first connection means places the frequency conversion means into a receive mode in which it controls the frequency conversion means to convert signals received at the second connection means to the frequency suitable for use by the radio communications device.
2. A device according to Claim 1, wherein the satellite antenna is an L-band satellite antenna.
3. A device according to Claim 1 or Claim 2, wherein the control unit is operable to introduce a switching delay when the frequency conversion means is switched between its transmit and receive modes.
4. A device according to Claim 3, wherein the switching delay is of the order of 100-200ms in duration.
5. A device according to any of the preceding claims, further comprising a power supply operable to power the control unit and the frequency converter.
6. A device according to any of the preceding claims, further comprising a temperature S sensor) the control unit being operable to activate a warning in the event that the sensed temperature falls outside of a predetermined range.
7. A device according to Claim 6, wherein the transmit and receive modes are disabled if the sensed temperature exceeds an upper limit of the predetermined range.
8. A device according to any of the preceding claims, further comprising diagnostic means monitoring a transmission path current, an antenna voltage and/or an antenna current, and operable to activate a warning in the event that one or more of these parameters falls outside of a predetermined range.
9. A device according to Claim 8 wherein the predetermined ranges for these parameters depend, at least to some extent, upon whether the device is in its transmit mode or its receive mode at any given time.
10. A device according to Claim 8 or Claim 9, wherein the transmit and/or receive modes are disabled if the warning is activated.
11. A communications system comprising a radio communications device, a satellite communications antenna and a communications device as claimed in any of the preceding claims, the radio communications device having an output connected to the first connection means of the communications device and the satellite communications antenna having an output connected to the second connection means of the communications device.