DESC:TECHNICAL FIELD
[1] The present invention relates to the general area of Radio Frequency (RF) communication, and more specifically to an upsampling system, an upsampling method, and an UWB receiver thereof.

BACKGROUND
[2] In UWB surveillance systems, parameter extraction of Intermediate Frequency (IF) signals such as frequency, pulse width, pulse repetitive interval, direction of arrival, amplitude, etc., depends upon the characteristics of IF to ADC. Each receiver of UWB surveillance system is designed on the basis of a few technical assumptions to achieve its objectives. These objectives are divided into various technical specifications. These specifications are further divided into requirements of parameter accuracies and resolutions, such as frequency accuracy & resolution, pulse width accuracy & resolution, etc. As the sampling frequency is higher and higher, then better is the time resolution. Moreover, according to sampling theory and FFT principles, the minimum sampling frequency is derived from the equation, fin=fs/N. Generally, N is constant and hence, input frequency resolution is directly proportional to the input sampling frequency. Therefore, for higher input sampling frequencies, lesser frequency resolution is achieved. But the limitation in processing is that frequency resolution is increased with increasing in the number of FFT Computations. Therefore, a trade-off between frequency resolution and time resolution needs to be made during the design process. This puts limitation on selection of ADC for UWB receiver and plays a critical role, because it directly affects the system performance in meeting stringent/advanced specifications. The other important parameters such as SNR and input bandwidth are also to be considered during the design of the UWB receiver. Considering all these criticalities, the best available ADC in the world is also not sufficient to meet the current and future requirements of the systems. Thus, puts limitation on measurement of resolution of various parameters of UWB surveillance systems.
[3] In a conventional method for adaptive upsampling for spatially scalable coding limitation of sampling frequency is addressed through re-sampling method, which is used in image processing applications, where processing time is sufficiently large. Further, the method also indicates that a few more limitations can be overcome in digital domain with the help of signal processing algorithms.
[4] There is still a need for effective handling of sampling frequencies for UWB systems.

SUMMARY
[5] This summary is provided to introduce concepts related to an upsampling system, an upsampling method, and a UWB receiver thereof. This summary is neither intended to identify essential features of the present invention nor is it intended for use in determining or limiting the scope of the present invention.
[6] In an embodiment of the present invention, an Ultra-Wideband (UWB) receiver is provided. The UWB receiver includes an RF front end, an Analog to Digital Converter (ADC), and an upsampling unit. The upsampling unit includes a bandpass filter (BPF) and a First In First Out register (FIFO) register, a plurality of Finite Impulse Response (FIR) filters, and a FIFO. The RF front end receives an RF signal and converts the RF signal into an Intermediate Frequency (IF) signal. The ADC converts the IF signal into an input digital signal. The BPF and FIFO split the input digital signal into a plurality of digital channels. The plurality of FIR filters upsample the plurality of digital channels. The FIFO combines the plurality of upsampled digital channels into an output signal. The output signal is of a higher data rate than the input digital signal.
[7] In another embodiment of the present invention, an upsampling unit is provided. The upsampling unit includes a bandpass filter (BPF) and a First In First Out register (FIFO) register, a plurality of Finite Impulse Response (FIR) filters, and a FIFO. The BPF and FIFO split an input digital signal into a plurality of digital channels. The plurality of FIR filters upsample the plurality of digital channels. The FIFO combines the plurality of upsampled digital channels into an output signal. The output signal is of a higher data rate than the input digital signal.
[8] In yet another embodiment of the present invention, an upsampling method is provided. The method includes receiving an RF signal by an RF front end and converting the RF signal into an Intermediate Frequency (IF) signal. The IF signal is converted into an input digital signal by an Analog to Digital Converter (ADC). The input digital signal is split into a plurality of digital channels by a bandpass filter (BPF) and First In First Out register (FIFO) register. The plurality of digital channels are upsampled by a plurality of Finite Impulse Response (FIR) filters. The plurality of upsampled digital channels are combined by a FIFO into an output signal. The output signal is of a higher data rate than the input digital signal.
[9] In an exemplary embodiment, the UWB receiver includes a parameter extraction unit. The parameter extraction unit receives the output signal from the FIFO and extracts one or more predefined parameters of the IF signal based on the output signal.
[10] In another exemplary embodiment, the upsampling unit includes a RAM and a multiplexer. The RAM stores a plurality of filter coefficient values. The multiplexer has a plurality of input terminals connected to the RAM, a select terminal connected to a bandwidth select signal, and an output terminal connected to one or more FIR filters such that the multiplexer sets a bandwidth of the FIR filter based on a value of the bandwidth select signal.
[11] In yet another exemplary embodiment, the bandwidth select signal is controllable by a user during run-time.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[12] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
[13] Fig. 1 depicts a schematic block diagram of an Ultra-Wideband (UWB) receiver in accordance with an embodiment of the present invention.
[14] Fig. 2 depicts a schematic block diagram of an upsampling block in accordance with an embodiment of the present invention.
[15] Fig. 3 depicts a filter implementation for upsampling bandwidth selection in accordance with an embodiment of the present invention.
[16] Fig. 4 is a flowchart illustrating an upsampling method in accordance with an embodiment of the present invention.
[17] It should be appreciated by those skilled in the art that any block diagram herein represents conceptual views of illustrative systems embodying the principles of the present invention. Similarly, it will be appreciated that any flow chart, flow diagram, 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
[18] The various embodiments of the present invention provide an upsampling system, an upsampling method, and an UWB receiver thereof.
[19] In the following description, for purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.
[20] 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 present invention and are meant to avoid obscuring of the present invention.
[21] Furthermore, connections between components and/or modules within the figures are not intended to be limited to direct connections. Rather, these components and modules may be modified, re-formatted or otherwise changed by intermediary components and modules.
[22] References in the present invention to “embodiment” or “embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment or the embodiment is included in at least one embodiment or embodiment of the invention. The appearances of the phrase “in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
[23] The various embodiments of the present disclosure provide a method to sample the input frequency by digital re-sampling process, where the down or up sampling is used for sampling of input ADC sampled data. If the input ADC sampled data is upsampled, more and more, then the data rate of the sampled data increases. In this situation, if FFT processing length is kept unchanged, it results in the improved time resolution by the factor selected for upsampling. Therefore, pulse width measurement resolution increases by the upsampling factor.
[24] In an embodiment, the present invention provides an UWB surveillance receiver that not only intercept and extract the parameters, but also meets the resolution. In an embodiment, a suitable ADC is chosen based on the specifications of the UWB surveillance receiver. Frequency resolution allows distinguishing closely spaced emitters in frequency domain. Similarly, time resolution allows differentiating different closely spaced radar pulses by either same or different emitters. Pulse resolution provides indirect advantage in PRI processing and improves PRI accuracy along with pulse width accuracy. Both the time as well as frequency resolutions are equally important as the vital emitter information lies in the combination of both.
[25] In another embodiment, a method to improve time resolution in digital receivers with upsampling/re-sampling technique for UWB surveillance receivers is disclosed. The method discloses a high-end FPGA based hardware specifically optimised for capturing high speed samples for improving time resolution in digital receivers. An algorithm developed for the specific task of re-sampling and upsampling for attaining time synchronization is provided. The UWB surveillance receivers use the upsampling or re-sampling technique. The upsampling method includes upsampling of ADC output before applying for N-point FFT. A high-end FPGA based hardware is used for upsampling of the N-Point FFT. The hardware is implemented using decimated filters to incorporate N-bandwidths. The upsampling method includes selecting instantaneous bandwidth through the software algorithm.
[26] In an embodiment of the present invention, a Radio Frequency (RF) receiver is provided. The UWB receiver includes an RF front end, an Analog to Digital Converter (ADC), and an upsampling unit. The upsampling unit includes a bandpass filter (BPF) and a First In First Out register (FIFO) register, a plurality of Finite Impulse Response (FIR) filters, and a FIFO. The RF front end receives a RF signal and converts the RF signal into an Intermediate Frequency (IF) signal. The ADC converts the IF signal into an input digital signal. The BPF and FIFO split the input digital signal into a plurality of digital channels. The plurality of FIR filters upsample the plurality of digital channels. The FIFO combines the plurality of upsampled digital channels into an output signal. The output signal is of a higher data rate than the input digital signal.
[27] In another embodiment of the present invention, an upsampling unit is provided. The upsampling unit includes a bandpass filter (BPF) and a First In First Out register (FIFO) register, a plurality of Finite Impulse Response (FIR) filters, and a FIFO. The BPF and FIFO split an input digital signal into a plurality of digital channels. The plurality of FIR filters upsample the plurality of digital channels. The FIFO combines the plurality of upsampled digital channels into an output signal. The output signal is of a higher data rate than the input digital signal.
[28] In yet another embodiment of the present invention, an upsampling method is provided. The method includes receiving an RF signal by an RF front end and converting the RF signal into an Intermediate Frequency (IF) signal. The IF signal is converted into an input digital signal by an Analog to Digital Converter (ADC). The input digital signal is split into a plurality of digital channels by a bandpass filter (BPF) and First In First Out register (FIFO) register. The plurality of digital channels are upsampled by a plurality of Finite Impulse Response (FIR) filters. The plurality of upsampled digital channels are combined by a FIFO into an output signal. The output signal is of a higher data rate than the input digital signal.
[29] In an exemplary embodiment, the UWB receiver includes a parameter extraction unit. The parameter extraction unit receives the output signal from the FIFO and extracts one or more predefined parameters of the IF signal based on the output signal.
[30] In another exemplary embodiment, the upsampling unit includes a RAM and a multiplexer. The RAM stores a plurality of filter coefficient values. The multiplexer has a plurality of input terminals connected to the RAM, a select terminal connected to a bandwidth select signal, and an output terminal connected to one or more FIR filters such that the multiplexer sets a bandwidth of the FIR filter based on a value of the bandwidth select signal.
[31] In yet another exemplary embodiment, the bandwidth select signal is controllable by a user during run-time.
[32] Fig. 1 depicts a schematic block diagram of Ultra-Wideband (UWB) Receiver (100) in accordance with an embodiment of the present invention. The UWB receiver (100) includes an antenna (102), an RF front end (104), an Analog to Digital Converter (ADC) (106), a First In First Out (FIFO) register (108), and a processor (110). The RF front end (104) includes a signal conditioning unit (112) and a down converter (114). The processor (110) includes an upsampling unit (116), an N point Fast Fourier Transform (N-FFT) unit (118), and a parameter extraction unit (120).
[33] The antenna (102) receives RF signals and passes the RF signals to the RF front end (104). The signal conditioning unit (112) conditions the RF signal as per the requirements of the application. That is, the signal conditioning unit (112) either amplifies or attenuates the RF signal. The down converter (114) converts the RF signal into Intermediate Frequency (IF) signal. The IF signal is passed to the ADC (106). The ADC (106) converts the IF signal into an input digital signal. The FIFO (108) receives the input digital signal and passes the input digital signal serially to the upsampling unit (116). The upsampling unit (116) upsamples the input digital signal and passes the upsampled signal to the N-FFT unit (118). The N-FFT unit (118) performs an N-point FFT on the upsampled signal and passes FFT data to the parameter extraction unit (120). The parameter extraction unit (120) extracts specified parameters of the IF signal based on the FFT data.
[34] In an exemplary embodiment, wide band electromagnetic spectrum is intercepted with the help of antennae and down converted to Intermediate frequency (IF) signal with the help of down-converter. Further ADC digitizes the IF signal with the fix input sampling frequency. Digital modules implemented in digital processor manage data rates, re-samples, extract and represent the extracted emitter information in predefined format. The upsampling the input sampled data by 8 times ADC provides nanosecond resolution achieving the expected time resolution, at the cost of increased data rate. The Input data rate of the upsampler module is x, but the output data rate is 8x and therefore, it is critical to manage high data rate. Upsampler realization with the implementation of Parallel Decimated Filter Architecture Implementation inside the processor maintains high data rate managing highest clock rate.
[35] Fig. 2 depicts a schematic block diagram of an upsampling unit (110) in accordance with an embodiment of the present invention. The upsampling unit (110) includes a Band Pass Filter (BPF) (202), a FIFO (204), and 1st through 8th Finite Impulse Response (FIR) filters (FIR1 – FIR8), and a FIFO (206).
[36] The BPF receives a data stream the output of the FIFO (108). The BPF (202) and the FIFO (204) decimate the data stream into 8 data streams on 8 channels. Each channel is provided with a FIR filter. The output of the 8 FIR filters (FIR1 – FIR 8) is merged by the FIFO (206). Hence, the upsampled data stream has a data rate which is 8x (i.e. 8 times) of the data rate of the input data stream.
[37] In an exemplary embodiment, to accommodate the high data rates the upsample filter implementation is divided into several small filters. The coefficient of the 8 small filters is derived by decimating upsample filter by 8. Each of these filters is applied on the input data simultaneously, which allows each filter to operate on 8x8 clock frequency. This parallel filter architecture allows achieving the expected sampling frequency with the available lower clock frequency. Moreover, selectable filters are incorporated in the Parallel Decimated Filter Architecture to chose the correct instantaneous bandwidth, which help to improve the pulse width accuracy and SNR.
[38] Fig. 3 depicts a filter implementation for upsampling bandwidth selection in accordance with an embodiment of the present invention.
[39] Each of the 8 FIR filters (FIR1 – FIR8) is tuned to a corresponding bandwidth. In order to increase the Signal to Noise ratio (SNR), the bandwidth of the FIR filter may be reduced. The upsampling unit (116) provides for dynamic variation of bandwidth of the 8 FIR filters (FIR1 – FIR8). Each of the 8 FIR filters (FIR1 – FIR8) may be tuned to one of the N-Bandwidths. The N-Bandwidth coefficients are saved in a block RAM (302) within the upsampling unit (116). The block RAM (302) is connected to input terminals of a multiplexer (MUX) (304). A select line of the MUX acts as a bandwidth select signal which may be provided by the use in run-time. Based on the bandwidth select signal, the MUX (304) provides a bandwidth value as an output. Hence, the 8 FIR filters (FIR1 – FIR8) may be tuned to desired bandwidths as per the requirements of the application.
[40] In another embodiment of the present invention, an upsampling method is provided. Referring now to Fig. 4, a flowchart illustrating an upsampling method in accordance with an embodiment of the present invention is shown.
[41] At step 402, the RF front end (104) receives the RF signal and converts the RF signal into the IF signal.
[42] At step 404, the ADC (106) converts the IF signal into the input digital signal.
[43] At step 406, the BPF (202) and the FIFO (204) registers split the input digital signal into the plurality of digital channels.
[44] At step 408, the plurality of FIR filters (FIR1 – FIR8) upsample the plurality of digital channels.
[45] At step 410, the FIFO (206) combines the plurality of upsampled digital channels into the output signal.
[46] In operation, the RF front end (104) receives the RF signal and converts the RF signal into the IF signal. The ADC (106) converts the IF signal into the input digital signal. The BPF (202) and FIFO (204) split the input digital signal into a plurality of digital channels. The plurality of FIR filters (FIR1 – FIR8) upsample the plurality of digital channels. The FIFO (206) combines the plurality of upsampled digital channels into an output signal. The output signal is of a higher data rate than the input digital signal. The parameter extraction unit (120) receives the output signal from the FIFO (206) and extracts one or more predefined parameters of the IF signal based on the output signal. The RAM (302) stores a plurality of filter coefficient values. The multiplexer (304) has the plurality of input terminals connected to the RAM (302), a select terminal connected to a bandwidth select signal, and an output terminal connected to one or more FIR filters (FIR1 – FIR8) such that the multiplexer (304) sets a bandwidth of the FIR filter based on a value of the bandwidth select signal.
[47] Advantageously, the SNR is maintained with a constant high data rate, thereby improving the efficiency of the UWB receiver (100).
[48] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the invention.

,CLAIMS:

1. An Ultra-Wideband (UWB) receiver (100) comprising:
a RF front end (104) configured to receive an RF signal and convert the RF signal into an Intermediate Frequency (IF) signal;
an Analog to Digital Converter (ADC) (106) configured to convert the IF signal into an input digital signal; and
an upsampling unit (116) comprising:
a bandpass filter (BPF) (202) and a First In First Out register (FIFO) register (204), collectively configured to split the input digital signal into a plurality of digital channels;
a plurality of Finite Impulse Response (FIR) filters (FIR1-FIR8) configured to upsample the plurality of digital channels; and
a FIFO (206) to combine the plurality of upsampled digital channels into an output signal, wherein the output signal is of a higher data rate than the input digital signal.

2. The UWB receiver (100) as claimed in claim 1, further comprising a parameter extraction unit (120) configured to receive the output signal from the FIFO (206) and extract one or more predefined parameters of the IF signal based on the output signal.

3. The UWB receiver (100) as claimed in claim 1, wherein the upsampling unit (116) comprises:
a RAM (302) storing a plurality of filter coefficient values;
a multiplexer (304) having a plurality of input terminals connected to the RAM (302), a select terminal connected to a bandwidth select signal, and an output terminal connected to one or more FIR filters (FIR1 - FIR8) such that the multiplexer sets a bandwidth of the FIR filter based on a value of the bandwidth select signal.

4. The UWB receiver (100) as claimed in claim 3, wherein the bandwidth select signal is controllable by a user during run-time.

5. An upsampling unit (116) for an UWB receiver (100) comprising:
a bandpass filter (BPF) (202) and a First In First Out register (FIFO) register (204), collectively configured to split an input digital signal into a plurality of digital channels;
a plurality of Finite Impulse Response (FIR) filters (FIR1-FIR8) configured to upsample the plurality of digital channels; and
a FIFO (206) to combine the plurality of upsampled digital channels into an output signal, wherein the output signal is of a higher data rate than the input digital signal.

6. An upsampling method comprising:
receiving, by a RF front end (104), an RF signal and converting the RF signal into an Intermediate Frequency (IF) signal;
converting, by an Analog to Digital Converter (ADC) (106), the IF signal into an input digital signal;
splitting the input digital signal into a plurality of digital channels by a bandpass filter (BPF) (202) and a First In First Out register (FIFO) register (204);
upsampling, by a plurality of Finite Impulse Response (FIR) filters (FIR1-FIR8), the plurality of digital channels; and
combining, a FIFO (206), the plurality of upsampled digital channels into an output signal, wherein the output signal is of a higher data rate than the input digital signal.