DESC:TECHNICAL FIELD OF THE INVENTION
[0001] The present disclosure relates in general to field of wireless communication systems, and more particularly, relates to a system and method for gain segmentation and control for received narrowband radio frequency (RF) signals of voice/data.
BACKGROUND OF THE INVENTION
[0002] In recent times, there has been a significant development in semiconductor technologies thus resulting radio frequency (RF) to digital transceiver devices for wireless communication systems. Many receivers also include a device which automatically adjusts the gain of the amplifier according to the level of the received signal. Typically, the process of adjusting the gain, according to which a received signal should be amplified/attenuated, is referred as Automatic Gain Control (AGC). In other words, automatic gain control (AGC) is a closed loop feedback circuit that are generally used in wireless communication systems for maintaining a suitable signal amplitude at output. It is to be noted that the accuracy of AGC depends on initial stage of RF signal processing with proper conditioning/filtering, over the air RF signal impairments and AGC tuning algorithm.
[0003] There has been various methods and systems developed for AGC in wireless communication systems. One approach is multi carrier wireless systems with orthogonal frequency division multiplexing (OFDM) type of receive signals. In this approach, initially the gain programming is started with low level control, post the gain control the received signal power is computed. The gain is tuned till the received power based on a predefined threshold level, and this procedure is maintained continuously for the received signal.
[0004] Another approach relates to a method of AGC circuit operation and its fast and slow attack controls. In this approach, the received signal power is computed from the corresponding digital input/output samples followed by AGC control circuits, Further, AGC is implemented using a first order loop due to its stability and enhancement of first order AGC to overcome rapid signal variation in the context of frequency hopped receive RF signals. In this method the received average signal energy is compared with a threshold to decide fine or course gain mode gain settings on an error amplifier. Further, the received signal is passed through the channel filter to arrive a power level set point. The error between the average of received signal and the power set point is used to program the error amplifier.
[0005] Another approach is related to the digital AGC implementation using linearized AGC control at transmitter and received signal strength indicator (RSSI) based AGC control at the receiver. The method particularly relates to the gain control process in the context of Code Division Multiple Access (CDMA) type broadband signals. A received signal is demodulated to provide I and Q digital baseband signals, and a logarithmic RSSI is computed and subtracted with the logarithmic of designed desired signal. The resultant output is positive for the input signals larger than log of desired and negative for the signals smaller than the log of desired signals. The corresponding signal is integrated to control the receiver AGC. Further. an integrator is coupled to the received signal strength detector and is configured to integrate the digital power level signal to generate a digital AGC adjust signal, which is presumed to be linearly related to the desired receive gain setting (in dB). A receive AGC linearizer is coupled to the integrator. The receive AGC linearizer predistorts the linear digital AGC adjust signal to compensate for the nonlinearities in the AGC amplifier's response to the adjust signal.
[0006] Yet another approach of the automatic AGC is implemented using a variable gain AGC amplifier in the forward transmission path for processing the input RF signal before the mixer. This approach may particularly relate AGC gain control of time division multiple access (TDMA) type of signals. The capacitor acts as an integrator in connected with a voltage source primarily controls the AGC amplifier gain. The integrator charging and discharging controlled by the switch based on the received signal power detector level. Further, the method disclosed in this approach may include two operational modes. In the first mode start with a known reference time where in the slot is without signal energy, hence the charging capacitor charge with full voltage which in turn configures the AGC with full gain. The second mode includes catering of signal slots by closing the loop in conjunction detection signal energy there by charging and discharging of capacitor voltage which in turn controls the AGC amplifier gain to be increased/decreased.
[0007] However, the methods and systems discussed in the above approaches possesses challenges with fast and dynamic varying of received signals due to over the air obstructions, fading, system induced non linearities, RF signal impairments due to movement of system etc. This results in erroneous received signal amplitude, thus leading to programming of the system with wrong gain values. To that effect, the received signals attain saturation which results in impairments in recovered voice signal or data. Further, the existing methods and systems do not provide the received signal dynamic range for AGC gain tuning and allows overflow of the received signal at certain instances which is undesirable.
[0008] Therefore, there is a need for techniques for addressing the above-mentioned problems related to gain segmentation and gain control in the received signals, in addition to providing other technical advantages.
OBJECTIVE OF THE INVENTION
[0009] The main objective of the present invention is to provide an apparatus and a method for automatic gain control for radio frequency (RF) signals based on gain segmentation.

SUMMARY OF THE INVENTION
[0010] An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below.
[0011] Accordingly, in one aspect of the present invention relates to an apparatus for automatic gain control for radio frequency (RF) signals, the apparatus comprising: a Radio Frequency (RF) to digital transceiver to receive RF signals via a radio frequency (RF) front end of the apparatus, a controller communicably coupled to the RF to digital transceiver and a baseband processor and the controller configured to: determine a present received signal strength indicator (RSSI) corresponding to each of the received RF signals, determine if the present RSSI is less than a previous RSSI, store the present RSSI as previous RSSI for computation of an upcoming received RF signal, calculate gain value of the received RF signal and segment the received RF signals based on the calculated gain values and control the gain value for received RF signals based on the gain segmentation.
[0012] Accordingly, another aspect of the present invention relates to a method for automatic gain control for radio frequency (RF) signals by an apparatus, the method comprising: receiving RF signals, by a Radio Frequency (RF) to digital transceiver via a radio frequency (RF) front end of the apparatus, determining, by a controller of the apparatus, a present received signal strength indicator (RSSI) corresponding to each of the received RF signals, determining, by the controller, if the present RSSI is less than a previous RSSI, storing, by the controller, the present RSSI as previous RSSI for computation of an upcoming received RF signal, calculating, by the controller, gain value of the received RF signal and segment the received RF signals based on the calculated gain values and controlling, by the controller, the gain value for the received RF signals based on the gain segmentation, wherein the controller is communicably coupled to the RF to digital transceiver and the baseband processor.
[0013] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0014] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and modules.
[0015] FIG. 1 illustrates a simplified block diagram representation of an apparatus for gain segmentation and gain control, in accordance with an embodiment of the present disclosure;
[0016] FIG. 2 illustrates a simplified block diagram representation of the apparatus including processing components, in accordance with an embodiment of the present disclosure;
[0017] FIG. 3 illustrates a flowchart for creating a training data for training a controller of the apparatus of FIG. 1, in accordance with an embodiment of the present disclosure;
[0018] FIG. 4 is a graphical representation variation of RSSI values and RF signal level showing gain segmentation, in accordance with an embodiment of the present disclosure;
[0019] FIG. 5 illustrates a flowchart depicting a workflow of automatic gain control for received radio frequency (RF) signals, in accordance with an embodiment of the present disclosure; and
[0020] FIG. 6 illustrates a flowchart depicting a method for automatic gain control for radio frequency (RF) signals by an apparatus 100, in accordance with an embodiment of the present disclosure.
[0021] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative methods embodying the principles of the present disclosure. Similarly, it will be appreciated that any flow charts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
[0023] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
[0024] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.
[0025] References in the specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
[0026] Figures discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged communications system. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions in no way limit the scope of the invention. Terms first, second, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. A set is defined as a non-empty set including at least one element.
[0027] In the following description, for purpose of explanation, specific details are set forth in order to provide an understanding of the present disclosure. It will be apparent, however, to one skilled in the art that the present disclosure may be practiced without these details. One skilled in the art will recognize that embodiments of the present disclosure, some of which are described below, may be incorporated into a number of systems.
[0028] However, the systems and methods are not limited to the specific embodiments described herein. Further, structures and devices shown in the figures are illustrative of exemplary embodiments of the presently disclosure and are meant to avoid obscuring of the presently disclosure.
[0029] It should be noted that the description merely illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present invention. Furthermore, all examples recited herein are principally intended expressly to be only for explanatory purposes to help the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.
[0030] The various embodiments of the present disclosure/invention describe an apparatus and method for automatic gain control for radio frequency (RF) signals.
[0031] In an embodiment of the present invention, an apparatus and method for real-time gain tuning of automatic gain control (AGC) for improved signal/data detection. In particular, the apparatus is configured to monitor signal variations in the received radio frequency (RF) signal. Thereafter, the apparatus formulates the required gain for different levels of the received RF signal based on required gain statistics. The apparatus implements gain segmentation technique by differentiating linear gain and fixed gain regions for very low and very high-power signals for controlling the received RF signal. In addition, the apparatus is configured to monitor random and rapid gain variations associated with the received RF signal to avoid AGC control with false gain controls. Further, the apparatus facilitates AGC gain control period using different time windows which controls gain control selectively for different modulation types (frequency modulation (FM) / amplitude modulation (AM)). Also, the apparatus operates dynamically that offers flexibility to tailor for any applications that includes of burst inputs signals with different modulated RF signals.
[0032] Various embodiments of the present disclosure are further described with reference to FIG. 1 to FIG. 6.
[0033] FIG. 1 illustrates a simplified block diagram representation of an apparatus 100, in accordance with an embodiment of the present disclosure. The apparatus 100 is configured to facilitate gain control using gain segmentation technique. The apparatus 100 corresponds to radio frequency (RF) to digital converter-based transceiver chip that is interfaced with microcontroller and a baseband processor which is explained further in detail.
[0034] The apparatus 100 includes a radio frequency (RF) front end 102, a RF to Digital transceiver 104, a baseband processor 106 and a controller 108. Further, the components of the apparatus 100 provided herein may not be exhaustive, and the apparatus 100 may include more or fewer components than that of depicted in FIG. 1. Further, two or more components may be embodied in one single component, and/or one component may be configured using multiple sub-components to perform the desired functionalities. Some components of the apparatus 100 may be configured using hardware elements, software elements, firmware elements, and/or a combination thereof.
[0035] As shown, the RF front end 102 is configured to receive an input signal from an antenna. The input signal includes a raw RF signal. For example, the raw RF signal may contain voice/data signals. The RF front end 102 include suitable logic and/or interfaces for RF signal pre-processing for conditioning the received raw RF signal. In other words, the RF front end 102 performs RF signal pre-processing for filtering the received raw RF signal and noise removal thereby boosting the received raw RF signal to a threshold level defined for the RF signal pre-processing in the RF front end 102. Thereafter, the conditioned RF signal is transmitted to the RF to digital transceiver 104 for further processing.
[0036] The RF to digital transceiver 104 and the baseband processor 106 are based on programmable logic device and the controller 108 is interfaced with the RF to digital transceiver 104 and the baseband processor 106. In other words, the controller 108 is communicably coupled to the RF to digital transceiver 104 and the baseband processor 106 via an input/output interface. Some non-exhaustive examples of input/output interface may include, but not limited to, Serial Peripheral Interface (SPI), general purpose input/output (GPIO).
[0037] The controller 108 corresponds to a microcontroller. The controller 108 may include one or more processing units (e.g., single core processors, multi-core processors, etc.). In an embodiment, the controller 108 may be implemented by one or more application specific integrated circuits (ASIC), digital signal processors (DSP), digital signal processing devices (DSPD), programmable logic devices (PLD), field programmable gate array (FPGA), controller, microprocessor, or other electronic components, used to perform the above-mentioned methods.
[0038] The controller 108 is used to initialize and control the RF transceiver using its memory mapped registers set. The controller 108 is configured to perform one or more operation of the method described herein for performing gain control. In general, the controller 108 executes the method by accessing and programming the RF to digital transceiver 104 programmable registers. Thereafter, the baseband processor 106 collects samples from the RF to digital transceiver 104 and process with demodulation techniques to recover the final audio samples or data based on modulation techniques which will be explained further in detail.
[0039] Referring to FIG. 2 in conjunction with FIG. 1, a simplified block diagram representation of the apparatus 100 including processing components of the apparatus 100 is shown, in accordance with an embodiment of the present disclosure. As shown, the apparatus 100 includes a RF pre-processing block 202. The RF pre-processing block 202 is associated with the RF front end 102. The RF pre-processing block 202 executes the functions of filtering, amplification, and limiting of received signal with excess amplitude as explained above. Thereafter, the pre-amplified RF signal (i.e., the conditioned RF signals) is transmitted to the transceiver 104.
[0040] The transceiver 104 includes an RF to digital samples converter 204. The RF to digital samples converter 204 converts the conditioned RF signal to digital samples. In particular, the RF to digital converter 204 outputs In-phase / Quadrature (I/Q) signals to a digital samples’ processor 206. In general, I/Q signaling refers to the use of two sinusoids that have the same frequency and a relative orthogonal phase shift. Thus, amplitude, phase, and frequency modulation can be performed by summing amplitude-modulated I/Q signals.
[0041] The digital samples processor 206 is an example of the baseband processor 106 of FIG. 1. The baseband processor 106 is configured to decode the received RF digital samples (i.e., I/Q data) from the RF to digital converter 204 and produce the final recovered audio samples or recovered data bits based on voice or data demodulation techniques.
[0042] Further, the controller 108 is interfaced with the RF to digital transceiver 104 and the baseband processor 106 to control various settings such as RF frequency, sampling rate, gain mode with manual/automatic, gain setting in manual gain mode, etc., The controller 108 also receives information on receive/transmit mode, receive sample time, etc. Thus, it is to be noted that the controller 108 configures the programmable logic device (i.e., the transceiver 104 and the baseband processor 106) with mode of operation such as voice (FM/AM)/data mode configurations.
[0043] FIG. 3 illustrates a flowchart 300 for creating a training data for training the controller 108, in accordance with an embodiment of the present disclosure.
[0044] At 302, received signal strength indicator (RSSI) for different input RF signals are identified. Specifically, the input RF signals of different frequencies may be generated by a signal generator and corresponding RSSI for each of the input RF signals are determined.
[0045] At 304, a look-up table is created by including data related to RSSI values for different RF signals. Thereafter, gain values are determined for the RSSI values associated with the received input RF signals. The gain values are determined based on an output threshold (see, 306). Specifically, the RSSI versus gain relation is formulated by feeding the wireless communication receiver with the known modulated RF signals. The input RF signal level is varied for the receiver dynamic range 0dBm to -113dBm and gain versus RSSI mapping is derived. For example, the output threshold for an audio signal is referred using Signal-to-noise and distortion ratio (SINAD). The standard SINAD or the output threshold (i.e., SINAD) may be 12 decibels (dB). It is to be noted that the SINAD is fixed as 12 dB for 25 kilohertz (kHz). Thus, the gain values adjusted for various input RF signals based on the output SINAD is determined and augmented in the loop-up table (see, 306).
[0046] Further, the gain values in the look-up table are segmented (see, 308). The gain values are segmented or grouped as at least a linear gain range, constant gain range, ensure maximum gain, and no overflow. The segmentation of the gain values is explained with reference to FIG. 4. Thereafter, the controller 108 is trained with the look-up table data for performing automatic gain control in real-time for the input RF signals.
[0047] Referring to FIG. 4, a graphical representation variation of RSSI values and RF signal level is shown, in accordance with an embodiment of the present disclosure. In this scenario, the RF transceiver 104 is provided with dynamic range (i.e., 0 dBm to -113 dBm) of input signals for 25 KHz FM signals and the corresponding RSSI values are identified. As shown, the curve depicting the variation of RSSI, and the input RF signals is divided (or segmented) into 3 regions or ranges. For example, the RF signal level of range 0 dBm to -10 dBm and of range -67 dBm to -113 dBm corresponds to a RSSI low region for high power RF signals and a RSSI high region for low power signals, respectively. The RF signal level of range -10 dBm to -67 dBm corresponds to linear range for which the gain is also linear. The high power and low power signals the gain is an optimal constant value. Thus, the controller 108 applies the gain based on the graphical representation as shown in FIG. 4 to obtain the output of the audio data of SINAD of 12 dB.
[0048] FIG. 5 illustrates a flowchart 500 depicting a workflow of automatic gain control for received RF signals, in accordance with an embodiment of the present disclosure. The steps depicted in the flowchart 500 may be executed by, for example, the apparatus 100. Further, steps of the flowchart 500, and combinations of steps in the flow diagram, may be implemented by, for example, hardware, firmware, a processor, circuitry, and/or a different device associated with the execution of software that includes one or more computer program instructions.
[0049] At 502, the controller 108 is configured to monitor the RSSI values of the reading of RSSI. In other words, the controller 108 reads the RSSI value from the RF transceiver 104 for every instant of microseconds over the SPI interface.
[0050] At 504, the controller 108 checks if the current RSSI is less than a previous RSSI. In this scenario, the previous RSSI corresponds to at least a fixed RSSI or the RSSI value computed during a previous instance. The current RSSI is compared with a previous RSSI to determine whether current received RF signal is low power or high-power signals.
[0051] In one scenario, the controller 108 determines the current RSSI is less than the previous RSSI. In this scenario, the received RF signal corresponds to a high-power signal, and step 506 is performed. At 506, the controller computes the gain value for the current RSSI based on the training data. At 508, the controller stores the current RSSI as previous RSSI for computation of the received RF signal in future instances. For example, the RSSI may be determined to be -9dB and the previous RSSI is set as -4dB. In this scenario, the gain for -9dB signal is computed and -9dB is set as a reference (or the previous RSSI) for next instant AGC processing.
[0052] In another scenario, the controller 108 determines that the current RSSI is not less than the previous RSSI. In this scenario, the received RF signal corresponds to a low-power signal, and step 510 is performed. At 510, the controller 108 monitors for a predefined period of time for confirming whether the current RF signal is a low power signal. The predefined period of time may be a few microseconds in the context of narrowband voice communications. For instance, the low power signals are identified in a case where there is sudden variation or fluctuations (i.e., spike or dip) in the current RF signals. The sudden variation may be caused due to system faults, noise, or mobility or over the air impairments, etc. In such cases, the high-power signals or the ideal signals are determined as low-power signals due to sudden variation. To mitigate such scenarios, the controller 108 monitors the low power signal for the predefined period of time for confirming if the current RF signal is a low power signal. To that effect, programming with wrong gain values with abrupt/random RSSI can be avoided. Further, the controller 108 performs steps 512 and 514 for computing the gain value for the RSSI of the received RF signal and storing the current RSSI as previous RSSI similar to steps 506 and 508.
[0053] As such, storing the current RSSI as the previous RSSI for both the high and low power signals will result in determining if the gain to be increased or decreased or retained in further AGC processing. As explained above, the gain values for a set of RSSI values are derived a priori based on the readings derived by feeding the known signal to the RF transceiver 104 with different levels for maximum SNR which yields good SINAD of demodulated audio. Further, the required gain values and ranges are segmented with programmable range, and fixed ranges for very high and low power signal ranges as explained with reference to FIG. 4.
[0054] The decisions of required gain value are derived and send to the RF transceiver 104 to increase/decrease or attenuate the signal level. As explained above, the gain linear range is set to be 10dB to 67dB. The gain is fixed at 10dB for high power signals, and 72dB for low power signals. Fixing gain (10dB and 72dB avoids abrupt unnecessary gain control and oscillations of the signals at these extreme low/high ranges. In general, these range depends on preamplifier fixed gain (before RF transceiver), and gain/attenuation as part of pre-conditioning. The gain is adjusted for high and low power signals and for the signals falling in the linear range to attain the optimal output threshold for reliable demodulation (e.g., obtaining the SINAD of 12dB) which is further explained in detail.
[0055] At 518, the controller 108 checks if the computed gain is in the linear range. As explained above, the gain of the received RF signal is computed based on the RSSI value. In one example scenario, the controller 108 determines that the RSSI value is -25dBm. In this example scenario, the controller 108 computes the gain as per the RSSI value (-25dBm) and determines that the received RF signal is within the linear range. For linear RSSI range in Fig.4, the gain is offset difference between current RSSI and 0dBm reference. Thereafter, the controller 108 applies gain control to adjust the gain value based on considering the RSSI of 72dBm for the received RF signal as the reference (see, 520). This way, the controller 108 applies gain control to the received RF signal within the linear range. In another example scenario, the controller 108 determines that the RSSI value does not fall within the linear range, and step 522 is performed.
[0056] At 522, the controller 108 checks if the gain is less than 10dB. In one scenario, the controller 108 determines that the gain value is less than 10dB, and step 524 is performed. At 524, the controller 108 adjusts the gain of the received RF signal to 10dB. In particular, the controller 108 determines that the received RF signal is a high-power signal, and adjusts the gain value to 10dB. For example, the gain value may be 9dB. In this example scenario, the controller 108 adjusts the gain value as 10dB, considering the received RF signal to be high-power signal with 0dBm to -10dBm range for which RSSI is observed as constant as per Fig.4. It is to be noted that for an ideal signal, the RSSI is ‘0’. However, adjusting the gain value of 9dB corresponding to the ideal signal may introduce saturation with furthered high-power signals. Thus, to avoid the different gain for high power signals the controller 108 is programmed to adjust the gain value for the high-power signal with a fixed gain of 10dB. In another scenario, the gain value is determined to be not less than 10dBm. In this scenario, step 526 is performed.
[0057] At 526, the controller 108 adjusts the gain of the received RF signal with a fixed gain of 72dB. Specifically, the controller 108 determines that the received RF signal is a low power signal and adjusts the gain value to 72dB. It is to be noted that, the gain value is checked in steps 518 and 522 i.e., if the gain value is within the linear range 10dB to 67dB and if the gain value is less than 10dB. Thus, it will be apparent that the gain value is greater than 67dB, if the gain value fails both the condition mentioned in the steps 518 and 522. For example, the RSSI value may be determined to be -69dBm. In this scenario, the controller 108 determines adjusts the gain value to 72dB considering the received RF signal is a low power signal.
[0058] In addition, the rate of execution of the method (as shown in FIG. 5) as a subroutine in the controller 108 is controlled with a delay time (see, 528) variable to make the process slow or fast to cater frequency and amplitude modulations. The delay is dynamic or variable in nature. The delay is minimum for frequency modulated signals and maximum for the amplitude modulated signals to avoid erroneous gain control for envelop variations.
[0059] FIG. 6 illustrates a flowchart depicting a method for automatic gain control for radio frequency (RF) signals by an apparatus 100, in accordance with an embodiment of the present disclosure.
[0060] Referring to Figure 6, at step 610, the method comprises receiving RF signals via a radio frequency (RF) front end 102 of the apparatus 100. For example, a Radio Frequency (RF) to digital transceiver 104 is configured to receive RF signals via a radio frequency (RF) front end 102 of the apparatus 100.
[0061] At step 620, the method comprises determining a present received signal strength indicator (RSSI) corresponding to each of the received RF signals. For example, the controller 108 of the apparatus 100 is configured to determine/read a present received signal strength indicator (Current RSSI) corresponding to each of the received RF signals.
[0062] At step 630, the method comprises determining if the present RSSI is less than the previous RSSI. For example, the controller 108 of the apparatus 100 is configured to determine if the present RSSI/Current RSSI is less than the previous RSSI.
[0063] At step 640, the method comprises storing the present RSSI as previous RSSI for computation of an upcoming received RF signal. For example, the controller stores the present RSSI/current RSSI as previous RSSI for computation of the received RF signal in future instances.
[0064] At step 650, the method comprises calculating gain value of the received RF signal and segment the received RF signals based on the calculated gain values. For example, the controller is configured to calculate gain value of the received RF signal and segment the received RF signals based on the calculated gain value.
[0065] At step 660, the method comprises controlling the gain value for the received RF signals based on the gain segmentation. The controller 108 is communicably coupled to the RF to digital transceiver 104 and the baseband processor 106.
[0066] The current method of invention has flexibility in gain tuning, controlling the attach and decay times, and formulation of RSSI and gain relation as suited for different RF frontend configurations, and can be tailored for different RF modulated signals with continuous or busty in nature.
[0067] The various embodiments described above are specific examples of a single broader invention. Any modifications, alterations or the equivalents of the above-mentioned embodiments pertain to the same invention as long as they are not falling beyond the scope of the invention as defined by the appended claims. It will be apparent to a person skilled in the art that the apparatus and method for gain segmentation and control may be provided using some or many of the above-mentioned features or components without departing from the scope of the invention. It will be also apparent to a skilled person that the embodiments described above are specific examples of a single broader invention which may have greater scope than any of the singular descriptions taught. There may be many alterations made in the invention without departing from the spirit and scope of the invention.
[0068] Figures are merely representational and are not drawn to scale. Certain portions thereof may be exaggerated, while others may be minimized. Figures illustrate various embodiments of the invention that can be understood and appropriately carried out by those of ordinary skill in the art.
[0069] In the foregoing detailed description of embodiments of the invention, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description of embodiments of the invention, with each claim standing on its own as a separate embodiment.
[0070] It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein,” respectively.
,CLAIMS:
1. An apparatus (100) for automatic gain control for radio frequency (RF) signals, the apparatus comprising:
a Radio Frequency (RF) to digital transceiver (104) to receive RF signals via a radio frequency (RF) front end (102) of the apparatus (100);
a controller (108) communicably coupled to the RF to digital transceiver (104) and a baseband processor (106) and the controller (108) configured to:
determine a present received signal strength indicator (RSSI) corresponding to each of the received RF signals;
determine if the present RSSI is less than a previous RSSI;
store the present RSSI as previous RSSI for computation of an upcoming received RF signal;
calculate gain value of the received RF signal and segment the received RF signals based on the calculated gain values; and
control the gain value for received RF signals based on the gain segmentation.
2. The apparatus (100) as claimed in claim 1, the gain values are segmented as at least one of a RSSI low region for high-power RF signals, a RSSI high region for low power signals and a linear region/range.
3. The apparatus (100) as claimed in claim1, wherein when the present RSSI is less than the previous RSSI, the controller (108) is configured to:
determine that the received RF signal corresponds to a high-power signal;
determine the gain value for the present RSSI corresponding to the received RF signal based on a training data; and
store the present RSSI as the previous RSSI for computation of the upcoming received RF signal;
calculate the gain value of the received RF signal and determine if the calculated gain value is in a linear range; and
when the calculated gain is in the linear range, the controller (108) is configured to apply gain control to adjust the gain value, for which the gain value is linear in the range of 10dB to 67dB.
4. The apparatus (100) as claimed in claim 3, wherein when the calculated gain is not in the linear range, the controller (108) is configured to:
determine if the calculated gain is less than 10dB; and
when the calculated gain is less than 10 dB, the controller (108) is configured to determine that the received RF signal is a high-power signal and adjust the gain value to 10dB.
5. The apparatus (100) as claimed in claim 4, wherein when the calculated gain is not less than 10dB, the controller (108) is configured to:
determine that the received RF signal is a low power signal and adjust the gain value to 72dB.
6. The apparatus (100) as claimed in claim 1, wherein when the present RSSI is not less than the previous RSSI, the controller (108) is configured to:
monitor the received RF signal for a predefined period of time for confirming whether the received RF signal is a low power signal;
determine the gain value for the present RSSI corresponding to the received RF signal based on a training data;
store the present RSSI as the previous RSSI for computation of the upcoming received RF signal;
calculate the gain value of the received RF signal and determine if the calculated gain value is in the linear range; and
when the calculated gain is in the linear range, the controller (108) is configured to apply gain control to adjust the gain value, for which the gain value is linear in the range of 10dB to 67dB.
7. The apparatus (100) as claimed in claim 6, wherein when the calculated gain is not in the linear range, the controller (108) is configured to:
determine if the calculated gain is less than 10dB; and
when the calculated gain is less than 10 dB, the controller (108) is configured to determine that the received RF signal is a high-power signal and adjust the gain value to 10dB.
8. The apparatus (100) as claimed in claim 7, wherein when the calculated gain is not less than 10dB, the controller (108) is configured to:
determine that the received RF signal is a low power signal and adjusts the gain value to 72dB.
9. The apparatus (100) as claimed in any one of claims 3 or 6, when the controller (108) determines the gain value for the present RSSI based on the training data, the controller (108) is configured to:
determine corresponding RSSI for each of input RF signals of different frequencies;
create a look-up table by including data related to RSSI values corresponding to different RF signals;
determine gain values for the RSSI values associated with the input RF signals in the look-up table based on an output threshold; and
segment the gain values in the look-up table and the controller (108) is trained with the look-up table data for performing automatic gain control in real-time for the input RF signals.
10. The apparatus (100) as claimed in claim 6, wherein the predefined period of time for confirming whether the received RF signal is a low power signal is a few microseconds for narrowband voice communications.
11. The apparatus (100) as claimed in claim 1, wherein the controller 108 is controlled with a delay time to cater frequency modulation or amplitude modulation and the delay is minimum for frequency modulated signals and maximum for amplitude modulated signals.
12. The apparatus (100) as claimed in claims 1 to 11, wherein the gain is adjusted for high power signals and low power signals and for signals falling in the linear range to attain an output threshold for reliable demodulation.
13. The apparatus (100) as claimed in claim 1, wherein the received RF signal is one of voice signal or data signal.
14. The apparatus (100) as claimed in claim 1, wherein the baseband processor (106) is configured to collect and decode received RF digital samples from the RF to digital transceiver (104) and to recover audio samples based on voice or data demodulation techniques.
15. A method (600) for automatic gain control for radio frequency (RF) signals by an apparatus (100), the method comprising:
receiving RF signals (610), by a Radio Frequency (RF) to digital transceiver (104) via a radio frequency (RF) front end (102) of the apparatus (100);
determining (620), by a controller (108) of the apparatus (100), a present received signal strength indicator (RSSI) corresponding to each of the received RF signals;
determining (630), by the controller (108), if the present RSSI is less than a previous RSSI;
storing (640), by the controller (108), the present RSSI as previous RSSI for computation of an upcoming received RF signal;
calculating (650), by the controller (108), gain value of the received RF signal and segment the received RF signals based on the calculated gain values; and

controlling (660), by the controller (108), the gain value for the received RF signals based on the gain segmentation, wherein the controller (108) is communicably coupled to the RF to digital transceiver (104) and a baseband processor (106).