WO1993026097A1

WO1993026097A1 - Radio transmitting and receiving apparatus

Info

Publication number: WO1993026097A1
Application number: PCT/GB1993/001188
Authority: WO
Inventors: Nigel Corrigan
Original assignee: Premiair Systems Limited
Priority date: 1992-06-06
Filing date: 1993-06-04
Publication date: 1993-12-23
Also published as: GB9212067D0

Abstract

A radio transmitting and receiving apparatus including means for detecting simultaneous transmitter activity is provided with further means for controlling the operation following detection of the simultaneous transmission.

Description

RADIO TRANSMITTING AND RECEIVING APPARATUS

The present invention relates to a radio transmitting and receiving apparatus and more particularly to means for alerting an operator to a blocked transmit operation.

UK Patent No. 2083979, in the name of the present applicant, describes a means of blocking the operation of a second radio transmitter when a first transmitter is occupying the frequency and provides for the associated receiver of the second transmitter to remain operational despite a transmit action by the second operator. This continuing reception, of the first transmission by the second operator, alerts the second operator to a blocked transmit action. It is possible, particularly in aircraft, that background noise may obscure this alerting reception and leave the operator with no warning that a transmit action has failed to produce a transmission. Additional alerting tones, over the received audio, are inappropriate in aircraft as numerous tones are already used for other systems. It would be advantageous to present to the operator an audio cue that is unmistakably receiver activity and, additionally to cause an automatic increase in received signal volume whenever a blocked press-to- transmit action is detected. UK Patent No. 2083979 also provides a means of operator override of the blocking means to allow transmitter activation despite the detection of receiver activity. The means of override may be repeated operation of the press-to-transmit switch within a certain time period. In the event of an external and unintentional transmission disrupting the channel the operator is required to apply an override action for each transmission. Voice radio exchanges produce periodic channel activity and inactivity. In the case of normal aircraft communications uninterrupted channel activity never exceeds sixty seconds. This characteristic may be used to further improve the invention described in UK Patent No. 2083979 by detecting the presence of abnormally lengthy transmissions, such as those produced by a transmitter operating unintentionally and, by selectively disabling the blocking means, to eliminate the need for repeated override actions during such periods.

Accordingly, the present invention provides a switching means, operable only on detection of a blocked transmit action, and an audio signal consisting of wide-band noise, as results from operation of a conventional receiver test switch. Operation of the switching means applies the noise signal to the operators audio system. Preferably, the switching means is delayed for a period following a blocked press-to- transmit with its duration limited to a preset period. Additionally, a level of received audio signal greater than that normally supplied to the associated audio system is generated and routed to the audio system of the operator. Also provided is a switching means, operable following continuous receiver activity which exceeds a pre-set period, to cause deactivation of the transmitter blocking means until detection of receiver inactivity when the blocking means is reactivated for the period of the time delay.

The present invention provides a radio transmitting and receiving apparatus including means for detecting an incoming signal on a set frequency and for disabling the transmitter of said apparatus to prevent simultaneous transmitter operation on the set frequency and including further means for additionally controlling the operation of the transmitting and receiving apparatus following detecting of the incoming signal.

The apparatus preferably comprises means for providing an enhanced audible warning to the operator of the transmitting and receiving apparatus of the detection of an attempted simultaneous transmission. The apparatus further preferably comprises means for providing a hash warning signal to the operator of the transmitting and receiving apparatus on detection of an attempted simultaneous transmit operation by the operator.

Embodiments of the present invention will now be described by way of example, with reference to the accompanying drawing in which;

Figure 1 shows diagrammatically, circuitry according to the present , invention, and

Figure 2 shows a timing diagram illustrating the operation of the circuitry of Figure 1.

Figure 1 shows a partial embodiment of apparatus according to UK

Patent No. 2083979 by which a transmitter press-to-talk line 1 is controlled by switching means 2 to prevent transmission when an incoming transmission is detected ie. when there would be simultaneous transmission if the transmission was allowed to be commenced. Additional to switching means 2, an associated switching means 3 is incorporated. Switching means 3 serves to enable a preset time delay 4. Preset time delay 4 is configured to operate on receipt of a maintained signal from switching means 3, as shown, and to output a control signal 5 on expiry of the preset delay. Control signal 5 serves to enable an audio HASH generator 6 configured to provide a HASH signal, preferably of white noise and of a preset time period. A control link 106 from audio output stage 10 to hash generator 6 enables 6 only when receiver audio from 10 and control signal 5 are present. Thus, a press-to-talk signal blocked by the operation of switching means 2, as described in UK Patent No. 2083979, causes the HASH audio signal, delayed by preset time delay 4, to be applied to the operator's headphones 7 or associated audio control system. Additionally, switching means 3 controls a switching means 8 to operate and to switch out a resistor 9. A receiver output stage 10 is the audio output stage of the radio receiver with which the circuitry is associated by the audio signal path 11. Resistor 9, on being switched by switching means 8, causes an increase in received audio signal level at the operator's headphones 7. Alternatively, switching means 8 may be arranged to increase amplification of the receiver output stage 10. Thus the operator will be provided with either an increased audio signal or to a hash signal which will automatically alert him to the fact that his proposed transmit action has been prevented.

Additionally, switching means 2 is further controlled, by a time delay provided by a preset timer 12 and switching means 13. A control signal 14, for switching means 2, is routed through switching means 13 such that the control signal 14 may be disconnected from switching means 2. Preset timer 12 and switching means 13 respond to the control signal 14 in the following manner. Control signal 14 triggers preset timer 12 which, on expiry of the time delay, operates switching means 13. A control signal 14 which would relax switching means 2 resets the timer 12 to zero. Press-to-talk switches 15 operate as described in UK Patent No. 2083979.

This therefore operates to detect if a continuous transmission is detected for a preset period, for example 60 seconds. If it is then because in normal transmission there is not any signal which lasts for 60 seconds then it is assumed that there is a fault, for example a stuck microphone.

Without this additional circuitry the operator would not suspect a stuck microphone or other fault and on attempting to transmit would be blocked. On trying again later the operator would also be blocked but may assume a normal busy channel. Thus an operator could be blocked for several attempts.

The additional circuitry ensures that this is not so. After the delay the continuous transmission circuitry is de-energised and the operator can transmit over any incoming signal.

The operation of delay means 4 is illustrated with reference to Figure 2.

In Figure 2(a) the RF output of third parties is shown. Party A transmits up to T₀ but finishes speech at Tj.

With reference to Figure 2(b) party C operating the circuitry of

Figure 1 attempts a PTT at T₂ (between T, and T₀) when he detects that party A has finished speaking.

Because part A is still transmitting until T₀, party C is blocked by the "CON TRAN" equipment as described in UK Patent No 2083979.

As described in UK Patent Application No 2191659 a random clock in party C's equipment is triggered at time T₀ (providing T₀ is within a set time eg. 500 msec from T₂) and runs for example, for 200 msecs (T_RC). (If the time T₂ to T₀ is greater than 500 msec then party C is locked out).

At the end of this random clock a third party B has commenced transmission and thus party C is blocked from transmitting by the circuitry of UK Patent No 2083979. Delay 4 is operative to deliver the hash signal (HS) at a time T_D4 after its delay period which is for example, set at 1 second from T₂. The operator may realise prior to end of T_D4 that he has been blocked from transmitting by the absence of side tone, but if he does not, then the hash signal will be generated for the fixed period of for example, 500 msecs. The hash is, as described above, not provided if audio is being received.

Claims

1. A radio transmitting and receiving apparatus including means for detecting an incoming signal on a set frequency and for disabling the transmitter of said apparatus to prevent simultaneous transmitter operation on the set frequency and including further means for additionally controlling the operation of the transmitting and receiving apparatus following detecting of the incoming signal.

2. A radio transmitting and receiving apparatus as claimed in claim 1 in which the further means comprises means for providing an enhanced audible warning to the operator of the transmitting and receiving apparatus of the detection of an attempted simultaneous transmission.

3. A radio transmitting and receiving apparatus as claimed in claim 1 in which the further means comprises means for providing a hash warning signal to the operator of the transmitting and receiving apparatus on detection of an attempted simultaneous transmit operation by the operator.

4. A radio transmitting apparatus as claimed in claim 1 in which the further means comprises means for detecting the presence of an incoming transmission signal for a continuous preset period of time and including means responsive to such detection for overriding the disabling of the transmitter to enable the operator to transmit normally over the incoming transmission.

5. A radio transmitting and receiving apparatus as claimed in claim 2 in which the enhanced audible warning is provided by short circuitry of a series resistive element in a lead to earphones used by the operator.

6. A radio transmitting and receiving apparatus as claimed in claim 5 in which the short circuitry of the series resistive element is by means of a relay, said relay being energised by said means for detecting an incoming signal.

7. A radio transmitting and receiving apparatus as claimed in claim 3 in which the hash signal is provided by a hash signal generator connected in series with eaφhones used by said operator said hash signal generator being energised by said means for detecting an incoming signal.

8. a radio transmitting and receiving apparatus as claimed in claim 3 in which said means for providing the hash warning signal is actuated via a delay circuit.

9. A radio transmitting and receiving apparatus substantially as described with reference to the accompanying drawings.