Transmitter battery like indication apparatus and method

• US 5,794,125 A
• Filed: 04/16/1996
• Issued: 08/11/1998
• Est. Priority Date: 04/16/1996
• Status: Expired due to Term

• Current Assignee: Shure Incorporated
• Original Assignee: Shure Brothers Incorporated
• Inventors: Grad, Steven M.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Bhattacharya, Sam
• Application Number:
  US08/632,677
• Time in Patent Office: 847 Days
• Field of Search: 455/38.3, 455/38.4, 455/67.1, 455/67.4, 455/67.7, 455/89, 455/115, 455/218, 455/343, 455/450, 364/710.12, 320/48, 340/636, 379/390, 379/421
• US Class Current: 340/636.1
• CPC Class Codes: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus for determining the status of a battery that powers a wireless microphone transmitter. The transmitter has a tone oscillator that produces a tone of a frequency beyond the audible limit which is transmitted, along with acoustical signals, to a receiver. The amplitude of the tone is changed as the battery voltage of the transmitter decreases. The receiver for the transmitter includes a circuit that detects the changes in amplitude of the high frequency tone. The front panel of the receiver, for example, may contain an LCD display on which a battery fuel gauge is present, indicating the remaining battery life of transmitter. When an amplitude change beyond a threshold is detected, the fuel gauge is updated, and the respective bar on the gauge is turned off.

Claims

1. In a wireless communication system comprising a transmitter having a battery and a receiver, a method for determining the status of said battery, comprising the steps of:

(a) transmitting a tone used for unsquelching the receiver from said transmitter to said receiver, said transmitter tone having a first amplitude associated with said battery being in a normal condition;

(b) changing the amplitude of said tone from said first amplitude to a second amplitude when the condition of said battery changes from a normal condition to a low battery condition;

(c) receiving said tone with said receiver;

(d) detecting said change in amplitude of said tone; and

(e) responsively alerting a user of said system of the low battery condition of said battery when said amplitude of said tone changes.

2. The method of claim 1, wherein said transmitter comprises a wireless microphone transmitter.

3. The method of claim 2, wherein said tone comprises a tone used for tone coded squelch.

4. The method of claim 3, wherein said tone comprises a sine wave having a frequency above the audible limit of a human.

5. The method of claim 4, wherein said tone comprises a 32.768 Khz sine wave.

6. The method of claim 1, wherein said step of changing the amplitude comprises the step of lowering the amplitude of said tone.

7. The method of claim 1, wherein said tone is generated by a tone oscillator, and wherein said step of changing the amplitude of said tone comprises the step of changing the amplitude of the output signal from said tone oscillator.

8. The method of claim 1, wherein said tone is generated by a crystal oscillator.

9. In a wireless communication system comprising a transmitter and a receiver, apparatus for indicating the status of a transmitter battery, comprising:

(a) tone generation means in said transmitter for generating a tone used for unsquelching the receiver, said tone having a first amplitude associated with said battery being in a normal condition;

(b) a circuit in said transmitter for detecting a change in voltage of said battery and responsively causing said tone generation means to change the amplitude of said tone from said first amplitude to a second amplitude when the condition of said battery changes from a normal condition to a low battery condition;

(c) means for transmitting said tone from said transmitter to said receiver;

(d) means in said receiver for receiving said tone;

(e) a low battery detection circuit in said receiver for detecting the change in amplitude of said tone from said first amplitude to said second amplitude and responsively generating a low battery signal; and

(f) an indicator responsive to said low battery signal, said indicator indicating the status of said transmitter battery.

10. A wireless microphone system, comprising:

(a) a microphone transmitter comprising

a battery;

a tone oscillator generating a high frequency tone used for unsquelching a receiver;

means for changing the amplitude of said tone from a first amplitude when the voltage level of said battery is in a normal condition to a second amplitude when the voltage level of said battery falls below a predetermined threshold; and

a transmitter for transmitting said tones;

(b) a receiver comprising

a circuit for detecting and amplifying said transmitted tones;

a low battery means for detecting when the amplitude of said tones generated by said oscillator have changed from said first amplitude to said second amplitude, said low battery detection circuit responsively generating a low battery signal; and

means for supplying said low battery signal to an indicator circuit alerting a user of said microphone system of the low battery condition of said transmitter battery.

11. The microphone system of claim 10, wherein said transmitter further comprises a DC--DC converter connected to said battery and supplying a constant voltage to the transmitter, the said tone oscillator being powered by a source which decreases with said battery via a DC amplifier.

12. The microphone system of claim 10, wherein said tone oscillator further comprises an output conductor, and wherein said means for changing the amplitude of said tone including means powering said tone oscillator.

13. The microphone system of claim 10 including:

a microcontroller connected to said battery and responsively issuing an output signal, said output signal comprising a first signal when said battery voltage is above a threshold level and a second signal when said battery voltage drops below said threshold,

a transistor receiving said first and second output signals from said microcontroller; and

resistance means in circuit with said transistor and said output conductor of said tone oscillator;

whereby said transistor changes the voltage drop across said resistance means in response to said output signal from said microcontroller, causing the output voltage of said tone oscillator on said output conductor to change depending on the condition of said battery.

14. A wireless microphone transmitter, comprising:

a transmitter battery;

an audio circuit receiving sound waves from a sound source and responsively generating an audio signal;

a tone oscillator generating a high frequency tone signal used for unsquelching a receiver; and

a summing means for combining said audio signal with said tone signal;

means for changing the amplitude of said tone from a first amplitude when the voltage level of said battery is in a normal condition to a second amplitude when the voltage level of said battery falls below a predetermined threshold; and

an RF circuit for transmitting said summed tone signal and said audio signal to a receiver for said microphone transmitter.

15. A wireless microphone receiver for receiving signals from a wireless microphone transmitter having a battery, comprising:

a detection circuit for detecting and amplifying high frequency tones for unsquelching the receiver from said microphone transmitter;

means for detecting when the amplitude of said tones changes from a first amplitude associated with said battery being in a normal condition to a second amplitude when the condition of said battery changes from a normal condition to a low battery condition and for indicating this change via a low battery signal; and

means for supplying said low battery signal to an indicator circuit, said indicator circuit activated upon receipt of said low battery signal.