Distributed test equipment system for testing analog communications systems

A distributed test equipment system for testing analog communications systems. One or more analog signal receivers and one or more computers are connected via a packet-switched network such that each computer can remotely control and receive signal data from each receiver. Analog signal data measured by each receiver is available for relaying to each computer where it is processed for analysis in conformance with respective user commands.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to test equipment and systems for communications systems, and in particular, to test equipment for testing analog communication systems using remote control and processing of test data.

2. Description of the Related Art

As test equipment for communication systems has become more sophisticated, increasing amounts of processing power are included within the test unit. This has become more common as the systems being tested become increasingly complex. For example, it is increasingly common for the virtual equivalent of a computer, such as a personal computer, to exist within the test equipment, thereby allowing it to run many of the more complex operating systems, such as Windows by Microsoft Corporation. For many users, this increases the utility of the equipment since the user is generally familiar with the user interfaces made possible by such operating systems. It also allows the user to install third party software as well as writing his own software targeted to the particular application for which the test equipment is being used.

While this approach can make the test equipment powerful when used as a stand-alone unit, it becomes quite difficult to provide significant and fast interaction with more than one user, particularly when the user is trying to access the test equipment remotely, e.g., via a network of some kind. Since such test equipment not only measures the various signal parameters, but also processes the data to compute various characteristics of the signal, the interface between the test equipment and remote user becomes quite complex. Hence, the sophistication and processing power which is advantageous for stand alone testing becomes an impediment for accessing control by a remote user as well as multiple users.

SUMMARY OF THE INVENTION

In accordance with the presently claimed invention, a distributed test equipment system for testing analog communications systems includes one or more analog signal receivers and one or more computers connected via a packet-switched network such that each computer can remotely control and receive signal data from each receiver. Analog signal data measured by each receiver is available for relaying to each computer where it is processed for analysis in conformance with respective user commands.

In accordance with one embodiment of the presently claimed invention, an apparatus including a distributed test equipment system for testing analog communications systems includes a packet-switched network interface, an analog signal receiver, a server and a client computer. The packet-switched network interface includes a server connection node and a client connection node for relaying a plurality of packetized test commands and a plurality of packetized signal data. The analog signal receiver is responsive to an analog signal received from an external signal source by measuring the analog signal and generating a plurality of measurement data representing the analog signal. The server is coupled to the server connection node and the analog signal receiver, and is responsive to the plurality of packetized test commands by packetizing and transmitting, via the server connection node, the plurality of measurement data as the plurality of packetized signal data. The client computer, including a user interface, is coupled to the client connection node, responsive to a plurality of user commands received via the user interface by generating and transmitting the plurality of packetized test commands, and is further responsive to the plurality of user commands and the plurality of measurement data by processing the plurality of measurement data to produce a plurality of processed signal data representing a plurality of characteristics of the analog signal.

In accordance with another embodiment of the presently claimed invention, an apparatus including a distributed test equipment system for testing analog communications systems includes packet-switched network means, analog signal receiver means, server means and client computer means. The packet-switched network means is for relaying a plurality of packetized test commands and a plurality of packetized signal data. The analog signal receiver means is for measuring an analog signal received from an external signal source and generating a plurality of measurement data representing the analog signal. The server means is for receiving the plurality of packetized test commands and in response thereto packetizing and transmitting the plurality of measurement data as the plurality of packetized signal data. The client computer means is for receiving a plurality of user commands via a user interface and in response thereto generating and transmitting the plurality of packetized test commands, and processing the plurality of measurement data to produce a plurality of processed signal data representing a plurality of characteristics of the analog signal.

In accordance with another embodiment of the presently claimed invention, a method for testing analog communications systems in a distributed testing environment includes: receiving a plurality of user commands via a computer user interface;

generating a plurality of packetized test commands in response to the plurality of user commands;

relaying the plurality of packetized test commands via a packet-switched network;

receiving an analog signal from an external signal source;

measuring the analog signal and generating a plurality of measurement data representing the analog signal;

packetizing the plurality of measurement data as a plurality of packetized signal data in response to the plurality of packetized test commands;

relaying the plurality of packetized signal data via the packet-switched network; and

processing the plurality of measurement data in response to the plurality of user commands to produce a plurality of processed signal data representing a plurality of characteristics of the analog signal.

DETAILED DESCRIPTION OF THE INVENTION

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.

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.

Referring toFIG. 1, a distributed test equipment system10for testing analog communications systems in accordance with the presently claimed invention includes, as its primary components, a signal test, or capture, unit30and a post-processing unit14, interconnected via a standard packet-switched network12, e.g., a Transmission Control Protocol-Internet Protocol (TCP/IP) network, such as an Ethernet or Fast Ethernet network. Accordingly, the user interface is removed from the test equipment itself and now resides in the computer, e.g., a standard personal computer (PC), and communicate via the standard network. As a result, it is now possible to move virtually all of the processing from the test equipment to the PC, thereby enabling the user to update the system over time to acquire more processing power and enable the test system to support more features by simply upgrading software within the PC.

Further, by separating the tester30and the user interface16, including the final processing, new user scenarios become enabled. For example, multiple users can share a single tester30and test setup by simply logging into the tester30, performing their measurement on the setup, and then processing the data within their respective PC14. Alternatively, one PC14acan be used to control multiple testers30, such as in the case of a production line where one PC can process data from one tester while one or more testers acquire further data. As a still further alternative, as discussed in more detail below, in a highly integrated tester, various portions of the tester can be available for control individually by separate computers and users. For example, one PC14acould control a test setup that performs tests using the transmitter portion36of the tester30, while another PC14bcan control a test setup using the receiver portion34. (One example of such an integrated tester is described in commonly assigned, co-pending U.S. patent application Ser. No. 10/770,020, filed on even date herewith and entitled, “Integrated Radio Frequency (RF) Tester”, the disclosure of which is incorporated herein by reference.)

Referring again toFIG. 1, a distributed test equipment system10in accordance with various embodiments of the presently claimed invention includes one or more analog signal testers30a,30band one or more computers14a,14b, all communicating via a packet-switched network12, often referred to as a wide area network (WAN) in the case of the Internet or a local area network (LAN) which may be in the form of a network residing behind a router or firewall for connection to the Internet. Each tester30can be connected to one or more devices under test (DUT)50for providing various signals for transmission to the DUT50or receiving various signals from the DUT50. (A tester for use in accordance with the presently claimed invention has been implemented for purposes of testing RF transceivers intended for use according to the IEEE 802.11 standard, using the frequencies of 2.4-2.485 gigahertz and 4.9-5.85 gigahertz. However, it will be understood by one of ordinary skill in the art that other types transceivers can also be used and controlled in a distributed test equipment system as discussed herein.)

The tester30includes a receiver section34and a transmitter section36, both of which can be interfaced with one or more external connections49a,49bvia a switch network38in accordance with well known techniques. A server/controller32controls the receiver34and transmitter36and provides an interface31ato the network12. The computer14includes a user interface16through which the user controls the computer14and tester30which is being accessed. Such user interface16includes a graphic user interface18and software20, as well as inputs for user devices such as a keyboard or mouse (not shown). An independent interface19amay also be provided between the computer14aand DUT50afor certain specific direct control of the DUT50aby the computer14aor reporting of specific test conditions by the DUT50ato the computer14ain accordance with well known techniques (e.g., via hard wired connection, wireless connection, etc.).

One good example of the network12would be that of a TCP/IP network such that the server/controller32of the tester30will have its own Internet protocol (IP) address, as will the computer14abeing used to control the specific tester30a. Communication between these devices32,14ais in accordance with well known packet-switch networking techniques.

As noted above, a second computer14b, also with its own IP address, can also be part of the network and connected to the same tester30afor sharing the resources of the tester30abeing controlled with the first computer14a. Further, the server/controller32can provide separate controls and interface capabilities for the receiver34and transmitter36such that while one computer14ais controlling and accessing the receiver34, the other computer14bcan be controlling and accessing the transmitter36. Such control and access might be in the form of one computer14aaccessing measured signal data from the receiver34for processing by the computer14a, while the other computer14baccesses and controls the transmitter36by providing specific signal data to be transmitted to a DUT50b.

Referring toFIG. 2, one example of a receiver34includes a frequency down converter section341, an intermediate frequency (IF) section342and a baseband section343. In the input section341, the incoming signal is attenuated and amplified in a gain controlled manner, filtered in a bandpass manner and down converted in frequency in accordance with well known techniques to produce an IF signal. In the IF section342, this IF signal is demodulated, e.g., quadrature demodulated, and filtered in a low pass manner to produce one or more baseband signals. In the baseband section343, these baseband signals are attenuated or amplified as necessary and converted from analog to digital signals.

Referring toFIG. 3, one example of a transmitter36for use in the tester30includes a baseband section361, an IF section362and a frequency up-conversion section363. In the baseband section361, one or more baseband signals, e.g., quadrature data signals, are converted from analog to digital signals and filtered in a low pass manner. The resulting signals are modulated, e.g., quadrature modulated, in the IF section362and filtered in a bandpass manner. This signal is then up-converted in frequency, filtered in a bandpass manner and amplified or attenuated as necessary in the frequency up-conversion section363.

As noted above, the receiver30includes a receiver section34and a transmitter section36. One example of such a tester30has been designed for analyzing complex signals generated in IEEE 802.11a/b/g systems. The receiver section operates as a vector signal analyzer, while the transmitter operates as a vector signal generator. The vector signal analyzer is used to perform data capture on analog (RF or baseband) signals and perform a number of different analyses of the captured data for verifying the transmitter performance of the DUT50. The vector signal generator is used to generate complex signals for verification of the receiver portion of the DUT50. In addition to the following discussion, more detailed information on such a tester can be found in Appendix A, the contents and disclosure of which are incorporated herein by reference.

Referring toFIG. 4, one example of a computer display400provides information following data capture by the receiver34and data analysis by the computer. The start button1allows the user to initiate single or continuous data capture and analysis, and is identified by the single/continuous mode indicator2. An IQ swap indicator3identifies when the quadrature channel data is reversed. A wide frequency synchronization indicator4identifies when data analysis with a wider than normal frequency error is enabled. An auto level indicator identifies when automatic gain control is enabled. Additional indicators identify the input RF channel6, the input signal level7, external gain8and baseband gain9.

A window10provides measurement results, such as peak, root mean square (RMS) and maximum average power. A zoom slider11allows the user to zoom in on the captured data to analyze it and show it within the top graph window15. A graph selector12allows the user to select the type of graph shown in the right graph window. Another selector13allows the user to select the type of graph shown in the left graph window. A time slider14allows the user to move the visible portion of the data in the top graph15to the left or right. The top graph window15illustrates a graphical representation of the measured data, and can illustrate various signal characteristics such as peak amplitude value as well as a moving average.

Referring toFIG. 5, a computer display500illustrating how the user may instruct and control the signal data to be downloaded to the transmitter36is shown. The start button1is used to start and stop the vector signal generator operation. The RF output selector2allows the user to select the output mode of the baseband and RF ports of the transmitter36. The RF channel selector3controls the RF output channel. An IQ swap selector4allows the user to reverse the quadrature signals. A signal selector5allows the user to select the type of signal modulation. A signal level indicator6displays the current output RMS signal level. A signal level slider7is used to set the output signal level. An information window8displays textual information about the signal being generated. A window9shows a graphical representation of the output signal to be generated.