Method and system for configuring a tower top low noise amplifier

1. A method of protecting a low noise amplifier (LNA), the method comprising:

acquiring a radio frequency control channel signal at a tower top low noise amplifier (TTLNA) system; and

determining LNA mode information from the acquired radio frequency control channel signal, wherein the step of determining LNA mode information from the acquired radio frequency control channel signal comprises detecting one of a plurality of predetermined frequencies within the acquired radio frequency control channel signal, wherein the step of detecting the one of the plurality of predetermined frequencies comprises:

detecting a first predetermined frequency of the plurality of predetermined frequencies to be within a first range of frequencies, and in response configuring the LNA to transmit mode, and

detecting a second predetermined frequency of the plurality of predetermined frequencies to be within a second range of frequencies, and in response configuring the LNA to receive mode.

2. The method of claim 1 , further comprising:

determining that the TTLNA is being initialized, and in response, setting the TTLNA into transmit mode.

3. The method of claim 1 , wherein the LNA mode information alternates from transmit mode to receive mode at least 200 times per second.

4. The method of claim 1 , wherein configuring the LNA comprises switching modes according to a time-division duplex (TDD) transmission scheme.

5. The method of claim 1 , wherein the step of configuring the LNA to transmit mode comprises isolating the LNA amplifier circuit from a downlink power amplifier.

6. The method of claim 1 , wherein the plurality of predetermined frequencies are in accordance with a frequency-shift keying (FSK) modulation format.

7. A method of protecting a low noise amplifier (LNA), the method comprising:

acquiring a radio frequency control channel signal at a tower top low noise amplifier (TTLNA) system;

determining LNA mode information from the acquired radio frequency control channel signal comprising detecting a sequence of predetermined frequencies within the acquired radio frequency control channel signal, wherein detecting a sequence of predetermined frequencies within the acquired radio frequency control channel signal comprises:

(i) detecting a first sequence of predetermined frequencies, and (ii) in response configuring the LNA to transmit mode, and

(iii) detecting a second sequence of predetermined frequencies, and (iv) in response configuring the LNA to receive mode;

configuring the LNA to receive mode when the LNA mode information indicates receive mode; and

configuring the LNA to transmit mode when the LNA mode information indicates transmit mode.

8. The method of claim 1 , further comprising,

detecting a loss of DC power at the TTLNA system and in response configuring the LNA to bypass mode.

9. The method of claim 1 , further comprising,

detecting an acquisition loss of the acquired radio frequency control channel signal and in response configuring the LNA to bypass mode.

10. The method of claim 9 , wherein configuring the LNA to receive mode occurs after transmit energy falls below a threshold level.

11. The method of claim 1 , wherein the steps of claim 1 are carried out in a Worldwide Interoperability for Microwave Access (WiMAX) system.

12. A tower top low noise amplifier (TTLNA) system comprising:

a signal extractor connected to a feed line, the signal extractor operable to extract a radio frequency control channel signal from the feed line;

a TTLNA controller connected to the signal extractor, the signal extractor providing the extracted radio frequency control channel signal to the TTLNA mode controller, the TTLNA controller operable to detect at least a first predetermined frequency within a first range of frequencies and a second predetermined frequency within a second range of frequencies from the provided signal;

a switching network connected to the TTLNA controller, the switching network comprising at least one low noise amplifier (LNA), the switching network operable to switch to an operating mode, wherein the operating mode is selected from the group consisting of a receive mode and a transmit mode,

wherein, in response to detecting the first predetermined frequency, the TTNLA configures the LNA to receive mode, and

wherein in response to detecting the second predetermined frequency, the TTNLA configures the LNA to transmit mode.

13. The TTLNA system of claim 12 , wherein the TTLNA controller demodulates the extracted radio frequency control channel signal before detecting the predetermined frequency.

14. The TTLNA system of claim 12 , wherein the TTLNA controller detects the receive frequency from the provided radio frequency control channel signal, and in response, instructs the switching network to switch to the receive mode.

15. The TTLNA system of claim 14 , wherein the switching network switches to the receive mode only when radio frequency transmit energy is not present in the feed line.

16. The TTLNA system of claim 12 , wherein the TTLNA controller detects the transmit frequency and in response, instructs the switching network to switch to the transmit mode.

17. The TTLNA system of claim 16 , wherein the switching network switches into the transmit mode by isolating the LNA.

18. The TTLNA system of claim 12 , where in the TTLNA controller detects a loss of the extracted radio frequency control channel signal, and in response, automatically instructs the switching network to switch into transmit mode.