Abstract:
A continuous bi-directional file-play-record voice and video quality tester system (“CFPR-VVQT”) for measuring the quality of voice or video communication links from a customer premises equipment (“CPE”) through a Network under Test to a voice and video quality tester (“VVQT”). The start and end of a set of quality testing sample signals are determined by a start flag signal and an end flag signal, respectively, generated by the CFPR-VVQT. The flag signals may be triple tone modulation frequency (“TTMF”) tones. The CFPR-VVQT will measure the quality testing sample signals, determine a signal quality test result, and then transmit the test results back through Network under Test to the originating VVQT.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of Invention  
         [0002]     The invention relates to telecommunication systems, and in particular, to telecommunication systems utilizing voice and video quality testing.  
         [0003]     2. Related Art  
         [0004]     The worldwide utilization of telecommunication systems is growing and adapting at a rapid pace and telephone and other service providers are continuously attempting to improve the quality of the voice and video communications that are carried on their telecommunication networks. In general, telephone service providers provide voice communications, while other service providers provide video communications, e.g., cable broadband companies.  
         [0005]     With respect to telephone service providers, these telecommunication networks are typically known as public switched telephone networks (“PSTNs”). With the advent of modem digital communication systems, many of these telephone service providers are utilizing digital communication techniques to communicate both voice and data signals across their PSTNs rather than transmitting analog voice signals generated from the speech of the user of a telephone at a customer premises (such as the user&#39;s home or office). The PSTN may convert an analog voice signal to a digital data signal that is transmitted through the numerous components of the PSTN before being converted back into a second analog voice signal that is transmitted to a second telephone at another customer premises.  
         [0006]     Generally known as Voice over Network (“VoN”), or Voice over Packet (“VoP”), this new telephone technology relies on packet-oriented digital networks delivering voice communication services as a digital stream. By sampling speech and recording it in digital form, encoding the digitized speech into packets, and transmitting the packets across different computer networks, VoN systems offer a lower cost alternative to the original PSTNs due to their inherent efficiencies and lower bandwidth requirements.  
         [0007]     At present, the most popular example of VoP is the Voice over Internet Protocol (“VoIP” or “Voice over IP”) services that utilize the Internet Protocol (“IP”). Additional examples include voice over frame relay (“VoFR”), voice over asynchronous transfer mode (“VoATM”), voice over digital subscriber line (“VoDSL”), and voice over cable (“VoCable”).  
         [0008]     These packet-oriented digital networks, such as such as the Internet, Ethernets and wireless networks, may also support other forms of media. As a result, digital video systems are replacing existing analog video systems and making possible many new telecommunication services (e.g., direct broadcast satellite, digital television, high definition television, video teleconferencing, telemedicine, e-commerce and Internet video) that are becoming an essential part of the U.S. and the world economy. Thus in addition to bursty non-real-time applications such as e-mail and file data transfers through numerous types of protocols including the file transfer protocol (“ftp”), this new digital technology now also supports real-time applications such as digital television, video teleconferencing and Internet video.  
         [0009]     Unfortunately, these digital techniques have made maintaining high levels of voice and video quality more complex because of the following factors. Because of the required higher bandwidth, these systems use voice and data compression and decompression algorithms when transmitting signals. Also, there are the problems inherent in any network, such as packet loss, noise, signal attenuation, and echo.  
         [0010]     Three important parameters of voice quality are (1) signal clarity; (2) transmission delays; and (3) signal echoes. These parameters are applicable to video quality, which is also is subject to additional visual impairments, such as tiling, error blocks, smearing, blurring, and edge noise. Ideally, there should be a set of performance parameters where each parameter is sensitive to some unique dimension of voice and video quality type or impairment type.  
         [0011]     In addition, measuring voice and video quality should be done in-service since taking the telecommunications system out-of-service and injecting known test signals will change the conditions under which the telecommunications system is actually operating. Therefore, because the performance of digital telecommunications systems is variable and dependent upon the dynamic characteristics of both the input media and the digital transmission, performance monitoring must be continuous, non-intrusive, and in-service. Moreover, with respect to wireless networks (e.g., mobile or cell phones), additional problems are created because of poor mobile phone quality, noise, acoustic and landline echo, and other distortions. As a result, transmission conditions that pose little threat to non-real-time data traffic may introduce severe problems to real-time packetized voice and video traffic. These conditions include real-time message delivery, gateway processes, packet loss, packet delay, and the utilization of nonlinear codecs.  
         [0012]     While the impact of voice and video quality is subjective in nature, objective measurement tools that effectively and inexpensively measure the voice and video quality over the network under test are required by end-users and service providers. These measurement tools must continuously, reliably and objectively measure the results of transmissions of voice and video over the network under test in both directions. Such results may be used by end-users and service providers, for example, for specification and evaluation of system performance, comparison of competing services, network design, maintenance and troubleshooting, and optimization of limited network resources by determining the exact effects of network configuration and design changes.  
         [0013]     The VoN industry has developed a number of test standards for measuring the quality of voice communication across packet-based networks. These test standards include: (a) the International Telecommunication Union (“ITU”) Perceptual Speech Quality Measure (“PSQM”), as described in ITU-T Recommendation P.861, titled “Objective quality measurement of telephone-band (300-3400 Hz) speech codecs;” (b) the Perceptual Evaluation of Speech Quality (“PESQ”), as described in ITU-T Recommendation P.862, titled “Perceptual evaluation of speech quality (“PESQ”): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs;” (c) the MOS-LQO described by ITU-T Recommendation P.800.1, titled “Mean Opinion Score (MOS) terminology;” (d) the ITU-T Recommendation P.563, titled “Single ended method for objective speech quality assessment in narrow-band telephony applications;” and (e) the R-Factor described by ITU-T Recommendation G.107, titled “The E-model, a computational model for use in transmission planning,” all of which objectively measure audio quality and are incorporated herein by reference.  
         [0014]     With respect to measuring video quality across packet-based networks, the most widely used standard is American National Standards Institute (“ANSI” ) T1.801.03-2003, “American National Standard for Telecommunication—Digital Transport of One-Way Video Signals—Parameters for Objective Performance Assessment.” ANSI T1.801.03-2003 defines an entire framework of objective parameters that can be used to measure the quality of digital video systems. There are also other American National Standards that can be used to gauge the quality of other aspects of digital video systems, e.g., ANSI T1.801.01-1995, ANSI T1.801.02-1996, and ANSI T1.801.04-1997.  
         [0015]     Specialized voice test equipment for PSTNs is well known and available from a number of providers. The test equipment ranges from simple hand-held testers for service technicians to sophisticated testers for automated network management. These testers are intended to enable telephone technicians to verify the proper operation and quality of voice communication on the PSTN and to track down faults.  
         [0016]     Remote telephone test units, also known as responders, provide added flexibility to the testing of telephone lines and equipment by providing calibrated reference signals and by measuring and detecting received signals. These responders are designed primarily for performing tests over circuit-switched connections.  
         [0017]     Video quality measurements have a shorter history than that of voice quality measurements. Generally, subjective testing techniques are more widely used presently. Objective video quality estimation software is available that records and measures video signals in accordance with ANSI T1.801.03-2003. Video processing, however, is more cumbersome because it entails use of recording and playback devices that may include digital video tape recorders, digital audio tape machines, CD players, and analog audio cassette machines.  
         [0018]     A Voice/Video Quality Tester (“VVQT”) is any device that measures various parameters of a voice or video signal to quantify the impairments created by transmission of that signal over a telecommunication network. The measurement set of the VVQT is specifically selected to analyze the type of signal being transmitted over either a circuit-switched or packet-switched telecommunication network and the relevant measurements may include clarity, echo, packet loss, network signal loss, network delay, distortion, blurring, tiling, etc., depending on the media being tested.  
         [0019]     As an example,  FIG. 1  shows an existing voice/video quality measurement system  100  utilized to continuously test the connection between two devices (referred to as customer premise equipment [“CPE”]) located at two separate locations  102 ,  112 . A Network under Test  110  is tested using VVQT 2  and VVQT 2    114 . For example, CPE 1  and CPE 2  may be video cameras used for remote video teleconferencing and VVQT 1    102  and VVQT 2  may be testing devices that include audio/video recording and playback devices and the appropriate testing software.  
         [0020]     The measurement process begins by establishing a network connection between location  102  and location  112 . The connection may be over the Internet and VVQT 1    102  may, in the case of a voice system, be transmitting a VoIP packet or, in the case of a video system, a video packet for video teleconferencing, to VVQT 2    104 . The network connection established in the direction of CPE 2    116  and VVQT 2    114  is referred to as the uplink  120  and the network connection established in the direction of CPE 1    106  and VVQT 1  is referred to as the downlink  124 . Once the network connections are established and the media path is active, a measurement set may be selected and configured to analyze the data path through the Network under Test  110 . For example, a voice or video packet is transmitted to the Network under Test  110  by VVQT 1    104 . The degraded voice or video packet is received and recorded by VVQT 2    114  and the uplink  120  voice/video quality score is then determined using the appropriate standard to compare the degraded voice or video packet with the original or a reference packet.  
         [0021]     The process is repeated in the direction of VVQT 1  by VVQT 2    114  transmitting a voice or data packet to VVQT 1  by way of the downlink  124 . The degraded voice or data packet is received and recorded by VVQT 1    102  and the voice/video quality score for the downlink  124  is then determined using the same standard utilized to measure the uplink  120  voice/video quality score. The results are transmitted over the Network under Test  110 , and then received and processed by the VVQT 2    114 , with the results subsequently displayed at either VVQT 2    114 , VVQT 1    104 , or both.  
         [0022]     A Testing Circle may be defined as a single testing cycle consisting of a test of one uplink  120  transmission and one downlink  124  transmission. To continuously test the Network under Test  110 , the Testing Circles are continuously repeated.  FIG. 2  is a signal flow diagram (which may also be referred to as a “sequence diagram”) of an example conventional process for synchronizing bi-directional continuous file transfer testing data exchange between two VVQTs.  
         [0023]     In  FIG. 2 , the process starts in step  206 , where synchronization begins between VVQT 1    202  and VVQT 2    204 . Essentially, this comprises of establishing a network connection between and VVQT 1    202  and VVQT 2    204  and determining which of the two VVQT&#39;s will initiate a Test Circle.  
         [0024]     In step  208 , VVQT 1    202  initiates the Test Circle by playing a file, e.g., transmitting a voice or video packet, and VVQT 2    204  is placed in record mode to receive the packet sample and record it for testing purposes in step  210 . For the play-record operation in the opposite or downlink direction, the steps  212 ,  214 , and  216  are repeated. This completes one Test Circle. This may be followed by a second Test Circle, comprising steps  218 ,  220 ,  222 ,  224 ,  226 , and  228 , which are identical to the corresponding steps in the prior Test Circle.  
         [0025]     The process in  FIG. 2  shows that synchronization between VVQT 1    202  and VVQT 2    204  is required each time either of these two VVQT&#39;s transmits and receives packet samples for testing. That is, synchronization requires that when one VVQT transmits a sample packet for testing, the receiving VVQT must be configured to accept the sample packet and then record and test the sample packet. If continuous, bidirectional testing is desired, synchronization is required for each uplink or downlink.  
         [0026]     Such synchronization entails overhead in that synchronization requires time, sometimes an additional 20 seconds, whereas the actual voice/video testing sample itself may be approximately 8.0 seconds in length. This may significantly reduce the efficiency of a voice and video quality testing system, particularly one that is operating continuously and is testing in-service a mobile phone system that is in motion, e.g., in an automobile.  
         [0027]     The second problem is that the synchronization may not be very reliable because of the inherent problems in the network under test, e.g., packet loss, packet delay jitter, signal attenuation, and noise. This problem may be exacerbated when testing mobile phone systems where one or both of the VVQT&#39;s used for testing may be mobile, e.g., in a moving vehicle such as a van. Moreover, in the future, VVQT&#39;s may be embedded in a mobile telephone. In this case, the network under test is not a fixed line telecommunications system but one with mobile communication links in which the exchange of voice/video quality test results are not as easily done.  
         [0028]     Unfortunately, existing VVQT systems do not provide solutions for these problems. Existing VVQT devices that support continuous and bi-directional voice and video quality testing require synchronization between the record and play processes that is time-consuming and potentially unreliable. Moreover, additional problems exist in voice and video testing systems when testing mobile communication links because existing testing systems do not readily support the exchange of test results between devices utilizing such links. Therefore, a need exists for a voice and video quality testing system that allows bidirectional, real time, and in-service objective testing of the quality of the communication link being used, efficiently, inexpensively, conveniently and quickly at any time.  
       SUMMARY  
       [0029]     A continuous bi-directional file-play-record voice and video quality tester (“CFPR-VVQT”) system and method are described for measuring the quality of a voice or video communication link from one customer device through a Network under Test to at least one other remote customer device. The CFPR-VVQT is capable of establishing communication links between itself and the CPEs, receiving quality testing sample signals from each of the CPEs, and transmitting these sample signals through the Network under Test to a voice and video quality tester (“VVQT”). A VVQT receiving quality testing sample signals will record the signals in memory, measure the recorded quality testing sample signals, determine a signal quality test result, and then transmit the test results back through Network under Test to a second VVQT. Quality testing sample signals are sent from one VVQT to another VVQT with a start flag signal and an end flag signal at the start and the end, respectively, of the quality testing sample signal. Decoding these flag signals allows a VVQT to match its recording and testing of quality testing sample signals with their transmission by the other VVQT. The flag signal may also be used to transmit test results from one VVQT to another. Flag signals may be triple tone modulation frequency (“TTMF”) tones.  
         [0030]     As an example of implementation of a VVQT in a CFPR-VVQT, the VVQT may include an Encode/Play Module in signal communication with at least one CPE and the Network under Test, a Decode/Record Module in signal communication with the Encode/Play Module and the Network under Test, a Testing Module in signal communication with the Encode/Play Module and the Decode/Record Module, and a Storage Module in signal communication with the Encode/Play Module and the Decode/Record Module. The Encode/Play Module is capable of generating the flag signals and transmitting quality testing sample signals to another VVQT, where a Decode/Record Module is capable of decoding the flag signals, recording the quality testing sample signals, and transmitting the quality testing sample signals to the Testing Module. The Testing Module measures the quality of the received quality testing sample signals, using an appropriate measurement set dependent on the media, i.e., voice or video. Test Results may be stored in the Storage Module and may also be embedded in flags signal and subsequently transmitted to the sending VVQT.  
         [0031]     Other systems, methods and features of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]     The invention can be better understood with reference to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.  
         [0033]      FIG. 1  is a block diagram of an existing voice/video quality measurement system utilized to continuously test the connection between two locations with voice or video devices through a Network under Test.  
         [0034]      FIG. 2  is a signal flow diagram of an example conventional process for synchronizing bi-directional continuous file transfer testing data exchange between two VVQTs.  
         [0035]      FIG. 3  is a signal flow diagram of an example implementation of the synchronization process in a Continuous File-Play-Record (“CFPR”)-VVQT system.  
         [0036]      FIG. 4  is a time sequence diagram of Flag Signals and a sample testing signal generated by the File Play Process of a CFPR-VVQT system.  
         [0037]      FIG. 5  is another time sequence diagram of Flag Signals and a sample testing signal generated by the File Play Process of a CFPR-VVQT.  
         [0038]      FIG. 6  is a block diagram of an example CFPR-VVQT system with TTMF.  
         [0039]      FIG. 7  is a flow chart for a TTMF generator of an example CFPR-VVQT system.  
         [0040]      FIG. 8  is a flow chart for a TTMF detector of an example CFPR-VVQT system. 
     
    
     DETAILED DESCRIPTION  
       [0041]     In the following description of the preferred embodiment, reference is made to the accompanying drawings that form a part hereof, and which show, by way of illustration, a specific embodiment in which the invention may be practiced. Other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.  
         [0042]      FIG. 3  is a signal flow diagram of an example implementation of the synchronization process in a CFPR-VVQT system. This synchronization process may utilize a Triple Tone Modulation Frequency (“TTMF”) tone to generate start and end flag signals (known as S-TTMF and E-TTMF signals, respectively) to signal the start and the end, respectively, of the playing and recording of a test sample. Dual Tone Modulation (or Multiple) Frequency (“DTMF”) tones or signals are well known in telecommunications. The signal generated by a DTMF encoder is a direct algebraic summation, in real time, of the amplitudes of two sine (cosine) waves of different frequencies. The touch tone telephone system uses pairs of tones to represent the various keys. To improve the efficiency of the CFPR-VVQT system, a TTMF tone may be used. Moreover, by embedding test results in the start and end flag signals, the CFPR-VVQT system is able to exchange test results regardless of the type of Network under Test,  
         [0043]     The TTMF tone consists of three sinusoids with three different frequencies. The different frequencies may be chosen differently for different applications or testing. For the example implementation of the synchronization process described below, eleven frequencies are used, as show in Table 1.  
                                                                                               TABLE 1                       Frequency Bank Used for TTMF.                                    Name                f1   f2   f3   f4   f5               Frequency    650 Hz    750 Hz    850 Hz    950 Hz   1050 Hz                        Name                    f6    f7   f8   f9   f10   f11               Frequency   1150   1250   1350   1450   1550   1650           Hz   Hz   Hz   Hz   Hz   Hz                  
 
         [0044]     In order to avoid harmonics, the three frequencies comprising a TTMF tone may be chosen according to the following rules: 
    (a) no frequency is a multiplier of another frequency;     (b) the difference between any two frequencies is not equal to any of the frequencies; and     (c) the sum of any three frequencies is not equal to any of the frequencies. 
 
 Thus a permitted TTMF tone is a tone signal comprising, e.g., three frequencies such as ƒ1, ƒ6, and ƒ7 (as shown in the second column of Table 1). 
   
 
         [0048]     The CFPR-VVQT system uses TTMF Flag Signals to implement the synchronization process and to exchange voice and video quality test results. As an example, the CFPR-VVQT system may use a File Start TTMF (“S-TTMF”) Flag Signal and a File End TTMF (“E-TTMF”) Flag Signal. The S-TTMF has two functions: (a) indicating the start of the played voice/video sample testing file; and (b) representing the integer part of a voice/video quality measurement result. For example, for a voice/video quality measurement using the PESQ Standard, a PESQ score of 4.23 would result in the integer portion of the test score, 4, being encoded into and sent out with the S-TTMF. In order to implement these two functions, the S-TTMF may be implemented as shown in Table 2.  
                                                                                       TABLE 2                       TTMF Frequency Combinations for the S-TTMF Flag Signal.                                    Digit                0   1   2   3   4               TTMF   (f1, f6, f7)   (f2, f6, f8)   (f3, f6, f9)   (f4, f6, f10)   (f4, f6, f11)       Fre-       quency       Combi-       nation                        Digit                5   6   7   8   9               TTMF   (f1, f6, f8)   (f2, f6, f9)   (f3, f6, f9)   (f4, f6, f11)   (f5, f6, f7)       Fre-       quency       Combi-       nation                  
 
         [0049]     It may be noted that in Table 2, frequency ƒ6 is present in all TTMF combinations shown and thus has been chosen to represent that the playing file is starting. In other words, if the frequency ƒ6=1150 Hz is detected in any TTMF tone, then this TTMF tone is an S-TTMF Flag Signal that may also embody the integer portion of a voice/video quality measurement result.  
         [0050]     The second type of Flag Signal, the E-TTMF Flag Signal, also has two functions: (a) indicating the end of the played voice/video sample testing file; and (b) representing the two digit decimal portion of the voice/video quality measurement result. For example, with reference to the same PESQ score of 4.23, the two digit decimal portion of the score, 23, would be encoded into and sent out with the E-TTMF. The first function may be easily implemented by not using the special frequency f6 in any E-TTMF Flag Signal because this special frequency is used only by the S-TTMF Flag Signal. Thus the E-TTMF Flag Signals may be implemented as shown in Table 3.  
                                                             TABLE 3                       TTMF Frequency Combinations for the E-TTMF Flag Signal.                                Two Decimal   00   01   02   03   04   05   06   07   08   09       Digits       TTMF Frequency   1, 2, 3   1, 2, 4   1, 2, 5   1, 2, 7   1, 2, 8   1, 2, 9   1, 2,   1, 2,   1, 3, 4   1, 3, 5       Combination                           10   11       Two Decimal   10   11   12   13   14   15   16   17   18   19       Digits       TTMF Frequency   1, 3, 7   1, 3, 8   1, 3, 9   1, 3,   1, 3,   1, 4, 5   1, 4, 7   1, 4, 8   1, 4, 9   1, 4       Combination               10   11                   10       Two Decimal   20   21   22   23   24   25   26   27   28   29       Digits       TTMF Frequency   1, 4,   1, 5, 7   1, 5, 8   1, 5, 9   1, 5,   1, 5,   1, 7, 8   1, 7, 9   1, 7,   1, 7,       Combination   11               10   11           10   11       Two Decimal   30   31   32   33   34   35   36   37   38   39       Digits       TTMF Frequency   1, 8, 9   1, 8,   1, 8,   1, 9,   1, 9,   1, 10,   2, 3, 4   2, 3, 5   2, 3, 7   2, 3, 8       Combination       10   11   10   11   11       Two Decimal   40   41   42   43   44   45   46   47   48   49       Digits       TTMF Frequency   2, 3, 9   2, 3,   2, 3,   2, 4, 5   2, 4, 7   2, 4, 8   2, 4, 9   2, 4,   2, 4,   2, 5, 7       Combination       10   11                   10   11       Two Decimal   50   51   52   53   54   55   56   57   58   59       Digits       TTMF Frequency   2, 5, 8   2, 5, 9   2, 5,   2, 5,   2, 7, 8   2, 4, 8   2, 4, 9   2, 4,   2, 4,   2, 5, 7       Combination           10   11               10   11       Two Decimal   60   61   62   63   64   65   66   67   68   69       Digits       TTMF Frequency   2, 8,   2, 9,   2, 9,   3, 4, 5   3, 4, 7   3, 4, 8   3, 4, 9   3, 4,   3, 4,   3, 5, 7       Combination   11   10   11                   10   11       Two Decimal   70   71   72   73   74   75   76   77   78   79       Digits       TTMF Frequency   3, 5, 8   3, 5, 9   3, 5,   3, 5,   3, 7, 8   3, 7, 9   3, 7,   3, 7,   3, 8, 9   3, 8,       Combination           10   11           10   11       10       Two Decimal   80   81   82   83   84   85   86   87   88   89       Digits       TTMF Frequency   3, 8,   3, 9,   3, 9,   4, 5, 7   4, 5, 8   4, 5, 9   4, 5,   4, 5,   4, 7, 8   4, 7, 9       Combination   11   10   11               10   11       Two Decimal   90   91   92   93   94   95   96   97   98   99       Digits       TTMF Frequency   4, 7,   4, 7,   4, 8, 9   4, 8,   4, 8,   4, 9,   4, 9   5, 7, 8   5, 7, 9   5, 7,       Combination   10   11       10   11   10   11           10                  
 
         [0051]      FIG. 3  is a signal flow diagram  300  of an example implementation of the file-play-record process in a CFPR-VVQT system that utilizes the TTMF Start and End Flag Signals shown in Tables 2 and 3 to implement continuous bi-directional voice and video quality testing without the synchronizing shown in  FIG. 2 . The left column represents those processes taking place in VVQT 1    302  on the downlink side of a CFPR-VVQT system, the right column those taking place in VVQT 2    304  on the uplink side of a CFPR-VVQT system. There may be additional VVQT&#39;s connected to a single CFPR-VVQT system and each VVQT may be located anywhere in the world including the central office of a PSTN telephone service provider or the different offices of a company utilizing the Internet for VoIP. By the same token, two or more VVQT&#39;s may be located at a single site that may be remote from the location of the CPEs that provide the voice/video signals to be tested. Moreover, there may be multiple CPEs on either side of an uplink or downlink comprising a Test Circle.  
         [0052]     The process starts in step  306 , which is a pause undertaken by VVQT 1    302  in order to allow VVQT 2    304  to start its File Record Process  312  before VVQT  302  starts its File Play Process  308  (as will be further explained below with reference to Test Circle  2 ). Test Circle  1  consists of a File Play process (uplink  1   310 ) and a File Record process (downlink  2   316 ). The File Play process starts in step  308 , which comprises VVQT 1    302  generating start and end flag signals, and transmitting these flag signal and a quality testing sample signal from a first CPE (not shown) in signal communication with VVQT 1    302 .  
         [0053]     In step  312 , VVQT 2    304  starts a File Record process. This process comprises VVQT 2    304  receiving the flag signals and the quality testing sample signals, with the start flag and the end flag signals being decoded and used to start and end, respectively, the recording of the quality testing sample signals to memory in VVQT 2    304 . After recording, the quality testing sample signals are transmitted to the Testing Module  624 ,  FIG. 6 , where test results are produced using a measurement set appropriate to the type of media being tested.  
         [0054]     The downlink  316  portion of Test Circle  1  takes place in steps  314 ,  316 , and  318 . These step are the reverse of the uplink  310  portion, with the quality testing sample signals being those received from a second CPE (not shown) in signal communication with VVQT 2    304 . In addition, because VVQT 2    304  has just obtained test results of the uplink  310  portion, these test results will be embedded in the flag signals generated in step  314 , as shown in tables 2 and 3.  
         [0055]     Test Circle  1  is followed by Test Circle  2 , comprising steps  320 ,  322 ,  324 ,  326 ,  328 , and  330 . It should be noted that there is always a pause (such as step  306 ) before a VVQT begins a File Play process (steps  308 ,  314 ,  320 ,  326 ) so that the corresponding File Record Process (steps  312 ,  318 ,  324 , and  330 , respectively) has started and is waiting for the opposite VVQT to start its File Play Process. This will ensure that there will be no data lost because quality testing sample signals arrive at a VVQT before it is ready to receive and record them. For example, the File Record Process  324  of VVQT 2    304  is started and ready to receive quality testing sample signals before the File Play Process  320  of VVQT 1    302  starts. The pause inserted before File Play Process  320  starts is dependent on the time needed for VVQT 2    304  to complete its File Play Process  314  and network transmission delay.  
         [0056]      FIG. 3  is a signal flow diagram of two Test Circles. These may be followed by other Test Circles, with voice and video quality testing continuing until terminated manually by operator intervention, automatically by lack of quality testing sample signals, or any other method of controlling the operation of the CFPR-VVQT.  
         [0057]      FIG. 4  is a time sequence diagram of Flag Signals and a sample testing signal generated by the File Play Process of a CFPR-VVQT system. Specifically,  FIG. 4  is a graphic representation of the uplink  310  task of  FIG. 3 .  FIG. 4  has a horizontal Time Axis t  402 , starting at the left of the time sequence diagram. In time sequence  400 , a TTMF generator first generates an S-TTMF Flag Signal  404 . In order to accommodate different communication systems and adapt to varying testing conditions, the length of the Flag Signals may be manually or automatically adjustable. For a manually adjustable process, the testing operator can initially set the length of the Flag Signal to a standard length, for example, 0.30 second. Then the testing operator observes if the Flag Signals can be successfully detected. If the Flag Signal is successfully detected, then the testing operator may continue the testing; otherwise, the length of the signal may be increased until it is successfully detected. For an auto-adjustable process, the transmission and detection of Flag Signals may be determined automatically by software or hardware until a suitable signal length is selected.  
         [0058]     In time sequence  400 , the S-TTMF Flag Signal is followed by period of silence  406 , which may be, for example, 0.20 second. The silence  406  is followed by the voice/video quality sample testing signal  408 . As an example, test clips for audiovisual media may vary from 7.48 to 8.84 seconds. The voice/video quality sample testing signal  410  is followed by another period of silence  410 . The time sequence for the first half of a single Test Circle ends with an E-TTMF Flag Signal  412 , whose length is determined in the same manner as that of the S-TTMF Flag Signal  404 . The two periods of silence are used to identify the end and start points of the S-TTMF Flag Signal and the S-TTMF Flag Signal, respectively, more reliably and accurately.  
         [0059]      FIG. 5  is a graphic representation of the downlink  320  task of  FIG. 3  and is similar to  FIG. 4 . Accordingly, the sequence and length of the Flag Signals  504 ,  512  and the voice/video quality sample testing signal  508  is the same as that of  FIG. 4 . However, because  FIG. 5  is a graphic representation of the second half of a Test Circle, it also supports the function of exchanging quality measurement test results. Therefore, the S-TTMF Flag Signal  504  has encoded in it the integer portion of the voice/video quality testing result for the voice/video quality sample testing signal  408 ,  FIG.4 , according to Table 2, and the E-TTMF Flag Signal  512  has the two digit decimal portion according to Table 3. Again, the two periods of silence are used to identify the end and start points of the S-TTMF Flag Signal and the S-TTMF Flag Signal, respectively, more reliably and accurately.  
         [0060]     In  FIG. 6 , a block diagram of an example of an implementation of a VVQT  600  used in a CFPR-VVQR system is shown in signal communication with a Network under Test  602 . Three CPEs, CPE 1    604 , CPE 2    606 , and CPE 3    606  are shown in signal communication with the Network under Test  602 . The VVQT  600  may include four modules that are in signal communication with each other: the Decode/Record Module  620 , the Testing Module  624 , the Encode/Play Module  628 , and the Storage Module  632 . The Decode/Record Module  620  and the Encode/Play Module  628  may be in signal communication with the Network under Test  602  via signal path  612 . A Test Circle may start with receipt of voice or video signal at Decode/Record Module  620  via signal path  612 . Once the Decode/Record Module  620  is activated, it constantly monitors signals from the Network under Test  602  via signal path  612 , looking for an S-TTMF Flag Signal. When an S-TTMF Flag Signal is detected by the Decode/Record Module  620 , the testing process begins.  
         [0061]     Having detected an S-TTMF Flag Signal, Decode/Record Module  620  starts to record the voice/video quality sample testing signal until an E-TTMF Flag Signal is detected. Upon receiving the voice/video quality sample testing signal, Decode/Record Module  620  sends the voice/video quality sample testing signal to Testing Module  624  via signal path  614 . Decode/Record Module  620  also sends voice/video quality sample testing signal to Storage Module  626  via signal path  616 .  
         [0062]     Upon receipt of the voice/video quality sample testing signal, Testing Module  624  tests the voice/video quality sample testing signal using the appropriate measurement set and calculates a voice/video quality score, which may be a PESQ, PAMS, PSQM, or MOS score if the testing signal is a voice VoIP signal, or an objective parameter under ANSI T1.801.03-2003 in the case of video testing signal. At the same time, Storage Module  632  may save the recorded voice/video quality sample testing signal, with a time stamp, in cache memory  634 , and may also save the test scores in another cache memory  636 . After testing is completed, Storage Module  632  may save the voice/video quality sample testing signal and the test score on a hard drive or any other more permanent storage media that may be used to construct a database for analysis of the test results.  
         [0063]     Testing Module  624  completes the testing function by sending the test score to Encode/Play Module  628  via signal path  626 . Encode/Play Module  628  encodes the test score in a series of signals as shown in  FIG. 5 , that is, an S-TTMF Flag Signal and E-TTMF Flag Signal, together with another voice/video quality sample testing signal from a CPE (not shown) in signal communication with Encode/Play Module  628 . The Test Circle ends with Encode/Play Module  628  sending the Flag Signals and a voice/video quality sample testing signal to the Network under Test  602  via signal path  612  for transmission to another VVQT connected to the Network under Test  602 .  
         [0064]      FIG. 7  is a flow chart  700  for a File Play Process within the Encode/Play Module  628 ,  FIG. 6 , of an example CFPR-VVQT system. The File Play Process starts in step  702 . In step  704 , the Encode/Play Module  628 ,  FIG. 6 , monitors for receipt of a voice/video quality testing result from Testing Module  624 ,  FIG. 6 , via signal path  626 ,  FIG. 6 . If it is determined in decision step  706  that a voice/video quality testing result has been received, the VVQT goes to step  708 . Otherwise, the process returns to step  704  to continue monitoring for a test result.  
         [0065]     In step  708 , the Encode/Play Module  628  generates an S-TTMF Flag Signal and an E-TTMF Flag Signal according to the test score received in accordance with Tables 2 and 3, respectively. In step  710 , the Encode/Play Module  628  plays the S-TTMF Flag Signal to the other VVQT by transmitting the S-TTMF Flag Signal through the Network under Test. This is followed by a pause (the silence  506 ,  FIG. 5 ). In step  712 , the Encode/Play Module  628  plays a voice/video quality sample testing signal to the other VVQT by transmitting the sample testing signal through the Network under Test. Again, this followed by a pause (the silence  510 ,  FIG. 5 ). In step  714 , the Encode/Play Module  628  plays the E-TTMF Flag Signal to the other VVQT by transmitting the E-TTMF Flag Signal through the Network under Test. This completes the File play process, and in step  720 , the CFPR-VVQT goes to the File Record process shown in  FIG. 8 .  
         [0066]      FIG. 8  is a flow chart  800  for a File Record Process within the Decode/Record Module  620 ,  FIG. 6 , of an example CFPR-VVQT system. The File Play Process starts in step  802 . In step  804 , the Decode/Record Module  620 ,  FIG. 6 , continuously monitors incoming voice/video signals. In decision step  806 , if the incoming voice/video signal is an S-TTMF Flag Signal, the process goes to step  808 . Otherwise, the process returns to step  806  and continues to monitor the incoming voice/video signals. In step  808 , the Decode/Record Module  620  begins recording a voice/video quality sample testing signal in computer memory.  
         [0067]     While recording the voice/video quality sample testing signal, the process in step  810  monitors incoming voice/video signals for an E-TTMF Flag Signal. In decision step  812 , if the incoming voice/video signal is not an E-TTMF Flag Signal, the process returns to step  808 , continues recording the voice/video quality sample testing signal in computer memory, and then returns to step  810 . If the incoming voice/video signal is an E-TTMF Flag Signal, the process goes to step  814 , in which the recording of voice/video quality sample testing signals is ended. In step  816 , the process decodes the recently-received S-TTMF and E-TTMF signals and obtains the test score. The process then goes to step  818  in which the recorded voice/video quality sample testing signals are sent to the Testing Module  624 ,  FIG. 6 , and the Storage Module  632 ,  FIG. 6 . This completes the File Record process, and in step  820 , the CFPR-VVQT returns to the start of the File Play process shown in  FIG. 7 .  
         [0068]     Persons skilled in the art will understand and appreciate, that one or more modules or submodules described in connection with  FIG. 6  and the processes, sub-processes, or process steps described in connection with  FIGS. 7 and 8  may be performed by hardware and/or software. Additionally, the CFPR-VVQT  300  may be implemented completely in software that would be executed within a microprocessor, general purpose processor, combination of processors, digital signal processor (“DSP”), and/or application specific integrated circuit (“ASIC”). If the process is performed by software, the software may reside in software memory (not shown) in the CFPR-VVQT  300 . The software in software memory may include an ordered listing of executable instructions for implementing logical functions (i.e., “logic” that may be implemented either in digital form such as digital circuitry or source code or in analog form such as analog circuitry or an analog source such an analog electrical, sound or video signal), and may selectively be embodied in any computer-readable (or signal-bearing) medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that may selectively fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “computer-readable medium” and/or “signal-bearing medium” is any means that may contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable medium may selectively be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples, but nonetheless a non-exhaustive list, of computer-readable media would include the following: an electrical connection (electronic) having one or more wires; a portable computer diskette (magnetic); a RAM (electronic); a read-only memory “ROM” (electronic); an erasable programmable read-only memory (EPROM or Flash memory) (electronic); an optical fiber (optical); and a portable compact disc read-only memory “CDROM” (optical). Note that the computer-readable medium may even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.  
         [0069]     While the foregoing description refers to the use of a Continuous File Play Record Voice/Video Quality Test System, the subject matter is not limited to such a system. Any Voice/Video Quality Testing system that could benefit from the functionality provided by the components described above may be implemented in the Continuous File Play Record Voice/Video Quality Test System  300 .  
         [0070]     Moreover, it will be understood that the foregoing description of an implementation has been presented for purposes of illustration and description. It is not exhaustive and does not limit the claimed inventions to the precise form disclosed. Modifications and variations are possible in light of the above description or may be acquired from practicing the invention. The claims and their equivalents define the scope of the invention.