Methods and systems for gain adjustment in two-way communication systems

• US 6,101,375 A
• Filed: 07/07/1998
• Issued: 08/08/2000
• Est. Priority Date: 07/06/1992
• Status: Expired due to Term

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Tuttle, John R., Snodgrass, Charles K.
• Primary Examiner(s): Tsang, Fan S.
• Assistant Examiner(s): Nguyen, Lee
• Application Number:
  US09/111,048
• Time in Patent Office: 763 Days
• Field of Search: 455/69, 455/522, 455/88, 455/70, 455/38.3, 455/343, 455/92, 455/127, 455/68, 340/825.54, 340/825.06, 340/825.44, 340/539, 375/345
• US Class Current: 455/127.2
• CPC Class Codes: H04W 52/48 during retransmission after error or non-acknowledgment
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment

Abstract

A method for reducing the dynamic range required of an automatic gain control (AGC) circuit in a remote transceiver in 2-way communication between local and remote transceivers. By repeatedly transmitting a signal with successively increasing power from one transceiver until a response is received from the other transceiver, the dynamic range and hence complexity of the receiving circuit may be greatly reduced. The operating power of the remote transmitter can then be adjusted according to the level used by the local transmitter, thereby promoting the efficent use of the remote'"'"'s power supply.

Claims

1. A method of interrogating a portable RF transceiver, comprising the steps of:

providing an interrogator RF transceiver;

providing a portable RF transceiver that is substantially smaller and lighter than the interrogator RF transceiver;

the portable RF transceiver detecting whether it receives an interrogation RF signal;

in response to receiving an interrogation RF signal, the portable RF transceiver transmitting a Response RF signal;

the interrogator RF transceiver transmitting a first interrogation RF signal at a first power level;

after transmitting the first interrogation RF signal, the interrogator RF transceiver detecting whether it receives said Response RF signal;

if the interrogator RF transceiver does not detect that it has received said Response RF signal within a period of time following the transmitting of the first interrogation RF signal, the interrogator RF transceiver transmitting a second interrogation RF signal at a second power level that is higher than the first power level; and

if the interrogator RF transceiver receives said Response RF signal from the portable RF transceiver, the interrogator RF transceiver transmitting additional signals to the portable RF transceiver at a power level which exceeds by a predetermined amount the power level value of the interrogation signal in response to which the portable RF transceiver transmitted said Response RF signal.

2. A method according to claim 1, further comprising the subsequent steps of:

after the step of transmitting the second interrogation RF signal, the interrogator RF transceiver detecting whether it receives said Response RF signal;

if the interrogator RF transceiver does not detect that it has received said Response RF signal within a period of time following a last transmitted interrogation RF signal, the interrogator RF transceiver determining whether the power level of the last transmitted interrogation RF signal is less than a maximum allowable power level and, if not, then returning to the step of transmitting the first interrogation RF signal;

the interrogator RF transceiver transmitting an interrogation RF signal at a power level that is higher than the power level of the last transmitted interrogation RF signal; and

returning to the step of, after transmitting the second interrogation RF signal, the interrogator RF transceiver detecting.

3. The method according to claim 1, wherein

each of the interrogator RF transceiver transmitting steps further comprises the interrogator transceiver encoding the interrogation RF signal to indicate a current power level value;

and

the portable RF transceiver transmitting step further comprises the portable RF transceiver transmitting the Response RF signal at a power level based on the current power level value encoded in the interrogation RF signal received by the portable RF transceiver.

4. The method according to claim 1, further comprising the step of:

before the step of the interrogator RF transceiver transmitting the first interrogation RF signal, the interrogator RF transceiver transmitting a wake-up RF signal at a power level substantially higher than the first power level.

5. An RF communications system, comprising:

a portable RF transceiver configured to detect an interrogation RF signal and to transmit a Response RF signal in response to the interrogation RF signal being detected; and

an interrogator RF transceiver including

an RF transmitter circuit,

an RF receiver circuit configured to detect when the interrogator RF transceiver receives said Response RF signal, and

a power level control circuit configured to command the transmitter circuit of the interrogator RF transceiver to transmit a first interrogation RF signal at a first power level and, if the transceiver circuit of the interrogator RF transceiver does not detect said Response RF signal in response to the first interrogation RF signal, to transmit a second interrogation RF signal at a second power level that is higher than the first power level, said power level control circuit further comprising;

means for controlling the transmitter circuit of the interrogator RF transceiver, after the receiver circuit of the interrogator RF transceiver senses the Response RF signal, to transmit additional signals to the portable RF transceiver at a power level which exceeds by a predetermined amount the power level of the interrogation RF signal in response to which the portable RF transceiver transmitted said Response RF signal;

wherein the portable RF transceiver is substantially smaller and lighter than the interrogator RF transceiver.

6. The RF communications system according to claim 5, wherein:

the RF transmitter circuit of the interrogator RF transceiver encodes each interrogation signal to indicate the power level at which that interrogation signal is transmitted; and

the portable RF transceiver transmits the Response RF signal at a power level based on the power level encoded in the interrogation signal received by the portable transceiver.

7. The RF communications system according to claim 5, wherein the power level control circuit of the interrogator RF transceiver further comprises means for commanding the RF transmitter circuit of the interrogator RF transceiver to transmit, before transmitting the first interrogation RF signal, a wake-up RF signal at a power level substantially higher than the first power level.

8. A method of interrogating a portable RF transceiver, comprising:

providing an interrogator RF transceiver configured for transmitting interrogation RF signals at a plurality of power levels;

providing a portable RF transceiver configured for communicating with said interrogator RF transceiver, wherein said portable RF transceiver is substantially smaller and lighter than said interrogator RF transceiver;

setting a transmission power of said interrogator RF transceiver at a first power level;

transmitting an interrogation RF signal with said interrogator RF transceiver set at said first power level and waiting for a brief period of time for a response RF signal from said portable RF transceiver to said interrogator RF transceiver;

if said interrogator RF transceiver detects a response RF signal from said portable RF transceiver within said brief period of time, continuing communication between said interrogator RF transceiver and said portable RF transceiver at least at said first power level until communication is complete;

if said interrogator RF transceiver fails to detect a response RF signal from said portable RF transceiver within said brief period of time, increasing said transmission power of said interrogator RF transceiver to a second power level higher than said first power level;

transmitting an interrogation RF signal with said interrogator RF transceiver set at said second power level and waiting for a brief period of time for a response RF signal from said portable RF transceiver to said interrogator RF transceiver; and

if said interrogator RF transceiver detects a response RF signal from said portable RF transceiver within said brief period of time, continuing communication between said interrogator RF transceiver and said portable RF transceiver at least at said second power level until communication is complete.

9. The method of claim 8, further comprising increasing said transmission power of said interrogator RF transceiver from a level at which a response RF signal from said portable RF signal is detected before continuing communication with said portable RF transceiver.

10. The method of claim 8, further comprising including informational content of said interrogation RF signal prior to transmission thereof to indicate the power level thereof.

11. The method of claim 8, further including:

if said interrogator RF transceiver fails to detect a response RF signal from said portable RF transceiver responsive to transmission of said interrogation RF signal at said second power level within said brief period of time, increasing said transmission power of said interrogator RF transceiver to a third power level higher than said first power level;

transmitting an interrogation RF signal with said interrogator RF transceiver set at said third power level and waiting for a brief period of time for a response RF signal from said portable RF transceiver to said interrogator RF transceiver; and

if said interrogator RF transceiver detects a response RF signal from said portable RF transceiver within said brief period of time, continuing communication between said interrogator RF transceiver and said portable RF transceiver at least at said third power level until communication is complete.