GB2211701A - An audio frequency sensing switch - Google Patents

Abstract

An audio frequency sensing switch Fig 1 has an ability to detect an incoming audio frequency signal from a secondary radio system and, consequent upon sufficient input, switch the use of selected primary radio circuits to the requirements of the secondary radio system. <IMAGE>

Description

AUDIO PPBQW1%Y SEJSIlG SVITCH This invention relates to an Audio Frequency Sensing Switch that detects a user selectable strength audio frequency and triggers action in another circuit.

The circumstances in which a number of individual radios are in use at the same time are well known in such operations as Taxing, Shipping, Aviation, Citizens' Band Radio and Cellular Telephones. The problem that the user of such configurations discovers is that the message from the secondary radio system may well be swamped by the traffic on the prime radio system. This problem is particularly relevant to Shipping and Aircraft where monitoring of emergency frequencies is undertaken and to Taxis where conflictions exist between entertainment reception and essential messages. (In the context of this application, the expression "system" is used to describe single and multiple radio installations.) The situation is that the prime radio system is set at a volume that makes it difficult, if not impossible, to hear the messages on the secondary radio system.

According to the present invention comprising two elements there is provided an Audio Frequency Sensing Unit as a primary electrical device to detect an incoming Audio Frequency (AF) signal in the secondary system and the Switching Circuit triggered by the first element to modify the normal output of the primary system.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows the Audio Frequency Sensing Unit; and Figure 2 shows the Switching Circuit (referred to as "Load" in Figure 1) when the system is applied to a Taxi operation in a four speaker mode and switched in idle mode, i.e. not initialised by the Audio Frequency Sensing Unit.

Referring to the drawing, the receiving secondary system passes an Audio Frequency (AF) signal to its speakers. These speakers are not connected to the system but the signal is directed to the detecting unit Figure 1. Upon detecting an AF signal, the detecting unit triggers the Switching Unit "Load" in Figure 1 to change the configuration of the speaker system Figure 2 mounted in the vehicle.

Once the AF signal ceases, the detecting circuit Figure 1 detects the loss of input and reverts to its quiescent state, thus allowing the Switching Unit "Load" Figure 1 to revert to its normal operation of passing the prime system's radio traffic as shown in Figure 2.

Claims (5)

CLA I luLS

1. An Audio Frequency Sensing Switch where the Audio Frequency Sensing Unit detects an Audio Frequency (AF) input and upon receiving such a signal outputs a signal to a Switching ("Load", e.g. relay) Circuit.

2. An Audio Frequency Sensing Switch that detects an AF input as in Claim 1 wherein the input AF value is user adjustable by means of a rheostat or variable resistor.

3. An Audio Frequency Sensing Switch as claimed in Claim 1 or Claim 2 wherein the "Load" (relay) circuit isolates a prime system circuit and feeds the secondary AF signal to the user determined circuit.

4. An Audio Frequency Sensing Switch as claimed in Claim 2 or Claim 3 wherein the prime systeins circuit is switched to an alternative circuit to provide for (e.g.) reduced volume.

5. kn Audio Frequency Sensing Switch substantially as described herein with reference to Figure i & 2 of the accompanying drawings.