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Broadcast receiver having integrated spectrum analysis

Broadcast receiver having integrated spectrum analysis description/claims

This application is a divisional of U.S. application Ser. No. 11/508,632, filed on Aug. 23, 2006, which claims the benefit of the filing date of U.S. Provisional Patent Application No. 60/710,833, filed Aug. 24, 2005, the disclosure of which is hereby incorporated herein by reference.

The frequency band that the broadcasters use for electronic news gathering (ENG) is transitioning from 17 MHz bandwidth channels to 12 MHz bandwidth channels. To maintain a substantially consistent level of quality, the current analog FM modulation scheme will be changed to a digital modulation scheme. The current workflow for establishing and maintaining a link between antennas typically requires aligning a simplex link using verbal feedback from the receive site back to the transmitter site. The feedback is usually provided by having an operator at a transmit site make a voice connection using 2-way radio or cell phone. The operator then performs initial antenna alignment in the analog FM domain using feedback from another operator at a receive antenna. Once antenna alignment is confirmed in the analog domain, a switch is then made to digital modulation. This process works adequately in a static environment. Once in the digital mode it is typically impossible to detect the presence of an adjacent channel transmitter that may cause interference until the picture starts to breakup or the BER deteriorates. By then, however, it is usually too late. When this occurs the user must switch back to analog mode to diagnose the problem.

In general, there are no tools currently available to adequately assist the operator in diagnosing link reliability issues in the digital mode. A solution that has been proposed and implemented is to add a spectrum analyzer to the 70 MHz intermediate frequency (IF) output of the receiver. This has proven to be a viable solution for isolating or identifying only a few problems related to on channel or co-channel interference. Such problems are incorrect modulation type of the transmitter or co-channel interference.

FIG. 1 is a diagram that illustrates a standard system configuration 100. As shown, a radio frequency (RF) signal 110 is received and amplified with an amplifier (LNA) 116. This signal is then down converted from the received RF frequency to a first IF frequency typically using a mixer 118 and synthesizer 122. The signal is then filtered with a wide band pass filter 126. The frequency of this first conversion is generally in the 800 MHz range. The specific frequency may vary based on the manufacturer's architecture. The signal is then further amplified at amplifier 130 and further down converted to a second IF frequency using mixer 134 and synthesizer 138. This is typically 140 or 70 MHz but not limited to these frequencies. The signal, now at a lower frequency, can be further filtered via filter 142 to remove adjacent channel signals located above and below the desired channel. After the filter 142, which is typically a narrow band-pass filter, the signal is usually further amplified using amplifier 146, i.e., automatic gain control (AGC), and applied to a demodulator 150 to recreate the original signal transmitted. Manufacturers of receivers will often provide an auxiliary IF output 156 for monitoring purposes. In this system architecture, a spectrum analyzer 160 can be connected external to the IF monitor point 156.

The system of FIG. 1 has generally been deployed and used to conduct link reliability analysis. The architecture of FIG. 1 has not, however, proven to be optimal for diagnosing the majority of link conditions that lead to link failure or reduce link reliability. A reason the aforementioned architecture is flawed is that many problems cannot be detected after filtering and after AGC amplification. Specifically, most interfering signals cannot be detected unless the transmitter is placed into standby mode, which results in the inability to see some types of adjacent or co-channel interference. Furthermore, when the transmitter is placed in standby mode, it is also very difficult to diagnose link problems because the AGC circuit in the receiver brings the noise floor or interference up to a level similar to the desired signal thereby disguising the real problem. This can cause operators or maintenance personnel to become confused and further complicate their job.

One place to monitor the link spectrum would be at the RF input. In this way, the full spectrum can be viewed relative the power levels of the channels of interest. But this architecture is relatively expensive as it duplicates the LNA and synthesizer circuitry. This method may also reduce the receiver's sensitivity because power intended for the receiver will be diverted to the spectrum analyzer.

As is further described in detail below, an aspect of the present invention is a receiver for receiving a broadcast channel comprising a spectrum analyzer integrated into the receiver and operative to receive an intermediate frequency signal and process the spectral contents of the receive signal.

In accordance with this aspect of the present invention, the intermediate frequency signal comprises a portion of a signal that results from a first down conversion of a radio frequency signal inputted into the receiver. Most preferably, the intermediate frequency signal is at a frequency of 800 MHz.

Further in accordance with this aspect of the present invention, the intermediate frequency signal may comprise a portion of a signal that results from a second down conversion of a radio frequency signal inputted into the receiver. Most preferably, this intermediate frequency signal is at a frequency of 70 MHz, but may also be at a frequency of 140 MHz.

In another aspect of the present invention, a broadcast receiver is provided. The receiver preferably comprises a spectrum analyzer that is physically integrated into the receiver and operative to receive an intermediate frequency signal and process the spectral contents of the receive signal.

In another aspect of the present invention, a broadcast receiver is provided. The receiver preferably comprises a spectrum analyzer that is externally integrated with the receiver and operative to receive an intermediate frequency signal and process the spectral contents of the receive signal. The externally integrated spectrum analyzer may desirably process a signal having a frequency of 800, 140 or 70 MHz.

In another aspect, the present invention is a system for performing antenna alignment in a broadcast system. The system preferably comprises a receiver having a spectrum analyzer integrated therein, a remote control unit connected to the receiver and operative to receive spectral data processed by the spectrum analyzer and a controller for processing the spectral data. Most preferably, the controller is connected to the remote control unit, although in some embodiments processing may be done at the remote control unit.

In accordance with this aspect of the present invention, the spectrum analyzer may be physically integrated into the receiver. Further in accordance with this aspect of the present invention, the spectrum analyzer is externally connected to the receiver.

Further in accordance with this aspect of the present invention, the spectrum analyzer is adapted to receive a signal selected from the group consisting of 800 MHz, 140 MHz or 70 MHz.

A further aspect of the present invention is a receiver for processing a broadcast signal. The receiver preferably comprises a first amplifier for amplifying a radio frequency signal; a mixer and synthesizer for down converting the amplified signal to a first intermediate frequency signal; and a spectrum analyzer integrated in the receiver for receiving a portion of the first intermediate frequency signal. In accordance with this aspect of the present invention, the first intermediate frequency signal of the receiver comprises a digital signal centered at a frequency of substantially 800 MHz.

Further in accordance with this aspect of the present invention, the radio frequency signal comprises a signal having a frequency of at least 2.0 GHz. Further still, the radio frequency signal comprises a signal that is less than 2.7 GHz. Yet further still, the synthesizer may desirably comprise a local oscillator having a frequency between 2.810 and 3.510 GHz.

Further in accordance with this aspect of the present invention, the receiver further preferably comprises a data port for communicating data signals associated with the digital signal. In addition, the data port is preferably selected from an interface selected from the group consisting of an RS 232 or universal serial bus interface.

In another aspect, the present invention comprises a system for aligning a radio antenna for a radio frequency broadcast signal, comprising: a receiver operable to receive the radio frequency signal and to produce an intermediate frequency signal having a frequency of approximately 800 MHz from the radio frequency signal; a remote control unit having a spectrum analyzer and adapted to receive the 800 MHz signal and data signals associated with the bit error ratio and receive level of the radio frequency signal, the remote control unit being further adapted to display a spectral content of the 800 MHz signal.

• Provisional Patent
• Utility Patent

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