Abstract:
An exemplary device samples a converter signal (e.g., input to a block up converter or output from a low noise block) at a very small aperture terminal site and identifies, as between a site converter and a site modem, a more likely faulty component to aid site diagnosis and repair.

Description:
BACKGROUND INFORMATION 
       [0001]    When communications via a Very Small Aperture Terminal (VSAT) site fail or degrade, the site owner/operator typically dispatches a technician to diagnose and correct the problem. When initial diagnosis indicates that site components are likely faulty, the owner/operator sends replacement parts to the site. Because known diagnostic tools and techniques limit the dispatcher&#39;s ability to precisely isolate faulty components absent a trial-and-error swapping-out of suspect parts, the owner/operator sometimes sends a number of different replacement parts and instructs the dispatcher to return any parts that are ultimately deemed unnecessary for site repair. This back-and-forth treatment of spare components not only drives up shipping costs for the owner/operator, but also forces the owner/operator to expend resources in testing whether returned equipment is suitable for future use—even though such equipment may have been returned by a dispatcher without the dispatcher ever having removed it from its packaging. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  depicts an exemplary system for diagnosing an under performing VSAT site in accordance with exemplary embodiments; 
           [0003]      FIG. 2  depicts an exemplary diagnostic device for use in the system of  FIG. 1 ; and 
           [0004]      FIG. 3  depicts an exemplary process for diagnosing an under performing VSAT site in accordance with exemplary embodiments. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0005]    The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. The following detailed description does not limit the invention. 
         [0006]      FIG. 1  depicts an exemplary VSAT site diagnostic system  100 , As shown, exemplary system  100  includes a modem  110 , a transmit link  120 , a receive link  130 , a transmit converter  140 , a receive converter  150 , and a diagnostic device  160 . As indicated by dashed lines in the figure, modem  110  is typically housed within a VSAT site indoor unit (IDU), while converters  140 ,  150  are typically housed within a VSAT site outdoor unit (ODU). Also, links  120 ,  130  form an inter-facility link (IFL) between modem  110  and converters  140 ,  150 , as is well known. 
         [0007]    Modem  110  can be any known VSAT modem suitable for facilitating bi-directional communication between an earth station and a satellite. In the ground-to-satellite or transmit direction, modem  110  combines an intermediate frequency transmit signal (designated TX-IF in  FIG. 1 ) with direct current (DC) power and a reference signal (indicated, by way of example, as a 10 MHz sinusoid in  FIG. 1 ) for conveyance via transmit link  120  to transmit converter  140 . 
         [0008]    Transmit link  120  can be any suitable wire-line or wireless link, and typically takes the form of one or more coaxial cables. Transmit converter  140  can be any suitable VSAT transmit converter, and is generally known as a block up-converter, or BUC, inasmuch as it typically translates a band (or “block”) of frequencies from a lower portion of usable spectrum to a higher portion (e.g., from L band to Ku, C, or Ka band), as is well known. 
         [0009]    The DC power conveyed via transmit link  120  energizes BUC  140 , and BUC  140  utilizes the reference signal (e.g., as a phase locked loop reference) to up-convert and communicate the TX-IF signal to an earth satellite. More specifically, BUC  140  typically feeds an orthogonal mode transducer (OMT) which in turn drives a feed-horn for a reflector parabolic dish aimed at the satellite, as is well known. 
         [0010]    In the satellite-to-ground or receive direction, receive converter  150  typically accepts a high-frequency satellite signal (e.g., via the above noted OMT) and down-converts it to provide an intermediate frequency receive signal (designated RX-IF in  FIG. 1 ) for conveyance to modem  110  via receive link  130 . Receive converter  150  can be any suitable VSAT receive converter, and is generally known as a low noise block, or LNB, inasmuch as it down-converts blocks of frequencies and operates in isolation from other noise-inducing electronics. 
         [0011]    Like BUC  140 , LNB  150  can receive DC power and a reference signal from modem  110 , as is shown in  FIG. 1 . However, use of a reference signal by LNB  150  is relatively rare, occurring only in instances when highly stable and low phase noise LNB local oscillators are required in conjunction with advanced modulation/demodulation techniques, as is well known. 
         [0012]    Should any of the above described VSAT transmission or reception functions fail or deteriorate, diagnostic device  160  facilitates troubleshooting as described hereinafter. Device  160  can be, for example, a portable (e.g., handheld) device or a stationary device situated at the VSAT site (e.g., positioned near or integrated with the ODU that houses converters  140 ,  150 ). 
         [0013]      FIG. 2  depicts an exemplary diagnostic device  160 . As shown, exemplary device  160  includes signal conditioning circuitry  210 , a processor  220 , a memory  230 , a user interface  240 , and a communications interface  250 . As indicated by dashed lines in the figure, the depicted device components can communicate, using well known techniques, via a common bus. 
         [0014]    Signal conditioning circuitry  210  can be any known analog and/or digital circuitry suitable for sampling VSAT signals of interest (e.g., input/output at BUC  140  and/or LNB  150 ) and conveying the sampled signals for use by the various device components of  FIG. 2 . Toward this end, device  160  can be constructed such that inputs to conditioning circuitry  210  can be selectively coupled, physically or electronically, to transmit path  120  and/or receive path  130 . 
         [0015]    For example, device  160  can be constructed as a handheld device including appropriate (e.g., co-axial) connectors so that device  160  can be physically inserted in-line with BUC  140  and/or LNB  150 . Alternately, device  160  can be fixed at the VSAT site, and inputs to conditioning circuitry  210  can be electronically or manually switched to make or break contact at the input and/or output of BUC  140  and/or LNB  150 . 
         [0016]    Processor  220  can include any known processor, microprocessor, or other processing logic suitable for interpreting and executing instructions. Also, memory  230  can include a random access memory (RAM) or any type of dynamic storage device that may store information and instructions for execution by processor  220 . Memory  230  can also include a read-only memory (ROM) device, a disk drive, or any other type of static storage device suitable for storing data and/or instructions for use by processor  220 . 
         [0017]    User interface  240  can include any mechanism that permits a device operator to input information to device  160 , such as a keyboard, a mouse, a pen, a microphone, voice recognition and/or biometric mechanisms, remote controls, etc. User interface  240  can also include any mechanism suitable for conveying information to the device operator, including a display such as a liquid crystal display (LCD) or light emitting diode (LED) display, a speaker, a printer, etc. 
         [0018]    Communications interface  250  can include any known mechanism suitable for communicating information between device  160  and other external devices or systems. For example, interface  250  can include a serial port, a parallel port, and/or any modem or transceiver-like mechanism that enables device  160  to communicate with proximate and/or remote devices or systems (e.g., via any suitable wireline or wireless link or network). 
         [0019]    As described herein, device  160  can perform certain operations in response to processor  220  executing software instructions contained in a computer-readable medium, such as memory  230 . A computer-readable medium may be defined as a physical or logical memory device. The software instructions may be read into memory  230  from another computer-readable medium, such as a storage device, or from another device or system via communications interface  250 . 
         [0020]    Also, hardwired circuitry may be used in place of or in combination with software instructions to implement processes described herein. Consequently, processes described herein are not limited to any specific hardware and/or software combination. 
         [0021]    Although  FIG. 2  shows exemplary components of device  160 , in other implementations device  160  may contain fewer, different, or additional components than depicted in  FIG. 2 . In still other implementations, one or more components of device  160  may perform one or more other tasks described as being performed by one or more other components of device  160 . 
         [0022]    To understand operation and use of device  160 , it is instructive to consider the various types and causes of problems typically seen at a VSAT system such as system  100 . For example, low transmit power (i.e., low transmit carrier-to-noise, or C/N, ratio) can be caused by poor weather conditions, an improper maximum power setting on modem  110 , or failure of BUC  140 . If site  100  does not transmit at all, it may mean that modem  110  is improperly configured for the particular type of BUC  140  being used, that transmit link  120  (e.g., an IFL cable) is disconnected or damaged, or that one or both of modem  110  and BUC  140  is defective. 
         [0023]    Also, when site  100  exhibits low receive quality (i.e., low receive C/N ratio), it may be the result of poor weather conditions, or it may be that one or both of modem  110  and LNB  150  is faulty. If site  100  receives no signal at all, then the dish may not be properly aligned to the satellite, the receive link  130  (e.g., an IFL cable) may be disconnected or damaged, or one or both of modem  110  and LNB  150  may be defective. 
         [0024]    Troubleshooting certain of the above described faults is straightforward. For example, one can readily check weather conditions, confirm modem configuration, and verify IFL cable integrity. However, when these checks have been made (and remedied as necessary) and the site still does not function correctly, then typically either modem  110  or one of converters  140 ,  150  (depending upon whether the problem relates to transmission or reception, respectively) is defective, and as noted above, it is difficult for a dispatcher in the field to determine precisely which component is bad short of a trial-and-error swapping-in of replacement components. 
         [0025]    Advantageously, according to exemplary embodiments, empirical data can be utilized to facilitate identification of most likely faulty component(s) without swapping-in parts. For example, practice has shown that when a converter  140 ,  150  draws current, it will output at least a nominal signal. Though the output signal may be of insufficient power level or otherwise fail to meet manufacturer specifications, the output signal will nonetheless be present. Also, it has been observed that converters  140 ,  150  are rarely intermittently faulty—typically they either work continuously or don&#39;t work at all. By contrast, modem  110  is typically more complex in design, and may exhibit partial failure (e.g., everything works except the 10 MHz reference signal, etc.). 
         [0026]    Device  160  can be programmed to take advantage of these and other observations to enable early or preliminary identification of most likely faulty component(s). For example, if system  100  fails or exhibits degradation in the transmit direction, device  160  can detect the direct current (DC) voltage level and DC current draw at or near the input of BUC  140 , and determine whether the reference signal is present on the IFL cable at the input to BUC  140 . If the detected voltage and current levels are within specification for BUC  140 , it is highly probable that BUC  140  is operating as intended and that the transmit output of modem  110  is faulty. However, if the voltage level is within tolerance, but the current draw is incorrect (e.g., at or near zero, or otherwise out of spec), then BUC  140  is very likely defective. Also, if the reference signal is absent or incorrect, then modem  110  may be faulty irrespective of the voltage and current seen. 
         [0027]    Accordingly, device  160  can apply logic to the values seen at BUC  140  to conclude, or enable a device user to conclude, that one or both of modem  110  and BUC  140  is likely faulty and should be replaced. Device  160  can make similar measurements, and apply analogous logic, at LNB  150  when system  100  fails or exhibits degradation in the receive direction. For example, device  160  can measure DC voltage and current at LNB  150 , and (when appropriate) detect whether a reference signal is present at LNB  150 . If the voltage and current are correct, then LNB  150  is likely working and the receive function of modem  110  is likely faulty. But if the voltage is correct and the current is incorrect, then LNB  150  is likely faulty. Also, if the reference is needed by LNB  150  but is absent or incorrect, then modem  110  may be faulty. 
         [0028]    In view of the foregoing, exemplary troubleshooting logic is shown in table form below. The logic is applicable for both transmit and receive diagnostics in instances when the converter (i.e., BUC  140  when troubleshooting transmit problems, and LNB  150  when troubleshooting receive problems) requires a reference signal from modem  110 . This logic is most often suitable for troubleshooting transmit problems, since as noted above BUC  140  typically requires a reference signal and LNB  150  typically does not. 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 Exemplary Logic when Converter Requires Reference Signal 
               
             
          
           
               
                 Reference 
                 DC Voltage 
                 DC Current 
                 More Likely Faulty, 
               
               
                 Present? 
                 in Range? 
                 in Range? 
                 Modem vs Converter 
               
               
                   
               
               
                 No 
                 No 
                 No 
                 Modem 
               
               
                 No 
                 No 
                 Yes 
                 n/a 
               
               
                 No 
                 Yes 
                 No 
                 Inconclusive (Perhaps Both) 
               
               
                 No 
                 Yes 
                 Yes 
                 Modem 
               
               
                 Yes 
                 No 
                 No 
                 Modem 
               
               
                 Yes 
                 No 
                 Yes 
                 n/a 
               
               
                 Yes 
                 Yes 
                 No 
                 Converter 
               
               
                 Yes 
                 Yes 
                 Yes 
                 Inconclusive (Likely Neither) 
               
               
                   
               
             
          
         
       
     
         [0029]    The first three columns in the table refer to observations made at a converter (i.e., at BUC  140  or at LNB  150  as appropriate), and the fourth column shows diagnostic inferences that can be made based on the observations as described above. Device  160  can be constructed and programmed to compute and display any or all of the results shown in the table. For example, device  160  can display only yes/no results of some or all observations made at the converter, thus leaving it to a device user to draw the diagnostic inferences. Alternatively or in addition, device  160  can compute and display the diagnostic inferences for the user. Moreover, device  160  can display actual signal values seen at the converter (e.g., DC voltage, DC current, transmit/receive signal strength, etc.) to aid the device user in making a diagnosis or otherwise. 
         [0030]    In the table above, it is presumed that preliminary checks have been made and that weather, system power, modem configuration, IFL cable integrity, converter connections, etc. have checked out “OK.” Accordingly, an indication in the table (or a display by device  160 ) of “Modem” can be interpreted, for example, as “Modem likely faulty-replace and retest prior to replacing converter or other components.” Similarly, an indication/display of “Converter” can be interpreted as “Converter likely faulty-replace and retest prior to replacing modem etc.” 
         [0031]    However, if preliminary checks are not presumed, then an indication/display of “Modem” can be interpreted more broadly as, for example, “Likely modem error-check modem power, modem configuration, modem connections, etc. and retest prior to replacing components.” Likewise, an indication/display of “Converter” can be interpreted as, for example, “Likely converter error-check IFL cable, converter connections, etc. and retest before replacing parts.” 
         [0032]    Note that an indication in the table of “n/a” (i.e., “not applicable”) reflects a condition that generally should not occur (e.g., converter current in range when converter voltage is incorrect). Accordingly, if device  160  detects such a condition, it can display “Diagnostic Device Error” or the like. Also, note that an indication in the table of “Inconclusive” reflects a combination of observations that makes pinpointing a single most likely faulty device difficult. In such case, device  160  can display “Diagnosis Inconclusive” or the like, or it can display an inference relating to both modem and converter (e.g., “Both modem and converter may be faulty” when the reference signal is absent and the current is out of range, or “Neither the modem nor the converter is likely faulty” when the reference, voltage and current all appear correct). 
         [0033]    When the converter under test (i.e., BUC  140  for transmit diagnostics, and LNB  150  for receive diagnostics) does not require a reference signal from modem  110 , then the above described troubleshooting logic can be reduced to that shown in table form below. Such reduced logic is equivalent to applying the above described reference-required logic and always assuming that the reference signal is present. This reduced no-reference-required logic is most often suitable for troubleshooting receive problems, since LNB  150  typically does not use a reference. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Logic when Converter Does Not Require Reference Signal 
               
             
          
           
               
                 DC Voltage 
                 DC Current 
                 Likely Faulty, 
               
               
                 Present? 
                 in Range? 
                 Modem vs Converter 
               
               
                   
               
               
                 No 
                 No 
                 Modem 
               
               
                 No 
                 Yes 
                 n/a 
               
               
                 Yes 
                 No 
                 Converter 
               
               
                 Yes 
                 Yes 
                 Inconclusive (Likely Neither) 
               
               
                   
               
             
          
         
       
     
         [0034]    The precise logic implemented by device  160  can be pre-configured or read in from another device or system via communications interface  250 . Similarly, specification data for modem  110 , converters  140 ,  150 , etc. can be preconfigured in device  160  or fed into device  160  via interface  250  (e.g., from another proximate device via a serial or parallel port, or from a remote device or system via a network). Moreover, various aspects of the functionality of device  160  can be made user-selectable via user interface  240  (e.g., enabling the user to select between transmit and receive modes, or to select a particular modem and/or converter from a menu, etc.) 
         [0035]    Advantageously, device  160  can be constructed as a portable device for use by a dispatcher (e.g., as a handheld device, and possibly combined with well known satellite meter functionality such as that provided by the well known “Birdog” meters). Alternatively, device  160  can be fixed at site  100  and monitored/operated by a visiting dispatcher and/or by a remote operator (e.g., a technician situated at a central station to which device  160  is networked). In either case, useful functionality beyond that described above can be integrated into device  160 . 
         [0036]    For example, if device  160  is constructed to be inserted in-line with converters  140 ,  150 , then the output of device  160  can be made switchable such that the device user can selectively create an electrical “open” at the device output. Doing so would, for example, allow the user to observe changes in the voltage and current values on the IFL as the circuit is terminated or un-terminated and thus enable the user to answer routine diagnostic questions (e.g., is the voltage at the converter low because the modem output voltage is not high enough, or because there is too much voltage drop across the IFL?). Advantageously, making the output of device  160  switchable enables the user to answer such questions without having to disconnect cables during system operation, which can lead to accidental shorts and equipment damage as is well known. 
         [0037]    In view of the foregoing,  FIG. 3  depicts an exemplary process  300  for diagnosing an under-performing VSAT site. Process  300  begins at block  310 , in which one or more signals are detected at or near a converter of the underperforming site, Next, at block  320 , a determination is made, based on the detected signal(s), as to whether a DC voltage at the converter is within an acceptable range, whether a DC current draw by the converter is within an acceptable range, and optionally, whether a reference signal is present and within specification at the converter. 
         [0038]    These determinations are then used, at block  330 , to identify, as between the converter and a modem of the underperforming site, a most likely faulty component and a least likely faulty component. Finally, at block  340 , the most likely faulty component is replaced and the site is tested for proper operation before consideration is given as to whether to replace the least likely faulty component (i.e., replace the least likely faulty component only when replacing the most likely faulty component does not restore proper system operation). 
         [0039]    The above described exemplary embodiments promote swift and accurate identification of faulty VSAT components, thereby reducing the time and cost associated with maintaining a VSAT site. For example, exemplary embodiments may significantly reduce unnecessary shipping of replacement components to support on-site diagnostics. 
         [0040]    The foregoing description of implementations provides illustration and description, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. For example, while a series of blocks are described with regard to certain of the figures, the order of the blocks may be modified in other implementations. Moreover, non-dependent blocks may be performed in parallel. 
         [0041]    It will be apparent that embodiments, as described herein, may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures. The actual software code or specialized control hardware used to implement embodiments described herein is not limiting of the invention. Thus, the operation and behavior of the embodiments were described without reference to the specific software code—it being understood that software and control hardware may be designed to implement the embodiments based on the description herein. 
         [0042]    Further, certain portions of the invention may be implemented as “logic” that performs one or more functions. This logic may include hardware, such as an application specific integrated circuit or a field programmable gate array, or a combination of hardware and software. 
         [0043]    Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the invention. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. 
         [0044]    No element, act, or instruction used in the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Where only one item is intended, the term “one” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.