PATENT DOCUMENT

Publication Number: US-9448279-B2
Application Number: US-201113225290-A
Country: US
Kind Code: B2

Title: Test systems for electronic devices with wireless communications capabilities

Abstract:
A test system may be provided for performing wireless communications testing of electronic devices in a building. The test system may include a mobile cart that transports the device under test to test stations in the building. The test system may include a visible guide track having visible test station indicators. The mobile cart may include an optical sensor for detecting the visible guide track and the visible test station indicators. The mobile cart may transport the device under test to the test stations along the visible guide track. The mobile cart may include a rotating stage to which the device under test may be mounted. The rotating stage may be used to rotate the device under test while the device under test transmits test data to wireless communications equipment in the building during wireless communications testing of the device under test.

Claims:
What is claimed is: 
     
       1. A method of testing a device under test with a computer controlled mobile cart, wherein the computer controlled mobile cart includes a rotating stage on which the device under test is mounted and an additional stage on which interference equipment is mounted, the method comprising:
 with the computer controlled mobile cart, transporting the device under test to a plurality of test stations at different locations; 
 with the device under test, transmitting wireless test data in a communication channel while at each of the plurality of test stations; 
 with the interference equipment, wirelessly interfering with the device under test by transmitting radio-frequency signals in the communication channel concurrently with transmission of the wireless test data in the communication channel by the device under test; and 
 with the rotating stage, rotating the device under test while the device under test transmits the test data. 
 
     
     
       2. The method defined in  claim 1 , wherein the computer controlled mobile cart further comprises an optical sensor, the method further comprising:
 with the optical sensor, locating each of the plurality of test stations. 
 
     
     
       3. The method defined in  claim 2  wherein the optical sensor includes a plurality of light sensors, and wherein locating each of the plurality of test stations comprises:
 with the light sensors, detecting a visible test station indicator. 
 
     
     
       4. The method defined in  claim 3 , wherein the computer controlled mobile cart includes a plurality of motors, a plurality of wheels and a plurality of spools that store cables and wherein transporting the device under test to the plurality of test stations comprises:
 with a first portion of the plurality of motors, turning at least some of the plurality of wheels to move the computer controlled mobile cart; and 
 with a different portion of the plurality of motors, turning the plurality of spools to maintain a torque on the cables. 
 
     
     
       5. The method defined in  claim 4  wherein the visible test station indicator comprises a visible test station indicator on a visible guide track, the method further comprising:
 with the light sensors, detecting a first position of the computer controlled mobile cart with respect to the visible test track; and 
 with the at least some of the plurality of wheels, moving the computer controlled mobile cart to a second position with respect to the visible test track. 
 
     
     
       6. The method defined in  claim 1  further comprising:
 with wireless communications equipment, receiving the wireless test data transmitted by the device under test at each of the plurality of test stations; and 
 with computing equipment, storing and analyzing the wireless test data received by the wireless communications equipment. 
 
     
     
       7. A test system for wireless communications testing of a device under test, comprising:
 a mobile cart for transporting the device under test; 
 interference equipment mounted on the mobile cart that is configured to interfere with radio-frequency communication by the device under test by wirelessly transmitting radio-frequency signals in a communication channel concurrently with transmission of wireless test data by the device under test in the communication channel; 
 a telescoping support structure on the mobile cart that is configured to support the device under test while the mobile cart transports the device under test and that is configured to raise and lower the device under test during the wireless communications testing; 
 a visible test track along which the mobile cart transports the device under test; and 
 control equipment for controlling the mobile cart. 
 
     
     
       8. The test system defined in  claim 7  further comprising:
 wireless communications equipment for receiving wireless test data from the device under test. 
 
     
     
       9. The test system defined in  claim 8  further comprising:
 computing equipment for storing and analyzing the test data received by the wireless communications equipment and for generating signals to be conveyed by the control equipment when controlling the mobile cart. 
 
     
     
       10. The test system defined in  claim 7  wherein the mobile cart comprises:
 a rotating stage on which the device under test is mounted; 
 an optical sensor; and 
 a plurality of spools for storing cables on the mobile cart. 
 
     
     
       11. The test system defined in  claim 10  wherein the cables comprise:
 a power cable coupled to the control equipment; and 
 a communications cable coupled to the control equipment. 
 
     
     
       12. The test system defined in  claim 7 , wherein the mobile cart further comprises a rotating stage on which telescoping support structure is mounted, wherein the rotating stage is configured to rotate the device under test while the device under test transmits radio-frequency signals.

Description:
BACKGROUND 
     This relates generally to testing wireless electronic devices and more particularly, to testing wireless electronic devices in a real-world environment. 
     Electronic devices such as portable computers and cellular telephones are often provided with wireless communications capabilities. For example, electronic devices may use long-range wireless communications circuitry such as cellular telephone circuitry to communicate using cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz. Electronic devices may use short-range wireless communications circuitry to handle communications with nearby equipment. For example, electronic devices may communicate using the WiFi® (IEEE 802.11) bands at 2.4 GHz and 5 GHz and the Bluetooth® band at 2.4 GHz. 
     During normal operation, wireless electronic devices are often used to communicate data to wireless communications equipment in a building. For example, a wireless electronic device may exchange data with a remote computer or another wireless electronic device using a wireless communications router located in the building. The efficiency with which a wireless electronic device exchanges data with the computer is typically affected by the distance of the device from the router, orientation of the device and building structures such as walls, doors, windows, etc., between the device and the router. 
     During testing, wireless electronic devices under test (DUTs) are typically tested in fixed test stations. Fixed test stations provide repeatable test conditions for testing multiple devices under the same conditions. However, fixed test stations may not provide sufficient information on the communications performance of the DUT in real-world conditions that mimic the typical use of the device by a user. 
     It would therefore be desirable to provide improved test systems for electronic devices with wireless communications capabilities. 
     SUMMARY 
     A test system may be provided for performing wireless communications tests on electronic devices. The electronic devices may have wireless communications circuitry. The wireless communications circuitry may be used to communicate with the test system during testing. The test system may include a path in a building. The test system may include a computer controlled mobile cart for moving the device under test along the path in the building. The path may include one or more test stations at which the mobile cart may stop during wireless communications tests of the device under test. 
     The path may be defined by a visible guide track. The mobile cart may follow the visible guide track using optical sensors in the cart. The visible guide track may include visible test station indicators. The optical sensors on the cart may be configured to recognize visible test station indicators. The mobile cart may be configured to stop for wireless communications testing when the optical sensors recognize the visible test station indicators. 
     The mobile cart may include a rotating stage for mounting the device under test. The rotating stage may be configured to rotate the device under test during wireless communications testing at each test station. 
     The mobile cart may include one or more active spools for storing communications and power cables on the cart. The active spools may include torque sensors and motors. The motors may be configured to turn the spools based on torques measured by the torque sensors. The motors may be configured to maintain a constant tension in the communications and power cables by turning the spools. 
     The test system may include guide structures for guiding the communications and power cables as the mobile cart moves along the path. The test system may include control equipment for controlling the motion of the cart along the path and for controlling the rotating stage during wireless communications tests. The test system may include wireless communications equipment for communicating with the device under test during wireless communications testing. The test system may include computing equipment connected to the wireless communications equipment for gathering test data using the wireless communications equipment during wireless communications testing. 
     The computing equipment may be used to analyze and store the test data gathered during the wireless communications testing at each test station. Test data gathered during the wireless communications testing at each test station may include information on effects of multi-path communications interference in a real-world environment. 
     Further features of the present invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an illustrative wireless device under test wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 2A  is a diagram of an illustrative test system including a mobile cart, control equipment, computing equipment, wireless communications equipment and a visible guide track along which the mobile cart transports the device under test in accordance with an embodiment of the present invention. 
         FIG. 2B  is a diagram of an illustrative test system including wireless communications equipment on multiple floors of a building in accordance with an embodiment of the present invention. 
         FIG. 3  is a diagram of an illustrative mobile cart that has a rotating stage, spools for storing communications and power cables and multiple motors in accordance with an embodiment of the present invention. 
         FIG. 4  is a cross-sectional side view of an illustrative portion of a mobile cart of the type shown in  FIG. 3  having optical sensors, support wheels and drive wheels in accordance with an embodiment of the present invention. 
         FIG. 5  is a front view of an illustrative optical sensor of the type that may be included in the mobile cart shown in  FIG. 3  in accordance with an embodiment of the present invention. 
         FIG. 6  is an illustrative diagram showing how optical sensors of the type shown in  FIG. 5  may detect a turn in a visible guide track in accordance with an embodiment of the present invention. 
         FIG. 7  is an illustrative diagram showing how optical sensors of the type shown in  FIG. 5  may detect a visible test station indicator in a visible guide track in accordance with an embodiment of the present invention. 
         FIG. 8  is a diagram of an illustrative rotating stage for rotating a device under test in which the device under test is embedded in the rotating stage in accordance with an embodiment of the present invention. 
         FIG. 9  is a diagram of an illustrative rotating stage for rotating a device under test in which the device under test mounted to the rotating stage using mounting structures in accordance with an embodiment of the present invention. 
         FIG. 10  is a diagram of an illustrative rotating stage for rotating a device under test in which the device under test mounted to the rotating stage using mounting structures that mimic physical and electrical properties of human hands and arms in accordance with an embodiment of the present invention. 
         FIG. 11  is a diagram of an illustrative rotating stage for rotating a device under test in which rotating stage includes telescoping support structures in accordance with an embodiment of the present invention. 
         FIG. 12  is a diagram of an illustrative rotating stage for rotating a device under test in which rotating stage includes telescoping support structures mounted to a stage support structure in accordance with an embodiment of the present invention. 
         FIG. 13  is a diagram of an illustrative mobile cart that has more than one rotating stage in accordance with an embodiment of the present invention. 
         FIG. 14  is a flow chart of illustrative steps involved in performing wireless communications tests of devices under test in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Wireless electronic devices include antenna and transceiver circuitry that support wireless communications. Examples of wireless electronic devices include desktop computers, computer monitors, computer monitors containing embedded computers, wireless computer cards, wireless adapters, televisions, set-top boxes, gaming consoles, routers, or other electronic equipment. Examples of portable wireless electronic devices include laptop computers, tablet computers, handheld computers, cellular telephones, media players, and small devices such as wrist-watch devices, pendant devices, headphone and earpiece devices, and other miniature devices. 
     Devices such as these are often provided with wireless communications capabilities. For example, electronic devices may use long-range wireless communications circuitry such as cellular telephone circuitry to communicate using cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz (e.g., the main Global System for Mobile Communications or GSM cellular telephone bands). Long-range wireless communications circuitry may also handle the 2100 MHz band. 
     Electronic devices may use short-range wireless communications links to handle communications with nearby equipment. For example, electronic devices may communicate using the WiFi® (IEEE 802.11) bands at 2.4 GHz and 5 GHz and the Bluetooth® band at 2.4 GHz. It is sometimes desirable to receive satellite navigation system signals such as signals from the Global Positioning System (GPS). Electronic devices may therefore be provided with circuitry for receiving satellite navigation signals such as GPS signals at 1575 MHz. 
     In testing environments, the wireless electronic devices are sometimes referred to as devices under test (DUTs).  FIG. 1  shows an example of a test device such as DUT  10 . DUT  10  may be a portable electronic device, a cellular telephone, a computer, a multimedia device, or other electronic equipment. 
     DUT  10  may have storage and processing circuitry such as storage and processing circuitry  4 . Storage and processing circuitry  4  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  4  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Circuitry  4  may interact with wireless communications circuitry such as wireless communications circuitry  6 . Wireless communications circuitry  6  may include one or more antennas such as antenna  8 . Antenna  8  may configured to send and receive data at cellular telephone bands (e.g., 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz), WiFi® bands at 2.4 GHz and 5 GHz and the Bluetooth® band at 2.4 GHz. Wireless communications circuitry may include additional components such as an analog-to-digital converter (ADC), a digital-to-analog converter (DAC), a digital down-converter (DDC), a digital up-converter (DUC) or other components. 
     During testing, wireless communications circuitry  6  may be used to transmit data generated by storage and processing circuitry  4  to a test system for testing DUT  10 . 
     During testing, one or more wireless devices (e.g., one or more of DUTs  10 ) may be tested in a test system such as test system  20  of  FIG. 2A . As shown in  FIG. 2A , DUT  10  may be mounted to a computer controlled mobile cart such as computer controlled mobile cart  22  (sometimes referred to herein as mobile cart, mobile test station, roving test vehicle, automatic roving test vehicle, rover, cart, etc.). DUT  10  may be mounted to mobile cart  22  using mounting structures such as mounting structures  26 . Mounting structures  26  may be formed from plastic or other materials. Mounting structures  26  may include materials configured to mimic the physical and electrical properties of human arms or hands to simulate a user holding DUT  10  during testing. 
     Mobile cart  22  may include one or more rotating stages such as rotating stage  24 . Rotating stage  24  may be used for rotating DUT  10  in a direction such as direction  21  (or opposite to direction  21 ) during wireless communications testing of DUT  10 . Rotating stage  24  may be formed from any suitable non-conducting material (e.g., expanded polystyrene foam, Styrofoam® plastic, etc.) Rotating stage  24  may be mounted to a support structure such as support structure  28 . Support structure  28  may be formed from any suitable non-conducting material such as wood, plastic, etc. Support structure  28  may be used to support operational equipment for computer controlled mobile cart  22 . Operational equipment that may be mounted on support structure  28  may include one or more spools such as spools  38 , one or more motors such as motors  40 , cart control equipment  42 , one or more optical sensors such as optical sensors  32  or other operational equipment. Spools  38  may be used to store cables such as power cable  34  and communications cable  36  on mobile cart  22 . Cart control equipment  42  may include one or more torque sensors for sensing a torque on spools  38  due to cables  34  and  36 . Motors  40  may include one or more motors for turning spools  38  depending on torques measured by cart control equipment  42 . Cart control equipment  42  may be used to operate motors  40  when torques on spools  38  are above or below predetermined thresholds. Cart control equipment  42 , motors  40  and spools  38  may be configured to maintain a constant tension on cables  34  and  36  during operation of mobile cart  22 . 
     Mobile cart  22  may be supported on wheels such as wheels  30 . Wheels  30  may include wheels that connected to one or more motors  40  and wheels that are not connected to any motors. Wheels  30  that are connected to motors  40  may be used to drive and turn mobile cart  22 . Wheels  30  that are not connected to any motor may include wheels having hinges that help maintain the height of support structure  28 . Maintaining the height of support structure  28  may help mobile cart  22  follow a path such as path  44  during testing of DUT  10 . Path  44  may be formed from a visible guide track. Visible guide track  44  (sometimes referred to herein as visible test track, or test track) may be sensed by cart  22  using optical sensors such as optical sensor  32 . Optical sensors  32  may be mounted on or under support structure  28 . Optical sensors  32  may include one or more light sensors capable of detecting visible test track  44 . Cart control equipment  42  may be used to control a drive system configured to guide mobile cart  22  along path  44  using signals measured by optical sensors  32 . The drive system may include wheels  30  and some of motors  40 . Controlling the drive system to guide mobile cart  22  along path  44  may include using cart control equipment  42  to turn some of wheels  30  using some of motors  40  to direct mobile cart  22  along path  44  using signals measured by optical sensors  32 . Signals measured by optical sensors  32  may be transmitted using communications cable  36  to control equipment such as control equipment  54 . Control equipment  54  may be used to relay signals from optical sensors  32  to computing equipment  56 . Computing equipment  56  may be used to generate signals to be sent by control equipment  54  along communications cable  36  to direct motors  40  to turn wheels  30  in such a way that mobile cart  22  follows visible test track  44 . 
     Test track  44  may include one or more turns such as turn  49 , one or more bends such as bend  47  and one or more visible test station indicators such as visible test station indicators  48 . Optical sensors  32  may be configured to recognize turns  49 , bends  47  and visible test station indicators  48 . Turns  49  and bends  47  may be used to direct mobile cart  22  around structures such as structures  50  in a building. Structures  50  may include walls of a hallway, doorways, doors, floors, ceilings, other obstacles, or other building structures. Structures  50  may help generate multi-path communications interference that inhibits data transfer between DUT  10  and wireless communications equipment  58 . Test system  20  may be configured to test the effects of multi-path communications interference in a real-world environment. 
     Test stations such as test stations  46  that are indicated by visible test station indicators  48  of visible test track  44  may be arranged along track  44  such that multi-path communications interference may be monitored at multiple predefined positions with respect to wireless communications equipment  58 . Test stations  46  may be arranged along track  44  such that wireless communications tests may be conducted at locations having structures  50  interposed between DUT  10  and wireless communications equipment  58 . Wireless communications equipment  58  may include a wireless router that is connected to computing equipment  56 . DUT  10  may transmit test data to wireless communications equipment  58  that is relayed to computing equipment  56 . Computing equipment  56  may be used to store and analyze test data received by wireless communications equipment  58 . 
     Mobile cart  22  may be configured to stop for a predetermined amount of time when optical sensors  32  on cart  22  detect visible test station indicators  48 . Cart control equipment  42  mounted on support structure  28  may be used to drive one of motors  40  when cart  22  is stopped at test stations  46  such that rotating stage  24  turns DUT  10  in direction  21  (or opposite to direction  21 ). Wireless communications testing using test system  20  may include transmission of test data from DUT  10  to wireless communications equipment  58  while rotating stage  24  turns DUT  10 . Computing equipment  56  may be used to generate control signals using control equipment  54  that cause cart control equipment  42  to turn rotating stage  24  using motors  40  such that DUT  10  transmits test data at a plurality of orientations during wireless communications testing of DUT  10  at each test station  46  along path  44 . 
     Test system  20  may include guide structures such as guide structure  52 . Guide structure  52  may be configured to guide cables such as cables  34  and  36  around structures  50  as mobile cart  22  moves along path  44  during wireless communications testing of DUT  10 . Test system  20  may include portions on multiple floors of a building. 
     As shown in  FIG. 2B , test system  20  may be configured such that wireless communications equipment  58  (see  FIG. 2A ) includes a portion  58 L on a lower floor of a building and an upper portion  58 U on a relatively higher floor of a building. In the example of  FIG. 2B , structures  50  include building structures that form lower and upper floors of a building. Test stations such as test stations  46  of  FIG. 2A  may be arranged such that wireless communications tests are conducted at locations having structures  50  interposed between DUT  10  and upper wireless communications equipment  58 U and lower wireless communications equipment  58 L. Upper wireless communications equipment  58 U and lower wireless communications equipment  58 L may each include a wireless router that is connected to computing equipment  56 . At each test station  46 , DUT  10  may transmit test data alternately to upper wireless communications equipment  58 U and lower wireless communications equipment  58 L that is then relayed to computing equipment  56 . Computing equipment  56  may be used to store and analyze test data received by both upper wireless communications equipment  58 U and lower wireless communications equipment  58 L. Cart control equipment  42  mounted on support structure  28  may be used to turn rotating stage  24  in order to rotate DUT  10  during wireless communications testing of DUT  10 . Wireless communications testing using test system  20  may include transmission of test data from DUT  10  alternately to upper wireless communications equipment  58 U and lower wireless communications equipment  58 L while rotating stage  24  turns DUT  10 . If desired, computing equipment  56  may be configured to turn off a selected one of upper wireless communications equipment  58 U or lower wireless communications equipment  58 L while DUT  10  is transmitting test data to the other of upper wireless communications equipment  58 U or lower wireless communications equipment  58 L. In this way, interference from, for example, multiple wireless routers may be avoided during wireless communications testing of DUT  10 . 
       FIG. 3  is a diagram of an illustrative embodiment of computer controlled mobile cart  22 . As shown in  FIG. 3 , rotating stage  24  of computer controlled mobile cart  22  may be mounted to support structure  28  using a stage support such as stage support  60 . In order to limit interference by cart structures with wireless data transmitted from or received by DUT  10  during wireless communications testing, cart structures may be optimized to keep conducting structures and electrical components far from DUT  10 . For example, rotating stage  24  may be formed from any non-conducting material (e.g., expanded polystyrene foam, Styrofoam®, plastic, etc.). Stage support  24  may be formed from any suitable non-conducting material (e.g., plastic, glass, etc.). Stage support  60  may have a length L that is configured to isolate DUT  10  from cart control equipment  42  or other conducting or electrically active equipment on cart  22 . For example, length L may be more than one foot, more than two feet, more than three feet, etc. Rotating stage  24  may have a depth D that helps isolate DUT  10  from cart control equipment  42  or other conducting or electrically active equipment on cart  22 . For example, depth D may be more than one foot, more than two feet, more than three feet, etc. 
     In order to further isolate DUT  10  from conducting structures that may interfere with wireless communications testing, other cart structures that reach more than 3 to 4 inches above support structure  28  may preferably be formed from non-conducting materials. As an example, spools  38  may be formed from any suitable non-conducting materials (e.g., plastic, etc.). 
     As shown in  FIG. 3 , spools  38  may be used to store cables such as power cable  34  and communications cable  36  on cart  22 . Power cable  34  may be used to provide power to mechanical and electrical components of cart  22 . Communications cable  36  may include one or more optical fibers. In one preferred embodiment which is sometimes described herein as an example, communications cable  36  may include six optical fibers. Optical fibers in communications cable  36  may be used to convey signals (e.g., for controlling drive wheels  30 , rotating stage  24 , spools  38 ), or to convey data between cart components and computing equipment  56  (see  FIG. 2A ). In the example of  FIG. 3 , each spool  38  is controlled by a motor  40 . Motors  40  may be coupled to spools  38  using one or more gears such as gears  64  that transfer the motion of motors  40  to spools  38 . Motors  40  may be commanded by computing equipment  56  to turn spools  38  based on torque information gathered using torque sensors such as torque sensor  39  attached to spools  38 . Torque sensor  39  may be implemented as a part of motors  40  or may be implemented as a separate component mounted to spools  38 . Spools  38  may be mounted to support structure  28  using spool mounting structures such as spool mounting structures  68 . Cables  34  and  36  may be held in a particular position with respect to cart  22  using cable guide structures such as cable guide structures  70 . Cable guide structures  70  may be mounted to support structure  28  and may each include one or more rolling members that allow cables  34  and  36  to pass through cable guide structures  70 . 
     Cables  34  and  36  may be coupled to cart control equipment  42  using cable interfaces such as cable interface  66  of  FIG. 3 . Cart control equipment may be implemented as a single integrated module or may be distributed in several control modules as shown in  FIG. 3 . Portions of cart control equipment  42  (i.e., different modules of cart control equipment  42 ) may be coupled together using cables such as cable  72  that pass above support structure  28  or may be coupled together using cables that pass under support structure  28  (not shown). 
     As shown in  FIG. 3 , stage support  60  may be coupled to cart control equipment  42  using one or more geared platforms such as geared platform  62 . Geared platform  62  may be coupled to a motor housed in a module of cart control equipment  42  using a belt such as belt  63 . Belt  63  and geared platform  62  may be used to transfer motion of a motor associated with cart control equipment  42  to stage support  60 , thereby turning rotating stage  24  in a direction such as direction  21  during wireless communications testing of a DUT such as DUT  10  that is mounted to rotating stage  24  using mounting structures  26 . Direction  21  is merely illustrative. Rotating stage  24  may be configured to turn opposite to direction  21  if desired. 
     Cart control equipment may include a manual drive control module such as manual drive control module  71 . Manual drive control module  71  may be used to manually direct computer controlled mobile cart  22 . For example, manual drive control module  71  may be used to move cart  22  into position at the start of track  44  (see  FIG. 2A ), may be used to move cart  22  when cart  22  is not in use for wireless communications testing, etc. 
     Motors  40  may include one or more motors mounted on top surface  80  of support structure  28  and may include one or more motors mounted on the bottom surface of support structure  28 . As an example, motors  40  mounted on top surface  80  of support structure  28  may be used to control spools  38  while motors  40  mounted on the bottom surface of support structure  28  may be used to control drive wheels such as drive wheels  30 D that drive and turn cart  22 . In addition to drive wheels  30 D that drive and turn cart  22 , cart  22  may include support wheels such as support wheels  30 S that support cart  22  and help maintain a constant height for support structure  28  of cart  22 . 
     During normal operations of DUT  10 , a user may place DUT  10  on various surfaces (e.g., on desktop made from wood, metal, glass, etc.) In order to test the effect of placing DUT  10  on various surfaces, rotating stage  24  may be provided with a top surface  25  that is formed from a material that is different from the material that forms the bulk of rotating stage  24 . For example, top surface  25  may be formed from metal, wood, glass, stone, composite material or other suitable material. This is merely illustrative. If desired, top surface  25  may be formed from substantially the same material as rotating stage  24 . 
     As shown in  FIG. 4 , drive wheels  30 D may be mounted on bottom surface  82  of support structure  28 . Drive wheels such as drive wheels  30 D may be controlled using a motor such as motor  40  that is mounted to bottom surface  82  of support structure  82 . Mobile cart  22  may include any number of drive wheels  30 D. In one preferred embodiment that is sometimes described herein as an example, mobile cart  22  may include a left drive wheel and a right drive wheel. Mobile cart  22  may be driven by turning both right and left drive wheels with motors  40 . Mobile cart  22  may be turned by holding one drive wheel  30 D in place while turning another drive wheel  30 D. Alternatively, mobile cart  22  may be driven and turned by turning one drive wheel  30 D at a different rate from another drive wheel  30 D. Mobile cart  22  may include one or more support wheels such as support wheel  30 S mounted to bottom surface  82  of support structure  28 . Support wheels  30 S may be hinged wheels that can turn when mobile cart  22  is turned using drive wheels  30 D. Support wheels  30 S may help maintain optical sensors such as optical sensor  32  at a constant height above test track  44 . 
     Mobile cart  22  may include one or more optical sensors such as optical sensor  32  of  FIG. 4 . As an example, mobile cart  22  may include one optical sensor  32  mounted at the back of bottom surface  82  of support structure  28  and one optical sensor  32  mounted at the front of bottom surface  82  of support structure  28 . In a configuration in which mobile cart  22  includes an optical sensor at the front of cart  22  and an optical sensor at the back of cart  22 , information from both optical sensors may be used by computing equipment  56  (see  FIG. 2A ) to keep mobile cart  22  positioned on test track  44 . 
     Optical sensor  32  may include one or more light sensors such as light sensors  84  mounted to sensor support structures  88 . Light sensors  84  may be connected to cart control equipment  42  (see  FIG. 3 ) using wires such as wires  86 . Light sensors  88  of optical sensor  32  may be configured to sense visible guide track  44 . 
     An illustrative configuration that may be used for optical sensors  32  is shown in  FIG. 5 . In the example of  FIG. 5 , optical sensor  32  includes four light sensors  84  that are mounted to three sensor support structures  88 . Sensor support structures  88  are attached to bottom  82  of support structure  82 . Middle light sensors  84 M are attached on opposing sides of middle sensor support structure  88 . Middle light sensors  84  may be configured such that they remain over test track  44  (i.e., middle light sensors  84  may generate signals requiring no action when track  44  is detected below middle light sensors  84 M and may generate signals requiring corrective action when track  44  is not detected below.) 
     Light sensor  32  may include two additional light sensors  84  such as left light sensor  84 L and right light sensor  84 R mounted to two outer sensor support structures  88  that are mounted to support structure  24  on opposing sides of middle sensor support structure  88 . Left and right sensors  84 L and  84 R may be configured to remain on opposing sides of test track  44  (i.e., left and right light sensors  84 L and  84 R may generate signals requiring no action when track  44  is not detected below left and right light sensors  84 L and  84 R and may generate signals requiring corrective action when track  44  is detected below.) Signals generated by light sensors  84  may be conveyed to computing equipment  56  (see  FIG. 2A ) using wires such as wires  86 . 
     Middle light sensors  84 M mounted to middle sensor support structure  88  may be primarily configured to help mobile cart  22  navigate substantially straight portions of test track  44 . Left and right light sensors  84 L and  84 R mounted to outer sensor support structures  88  may be primarily configured to help mobile cart  22  navigate turns in test track  44  and detect visible test station indicators  48  at test stations  46  along test track  44 . 
     A diagram showing how light sensors  84  may be used to detect a turn in test track  44  is shown in  FIG. 6 . As shown in  FIG. 6 , as mobile cart  16  travels from point A to point B along test track  44 , middle light sensors  84 M remain over test track  44  along paths  90 M and continuously detect test track  44  while left and right light sensors  84 L and  84 R remain on opposing sides of test track  44  and do not detect test track  44 . When light sensors  84  reach point B, left light sensor  84 L detects test track  44  while right light sensor  84 R does not detect test track  44 . Left light sensor  84 L detecting test track  44  while right left light sensor  84 R does not detect test track  44  may indicate a left turn in test track  44 . 
     In response to signals from light sensors  84  indicating a left turn in test track  44 , computing equipment  56  (see  FIG. 2A ) may direct a left drive wheel  30 D (see  FIG. 4 ) to stop while a right drive wheel  30 D turns. This may cause left light sensor  84 L and one of middle light sensors  84 M to reverse direction along curved paths  92 L and  92 M, respectively. Stopping a left drive wheel  30 D while turning a right drive wheel  30 D may cause right light sensor  84 R to change direction along right path  92 R while a second one of middle light sensors  84 M moves forward along curved path  92 M. Mobile cart  22  may continue along curved paths  92  until left light sensor  84 L reaches point C along test track  44  and left light sensor  84 L detects test track  44 . After left light sensor  84 L detects track  44  at point C, both drive wheels  30 D of mobile cart  22  may again be turned together in order to move mobile cart  22  forward. Signals generated by middle light sensors  84 M may then be used to make minor adjustments to the path of cart  22  to complete the turn or an iterative process of detecting track  44  with left light sensor  84 L may be used to complete the turn. The 90 degree left turn of  FIG. 6  is merely illustrative and other types of turns (e.g., 90 degree right turns, left turns at other angles, right turns at other angles, etc.) may be executed in a similar manner. 
     Left and right light sensors  84 L and  84 R may be used to detect other types of indicators along test track  44 . For example, left and right light sensors  84 L and  84 R may be used to detect visible test station indicators such as visible test station indicator  48  of  FIG. 7 . As shown in  FIG. 7 , as mobile cart  16  travels from point D to point E along test track  44 , middle light sensors  84 M remain over test track  44  along paths  90 M and continuously detect test track  44  while left and right light sensors  84 L and  84 R remain on opposing sides of test track  44  and do not detect test track  44 . When light sensors  84  reach point E, both left and right light sensors  84 L and  84 R detect test track  44 . Left and right light sensors  84 L and  84 R detecting test track  44  may indicate a visible test station indicator such as visible test station indicator  48  in test track  44 . 
     In response to signals from light sensors  84  indicating a visible test station indicator in test track  44 , computing equipment  56  (see  FIG. 2A ) may direct all drive wheels  30 D (see  FIG. 4 ) to stop for a previously determined amount of time while wireless communications tests are conducted. Wireless communications test conducted at test stations such as test station  46  may include transmitting data from DUT  10  to computing equipment  56  (see  FIG. 2A ) while rotating stage  24  (see  FIG. 3 ) rotates DUT  10  through a fixed angle. Automatically detecting test stations such as test station  46  along test track  44  and rotating DUT  10  using rotation stage  24  may help compare multiple DUTs since it is known that each DUT was tested at the same location and in the same orientation. 
     An illustrative configuration that may be used for mounting DUT  10  to rotating stage  24  is shown in  FIG. 8 . In the example of  FIG. 8 , DUT  10  is embedded in rotating stage  24 . As described above in connection with  FIG. 3 , rotating stage  24  may be formed from a non-conducting material such as (for example) expanded polystyrene foam. Embedding DUT  10  in the expanded polystyrene foam may help facilitate testing of DUTs having a relatively small size or individual DUT components that have not been fully assembled into a consumer ready device. After DUT  10  is seated in rotating stage  24 , rotating stage  24  may be used to rotate DUT  10  in direction  21  (or opposite to direction  21 ) during wireless communications testing at test stations along a test track as described in connection with  FIG. 2A . 
     An alternative configuration that may be used for mounting DUT  10  to rotating stage  24  is shown in  FIG. 9 . In the example of  FIG. 9 , DUT  10  is mounted on rotating stage  24  using mounting structures  26 . Mounting structures  26  may be formed from any suitable non-conducting material (e.g., plastic, glass, or suitable materials). Mounting DUT  10  to rotating stage  24  using mounting structures  26  may facilitate exchange of DUTs in mounting structures  26  for testing of multiple DUTs. 
     An additional configuration that may be used for mounting DUT  10  to rotating stage  24  is shown in  FIG. 10 . In the example of  FIG. 10 , DUT  10  is mounted on rotating stage  24  using mounting structures  26  that have physical features that are similar to physical features of a user of a device. Because portable electronic devices are often operated while being held by a user, mounting structures  26  that have physical features that are similar to physical features of a user of a device may have a shape that is similar human hands and arms. Mounting structures  26  that have physical features that are similar to physical features of a user of a device may have electrical properties (e.g., resistance, conductivity, etc.) that are similar to electrical properties of human hands and arms. As an example, mounting structures  26  may be formed from silicon-carbonate material. 
     Mounting DUT  10  to rotating stage  24  using mounting structures  26  that are similar to physical features of a user of a device may improve the correlation of test results of wireless communications test of DUTs to the performance of devices during normal operation in a real-world environment. After DUT  10  is mounted to rotating stage  24  using mounting structures  26  of the type shown in  FIG. 9 or 10 , rotating stage  24  may be used to rotate DUT  10  in direction  21  (or opposite to direction  21 ) during wireless communications testing at test stations along a test track as described in connection with  FIG. 2A . The examples of  FIGS. 8, 9, and 10  are merely illustrative. If desired, DUT  10  may be placed on rotating stage  24  without mounting structures. 
     An illustrative configuration that may be used for stage support  60  of rotating stage  24  is shown in  FIG. 11 . As described in connection with  FIG. 3 , stage support  60  may be mounted to a geared platform such as geared platform  62 . As shown in  FIG. 11 , rotating stage  24  may include one or more telescoping supports such as telescoping supports  100 . Telescoping supports  100  may be configured to raise or lower rotating stage  24  in directions  102  or  104  respectively. Telescoping supports  100  may be raised or lowered by a test administrator prior to performing wireless communications testing on DUT  10 , may be raised or lowered using cart control equipment  42  (see  FIG. 3 ) prior to performing wireless communications testing on DUT  10  or may be raised or lowered into one or more positions during wireless communications testing at one or more test stations such as test stations  46  along test track  44  (see e.g.,  FIG. 7 ). Telescoping supports  100  may be formed from any suitable non-conducting material (e.g., plastic, etc.) so that telescoping supports  100  do not interfere with wireless testing of DUT  10 . Telescoping supports  100  may be mounted to geared platform  62  so that telescoping supports  100  rotate with rotating stage  24  in direction  21  (or opposite to direction  21 ) during wireless communications testing of DUT  10 . 
     Telescoping supports  100  may alternatively be mounted to stage support  60  as shown in  FIG. 12 . Mounting telescoping supports  100  to stage support  60  may reduce the area needed for mounting rotating stage  24  to support structure  28  of mobile cart  22  (see e.g.,  FIG. 3 ). As described in connection with  FIG. 11 , telescoping supports  100  may be used to raise or lower rotating stage  24  in directions  102  or  104  respectively and may be configured to rotate in direction  21  (or opposite to direction  21 ) along with rotating stage  24  and stage support  60  during wireless communications testing of DUT  10 . 
     During wireless communications testing of DUT  10 , it may sometimes be desirable to simultaneously test multiple devices, to test the effect on a single DUT  10  of an environment with multiple devices communicating simultaneously, or to test the effect of simultaneous communications using multiple technologies (e.g., WiFi®, Bluetooth®, etc.) with a single DUT  10 . In order to facilitate these tests, mobile cart  22  may be provided with more than one rotating stage  24 , as shown in  FIG. 13 . As shown in  FIG. 13 , each rotating stage  24  may be mounted to an associated stage support  60 . Each rotating stage  24  may be configured to rotate in a direction such as direction  21 , or in a direction opposite to direction  21 . Additional stages may be used to mount additional communications equipment such as interference equipment  109 . 
     Interference equipment  109  may include an additional device that is substantially similar to DUT  10  and/or communications equipment (e.g., Wifi® equipment, Bluetooth® equipment, Universal Mobile Telecommunications System equipment, Global System for Mobile Communications equipment, etc.) for communicating directly with DUT  10 . 
     Each rotating stage  24  may be configured to rotate at a substantially similar rotation rate as another rotating stage  24  or may be configured to rotate at a different rotation rate as another rotating stage  24 . Each rotating stage  24  may be configured to rotate in a same or different direction from the direction of rotation of another rotating stage  24 . If desired, some rotation stages  24  may rotate while other rotation stages  24  are stationary. If desired, rotating stages  24  that support interference equipment  109  may be configured to be slave to rotating stage  24  supporting DUT  10  (e.g., stage supports  60  may be controlled by a common motor of the type shown in  FIG. 3 ). 
     During wireless communications testing of DUT  10 , interference equipment  109  and DUT  10  may communicate with wireless communications equipment  58  in a common communications channel using a common communications technology (e.g., Wifi® equipment, Bluetooth® equipment, Universal Mobile Telecommunications System, Global System for Mobile Communications, etc.). During wireless communications testing of DUT  10  in which interference equipment  109  and DUT  10  communicate with wireless communications equipment  58  in a common communications channel, computing equipment  56  (see  FIG. 2A ) may be configured to store information corresponding to which of interference equipment  109  or DUT  10  first registers and/or establishes communication with wireless communications equipment  58 . 
     During wireless communications testing of DUT  10 , interference equipment  109  and DUT  10  may communicate with wireless communications equipment  58  in different communications channels using a common communications technology. If desired, DUT  10  and interference equipment  109  may each be Multiple-input multiple-output (MIMO) devices that actively select available communications channels. Computing equipment  56  may be configured to store information corresponding to the selection of channels in competing MIMO devices. 
     If desired, interference equipment  109  and DUT  10  may communicate with wireless communications equipment  58  using different communications technologies (e.g., DUT  10  may communicate using Wifi® communications technology while interference equipment  109  communicates using cellular telephone technology, Bluetooth® technology, or other technology). During wireless communications testing of DUT  10  in which interference equipment  109  and DUT  10  communicate with wireless communications equipment  58  using different communications technologies, computing equipment  56  may store data corresponding to wireless communications tests of more than one DUT  10  (i.e., interference equipment  109  may be an additional DUT that is tested concurrently with DUT  10 ). During wireless communications testing of DUT  10 , interference equipment  109  may be configured to only transmit data, to only receive data, or to emulate communication during normal operation of a device such as DUT  10 . 
     In an alternative embodiment, during wireless testing of DUT  10 , DUT  10  may exchange data directly with interference equipment  109 . In wireless communications tests in which DUT  10  exchanges data directly with interference equipment  109 , rotating stage  24  on which interference equipment  109  is mounted may remain stationary (i.e., may not rotate) while rotating stage  24  on which DUT  10  is mounted rotates. In wireless communications tests in which DUT  10  exchanges data directly with interference equipment  109 , DUT  10  may communicate with interference equipment  109  using a first communications technology while DUT  10  communicates with communications equipment  58  using a second communications technology that is different from the first communications technology (e.g., DUT  10  may communicate with communications equipment using Wifi® communications technology while DUT  10  communicates with interference equipment  109  using cellular telephone technology, Bluetooth® technology, or other technology). 
     To conduct wireless communications testing of a device under test using a computer controlled mobile cart, the steps of the illustrative flowchart of  FIG. 14  may be performed. 
     At step  200  a DUT  10  may be mounted to rotating stage  24  of mobile cart  22 . DUT  10  may be mounted to rotating stage  24  using mounting structures, may be embedded within rotating stage  24  or may be placed on rotating stage  24 . If desired, interference equipment  109  may also be mounted to an additional rotating stage  24 . 
     At step  202  mobile cart  22  may automatically (i.e., without human interaction) transport DUT  10  along a visible guide track such as test track  44  to a first test station  46 . Automatically transporting DUT  10  along test track  44  may include following one or more bends, or one or more turns in test track  44  using an optical sensor such as optical sensor  32  mounted to mobile cart  22 . 
     At step  204 , using an optical sensor such as optical sensor  32 , mobile cart  22  may automatically detect a visible test station indicator such as visible test station indicator  48  on test track  44 . 
     At step  206 , mobile cart  22  may automatically stop for a predetermined amount of time at a test station. The predetermined amount of time may correspond to a duration required to transmit a predetermined amount of test data. 
     At step  208 , while mobile cart  22  is stopped at the test station, rotating stage  24  may rotate DUT  10  through a predetermined rotation angle. While rotating stage  24  rotates DUT  10 , DUT  10  may transmit test data to wireless communications equipment  58 . If desired, while mobile cart  22  is stopped at the test station, DUT  10  may transmit test data to interference equipment  109  while transmitting data to communications equipment  58 . If desired, while mobile cart  22  is stopped at the test station, interference equipment  109  may transmit data to communications equipment  58  while DUT  10  transmits data to communications equipment  58 . 
     At step  210 , mobile cart  22  may automatically transport DUT  10  along test track  44  to the next test station  46 . Following step  210 , steps  204 ,  206 , and  208  may be repeated for subsequent test stations  46  along test track  44 . 
     At step  212 , test data transmitted by DUT  10  at step  208  may be received by wireless communications equipment  58 . Step  212  may be performed concurrently with step  210 . 
     At step  214 , test data received by wireless communications equipment  58  may be stored and analyzed using computing equipment  56 . Steps  212  and  214  may be repeated following each transmission of test data at step  208  at each test station along test track  44 . Steps  202 ,  204 ,  206 ,  208 ,  210 ,  212 , and  214  may subsequently be repeated for testing of additional DUTs  10 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20110902
Publication Date: 20160920
Grant Date: 20160920
Priority Date: 20110902
Inventors: HERNANDEZ DIEGO C.
CAMILLERI KEVIN
SEN INDRANIL
NARANG MOHIT
WALIA MANJIT
Assignee: APPLE INC
CPC Classifications: [{"code": "G01R31/3025", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01R31/2834", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01R31/3025", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01R31/2834", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 47753797