Abstract:
A portable network test meter device for a CATV network is disclosed which permits simultaneous operation of a measurement system including a first tuner and a communication system including a cable modem including a second tuner. Only a single RF input/output port is necessary for connection to the CATV network.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention claims priority from U.S. Provisional Patent Application No. 60/987,919 filed Nov. 14, 2007, which is incorporated herein by reference for all purposes. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a network testing device having the ability to receive two different frequencies via a single RF port for testing the network, while simultaneously communicating to another device over the RF network, and in particular to a testing device with the ability to loop back an MPEG stream from the network to a head-end device, which analyzes the data and provides a measurement result. 
       BACKGROUND OF THE INVENTION 
       [0003]    Some conventional testing devices have a built-in cable modem as well as a measurement tuner, but none provide the means by which two-way communications and an accurate test measurement can take place at the same time. 
         [0004]    United States Patent Publication No. 2005/0144648 published Jun. 30, 2005 in the name of Michael Gotwals et al. discloses a test meter having a modem and a test system, in which one tuner is shared between the cable modem and the cable test system. Thus the test meter is limited to half-duplex operation. 
         [0005]    Some current instruments have a capability to receive and analyze a raw data stream such as a MPEG stream, but it is an expensive solution and is not very portable to the field. The present invention provides a means to capture the raw data stream and then, via two-way communication with the head-end, send back the data to be analyzed. Accordingly, the present invention provides in essence a loop-back mode via a handheld device communicating to a more expensive and high tech device in the head-end to perform an analysis of the raw data stream. 
         [0006]    An object of the present invention is to overcome the shortcomings of the prior art by providing simultaneous data communication using a first tuner, while taking RF physical layer measurements of the network using a second tuner. 
       SUMMARY OF THE INVENTION 
       [0007]    A portable network test meter for a CATV network is disclosed comprising an input/output port providing an RF connection to the CATV network; a measurement system including a first tuner for receiving a first RF signal from the input/output port and conducting tests thereon; and a communication system including a cable modem with a second tuner for sending or receiving a second RF signal simultaneously with the first RF signal via the input/output port. 
         [0008]    A method is also described for testing an incoming data stream captured in the field from a CATV network with a handheld instrument comprising an RF input/output port, a measurement system including a first tuner, and a communication system including a cable modem with a second tuner. The incoming data stream is first captured from the CATV network through the RF input/output. 
         [0009]    Quality tests are then conducted on the incoming data stream with the measurement system and an information data stream is sent and received between the communication system and a network node on the CATV network simultaneously with the incoming data stream via the RF input/output port. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The invention will be described in greater detail with reference to the accompanying drawings which represent preferred embodiments thereof, wherein: 
           [0011]      FIG. 1  is a schematic diagram of the testing device of the present invention connected to a network; and 
           [0012]      FIG. 2  is a block diagram of testing system in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    With reference to  FIG. 1 , the present invention relates to a test system  100  in which a portable handheld meter  10  including a means for bi-directional communication is in communication with a network node or a head-end  11  over a network  12 , e.g. a cable television (CATV) network. The handheld meter  10  includes an input/output port  9 , a communication system  13 , e.g. a cable modem, with a first tuner  17   a ; a measurement system  14  with a second tuner  17   b ; and a digital controller  15  including memory  18  where instructions, programs such as a web browser and data are stored for controlling both the communication system  13  and the measurement system  14 , e.g. a micro-controller or a digital signal processor (DSP). The digital controller  15  has a graphical user interface  16  for displaying a status of the network, results of measurements, webpage content displayed by the web browser program or similar. The present invention is targeted at CATV, but the modem can be expanded to include telecommunication networks, e.g. Very High Speed Digital Subscriber Line (VDSL). 
         [0014]    Providing two separate tuners enables the communication system  13  using the first tuner  17   a  to remain in communication with remote communication equipment, e.g. two-way interaction with equipment in the head-end  11 , while the measurement system  14  undertakes test and measurement activities normally expected in CATV handheld tester devices using the second tuner  17   b . The first and second tuners  17   a  and  17   b  may be tuned to different frequencies or operate on different frequency channels. For example information, such as files, data, synchronization, etc., could be simultaneously exchanged with, or sent back to the head-end  11 ; equipment in the head-end  11  could be configured to perform something specific, so tests could be made on the network  12 . Alternatively, information, e.g. owner, specifications, etc. relating to specific devices on the network  12 , can be simultaneously downloaded from the head-end  11  by the communication system  13  to the digital controller  15 , while at the same time the testing system  14  tests the corresponding specific devices. Tests can be automatically downloaded via the communication system  13  to the digital controller  15 , run on the network  12  by the testing system  14 , and then captured and/or displayed by the digital controller  15  on the hand-held meter  10 . 
         [0015]    The use of a single connector at the input/output port  9  eliminates the need to expose an unused connector of either the communication system  13  or the testing system  14  to the outside environment. Moreover, the user is no longer forced to disconnect and reconnect a test cable to whichever system is desired at the time via separate input and output ports or to use an external splitter for connectivity. The two-way control is necessary to ascertain whether shared equipment in the head-end  11  is not currently being used by another user or program, and to get information from the shared equipment in the head-end  11  about the results being sent. 
         [0016]    The present invention provides a means of having a testing system  14  that can run independently from the communication system  13 , which provides several benefits, e.g.
       1) any combination of control signals can be sent from a remote location, e.g. from the head-end  11 , including: start and stop information for the testing system  14 ; which tests are to performed from a bank of tests in the memory of the digital processor  15 ; and the actual tests themselves to be performed by the testing system  14 ;   2) faster measurements when communication is not necessary by taking advantage of the dual tuner design;   3) the output of the tuner may be interleaved so that tuning speed is not the bottleneck;   4) two-way communication can be enabled with other parts of the network while at the same time taking a measurement, so that the user can compare results from remote parts of the network  12  with the local result for troubleshooting capabilities or so that the user can compare previous results stored in remote locations, e.g. the head-end  11 , with the local result.       
 
         [0021]    Furthermore the present invention does not require any external connection, such as a splitter, to provide the results. The use of splitters provides another level of failure and also a hassle to the user in order to get the desired functionality. 
         [0022]    An application of the present invention lowers the cost of analyzing signals in the field by utilizing one piece of expensive equipment at one location, e.g. the head-end  11 , whereby raw data is routed back thereto via the testing device  10  for analysis. 
         [0023]    Another benefit of the present invention is in work force management, in which a supervisor designs the tests to run and stores the tests in a remote device, e.g. in the head end  11 , that technical service personnel can access simply by selecting a web-page link with the graphical user interface  16  of the hand-held device  10 . In such a case the hand-held device  10  is attached to the network at a customer&#39;s premises and is associated with a specific customer. The communication system  13  of the hand-held device  10  links the web-page to the hand-held device  10 , and the measurement system  14  of the hand-held device  10  is able to run the tests and store the results in the digital processor  15  and/or memory associated therewith. Accordingly, the supervisor can control what tests are done in the field and manage the resulting data. 
         [0024]    Alternatively, the hand held unit  10  can be controlled by a supervisor remotely by contacting the digital controller  15 , via the communication system  13 , which instructs the measurement system  14  to proceed with testing as predetermined or selected by the supervisor from tests stored in the memory of the measurement system  14  or of the digital controller  15 . As above, the tests can also be downloaded from a remote location, e.g. head-end  11  via the communication system  13 , before being initiated by the measurement system  14 . 
         [0025]    Furthermore, the dual tuner system enables the hand-held device  10  to get information from the head-end  11  via the communication system  13  and simultaneously compare the information to the results seen in the field generated by the measurement system  14 . 
         [0026]    In a specific example, MPEG data collected by the measurement system  14  can be simultaneously sent back upstream by the communication system  13  to be analyzed, i.e. the hand-held device provides a loop back of a captured raw MPEG data stream to the head end  11  (or some other remote device), where the MPEG data stream can be analyzed. The graphical user interface  16  of the hand-held meter  10  may also include a data display screen or some other means for viewing the results of the signal analysis that was conducted at the head end  11 , which was transmitted back to the hand-held device  10  via the communication system  13 . 
         [0027]      FIG. 2  illustrates an exemplary MPEG test setup where a MPEG data stream is generated at a remote location, such as the head end  11 , using a MPEG generator  21 , which is connected to modulator  22 . Output from the modulator  22  is fed into an optical transmitter  23 , which transmits a corresponding optical signal over the network  12 . Handheld device  10  receives the optical signal and retransmits all or part of it (‘loopback’), as determined by a test program set up in the digital controller  15 , onto the network  12 . At the head end  11  an optical receiver  24  receives the retransmitted optical signal and transmits it to a MPEG analyzer  25 . 
         [0028]    If sufficient bandwidth is available on the network  12  (as, for example, with a DOCSIS 3.0 feature) the entire MPEG stream can be sent back to the remote MPEG analyzer  25 , at the head end  11 ; and then, utilizing the communication system  13  with a data-over-cable service interface specification (DOCSIS) communication channel, results of the tests on the MPEG stream can be sent back to the hand-held unit  10  and viewed with the graphical user interface  16  on the hand-held device  10  using a display format such as a web page. Accordingly, a relatively expensive testing unit, such as a DTS330, can be placed in the head-end  11  and a much less expensive meter, e.g. the hand-held unit  10 , can be placed out in the field, which would collect the MPEG data stream via the measurement system  14 , send the MPEG data stream back to the head-end  11  for testing via the communication system  13 , and then receive results of the tests back via the communication system  13 . 
         [0029]    If the bandwidth is limited, packet identifier (PID) filtering can be performed by the digital processor  15  to limit the amount of the MPEG stream to send back to the testing equipment in the head-end  11  for analysis instead of all PIDs in a 6 MHz or 8 MHz channel. It is important to note that the MPEG-2 stream returned to the remote analyzer, e.g. MPEG analyzer  25  in the head-end  11 , is a raw stream and not a stream that is recompressed, since that would be more like a Slingbox, rendering an analysis of signal integrity at the point in the network impractical. 
         [0030]    A Slingbox is a TV streaming device that enables consumers to remotely view their cable, satellite or personal video recorder (PVR) programming from an Internet-enabled computer with a broadband internet connection. The Slingbox connects a standard or high definition TV (HDTV) source, via coaxial cable, composite cables, or S-video cable, to an existing Internet connection. Digital video recorders and cable or satellite set top boxes can be controlled through a separate infrared (IR) cable that lets users change channels from the remote location. Software on a user&#39;s personal computer (PC) connects to the Slingbox and provides a user interface for viewing the video stream and changing channels.