Patent Application
20220244293
The invention relates to RF spectrum analysis and more particularly to tools for analyzing a spectrum to locate RF issues.
RF spectrum analysis is a technology that started in the 1960s. Since then, the performance of the sweep-tune spectrum analyzer was improved and led to the arrival of the real-time spectrum analyzer. However, the way the user operates a spectrum analyzer has not evolved much. There remains a need to improve the user experience, by considering the end-user point of view and looking into ways to make it easier to analyze and troubleshoot RF issues.
Traditionally, in a RF spectrum analyzer interface, users can display and use markers. The user may place such a marker on the spectrum trace and can move it manually along the frequency axis. Once placed at a chosen frequency, the marker reports the amplitude (usually in dBm) at this frequency using the trace data.
Markers are typically used by the user to obtain the amplitude and frequency data for one or more peaks in the spectrum. Peaks may represent RF interferences that the user is trying to locate to address in the field. Manually placing a marker in the general area of one peak is relatively easy for the user but it is not precise due to the limited resolution of the display and the sensitivity of the touch sensors (if screen gestures are used). Zooming the display can improve precision but requires tedious back and forth between spectrum spans. In general, having the marker fall exactly on the maximum of the chosen peak using a manual entry method requires substantial skill and trial-and-error effort. In general, a manual entry method does not yield a precise selection of the chosen peak in a convenient manner.
Automated ways of placing these markers are available on the market. The maximum peak of the trace is typically easy to identify and mark using a simple software solution. It requires searching through the trace data to find the point of highest amplitude. This becomes the maximum peak. This is usually referred to as the “Go-To-Peak” functionality. Upon selection of this tool, the software identifies the maximum value of the trace data and displays a marker aligned on the maximum peak, with its associated amplitude and frequency data, for the user. For example,
In some prior art solutions, another type of automated marker placement or localization is available, namely the “Next/Previous Peak” or peak identification feature. It locates and places a marker on the peak which is located to the immediate right or left of the currently-selected peak or cursor location. Typically, the algorithms of the prior art solutions work well for obvious peaks but have limited success in more complex situations. Indeed, except for the most obvious traces, it is difficult to implement a computer algorithm that will find the next important peak without being sidetracked by the noise on the trace or the shape of the trace. For certain signals, the user must press “Next/Previous Peak” several times to get to the peak of interest, while for other signals, the algorithm may altogether skip the desired peak, forcing the user to resort to the manual entry method.
Furthermore, the highest peak is never a perfect Dirac delta function, i.e., it has a given width. The peak is drawn on the user interface with many pixels. If the solution simply attempts to find a point of amplitude that is lower than the maximum peak itself, it will simply find the adjacent pixels to the maximum peak itself and not a separate and distinct peak. The algorithm has to keep searching until the amplitude rises again. But it cannot stop searching as soon as the amplitude rises, it has to continue searching until the amplitude stops rising. Then it identifies a next peak. If the trace is noisy and has many ups and downs, this can cause multiple identifications of relatively unimportant peaks. Many adjacent peaks can be found and identified rendering the feature useless as it can't determine the relative importance of the peaks.
Moreover, the spectrum trace usually includes more data points (amplitude values) than can be displayed. Therefore, it is possible that the actual maximum for a secondary peak is not even apparent on the spectrum as currently displayed and therefore cannot be found by manual entry methods.
The performance of the peak identification feature of prior art spectrum analyzers is therefore unsatisfactory and there remains a need for an improved peak selection method for RF spectrum analyzers to assist users in selecting peaks more precisely.
In order to improve the analysis of the RF interferences, there is provided a peak selection assistance method for selecting a local peak in an RF spectrum trace. The method provides a window on the spectrum trace display, which can be configured and/or moved by a user from user interaction on said user interface. When the window is defined, the method finds the highest peak within the window and optionally adds a marker on it. The method therefore snaps to the highest peak within the window. This improves the way of precisely detecting the maximum amplitude and the center frequency for almost any local peak on the spectrum.
In one embodiment, the window is first displayed at any position along the frequency axis and can be dragged along the frequency axis by user interaction. When the window is released by the user, the method identifies the highest peak within the frequency window as released and adds a marker on it.
According to one broad aspect of the present invention, there is provided a method for identifying a maximum value in a section of a trace displayed to a user on a RF spectrum analyzer interface. The method comprises providing a display of said trace using trace data including frequency and amplitude components on said RF spectrum analyzer interface; providing a movable window with a first edge and a second edge and a width between said first edge and said second edge, adapted to be displaced by user interaction along a frequency axis of said trace; receiving an indication that said movable window is at a chosen position along said frequency axis; selecting a subset of said trace data using said first edge and said second edge at said chosen position along said frequency axis; determining a maximum of said amplitude within said subset of trace data to obtain said maximum value; determining a corresponding frequency value for said maximum value; providing information about said maximum value of said amplitude and said corresponding frequency value.
In accordance with one aspect, there is provided a method for assisting a user in selecting a local peak in a spectrum trace obtained using a RF spectrum analyzer. The method comprises:
A marker may optionally be displayed on the display at the corresponding frequency value.
In accordance with another aspect, there is provided a non-transitory computer-readable storage medium comprising instructions that, when executed, cause a processor to perform the steps of:
In accordance with yet another aspect, there is provided an RF spectrum analyzer device comprising:
Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration example embodiments thereof and in which:
It will be noted that throughout the drawings, like features are identified by like reference numerals. In the following description, similar features in the drawings have been given similar reference numerals and, to not unduly encumber the figures, some elements may not be indicated on some figures if they were already identified in a preceding figure. It should be understood herein that elements of the drawings are not necessarily depicted to scale, since emphasis is placed upon clearly illustrating the elements and structures of the present embodiments. Some mechanical or other physical components may also be omitted in order to not encumber the figures.
The following description is provided to gain a comprehensive understanding of the methods, apparatus and/or systems described herein. Various changes, modifications, and equivalents of the methods, apparatuses and/or systems described herein will suggest themselves to those of ordinary skill in the art. Description of well-known functions and structures may be omitted to enhance clarity and conciseness.
Although some features may be described with respect to individual exemplary embodiments, aspects need not be limited thereto such that features from one or more exemplary embodiments may be combinable with other features from one or more exemplary embodiments.
The present method and system for peak selection assistance may be used to improve the analysis of the RF interferences by assisting the user to select and analyze a local peak in the RF spectrum. This method facilitates taking measurements with an RF spectrum analyzer.
In order to improve the analysis of the RF interferences, there is provided a peak selection assistance method for selecting a local peak in an RF spectrum trace. This feature is referred to herein as the “snap-to-peak” features.
It is noted that, due to the limited resolution of the display screen, the spectrum trace as displayed may have a reduced resolution compared to the whole trace data as measured by the RF spectrum analyzer.
Here, the user interface 10 also shows markers M1, M2, M3 positioned on the highest peak (located at marker position M1), as well as secondary peaks (located at marker positions M2 and M3) and selected using the peak selection assistance method. The user interface 10 further shows a peak analysis display area 14 which is used to output the maximum amplitude value and the frequency value corresponding to each marker M1, M2, M3 and therefore to each peak found using the peak selection assistance method.
The first embodiment is now herein described with reference to
As shown in
The window 20 may be initially displayed at any arbitrary position along the frequency axis, such as, for example, the center of the spectrum trace display 12 and may have an initial predetermined width between the lower edge and the upper edge, as per software configuration.
For example, the initial width of the window 20 may be defined as proportion (e.g., a percentage) of the full bandwidth of the displayed spectrum trace, or as a predetermined frequency bandwidth. For example, the window width may be between 1 and 15% of the full bandwidth. In an example embodiment, the default window width is 2.5% of the span of the displayed spectrum trace. This width of the window can be made predefined by software configuration or be made customizable by the user via settings. In an example embodiment, the width of the window is configurable between 2 and 5%. A user may input a preferred width by entering a percentage value or a frequency value in a settings field. In other embodiment, the window width may be defined by the user interaction on the user interface using, e.g., a two-finger gesture on a touchscreen interface, the space between the two fingers indicating the desired width of the window.
From user interaction on the user interface, a position of the window may be moved along the frequency axis. In this example embodiment, the window 20 can be dragged by the user using a pointing device and released at the desired position, i.e., over the peak to be analyzed. For example, the window 20 may be dragged using finger gestures on a touch screen or using a mouse click hold, depending on the interface used. When the user is satisfied with the position of the window, he/she releases the pointing device by, for example, lifting the finger from the touchscreen or releasing the mouse button. Releasing the window 20 herein constitutes an indication that that the window 20 is at a chosen position along the frequency axis.
As illustrated in
It is noted that, due to the limited resolution of the display screen, the spectrum trace as displayed may have a lower resolution compared to the whole trace data as measured by the RF spectrum analyzer. Various decimation methods as known in the art may be used to obtain the displayed trace with such a lower resolution. For example, in one embodiment, the spectrum trace as displayed may include 1024 pixels whereas the actual trace data includes 128 k FFTs. The trace has 128 times more data points and thus provides a precision that is increased by a factor of 128. In order to precisely find the local peak within the window 20, the software searches for the maximum amplitude value using the trace data instead of the displayed spectrum trace.
The software selects a subset of the trace data using the lower edge and the upper edge of the window as defined along said frequency axis. In other words, it looks only into the trace data for which the frequency values are between the frequencies corresponding to the lower and the upper edge. It then finds the maximum of the amplitude values within this subset of the trace data, as well as the corresponding frequency value. These values are then output to the user on the user interface, e.g., by being displayed in the peak analysis display area 14.
The method therefore searches for the precise peak within the window as defined by the user, within the trace data that contains more precise data. The actual frequency of the peak from the trace data can be identified without being limited by display resolution. This improves the way of precisely detecting the maximum amplitude and the center frequency for any peak within the RF spectrum.
The software finds the maximum amplitude value in the window as selected by the user, and not over the whole bandwidth, hence covering the region of interest as indicated by the user. The method thereby snaps to the highest peak within the window. This method allows to detect the maximum amplitude and the center frequency for almost any local peak on the spectrum.
Of course, there may be some exception cases such as, e.g., if more than two peaks are close enough to be encompassed together within the frequency span of the window. The central peak would then be difficult to isolate but selecting a smaller window may help to avoid such issue.
As shown in
The peak selection assistance feature may then be used again on the same spectrum trace in order to position as many other markers as necessary. A marker can then be positioned on each peak considered of importance by the user and its corresponding metrics be displayed in the peak analysis display area 14 which outputs a table showing the metrics associated with each marker.
When looking for harmonics, it is often desirable to determine the difference in amplitude and frequency (delta) between markers. Because the peak selection assistance feature provides a more precise selection of a peak in any region of the spectrum, the delta calculation between two peaks selected using this method is more precise. Such delta values may further be displayed in the peak analysis display area 14. The user interface may further allow to sort the marked peaks by amplitude level to create a priority list of the interferences that have the biggest impact.
Some other optional characteristics of the peak selection assistance feature may further assist the user.
In some embodiments, when the user moves the window 20 along the frequency axis, the software constantly identifies the highest peak within the window and updates the marker in real-time. This gives precious feedback to the user when selecting a peak. It is noted that the processing speed of the system may not be sufficient to make real-time calculations of the high peak based on the whole data set of the trace data. For this reason, the method may determine a preliminary maximum amplitude value and corresponding frequency value based on the lower-resolution spectrum trace being displayed. This preliminary calculation based on the lower-resolution data set may allow better real-time feedback to the user.
Accordingly, while the window is being moved or reconfigured, the following steps are continuously repeated. The software selects preliminary subset of the lower-resolution spectrum trace using the lower edge and the upper edge of the window as currently defined. In other words, it looks only into the lower-resolution spectrum trace data points for which the frequency values are between the frequencies corresponding to the lower and the upper edge. It then finds the maximum of the amplitude values within this subset, as well as the corresponding frequency value. These preliminary values are then output to the user on the user interface, e.g., by being displayed in the peak analysis display area 14 or anywhere else. The search for the highest peak within the window may be repeated multiple times per second and displayed to the user to give immediate feedback while the window is being moved.
Furthermore, once the position of the window is defined (e.g., the window is released), the software may optionally continuously update the maximum amplitude value associated with the marker as new measurement data comes in. To do so, as the software continuously receives and displays new trace data measured by the RF spectrum analyzer, it continuously repeats the steps of determining the amplitude value (updated amplitude value) at the frequency value of the marker; and outputting the updated amplitude value, e.g., in the peak analysis display area 14. According, the marker frequency remains fixed as previously determined and only the amplitude value is updated.
In other embodiments, the marker position may also be updated as new measurement data comes in. To do so, as the software continuously receives and displays new trace data measured by the RF spectrum analyzer, it continuously repeats the steps of selecting a subset on the new trace data using the lower and upper edges of the window, determining a maximum amplitude value and a corresponding frequency value within the subset, and outputting these values.
The embodiments described herein with reference to
Furthermore, once the window is positioned, the user interface may optionally allow the user to move a position of any one edge of the window along the frequency axis, e.g., by a drag and drop gesture on the edge.
It is noted that a similar method may be used to identify and mark edges of a plateau in the RF spectrum. Similarly, a ‘snap-to-edge’ feature may be used to position a window along the frequency axis, where to look for the edge of a plateau instead of a peak. An additional step of using a contrast-enhancing filter and edge detector (or any other combination of filters) can be used to first highlight the sides of the plateau. It can then look for the bottom and top peaks at each edge of the plateau.
It will be understood that state of the art RF spectrum signal processing can be used along with the peak selection assistance tool in order to improve detection of RF interferers hidden into noise. For example, filtering methods such as that described in U.S. Pat. No. 11,121,785 to Levesque may be applied to perform a localized peak auto-detection that is able to discern a peak hidden in noise. Such filtering method may be used to better position the marker on a peak within the defined window. It may also be used for moving peaks. For example, after positioning the window and selecting a peak, the algorithm may continue to track the peak position within the window, providing the capability to report statistics such as maximum peak displacement.
Referring to
Example of RF Spectrum Analyzer Device Architecture
The processor 1002 is a hardware device for executing software instructions. The processor 1002 may comprise one or more processors, including central processing units (CPU), auxiliary processor(s) such as a graphics processing unit, or generally any device for executing software instructions. When the RF spectrum analyzer device 1000 is in operation, the processor 1002 is configured to execute software stored within the memory 1010, to communicate data to and from the memory 1010, and to generally control operations of the RF spectrum analyzer device 1000 pursuant to the software instructions. The I/O interfaces 1004 can be used to receive user input from and/or for providing system output. User input can be provided via, for example, a keypad, a touch screen, a scroll ball, a scroll bar, buttons, barcode scanner, and the like. System output can be provided via a display device such as a liquid crystal display (LCD), touch screen, and the like, via one or more LEDs or a set of LEDs, or via one or more buzzer or beepers, etc. The I/O interfaces 1004 can be used to display a graphical user interface (GUI) that enables a user to interact with the RF spectrum analyzer device 1000 and/or output at least one of the values derived by the RF spectrum analyzer.
The signal is received by the RF antenna 1005 and the IQ data acquisition device 1006 is used to tune the signal and bring it to a proper level. It may include an RF front-end including, e.g., low-noise amplification, filtering, conditioning, etc., in hardware circuitry. The IQ data acquisition device 1006 further comprises an analog to digital converter to sample the resulting signal.
Data is then be processed using digital signal processing such as Fast Fourier Transforms (FFT), filtering, decimation, computing power density array, etc., to produce trace data representing RF signal amplitude values as a function of frequency. A digital signal processing module may be implemented in hardware (DSP hardware acceleration 1007), in software executed by the central processing unit, or a combination of both. If included, the optional DSP hardware acceleration unit 1007 may comprise dedicated hardware and/or FPGA circuitry to execute some DSP computations.
The data store 1008 may be used to store data, such as RF spectrum traces and measurement data files. The data store 1008 may include any of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, and the like)), nonvolatile memory elements (e.g., ROM, hard drive, tape, CDROM, and the like), and combinations thereof. Moreover, the data store 1008 may incorporate electronic, magnetic, optical, and/or other types of storage media.
The memory 1010 may include any of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, etc.)), nonvolatile memory elements (e.g., ROM, hard drive, etc.), and combinations thereof. Moreover, the memory 1010 may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory 1010 may have a distributed architecture, where various components are situated remotely from one another, but can be accessed by the processor 1002. The software in memory 1010 can include one or more computer programs, each of which includes an ordered listing of executable instructions for implementing logical functions. In the example of
It is noted that, in some embodiments, the I/O interfaces 1004 may be provided via a physically distinct mobile device (not shown), such as a handheld computer, a smartphone, a tablet computer, a laptop computer, a wearable computer or the like, e.g., communicatively coupled to the RF spectrum analyzer device 1000 via a radio antenna. In such cases, at least some of the programs 1016 may be located in a memory of such a mobile device, for execution by a processor of the physically distinct device. The mobile may then also include a radio and be used to transfer measurement data files toward a remote test application residing, e.g., on a server.
It should be noted that the RF spectrum analyzer device shown in
The embodiments described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 63145825 | Feb 2021 | US | |
| 63263993 | Nov 2021 | US |
