Device and method for digitizing a receiver signal strength indicator (RSSI) signal

• US 6,122,495 A
• Filed: 11/13/1998
• Issued: 09/19/2000
• Est. Priority Date: 08/19/1998
• Status: Expired due to Fees

• Current Assignee: Winbond Electronics Corporation
• Original Assignee: Winbond Electronics Corporation
• Inventors: Ho, Hsiang-Te, Chiang, Hsing-Ya
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): BEAMER, TEMICA M
• Application Number:
  US09/191,802
• Time in Patent Office: 676 Days
• Field of Search: 455/67.3, 455/226.2, 455/226.1, 455/226.4, 375/317, 375/318
• US Class Current: 455/226.2
• CPC Class Codes: H03M 1/504 using pulse width modulation
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

A device and method for digitizing a RSSI signal in a wireless transmission system is disclosed, which comprises a micro-controller having a ring counter and a controller, a low-pass filter, and a comparator. To start a digitization process, the controller gradually increases a numeric control signal to control a ring counter to generate a square wave with different duty cycle. Subsequently, the square wave is filtered by a low-pass filter to obtain a DC threshold voltage. If the threshold voltage is larger than the RSSI voltage, the digitization process is complete and the final numeric control signal represents the digitized RSSI signal.

Claims

1. A device for digitizing a receiver signal strength indicator (RSSI) signal in a wireless transmission system having a transceiver which outputs a RSSI signal, the device for digitizing a RSSI signal comprising:

a micro-controller comprising a controller and a counter, responsible for monitoring and controlling operations of the wireless transmission system and the device for digitizing a RSSI signal, wherein the counter receives a numeric control signal from the controller and generates a square wave whose duty cycle is proportional to the numeric control signal;

a low-pass filter for filtering the square wave from the counter to obtain an approximate DC threshold voltage; and

a comparator having two inputs connected to the RSSI signal and the threshold voltage, respectively, wherein the comparator generates a comparison signal coupled to the controller;

wherein

the controller changes the numeric control signal to control the duty cycle of the square wave from a smallest value, wherein the numeric control signal represents the digitized RSSI signal when the threshold voltage is larger than the RSSI signal during a digitization process.

2. The device for digitizing a RSSI signal of claim 1, wherein the low-pass filter comprises a resistor and a capacitor, wherein one terminal of the resistor receives the square wave and the other terminal of the resistor is coupled to a capacitor to generate the threshold voltage, wherein two terminals of the capacitor are connected to the resistor and a ground, respectively.

3. The device for digitizing a RSSI signal of claim 2, wherein the capacitor and the resistor are coupled to a discharging signal from the controller to discharge the capacitor before the digitization process begins.

4. A device for digitizing a receiver signal strength indicator (RSSI) signal in a wireless transmission system having a transceiver which outputs a RSSI signal, the device for digitizing a RSSI signal comprising:

a micro-controller comprising a controller and a counter, responsible for monitoring and controlling operations of the wireless transmission system and the device for digitizing a RSSI signal, wherein the counter receives a numeric control signal from the controller and generates a square wave whose duty cycle is proportional to the numeric control signal;

a low-pass filter for filtering the square wave from the counter to obtain an approximate DC threshold voltage; and

a comparator having two inputs connected to the RSSI signal and the threshold voltage, respectively, wherein the comparator generates a comparison signal coupled to the controller;

wherein

the controller changes the numeric control signal to control the duty cycle of the square wave from a largest value, wherein the numeric control signal represents the digitized RSSI signal when the threshold voltage is smaller than the RSSI signal during a digitization process.

5. The device for digitizing a RSSI signal of claim 4, wherein the low-pass filter comprises a resistor and a capacitor, wherein one terminal of the resistor receives the square wave and the other terminal of the resistor is coupled to a capacitor to generate the threshold voltage, wherein two terminals of the capacitor are connected to the resistor and a ground, respectively.

6. The device for digitizing a RSSI signal of claim 5, wherein the capacitor and the resistor are coupled to a discharging signal from the controller to discharge the capacitor before the digitization process begins.

7. A device for digitizing a receiver signal strength indicator (RSSI) signal in a wireless transmission system having a transceiver which outputs a RSSI signal, the device for digitizing a RSSI signal comprising:

a micro-controller comprising a controller and a counter, responsible for monitoring and controlling operations of the wireless transmission system and the device for digitizing a RSSI signal, wherein the counter receives a numeric control signal from the controller and generates a control signal whose duty cycle is proportional to the numeric control signal;

a transistor having a base coupled to the control signal via a resistor, an emitter coupled to a reference voltage, and a collector, wherein the transistor is ON when the control signal is activated so that a square wave is generated from the collector;

a low-pass filter for filtering the square wave from the transistor to obtain an approximate DC threshold voltage; and

a comparator having two inputs connected to the RSSI signal and the threshold voltage, respectively, wherein the comparator generates a comparison signal coupled to the controller;

wherein

the controller changes the numeric control signal to control the duty cycle of the square wave from a smallest value, wherein the numeric control signal represents the digitized RSSI signal when the threshold voltage is larger than the RSSI signal during a digitization process.

8. The device for digitizing a RSSI signal of claim 7, wherein the low-pass filter comprises a resistor and a capacitor, wherein one terminal of the resistor receives the square wave and the other terminal of the resistor is coupled to a capacitor to generate the threshold voltage, wherein two terminals of the capacitor are connected to the resistor and a ground, respectively.

9. The device for digitizing a RSSI signal of claim 8, wherein the capacitor and the resistor are coupled to a discharging signal from the controller to discharge the capacitor before the digitization process begins.

10. A method for digitizing a receiver signal strength indicator (RSSI) signal in a wireless transmission system having a transceiver which outputs a RSSI signal, the method for digitizing a RSSI signal comprising the steps of:

providing a numeric control signal;

generating a square wave according to the numeric control signal, wherein the duty cycle of the square wave is proportional to the numeric control signal;

filtering the square wave to obtain an approximate DC threshold voltage;

setting the numeric control signal with a smallest value;

gradually increasing the numeric control signal when the RSSI signal is larger than the threshold voltage until the threshold voltage exceeds the RSSI signal; and

recording the value of the numeric control signal as the digitized RSSI signal.