Abstract:
A system and method for facilitating comparison of radio frequency (RF) data signals transmitted by a device under test (DUT) and received by a test system. A RF data signal received from a DUT is analyzed to provide analysis data indicative of conformance of the DUT operation with one or more applicable signal standards. The RF data signal is also converted to related conversion data that can be stored with state machine data corresponding to states of the signal testing subsystem. This state machine data can then be processed as needed with the analysis data and conversion data for off-line tasks such as debugging new test programs and procedures.

Description:
BACKGROUND 
       [0001]    The present invention relates to testing wireless radio frequency (RF) data signal transmitters, and in particular, to facilitating comparison of RF data signals transmitted by a device under test (DUT) and received by a test system. 
         [0002]    Many communication devices use wireless technologies both for connectivity and for communications purposes. Because wireless devices transmit and receive electromagnetic waves, and because two or more wireless devices have the potential of interfering with the operations of one another by virtue of their signal frequencies and power spectral densities, these devices and their wireless technologies subscribe to various wireless-technology standard specifications. 
         [0003]    In the designing of such devices, engineers take extraordinary care to ensure that such devices will meet or exceed each included wireless technology&#39;s prescribed standard-based specifications. Furthermore, once these devices are being mass produced, they are tested to ensure that manufacturing defects will not cause improper operation, including their adherence to the included wireless technology standard-based specifications. 
         [0004]    As part of such manufacturing testing, current wireless device test systems employ a subsystem for analyzing signals received from a device under test (DUT), e.g., a subsystem such as a vector signal analyzer (VSA) for analyzing signals received from the DUT, and a subsystem such as a vector signal generator (VSG) for generating signals to be received by the DUT. The analysis performed by a VSA and the signals generated by a VSG are usually programmable so as to allow each to be used for testing a variety of wireless technology standards with differing frequency ranges, bandwidths, and modulation characteristics. 
         [0005]    Today&#39;s wireless devices typically include circuitry designed to operate in accordance with several wireless signal technologies, such as WiFi (e.g., 802.11x), Bluetooth, cellular radio access technologies (e.g., LTE), and the like. In addition, to keep test time and costs from increasing as more and more wireless signal technologies are incorporated in such devices, some of today&#39;s wireless signal test systems are designed to capture and analyze longer signal sequences that have physical characteristics prescribed by two or more wireless signal technology standards. 
         [0006]    In testing longer sequences of multiple technology characteristics, the test programs that control the test system (e.g., by controlling the VSA, VSG and other subsystems) become longer and more complex, and as does the test program debugging process. Often program debugging requires attaching external instruments, such as multi-channel oscilloscopes, to the test system and associated other test instruments in order to examine various control signals and power-versus-time displays so as to understand and solve problems related to the new-program debugging process. 
       SUMMARY 
       [0007]    In accordance with the presently claimed invention, a system and method are provided for facilitating comparison of radio frequency (RF) data signals transmitted by a device under test (DUT) and received by a test system. A RF data signal received from a DUT is analyzed to provide analysis data indicative of conformance of the DUT operation with one or more applicable signal standards. The RF data signal is also converted to related conversion data that can be stored with state machine data corresponding to states of the signal testing subsystem. This state machine data can then be processed as needed with the analysis data and conversion data for off-line tasks such as debugging new test programs and procedures. 
         [0008]    In accordance with one embodiment of the presently claimed invention, a test system for facilitating comparison of radio frequency (RF) data signals transmitted by a device under test (DUT) and received by the test system includes: 
         [0009]    signal routing circuitry for routing at least one RF transmit data signal to and at least one RF receive data signal from a DUT; 
         [0010]    data signal source circuitry coupled to the signal routing circuitry and responsive to a portion of a plurality of control signals and a plurality of transmit data by providing the at least one RF transmit data signal and a portion of a plurality of system data; 
         [0011]    data signal analysis circuitry coupled to the signal routing circuitry and responsive to another portion of the plurality of control signals by processing the at least one RF receive data signal and providing a plurality of signal analysis data and another portion of the plurality of system data; 
         [0012]    signal conversion circuitry coupled to the signal routing circuitry and responsive to the at least one RF receive data signal by providing a related plurality of receive conversion data; and 
         [0013]    a state machine coupled to the data signal source circuitry and the data signal analysis circuitry, and responsive to the plurality of system data by providing a plurality of state machine data. 
         [0014]    In accordance with another embodiment of the presently claimed invention, a method of facilitating comparison of radio frequency (RF) data signals transmitted by a device under test (DUT) and received by a test system includes: 
         [0015]    routing at least one RF transmit data signal to and at least one RF receive data signal from a DUT; 
         [0016]    receiving a portion of a plurality of control signals and a plurality of transmit data and in responsive thereto providing the at least one RF transmit data signal and a portion of a plurality of system data; 
         [0017]    receiving another portion of the plurality of control signals and in responsive thereto processing the at least one RF receive data signal and providing a plurality of signal analysis data and another portion of the plurality of system data; 
         [0018]    converting the at least one RF receive data signal to provide a related plurality of receive conversion data; and 
         [0019]    processing the plurality of system data with a state machine to provide a plurality of state machine data. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a block diagram of a conventional testing environment for testing a wireless signal device under test (DUT). 
           [0021]      FIG. 2  depicts intended and actual transmit signals from the DUT for the testing environment of  FIG. 1 . 
           [0022]      FIG. 3  is a functional block diagram of a conventional testing environment for testing a wireless signal DUT with the addition of external commercial test equipment for capturing the signal directly from the DUT. 
           [0023]      FIG. 4  depicts intended and actual transmit signals from the DUT along with corresponding capture control signals within the tester for the testing environment of  FIG. 3 . 
           [0024]      FIG. 5  is a functional block diagram of a wireless signal testing environment using a test system and supporting one or more test methods in accordance with exemplary embodiments of the presently claimed invention. 
           [0025]      FIG. 6  is functional block diagram of the testing environment of  FIG. 5  with the test system supporting one or more test methods in accordance with further exemplary embodiments of the presently claimed invention. 
           [0026]      FIG. 7  is a functional block diagram of a testing environment using a test system and supporting one or more test methods in accordance with further exemplary embodiments of the presently claimed invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The following detailed description is of example embodiments of the presently claimed invention with references to the accompanying drawings. Such description is intended to be illustrative and not limiting with respect to the scope of the present invention. Such embodiments are described in sufficient detail to enable one of ordinary skill in the art to practice the subject invention, and it will be understood that other embodiments may be practiced with some variations without departing from the spirit or scope of the subject invention. 
         [0028]    Throughout the present disclosure, absent a clear indication to the contrary from the context, it will be understood that individual circuit elements as described may be singular or plural in number. For example, the terms “circuit” and “circuitry” may include either a single component or a plurality of components, which are either active and/or passive and are connected or otherwise coupled together (e.g., as one or more integrated circuit chips) to provide the described function. Additionally, the term “signal” may refer to one or more currents, one or more voltages, or a data signal. Within the drawings, like or related elements will have like or related alpha, numeric or alphanumeric designators. Further, while the present invention has been discussed in the context of implementations using discrete electronic circuitry (preferably in the form of one or more integrated circuit chips), the functions of any part of such circuitry may alternatively be implemented using one or more appropriately programmed processors, depending upon the signal frequencies or data rates to be processed. Moreover, to the extent that the figures illustrate diagrams of the functional blocks of various embodiments, the functional blocks are not necessarily indicative of the division between hardware circuitry. Thus, for example, one or more of the functional blocks (e.g., processors, memories, etc.) may be implemented in a single piece of hardware (e.g., a general purpose signal processor, random access memory, hard disk drive, etc.). Similarly, any programs described may be standalone programs, may be incorporated as subroutines in an operating system, may be functions in an installed software package, etc. 
         [0029]    As discussed in more detail below, a system and method are introduced for adding and using additional subsystems, internal to a testing system, which will support program debug for virtually any and all test programs, particularly those that involve long multi-technology signal sequences. As such, overall costs are reduced by eliminating need for costly external testing adjuncts and by potentially shortening program debug time by providing insights unavailable when using external testing adjuncts. Furthermore, it allows one to visualize what is actually happening between the DUT and test system in the sense that the DUT and test system are controlled independently so that the sequences, while appearing to be highly coordinated, are more loosely coupled. Having a view of what&#39;s happening within the DUT and tester offers a more complete debugging picture. Also, this can be achieved without imposing a test-time penalty. During normal operations, it is a matter of simply keeping a record, in parallel with ongoing execution of the test program. In the event of an error, the signal and control capture signal data can then be used to diagnose what has occurred. 
         [0030]    Referring to  FIG. 1 , a conventional testing environment includes a test system  100 , or tester, for testing a wireless signal DUT  10 . The DUT  10  includes, among other subsystems, a RF transceiver  12  and a set  14  of pre-defined signal sequences to be initiated by one or more firmware routines, software commands or hardwired circuit structure(s) (various forms of each of which are well known in the art). The DUT  10  transmits a test signal sequence  13   t  over a signal communication medium  14  (which is typically a hardwired signal path for purposes of testing, but may also be a wireless signal connection if desired) for reception by the tester  100 . 
         [0031]    The tester  100  includes, among other subsystems, signal routing circuitry  112  (discussed in more detail below), signal analysis circuitry  114  (e.g., a VSA), test signal generating circuitry  116  (e.g., a VSG), data storage circuitry  118  (e.g., memory circuitry locally within the tester  100  or remotely available via a network) and control circuitry  120  (e.g., microprocessor- or microcontroller-based). The control circuitry  120  exchanges control signals in data  121   a,    121   g  with the VSA  114  and VSG  116 , and provides control signals  121   s,  as needed, for the signal routing circuitry  112 . The control circuitry  120  can also exchange control signals and data  121   c  with external circuitry, such as an external controller in the form of a personal computer (not shown). 
         [0032]    The signal routing circuitry  112 , in accordance with its control signals  121   s  as required, performs two basic functions: routing the DUT transmit signal  13   t  as the input signal  115  to the VSA  114 , and routing the VSG output signal  117  to the DUT as a DUT receive signal. The routing circuitry  112  can be a switch, such as a single-pole  124 , double-throw  126   a,    126   g  switch in which the signal path  122  switches between receive and transmit modes of the tester  100  (and transmit and receive modes of the DUT, respectively). Alternatively, the signal routing circuitry  112  can be implemented in other known ways (e.g., as a diplexer). 
         [0033]    As depicted in  FIG. 1 , in accordance with the pre-defined signal sequence  14 , the DUT transceiver  12  transmits a signal  13   t  having, for example, three sub-sequences of which the middle sequence has a significantly reduced signal level or power. This signal  13   t,  routed as the input signal  115  to the VSA  114 , results in a captured signal  119   aa  which is sampled and provided by the VSA  114  as digitized signal data  119   a  for storage in the memory  118 . As depicted in  FIG. 1 , the captured signal  119   aa  is lacking the middle sequence having significantly reduced signal power. 
         [0034]    Referring to  FIG. 2 , this can be better visualized. As depicted in the upper signal wave form diagram, the intended DUT transmit signal  13   i  was to include a middle sequence having increased signal power. As a result, all three signal sub-sequences A, B, C would have signal power sufficient to exceed the trigger level within the VSA  114  and thereby be assured of being captured all signal sub-sequences A, B, C. 
         [0035]    However, as depicted in the lower signal diagram, the actual DUT transmit signal  13   t  erroneously included a middle sequence B having significantly reduced signal power insufficient to exceed the trigger level, and, therefore, prevented from being captured by the VSA  114  as part of the captured test signal  119   aa . Accordingly, subsequent analysis of the captured data signal  119   aa  could erroneously conclude that the second sub-sequence captured corresponds to the intended second sub-sequence B when, in fact, it corresponds to the third sub-sequence C. As a result, the test program would result in an erroneous analysis, and without any other data describing or somehow otherwise related to the actual received signal  13   t,  detection and/or correction of this erroneous analysis would be difficult and de-bugging of the test program would require significantly more time. 
         [0036]    Referring to  FIG. 3 , one approach that has been used in an attempt to capture information about the actual DUT signal  13   t  includes the use of an external triggered instrument  132 , such as a triggering oscilloscope, which can sample and store signal data  133  corresponding to the actual DUT signal  13   t.  High resolution data is not required, and lower resolution signal data  133  will be adequate and can be stored using less memory  134 . This power-versus-time (PVT) data envelope  133  corresponding to the actual DUT signal  13   t  can be stored and later compared, e.g., in terms of timing of the signal peaks and valleys, among other characteristics, as part of any troubleshooting or debugging of a test program. 
         [0037]    Referring to  FIG. 4 , as before, the intended DUT signal  13   i  includes sub-sequences with the middle sub-sequence having increased signal power. However, the actual DUT signal  13   t  includes sub-sequences in which the middle sub-sequence erroneously has lower signal power. As a result, the signal profiles for the capture control signal associated with the intended DUT signal  13   i  will differ from that of the capture control signal profile as generated within the VSA  114  for the actual DUT signal  13   t.  Such difference in capture control signal profiles, e.g., differences in capture control signal pulses versus time, provide insight into possible causes of the program error. However, the capture control signal generated by the VSA  114  is not accessible to the external instrumentation  132 . Accordingly, one or more additional external sub-systems would be required to collect, compare and/or correlate the capture control signals produced by the VSA  114  and external instrumentation  132 . 
         [0038]    Referring to  FIG. 5 , in accordance with exemplary embodiments of the presently claimed invention, the tester  200  further includes a sub-system  202  for capturing signal data related to the actual DUT signal  13   t.  Also, the signal routing circuitry  112   a  has the additional ability to provide a signal  203  corresponding to the actual DUT signal  13   t.  For example, when implemented as a single-pole, double-throw switch, the pole  124   a  can include a power divider so that the VSA input signal  115  and the diverted input signal  203  both correspond to the actual DUT signal  13   t.    
         [0039]    This sub-system  202  includes a power detector  204 , analog-to-digital conversion (ADC) circuitry  206 , digital data storage circuitry  208  (e.g., memory circuitry) and a state machine  220 , interconnected substantially as shown. The power detector  204  detects the signal power envelope of the incoming signal  203 . The detected power envelope signal  205  is converted to a digital signal  207  by the ADC circuitry  206 . This digital data  207  is stored in the memory  208  in accordance with one or more control signals  221   s  from the state machine  220 . The state machine  220  also receives the VSA  121   a  and VSG  121   g  control signals and data, as well as control and/or data signals  221   a,    221   g  providing information about the sub-system states of the VSA  114  and VSG  116 . Such sub-system control information and data can also be stored in the memory  208  in accordance with the state machine control signals  221   s.  As a result, one or more state machine data signals  209  can be provided, e.g., depicting the signal power envelope  209   a  of the incoming DUT signal  203  and the capture control signals  209   b.    
         [0040]    This advantageously provides for capture and later access to a PVT record of signal sub-sequences A, B, C ( FIGS. 2 and 4 ), plus state machine data (e.g., capture control signal data) associated with the capture of the incoming DUT signal  203 . Since the power detector  204  measures the power envelope of the signal, fewer data bits are required and a lower sampling rate can be used, thereby minimizing the amount of capture memory needed. The system state machine  220  will reflect internal timing in controlling the capture and storage in the memory  208 . As a result, internal timing, which would not otherwise be accessible by external instruments ( FIG. 3 ), can be used to cross-reference, compare and/or correlate the captured PVT data against internal timing markers. For example, the state machine states  209   b  during the writing of the data  207  into memory  208  can be stored in the memory  208  along with the PVT envelope data  209   a.  This provides a more richly populated set of troubleshooting information for use when debugging new or modified test programs. 
         [0041]    Referring to  FIG. 6 , in accordance with further exemplary embodiments of the presently claimed invention, such a tester  200  can also be used for troubleshooting and debugging test programs during performance of receive signal tests of the DUT  10 , i.e., where the VSG  116  is providing a test signal  117  to be routed out to the DUT  10  via the test signal path  14  as a receive signal  13   r  for the DUT  10 . In this testing scenario, the power detector  204  and ADC circuitry  206  may or may not be needed. However, the state machine  220  can continue to provide state data  209   a,    209   b  for storage in the memory  208 . This data  209  can later be accessed when needed for troubleshooting or debugging a test program. 
         [0042]    Additionally, in DUT testing scenarios where frequency division duplex (FDD) signals are used, the VSA  114  and VSG  116  can both be active, with the VSA input signal  115  being received and processed by the VSA  114  while the VSG  116  is providing its output signal  117 . Test systems and methods in accordance with exemplary embodiments of the presently claimed invention allow for inspection of data packets received by the VSA  114 , e.g., to identify an erroneous synchronization event. 
         [0043]    Referring to  FIG. 7 , in accordance with further exemplary embodiments of the presently claimed invention, the test system  300  can be implemented to support testing of multiple DUTs  10   a,    10   b,    10   c,    10   d.  (This illustrative example involves a testing environment for four DUTs, but as will be readily appreciated by one of ordinary skill in the art, this implementation can be scaled down or up to support testing of smaller or larger numbers of DUTs). In this exemplary embodiment, the tester  300  includes corresponding numbers of routing circuits  12   aa    12   ab,    12   ac,    12   ad,  power detectors  204   a,    204   b,    204   c,    204   d,  ADC circuits  206   a,    206   b,    206   c,    206   d  and memory elements  208   a,    208   b,    208   c,    208   d  (as will be readily appreciated, however, a single memory element can also be used to provide sufficient memory for storing the converted data  207   a,    297   b,    207   c,    207   d ). The tester  300  also includes a multiplexor  302  and a signal splitter  304 . 
         [0044]    The DUT signals  13   ta,    13   tb,    13   tc,    13   td  from the DUT transceivers  12   a,    12   b,    12   c,    12   d  are routed by the signal routing circuits  112   aa ,  112   ab ,  112   ac ,  112   ad  to the multiplexor  302 , which, in accordance with one or more control signals  121   m  from the controller  120 , selects one of its input signals  115   a,    115   b,    115   c,    115   d  to be provided  115  to the VSA  114 , e.g., during successive time intervals t1, t2, t3, t4. As can be seen, the state machine subsystem  202  ( FIG. 5 ) is replicated in accordance with the number of the DUTs  10  to be tested. This allows the PVT envelope data of each diverted DUT signal  203   a,    203   b,    203   c,    203   d  to be sampled and stored, as discussed above. 
         [0045]    In this example, the third DUT  10   c  is providing an erroneous signal  13   tc,  which, unlike the remaining DUT signals  13   ta ,  13   tb ,  13   td , includes a signal sub-sequence with significantly reduced signal magnitude, as opposed to the intended significantly increased signal magnitude (e.g., corresponding to sub-sequence B as depicted in  FIGS. 2 and 4 ). This signal  13   tc  is routed by the multiplexor  302 , e.g., during time interval t3, to the VSA  114 . This results in the capture and storing of an incomplete signal sequence  119   aa   3 , similar to those as described above. Meanwhile, the state machine subsystem associated with the third DUT  10   c  produces PVT data  209   ca  and control signal  209   cb  to be made available as data  209   c  retrievable from the memory  208   c  for analysis in determining problems with the test program. 
         [0046]    Alternatively, for DUT receive system testing, the VSG output signal  117  is distributed by the splitter  304  and routing circuits  112   aa ,  112   ab ,  112   ac ,  112   ad  to the DUTs  10   a,    10   b,    10   c,    10   d.  As discussed above, the VSA  121   a  and VSG  121   g  control signals and other VSA and VSG state data  221   a ,  221   g  are captured by the state machine  220  and stored  221   s  in the memory  208   a,    208   b,    208   c,    208   d,  for later use in correlating signal emissions from the VSG  116  with internal system control states. 
         [0047]    As will be further appreciated, in accordance with this implementation  300 , one DUT signal is monitored by the VSA  114  during any given time interval. However, advantageously, all DUT signals can nonetheless be monitored by having their respective PVT envelopes sampled and stored along with state machine information for later analysis and use in program debugging. 
         [0048]    Various other modifications and alterations in the structure and method of operation of this invention will be apparent to those skilled in the art without departing from the scope and the spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. It is intended that the following claims define the scope of the present invention and that structures and methods within the scope of these claims and their equivalents be covered thereby.