Patent GB-1283224-A (GB)
Title: Improvements relating to aircraft ground control systems and simulators
Inventor: HARRISON ROBERT NEAL
IPC: G09B9/04
Filed: 1969-07-10
Abstract: 1283224 Communicating with aircraft ground controllers SOLARTRON ELECTRONIC GROUP Ltd 23 June 1970 [10 July 1969] 34881/69 Headings H4K and H4L A station of a communication system is accessible from more than one other station and, when occupied with a direct speech connection with one of the other stations, a second other station requiring access is connected to a recording and playback machine which indicates to the busy station that a communication has been recorded and requires attention. The arrangement can be applied to an aircraft controller's position whereby if an emergency call is made by a pilot over an emergency channel while the controller is engaged with another pilot on his normal channel, the emergency call is automatically switched to a recorder a lamp being lit to indicate to the controller that an emergency call has been received and requires attention. The arrangement is specifically described, however, as employed in an aircraft ground control simulation system in which a number of controllers' positions have access to a single operator of a pilot control desk at which the response and behaviour of a number of aircraft can be simulated to control radar displays for the individual controllers. In the simulation system the control desk operator may receive one communication at a time direct from a controller, an additional controller wanting to talk to the operator at the same time being automatically connected to a recording and playback machine so that the operator is warned by a lamp signal and can collect the message when he is free. In either use an interim acknowledgement may be played from an auxiliary recording machine if the recorded communication is not called up by the recipient within a short time. The recording and playback machine has separate recording and playback capstans so that a recorded message is stored in a scramble box between the capstans. To prevent playing back of an initially silent portion of tape the playback capstan is driven for a short period of time at the onset of recording so that demand for playback finds the recorded message waiting on the verge of the playback head. Similarly, so that the end of the message can be drawn across the playback capstan the recording capstan is driven for a short period of time beyond the detected end of the received message. Each channel is monitored for the presence of speech which is gated onwards if no other channel is busy. A busy channel locks out other channels and routes them to recording and playback apparatus provided for each channel, or causes connection of one such apparatus from a pool, when any other channel shows activity. An indication is obtained for the difference between the amount of tape recorded and the amount played back, this indication controlling final disconnection of the playback capstan at the end of a message and also controlling the sending of the interim standby message if the difference exceeds a preset amount. The interim message may alternatively be sent if no response has been made within a set time or if, although the message is being played back, the message has not been heard through. During playback of a message the channel associated with the message is made busy and steers the other channels to recorders should they become active.