Claims:
1. A method for processing narrow pulsed modulated signals, said method comprising:
converting, by a convertor (102), a radio frequency (RF) signal to an intermediate frequency (IF) signal, wherein said IF signal includes preamble pulses and data pulses;
computing, by a correlation module (104), a cross correlation value and a moving average energy value in said IF signal;
determining, by said correlation module (104), a threshold value based on said computed cross correlation value and said moving average energy value;
estimating, by a detection module (106), a variable threshold value by using said determined threshold value, and detecting one or more preamble pulses of said IF signal;
synchronizing, by a synchronization module (108), said detected preamble pulses and determining a position of each preamble pulse; and
decoding, by a decoder (110), one or more data pulses of said IF signal by using said determined position of said preamble pulse, and computing a data pulse stream.

2. The method as claimed in claim 1, wherein said cross correlation value is coincide with said moving average energy value with length equal to pulse duration under a high signal-to-noise ratio condition, to determine said threshold value.

3. The method as claimed in claim 1, wherein said cross correlation value is exceeds with said moving average energy value with length equal to pulse duration under a low signal-to-noise ratio condition, to determine said threshold value.

4. The method as claimed in claim 1, wherein said estimated variable threshold value is determined if n(n>=3) or more consecutive increasing sample of said computed cross correlation value and a pre-determined cross correlation value exceed said estimated variable threshold value.

5. The method is claimed in claim 4, wherein said estimated variable threshold value is determined by computing said cross correlation value and reset to a noise floor level after the required preamble is detected.

6. The method is claimed in claim 4, wherein if said cross correlation value exceeds said estimated variable threshold value, the ratio between a cross correlation peak and a moving average energy peak with length equal to pulse duration is used to find the preamble and the position of said pulse.

7. The method as claimed in claim 1, comprising: computing, by said synchronization module (108), spreading function by using said determined preamble pulse position.

8. A signal processing system (100) for narrow pulsed modulated signals, said system (100) comprising:
a convertor (102) configured to convert a radio frequency (RF) signal to an intermediate frequency (IF) signal, said IF signal includes preamble pulses and data pulses;
a correlation module (104) configured to cooperate with said convertor (102), said correlation module (102) configured to compute a cross correlation value and a moving average energy value in said IF signal and determine a threshold value;
a detection module (106) configured to cooperate with said correlation module (104), said detection module (106) configured to estimate a variable threshold value by using said determined threshold value, and detect one or more preamble pulses of said IF signal;
a synchronization module (108) configured to cooperate with said detection module (106), said synchronization module (108) configured to synchronize said detected preamble pulses and determine a position of each preamble pulse; and
a decoder (110) configured to cooperate with said synchronization module (108), said decoder (110) configured to decode one or more data pulses of said IF signal by using said determined position of said preamble pulse, and compute a data pulse stream.

9. The system (100) as claimed in claim 8, wherein said cross correlation value is coincide with said moving average energy value with length equal to pulse duration under a high signal-to-noise ratio condition, to determine said threshold value.

10. The system (100) as claimed in claim 8, wherein said cross correlation value is exceeds with said moving average energy value with length equal to pulse duration under a low signal-to-noise ratio condition, to determine said threshold value.

11. The system (100) as claimed in claim 8, wherein said estimated variable threshold value is determined if n(n>=3) or more consecutive increasing sample of said computed cross correlation value and a pre-determined cross correlation value exceed said estimated variable threshold value.

12. The system (100) is claimed in claim 11, wherein said estimated variable threshold value is determined by computing said cross correlation value and reset to a noise floor level after the required preamble is detected.

13. The system (100) is claimed in claim 11, wherein if said cross correlation value exceeds said estimated variable threshold value, the ratio between a cross correlation peak and a moving average energy peak with length equal to pulse duration is used to find the preamble and the position of said pulse.
14. The system (100) as claimed in claim 8, wherein said synchronization module (108) is configured to compute spreading function by using said determined preamble pulse position.
, Description:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[SEE SECTION 10, RULE 13]

A SIGNAL PROCESSING SYSTEM FOR NARROW PULSED MODULATED SIGNALS AND METHOD THEREOF

BHARAT ELECTRONICS LIMITED
WITH ADDRESS:OUTER RING ROAD, NAGAVARA, BANGALORE 560045, KARNATAKA, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

TECHNICAL FIELD
[0001] The present invention relates generally to signal processing systems. The invention, more particularly, relates to a signal processing system and method for narrow pulsed modulated signals.

BACKGROUND
[0002] Typically, the narrow pulses consist of preamble pulses and data pulses. The position of the preamble pulses is varied according to the spreading function. The spreading function contains a code which is required by a decoder to decode and demodulate the data pulses. The preamble embeds the information of the spreading function. Fixed number of preamble pulses are sent with varying positions by a transmitter to find the spreading function at a receiver. Synchronization is a first step in a receive processing chain and it asserts whether the received pulse is valid, and also it provides the preamble positions. The preamble is detected based on threshold of a correlation value. If the cross correlation value is higher than fixed threshold used by the receiver in presence of noise, then it may lead to false alarm.

[0003] US7636404 describes a method of improving packet detection in wireless devices based on autocorrelation coefficient. The fixed threshold value is compared with autocorrelation coefficient to make a decision on the packet arrival. Fixed threshold method may lead to false alarms in case of fluctuations in the received signal strength. If the narrow band interference signal present at the receiver, then an autocorrelation value produces strong peak above the threshold level and it may lead to false detection.

[0004] US8988506 describes a decoder scheme to operate the receiver at lower SNR. The threshold is based on a received signal strength indicator (RSSI) of the received signal. The correlation value is compared with the threshold value to detect the preamble. The RSSI value does not provide the exact position of the preamble as it may lead to multiple peaks of cross correlation.
[0005] Therefore, there is a need of a system and method which solve the above defined problems and detect preamble and data pulses in noisy environment with the dynamic threshold.

SUMMARY
[0006] This summary is provided to introduce concepts related to a signal processing system for narrow pulsed modulated signals and method 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.

[0007] For example, various embodiments herein may include one or more signal processing systems for narrow pulsed modulated signals and methods thereof are provided. In one of the embodiments, a method for processing narrow pulsed modulated signals includes a step of converting, by a convertor, a radio frequency (RF) signal to an intermediate frequency (IF) signal, wherein the IF signal includes preamble pulses and data pulses. The method includes a step of computing, by a correlation module, a cross correlation value and a moving average energy value in the IF signal. The method includes a step of determining, by the correlation module, a threshold value based on the computed cross correlation value and the moving average energy value. The method includes a step of estimating, by a detection module, a variable threshold value by using the determined threshold value, and detecting one or more preamble pulses of the IF signal. The method includes a step of synchronizing, by a synchronization module, the detected preamble pulses and determining a position of each preamble pulse. The method includes a step of decoding, by a decoder, one or more data pulses of the IF signal by using the determined position of the preamble pulse, and computing a data pulse stream.

[0008] In another embodiment, a signal processing system for narrow pulsed modulated signals includes a convertor, a correlation module, a detection module, a synchronization module, and a decoder. The convertor is configured to convert a radio frequency (RF) signal to an intermediate frequency (IF) signal, wherein the IF signal includes preamble pulses and data pulses. The correlation module is configured to compute a cross correlation value and a moving average energy value in the IF signal and determine a threshold value. The detection module is configured to estimate a variable threshold value by using the determined threshold value, and detect one or more preamble pulses of the IF signal. The synchronization module is configured to synchronize the detected preamble pulses and determine a position of each preamble pulse. The decoder is configured to decode one or more data pulses of the IF signal by using the determined position of the preamble pulse, and compute a data pulse stream.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0009] 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.

[0010] Figure 1 illustrates a block diagram depicting a signal processing system, according to an implementation of the present invention.

[0011] Figure 2 illustrates a block diagram depicting a receiver having both radio frequency and digital subsystems, according to an exemplary implementation of the present invention.

[0012] Figure 3 illustrates a block diagram depicting a signal processing system for pulse detection in a field programmable gate array, according to an implementation of the present invention.

[0013] Figure 4 illustrates a flow diagram depicting pulse detection and data decoding, according to an exemplary implementation of the present invention.

[0014] Figure 5 illustrates a schematic diagram depicting cross correlation for preamble detection, according to an exemplary implementation of the present invention.

[0015] Figure 6 illustrates a flow diagram depicting preamble estimation and detection, according to an exemplary implementation of the present invention.

[0016] Figure 7a illustrates graphical representation depicting received preamble and data pulses at very high SNR, according to an exemplary implementation of the present invention.

[0017] Figure 7b illustrates graphical representation depicting preamble detection at very high SNR, according to an exemplary implementation of the present invention.

[0018] Figure 7c illustrates graphical representation depicting transmitted preamble and data pulses at low SNR, according to an exemplary implementation of the present invention.

[0019] Figure 7d illustrates graphical representation depicting preamble detection at low SNR, according to an exemplary implementation of the present invention.

[0020] Figure 8 illustrates a flow diagram depicting a method for processing narrow pulsed modulated signals, according to an exemplary implementation of the present invention.

[0021] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present invention. Similarly, it will be appreciated that any flowcharts, 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
[0022] In the following description, for the 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.

[0023] The various embodiments of the present invention provide a signal processing system for narrow pulsed modulated signals and method thereof. 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.

[0024] References in the present invention 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.

[0025] In one of the embodiments, a method for processing narrow pulsed modulated signals includes a step of converting, by a convertor, a radio frequency (RF) signal to an intermediate frequency (IF) signal, wherein the IF signal includes preamble pulses and data pulses. The method includes a step of computing, by a correlation module, a cross correlation value and a moving average energy value in the IF signal. The method includes a step of determining, by the correlation module, a threshold value based on the computed cross correlation value and the moving average energy value. The method includes a step of estimating, by a detection module, a variable threshold value by using the determined threshold value, and detecting one or more preamble pulses of the IF signal. The method includes a step of synchronizing, by a synchronization module, the detected preamble pulses and determining a position of each preamble pulse. The method includes a step of decoding, by a decoder, one or more data pulses of the IF signal by using the determined position of the preamble pulse, and computing a data pulse stream.

[0026] In another implementation, the cross correlation value is coinciding with the moving average energy value with length equal to pulse duration under a high signal-to-noise ratio condition, to determine the threshold value.

[0027] In another implementation, the cross correlation value is exceeding with the moving average energy value with length equal to pulse duration under a low signal-to-noise ratio condition, to determine the threshold value.

[0028] In another implementation, the estimated variable threshold value is determined if n (n>=3) or more consecutive increasing sample of the computed cross correlation value and a pre-determined cross correlation value exceed the estimated variable threshold value.

[0029] In another implementation, the estimated variable threshold value is determined by computing the cross correlation value and reset to a noise floor level after the required preamble is detected.

[0030] In another implementation, if the cross correlation value exceeds the estimated variable threshold value, the ratio between a cross correlation peak and a moving average energy peak with length equal to pulse duration is used to find the preamble and the position of the pulse.
[0031] In another implementation, the method includes a step of computing, by the synchronization module, spreading function by using the determined preamble pulse position.

[0032] In another embodiment, a signal processing system for narrow pulsed modulated signals includes a convertor, a correlation module, a detection module, a synchronization module, and a decoder. The convertor is configured to convert a radio frequency (RF) signal to an intermediate frequency (IF) signal, wherein the IF signal includes preamble pulses and data pulses. The correlation module is configured to compute a cross correlation value and a moving average energy value in the IF signal and determine a threshold value. The detection module is configured to estimate a variable threshold value by using the determined threshold value, and detect one or more preamble pulses of the IF signal. The synchronization module is configured to synchronize the detected preamble pulses and determine a position of each preamble pulse. The decoder is configured to decode one or more data pulses of the IF signal by using the determined position of the preamble pulse, and compute a data pulse stream.

[0033] In another implementation, the cross correlation value is coinciding with the moving average energy value with length equal to pulse duration under a high signal-to-noise ratio condition, to determine the threshold value.

[0034] In another implementation, the cross correlation value is exceeding with the moving average energy value with length equal to pulse duration under a low signal-to-noise ratio condition, to determine the threshold value.

[0035] In another implementation, the estimated variable threshold value is determined if n(n>=3) or more consecutive increasing sample of the computed cross correlation value and a pre-determined cross correlation value exceed the estimated variable threshold value.

[0036] In another implementation, the estimated variable threshold value is determined by computing the cross correlation value and reset to a noise floor level after the required preamble is detected.

[0037] In another implementation, if the cross correlation value exceeds the estimated variable threshold value, the ratio between a cross correlation peak and a moving average energy peak with length equal to pulse duration is used to find the preamble and the position of the pulse.

[0038] In another implementation, the synchronization module is configured to compute spreading function by using the determined preamble pulse position.

[0039] In an embodiment, the system and method follow a windowing based approach to detect the preamble pulses and determine position of preamble pulses.

[0040] In an embodiment, the system and method provide time domain parameters which are associated to remove the inconsistency of cross correlation at different receiver sensitivities.

[0041] In an embodiment, the system and method provide dynamic threshold preamble detection based on cross correlation.

[0042] Figure 1 illustrates a block diagram depicting a signal processing system (100), according to an implementation of the present invention.

[0043] A signal processing system for narrow pulsed modulated signals (hereinafter referred to as “system”) (100) includes a convertor (102), a correlation module (104), a detection module (106), a synchronization module (108), and a decoder (110).

[0044] In an embodiment, the system (100) is configured to receive electromagnetic signals from one or more sources. The sources can include signal generation devices or signal transmission devices. In another embodiment, the signals can be radio frequency signals. In one embodiment, the system (100) includes a radio frequency (RF) receiver that consists of an antenna, an amplifier (for example, low-noise amplifier (LNA)), filters and mixer circuits. The antenna is configured receive the electromagnetic signals and converts to voltage or currents.

[0045] In an exemplary embodiment, the system (100) is configured to detect narrow pulsed modulated signals by using a windowing technique. The system (100) performs synchronization, detection of preamble pulses, and decoding of data pulses. In the system (100), the cross correlation peak value coincides with moving average energy of magnitudes with length equal to pulse duration under very high SNR (noise less) conditions, whereas the cross correlation peak value exceeds the moving average energy of magnitudes with length equal to pulse duration under very low SNR (noisy) conditions. In an embodiment, if the data pulses present in-between preamble pulses, then the system (100) can differentiate the data samples to avoid the false detection of preamble. In one embodiment, the system (100) provides the cross correlation for the detection of preamble pulses. In one embodiment, the system (100) is specifically used to determine the synchronization and decoding of data pulses.

[0046] The convertor (102) is configured to receive RF signals and is further configured to convert a radio frequency (RF) signal to an intermediate frequency (IF) signal. In an embodiment, the IF signal includes preamble pulses and data pulses.

[0047] The correlation module (104) is configured to cooperate with the convertor (102) to receive the IF signal. The correlation module (104) is further configured to compute a cross correlation value and a moving average energy value in the IF signal and determine a threshold value. In an embodiment, the cross correlation value is coincided with the moving average energy value with length equal to pulse duration under a high signal-to-noise ratio condition, to determine the threshold value. In another embodiment, the cross correlation value is exceeded with the moving average energy value with length equal to pulse duration under a low signal-to-noise ratio condition, to determine the threshold value.

[0048] The detection module (106) is configured to cooperate with the correlation module (104) to receive the determined threshold value. The detection module (106) is further configured to estimate a variable threshold value by using the determined threshold value, and detect one or more preamble pulses of the IF signal. In an embodiment, the estimated variable threshold value is determined if n(n>=3) or more consecutive increasing sample of the computed cross correlation value and a pre-determined cross correlation value exceed the estimated variable threshold value. In another embodiment, the estimated variable threshold value is determined by computing the cross correlation value and reset to a noise floor level after the required preamble is detected.

[0049] The synchronization module (108) is configured to cooperate with the detection module (106) to receive detected preamble pulses of the IF signal. The synchronization module (108) is further configured to synchronize the detected preamble pulses and determine a position of each preamble pulse. In an embodiment, if the cross correlation value exceeds the estimated variable threshold value, the ratio between a cross correlation peak and a moving average energy peak with length equal to pulse duration is used to find the preamble and the position of the pulse. In another embodiment, the synchronization module (108) is configured to compute spreading function by using the determined preamble pulse position.

[0050] The decoder (110) is configured to cooperate with the synchronization module (108) to receive the determined position of each preamble pulse. The decoder (110) is further configured to decode one or more data pulses of the IF signal by using the determined position of the preamble pulse, and compute a data pulse stream.

[0051] Figure 2 illustrates a block diagram depicting a receiver (200) having both radio frequency and digital subsystems, according to an exemplary implementation of the present invention.

[0052] In an embodiment, a receiver (200) is a radio frequency (RF) receiver which consists of an antenna, an amplifier, filters and mixer circuits. The antenna (202) is configured to receive the electromagnetic signals and converts the electromagnetic signals into voltage or currents. The receiver also includes a radio frequency sub-system (204) and a digital sub-system (206). The radio frequency sub-system (204) consists of an automatic gain controller (AGC), tuneable filters and low noise amplifiers (LNA). The digital sub-system (206) includes an analog-to-digital converter (ADC) (208), an Field Programmable Gate Array (FPGA) (210)and other digital signal processing (DSP) elements and the programmable logic blocks (not shown in a figure). In an exemplary embodiment, a transceiver device (not shown in a figure) converts the Radio frequency signal to baseband signal (zero IF) or any fixed intermediate frequency. In an embodiment, a convertor (102) of Figure 1 acts as a transceiver device that converts RF signal to IF signal. The ADC (208) includes a numerically controlled oscillator (NCO), half band filters, a decimator, and interpolator circuits. The FPGA (210) mainly consists of lookup tables (LUT), registers, DSP multipliers, Random-access memory (RAM), and Read-only memory (ROM) devices.

[0053] Figure 3 illustrates a block diagram (300) depicting a signal processing system (100) for pulse detection in a field programmable gate array (210), according to an implementation of the present invention.

[0054] In Figure 3, the radio frequency (RF) signal is received from the RF receiver, as shown at a block (302). The convertor (102) of Figure 1 converts the RF signal to intermediate frequency (IF) required for the operation, as shown at a block (304). The IF signal is having I and Q channel paths. A correlation module (104) includes cross correlation and average moving energy with length equal to pulse duration. A preamble decision block (306) is used to estimate the variable threshold and to detect the preamble pulses. A synchronized preamble pulse position is used to calculate the spreading function. The constant phase modulation (308) computes the modulation of data pulses in the receiver (202) and these pulses are obtained after despreading of Walsh's codes. A parallel despread data correlation block (310) includes the correlation of the data pulses in 'k' parallel paths for each data pulse. A detection module (106) at a block (312) detects data which will set the data threshold to reduce the false alarm rate of the data. A data pulse streams formation block (314) is used to combine all code words present in the data pulses.

[0055] Figure 4 illustrates a flow diagram (400) depicting pulse detection and data decoding, according to an exemplary implementation of the present invention.

[0056] In Figure 4, the operation of the RF signal to IF signal conversion is performed at a step (402). At a step (404), the operation of cross correlation and average energy computation is performed. At a step (406), the operation of threshold estimation and preamble detection is performed. At a step (408), the operation of identification of required number preambles is performed. At a step (410), the operation of realization of spreading function is performed. At a step (412), the despreading and data decoding operation is performed. If the pulse width of the transmitted signal is Tb and a receiver sample are receiving at the sampling rate of Fs, then the total number of samples present in that pulse duration is Tb* Fs. A shift register of Tb* Fs length is considered in the system (100) to shift the incoming sample and the total number of samples present in the pulse duration is N (Tb* Fs). The constant phase modulated preamble samples are stored in a lookup table and the total number of samples present in the lookup table are equal to the pulse duration.
[0057] Figure 5 illustrates a schematic diagram (500) depicting cross correlation for preamble detection, according to an exemplary implementation of the present invention.

[0058] The complex correlation is implemented in the hardware for the preamble detection is shown in the Figure 5. The received IQ samples are delayed by using D flip-flops (502) and the flipped preamble samples are stored in the lookup tables. The received samples are multiplied (504) and accumulated (506) with the stored samples to implement the complex cross correlation. The final correlation value is computed by taking an absolute value (508) of the multiplied and accumulated output. The total number of multipliers required for the correlation operation can be reduced by adding the repeated sample position and then multiplied. The received IQ samples are multiplied and accumulated with itself in the pulse duration to get the moving average energy values.

[0059] Figure 6 illustrates a flow diagram (600) depicting preamble estimation and detection, according to an exemplary implementation of the present invention.

[0060] In an embodiment, the received signal mainly consists of the transmitted signal and noise. The noise is considered as additive white Gaussian noise (AWGN) with mean zero and two sided power spectral density of N0/2. At a step (602), a noise floor level is calculated without the transmitted signal and the initial estimated threshold value is set to the noise floor level. At a step (604), the cross correlation (M1) and the moving average energy (M2) computed. At a step (606), a new estimated threshold value is updated only if n(n>=3) or more consecutive increasing samples of the cross correlation values and the present cross correlation value exceed the initial estimated threshold value. The updated dynamic threshold value is equal to 3dB down to the maximum correlation value at that instance. To rise and fall the pulse boundary 3dB down to maximum value of cross correlation value is considered. If the present cross correlation value is above the updated threshold value then rise the window boundary and the window boundary will fall when the present cross correlation value is less than updated threshold value. At a step (608), a maximum peak value of cross correlation and the maximum peak value of the average energy with length equal to pulse duration are calculated in the pulse boundary. If the peak value of the cross correlation is greater than 'p' times the peak value of the average energy in that pulse duration, then the detected peak is a valid preamble, as shown at a step (610). The value of 'p' must be greater than equal to 1. If a valid preamble is detected, then reset the estimated threshold value to noise floor and repeat the same process for the next preamble. The estimated threshold value is reset to noise floor because the maximum peak value of cross correlation changes from preamble to preamble. The updated dynamic threshold value can be calculated on the moving average energy with length equal to pulse duration. If the distance between pulses is less than the pulse width, then it is difficult to find the pulse boundary because the average energy will not fall below the updated threshold. The detection of preamble pulse is mainly based on windowing technique and the decision of preamble is taken at the falling edge of the window boundary so updated threshold can be calculated on average energy with length equal to pulse duration only if the distance between the pulses is more than pulse width.

[0061] In an embodiment, the preamble pulses and its positions are required to compute the start of data pulse stream. The last preamble must be computed without error because the data pulse streams are starts from the last preamble in a fixed time distance. The obtained preamble position is used to calculate the spreading function. The 'n' data chips are mapped into 'k' data chips using (k, n) Walsh's function and the spread spectrum gain is k/n. The Walsh's codes are orthogonal codes and the cross correlation between any two codes is zero. The data pulses are despreaded by using the spreading function and the spreading function is obtained from the preamble positions. The possible data code words are obtained by bitwise XOR of Walsh's function with the spreading function. Each pulse has 'k' possible data codes because the data pulse is spread by 'k' data chips. The possible data code words are constant phase modulated and stored as I1 and Q1 in the lookup tables (LUT). The cross correlation is computed between the stored samples and the received IQ samples. The number of multipliers required for the data correlators are less than the preamble correlators because the start position of the data pulses prior to known. There are 'k' parallel cross correlation paths for each data pulse because there are 'k' possible code words. The maximum peak correlation value of the 'k' parallel paths is decoded as 'n' chip data code for that received pulse. The final data pulse stream is computed after decoding all the data pulses.

[0062] Figure 7a illustrates graphical representation depicting received preamble and data pulses at very high SNR, according to an exemplary implementation of the present invention. An example design of preambles and burst data pulses is shown in the Figure 7a. It demonstrates that the transmitted pulse has five number of preambles and 32 burst data pulses. The transmitted data pulses are spread using spreading function to improve the detection capability of the receiver.

[0063] Figure 7b illustrates graphical representation depicting preamble detection at very high SNR, according to an exemplary implementation of the present invention. In Figure 7b, the preamble pulses at high SNR are detected. Figure 7b demonstrates that at high SNR, the peak value of cross correlation and peak value of energy in that pulse duration coincide.

[0064] Figure 7c illustrates graphical representation depicting transmitted preamble and data pulses at low SNR, according to an exemplary implementation of the present invention. The received preamble and data pulses at low SNR values are shown in the Figure 7c. It demonstrates that the received pulses are below the noise floor level at low SNR.

[0065] Figure 7d illustrates graphical representation depicting preamble detection at low SNR, according to an exemplary implementation of the present invention. The detection of preamble pulses at low SNR values are shown in the Figure 7d. It demonstrates that at low SNR the peak value of cross correlation is more than peak value of moving average energy peak with length equal to pulse duration.
[0066] Figure 8 illustrates a flowchart (800) depicting a method for processing narrow pulsed modulated signals, according to an exemplary implementation of the present invention.

[0067] The flowchart (800) starts at a step (802), converting, by a convertor, a radio frequency (RF) signal to an intermediate frequency (IF) signal, wherein the IF signal includes preamble pulses and data pulses. In an embodiment, a convertor (102) is configured to convert a radio frequency (RF) signal to an intermediate frequency (IF) signal. At a step (804), computing, by a correlation module, a cross correlation value and a moving average energy value in the IF signal. In an embodiment, a correlation module (104) is configured to compute a cross correlation value and a moving average energy value in the IF signal. At a step (806), determining, by the correlation module, a threshold value based on the computed cross correlation value and the moving average energy value. In an embodiment, the correlation module (104) is configured to determine a threshold value based on the computed cross correlation value and the moving average energy value. At a step (808), estimating, by a detection module, a variable threshold value by using the determined threshold value, and detecting one or more preamble pulses of the IF signal. In an embodiment, a detection module (106) is configured to estimate a variable threshold value by using the determined threshold value, and detecting one or more preamble pulses of the IF signal. At a step (810), synchronizing, by a synchronization module, the detected preamble pulses and determining a position of each preamble pulse. In an embodiment, a synchronization module (108) is configured to determine a position of each preamble pulse. At a step (812), decoding, by a decoder, one or more data pulses of the IF signal by using the determined position of the preamble pulse, and computing a data pulse stream. In an embodiment, a decoder (110) is configured to decode one or more data pulses of the IF signal by using the determined position of the preamble pulse, and computing a data pulse stream.

[0068] 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(s) 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.