Abstract:
A switched, digital high-broadband network provides automated control and in-service and out-of-testing of analog video signals, encoded and decoded real time, into MPEG 2 digitized format with a high level of security and protection of content and without attendant degradation of the analog signal sometimes experienced in satellite transmissions. The switch network, typically an asynchronous transfer mode (ATM) network, has multiple gateways for connection to video signal sources and sinks. Each gateway includes an analog/digital video switch for receiving the video signals and distributing them to an MPEG 2 encoder for conversion into digital packets. A multiplexer is coupled to the encoder and a digital switch for inserting the multiplexed signal into the switched ATM network. The multiplexer and the digital switch encode destination address information into the digital packets to ensure proper routing. Each gateway further includes a de-multiplexer and MPEG 2 decoder connected to the digital switch for separating the digital packets from the ATM network into separate MPEG 2 streams subsequently decoded into analog video and returned to the video sinks. A command and control center is coupled to each gateway for remote testing of point-to-point and point-to-multipoint circuits; testing a switch circuit before and after the establishment of a connection to a customer; in service testing of MPEG 2 encoding content; detecting and isolating digital network problems, and off-line network testing and automating network utilization. The command and control center includes test executives which ensure the quality and availability of video traffic. The test executives run continuously run without manual intervention providing network operators with network status through user consoles.

Description:
RELATED APPLICATIONS 
     The present invention is related to applications entitled ‘SYSTEM AND METHOD OF IN-SERVICE TESTING OF A COMPRESSED DIGITAL BROADCAST VIDEO NETWORK’, Ser. No. 09/221,865 filed Dec. 29, 1998 now U.S. Pat No. 6, 297,845 and ‘SYSTEM AND METHOD OF IN-SERVICE AUDIO/VIDEO SYNCHRONIZATION TESTING’, Ser. No. 09/221,868, filed Dec. 29, 1998 both dockets assigned to the same assignee as that of the present invention and fully incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates generally to video data transmission systems and more particularly to the control of communication networks and the measurement of video quality. 
     (2) Description of the Prior Art 
     An IBM Video System (IVS) includes a high-bandwidth, switched network connecting 6 cities in the continental United States that is used by broadcasters to transmit and receive broadcast video. The system converts a subscriber&#39;s analog or digital video to compressed digital format, then routes it to the destination over an asynchronous transfer mode (ATM) switched connection where the digital video is decompressed, converted back into analog or digital video and passed on to the receiving end. The video signal is compressed using MPEG-2 encoding format at a bit rate of 8-40 Mbps using real-time encoding and, in many cases, it is played out directly to air. 
     Using ATM as a backbone enables IVS to offer point to multipoint capability that is of value to the broadcast video industry. A single broadcast feed originating in New York City may be simultaneously routed to Los Angeles, Chicago and Atlanta. The ATM network provides subscribers with a high level of security and protection of content. 
     Typically, a broadcaster reserves in advance IVS network bandwidth for a given time slot. Immediately prior to the requested time, a connection(s) is established through the ATM network and the circuit is turned over to the broadcaster. At the end of the purchased time slot, the circuit is automatically disconnected. 
     Subscribers gain access to the IVS network via gateways referred to as Points-Of-Presence (POPS). All command and control are accomplished from a remotely located Command and Control Operations Center (CAC). There is no local control at the pops which are unmanned by designed. The volume of traffic, the intricacies of controlling network resources and the speed at which connections must be established preclude manual control of the network by operators. Operator intervention is far too cumbersome to achieve the necessary circuit connect/disconnect times. Network operations must be fully automated to provide the level of service expected by subscribers and to operate the network economically. 
     Broadcast engineers are a demanding customer set with exacting standards for video quality and availability of service. Since the subscriber&#39;s feed is broadcast directly to air via the IVS network, any degradation or interruption of video signal will be obvious to television viewers and may result in a significant loss of revenue to the broadcaster. In a communications network, the carrier is responsible for demonstrating that the circuit it is providing meets applicable engineering standards. The carrier is further responsible for isolating transmission anomalies so that the network can be eliminated as the possible source or cause of the perturbation. 
     Because the network points-of-presence are unmanned, circuit testing in the IVS network is problematic. Although the techniques of EIA/TIA 250 C in-service testing are well known to broadcasters and remote testing is commonplace within the communications industry, testing is always accomplished with an engineer at one of the two sites involved in the circuit under test. Other carriers do not perform remote testing of terrestrial point-to-multipoint digital video circuits. Video quality testing is required of each and every circuit in the network prior to release to the subscriber. These tests cannot have a duration longer than a few seconds and if a failure is encountered, another circuit must be established. All circuit reservations are guaranteed and connection provisioning must be completed prior to the reservation start time. 
     In addition to pre-service circuit testing, each circuit is periodically tested while the feed is active and once again prior to disconnection. This non-invasive monitoring of video and audio quality detects problems near-real time so that service may be restored with minimum outage. It is common practice in the broadcast industry to record the on-air feed and subscribers are able to provide evidence of circuit degradation. In-service testing indemnifies the network should a subscriber claim network culpability for any such circuit anomaly. 
     Operating in a network using real-time MPEG-2 compression and ATM routing can cause perturbations not normally seen in a non-compressed digital and even analog network. Such problems as video tiling or breakup, loss of video and audio synchronization, audio clipping, dropouts and video freeze frames require a wider range of tests to be run to ensure the network is not distorting the broadcast. 
     Quiesced hardware such as encoders, decoders, switch ports, etc. and idle ATM trunks, referred to hereafter as network resources, must be regularly tested to ensure availability. Future reservations are guaranteed based on this availability and when hardware failures are detected, the network resource database must be updated to reflect the loss of such components. Loss of resources that affect reservations in the near term requires network management software to recalculate the resource allocation necessary to honor those reservations. Lastly, as maintenance actions at the POPs are completed, diagnostic testing must be executed to verify the fix and update the network resource database to reflect the change in status. 
     For quality assurance and to minimize outages on high priority video circuits, video feeds must continuously be monitored by operations personnel in a round-robin fashion. This monitoring must be accomplished without manual intervention and must provide an accurate indication of what the subscriber is actually seeing. 
     Prior art related to remote out-of-service and in-service testing of a video transmission system without human intervention includes the following: 
     U.S. Pat. No. 5,506,832 (Arshi et al.) issued Apr. 9, 1996, discloses a method of testing a computer-based client/server conferencing system. A digitized video and voice data signal is sent from a server to a client that essentially checks the connectivity of the circuit. No test is performed for quality and user intervention is required to start the test. 
     U.S. Pat. No. 5,274,446 (Ashida) issued Dec. 28, 1993, discloses an internal self-diagnosis of an image transmission device that processes digital video. Circuit loop backs are employed throughout the device for isolating failures to a component. The diagnostic capability is limited to the device itself. No test signals are sent to the remote end which precludes testing of the transmission network. User intervention is required to initiate the self test. 
     U.S. Pat. No. 5,446,492/U.S. Pat. No. 5,596,364 issued Aug. 29, 1995, and Jan. 21, 1997 respectively, disclose a system and method for measuring the video quality of transmission channels. The quality is measured by the audio delay, the video delay and perceptual degradation in video quality using extracted signals from the source and destination audio-visual signals in the transmission channel which does not include a switched digital ATM network. These signals are easily and quickly communicated between source and destination locations. 
     Accordingly, a need exists for in-service and out-of-service testing without human intervention in high bandwidth, switched network video transmission systems. 
     SUMMARY OF THE INVENTION 
     An object of the invention is a set of software executives that automate testing of a compressed digital video network precluding the need for -manual intervention. 
     Another object is a set of software test executives which update the network resource and reservation databases as components of the network malfunction or undergo repair action. 
     Another object is a set of software test executives which automatically perform periodic in-service testing of active video feeds in a non-invasive, non-service affecting manner. 
     Another object is a set of software test executives which will automatically, and without operator intervention, reconfigure circuits to restore service to video feeds that fail in-service testing. 
     Another object is a set of software test executives which perform problem isolation to a failing system component when a test failure occurs. 
     Another object is a set of software test executives which periodically route video feeds into a Command And Control (CAC) center for real-time monitoring of video and waveform quality. 
     These and other objects, features and advantages are accomplished in a switched, digital high-broadband network which provides automated control and testing of analog video signals, encoded and decoded real time, into MPEG 2 digitized format with a high level of security and protection of content and without attendant degradation of the analog signal sometimes experienced in satellite transmissions. The switch network, typically an asynchronous transfer mode (ATM) network, has multiple gateways for connection to video signal sources and sinks. Each gateway includes an analog/digital video switch for receiving the video signals and distributing them to an MPEG 2 encoder for conversion into digital packets. A multiplexer is coupled to the encoder and a digital switch for inserting the multiplexed signal into the switched ATM network. The multiplexer and the digital switch encode destination address information into the digital packets to ensure proper routing. Each gateway further includes a de-multiplexer and MPEG 2 decoder connected to the digital switch for separating the digital packets from the ATM network into separate MPEG 2 streams subsequently decoded into analog video and returned to the video sinks. A command and control center is coupled to each gateway for remote testing of point-to-point and point-to-multipoint circuits; testing a switch circuit before and after the establishment of a connection to a customer; in service testing of MPEG 2 encoding content; detecting and isolating digital network problems, and off-line network testing and automating network utilization. The command and control center includes test executives which ensure the quality and availability of video traffic. The test executives run continuously run in parallel with network operations and reservation management software. The test executives both query and update the network resource and reservation databases. Testing is divided into two categories, in-service (IS) and out-of-service (OOS) testing. Although detailed test data are made available, operator consoles and logs provide pass/fail indications for ease of operability. To facilitate field maintenance actions and in-depth troubleshooting, the executives allow operators to take manual control of testing. A video feed monitor (VFM) routes all video feeds to a studio monitor and a waveform monitor/vectorscope in the CAC for quality assurance purposes. Each feed is viewed for 15 seconds at a time in serial fashion with the feed name displayed in graphics for identification. In this manner, a bank of 4 video and 4 waveform monitor/vectorscopes can assure 16 video feeds per minute. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be understood from the following description of a preferred embodiment taken in conjunction with an appended drawing, in which: 
     FIG. 1 is a simplified network diagram illustrating 3 sites or points-of-presence (POPs) and their configuration in a video transmission system controlled by a Command And Control (CAC) center incorporating the principles of the present invention. 
     FIG. 2 depicts the connection path of a point-to-multipoint video circuit originating in Los Angeles and terminating in Washington DC and New York. 
     FIG. 3 is an illustration of an out-of-service test performed on a point-to-point video circuit employing video and audio test equipment. 
     FIG. 4 is a detailed diagram of the CAC center in FIG.  1 . 
     FIG. 5 is an illustration of a Reservation Order web page for the system of FIG.  1 . 
     FIG. 6 is a diagram a network test manager and software test executive/network software components that execute in the CAC of FIG.  1 . 
     FIG. 7 is an illustration of representative television test signals. 
     FIG. 8 is an illustration of a RS-232 control interface of the POP test equipment of FIG.  1 . 
     FIG. 9 is an illustration of an in-of-service video quality test performed by a POP using the system of FIG.  1 . 
     FIG. 10 is a logic flow diagram for running the in-service test of FIG.  9 . 
     FIG. 11 is a logic flow diagram of an in-service software test executive in the system of FIG.  1 . 
     FIG. 12 is a logic flow diagram of an unscheduled connection request. 
     FIG. 13 is a logic flow diagram for establishing a connection. 
     FIG. 14 is a logic flow diagram of an out-of-service software test executive. 
     FIG. 15 is a logic flow diagram for isolation testing. 
     FIG. 16 is a logic flow diagram for checking resource commitments. 
     FIG. 17 is a logic flow diagram for breaking a video connection. 
     FIG. 18 is a logic flow diagram for checking for over-committed reservations. 
     FIG. 19 is a logic flow diagram for out-of-service testing of idle resources. 
     FIG. 20 is a logic flow diagram for selecting idle resources for the purposes of Out-Of-Service (OOS) testing. 
     FIG. 21 is a logic flow diagram of the pre/post-service circuit testing. 
     FIG. 22A is a representation of video screens on a studio monitor at a Command And Control (CAC) center for live monitoring purposes. 
     FIG. 22B is an illustration of the display output of a vectorscope. 
     FIG. 23 is a diagram of the network with a video circuit being monitored by a Video Feed Monitor (VFM). 
     FIG. 24 is a logic flow diagram for the main processing thread of the VFM of FIG.  23 . 
     FIG. 25 is a logic flow diagram for processing operator commands to the VFM. 
     FIG. 26 is a logic flow diagram of the alarm monitor. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, there are illustrated 3 points-of-presence (POP) or gateways into the IBM Video Service (IVS) Network, New York  110 , Los Angeles  100  and Washington DC  105 . The IVS network provides long distance services for high bandwidth, broadcast quality video and audio by digitizing and compressing the analog/digital video signal and transmitting it to the ran distant end via a switched asynchronous transfer mode (ATM) network where it is converted back to analog or digital format and passed on to the subscriber. 
     The 3 POPs are connected to an ATM network  115  through OC-3 (155 Mbps) access lines  118  from an ATM switch  140 . Each POP has a set of ingress/egress access lines that carry the video signal to  129  and from  128  nearby subscriber locations. The POP accepts video in either analog or digital (ITU-R601 General Digital Video and SMPTE 259M 270 Mbps Serial) form. The access lines are connected to an analog/digital switch  132  that allows the signals to be switched into dedicated MPEG-2 encoders  136  and decoders  137 . The POP interfaces with the ATM network via an ATM switch  140 . On the transmit side, ATM switch is connected to a mux  138  which multiplexes the output of the MPEG-2 encoders into a single OC-3 transport stream. Network data that is addressed to the POP is routed into the demux  139  that demultiplexes the OC-3 data into individual MPEG-2 transport streams. The output access lines  129  provide the signal to the subscriber. FIG. 1 is offered only as a representation of a POP configuration. Traffic load dictates the full complement of networking resources. 
     To test the video quality of each newly established video circuit, a vertical interval test signal (VITS) generator  130 , an audio signal generator  127  and a video/audio measurement set  134  are wired into the analog/digital switch  132 . A color bars generator  131  is also connected to a switch port in order to inject the color bar test pattern into all outbound (egress) lines. This assures the subscriber that there is continuity with the POP. The testing of the ATM switch and ATM trunks necessitates an ATM test generator  112  and an ATM test analyzer  114 . These test sets characterize the performance of the ATM switch and network. 
     Because the POPs are unmanned, they are remotely controlled from a Command and Control (CAC) Operations Center  120  located in New York. Video connections are established and broken by commands issued under program control of network operations software executing in computers  172 . These computers maintain continuous connections to each POP over a TCP/IP wide area network  174  to both control the POP equipment and monitor for alarm conditions. The CAC itself contains a small POP  175  since it accesses the ATM network in order to monitor video feeds  173  for quality assurance. 
     FIG. 2 depicts a point-to-multipoint video connection from a subscriber in Los Angeles  200  to Washington DC  205  and New York  210 . The video is sourced from a analog video from a video tape recorder  221  and received on the subscriber&#39;s private ingress line  228 . The signal  280  is switched by the analog/digital switch  232  into the first available MPEG-2 encoder  236 . The signal continues on into the mux  238  where it is given an ATM address that permits it to be properly routed by the ATM switch  240  and network  215 . At the receiving POP, Washington DC  205 , the demux  252  demultiplexes the aggregate OC- 3  signal received from the ATM switch  250  and routes the demultiplexed MPEG-2 transport stream  285  into its dedicated MPEG-2 decoder  254 . The baseband video output of the MPEG-2 decoder is passed to the analog/digital switch  256  which switches the signal into the customer&#39;s private egress line  262  for viewing on a video monitor  270 . The New York POP  210  likewise receives the signal  287  and routes it to the subscriber via the subscriber&#39;s egress line  288 . Immediately after establishing a connection, but prior to switching the subscribers ingress/egress lines  228   262   288  into the connection path  280   285   287 , a brief test is conducted to test the quality of the connection. 
     In FIG. 3, the VITS test equipment is switched  382  into the connection to send a NTSC color bar test pattern to the distant end. At the receiving ends of the multipoint connection  305   310 , the analog/digital switches  356   357  switch  388   383  the outputs of the audio/video connections  385   387  into their respective audio/video test measurement sets  358   391  for measurement and analysis. After a test duration of a few seconds, the test equipment is switched out and subscriber access lines  328   362   389  are switched  384   386   385  into the active connection and the circuit is turned over to the subscriber. If the color bar test had failed, a new video connection would have been established using an entirely different set of network resources. The new connection would then be tested prior to release to the subscriber. 
     FIG. 4 illustrates in detail the components of the Command and Control (CAC) Operations Center  402 . The CAC maintains a database  418  of each subscriber reservation. A subscriber makes reservations for video circuits from his/her computer  405  which is configured with a web browser. After connecting to the IVS reservation web server  416 , the subscriber is presented with a web page that solicits reservation data. The reservation request is passed on to the reservation system  414  which then queries the network resource manager  410  to ensure there are adequate resources in the network to establish the circuit at the requested time. The network resource manager  410  in turn queries the network resource database  412  to check the availability of access lines, encoders, decoders, and network bandwidth. If needed resources will be available to honor the future connection, the network resource manager updates resource database and responds affirmatively to the reservation system  414  which then updates its reservation database  418 . The reservation web server  416  informs the subscriber of the confirmed reservation by refreshing the reservation request web page. 
     FIG. 5 illustrates a reservation order web page  600  through which a subscriber reserves bandwidth for a future video transmission. The subscriber enters the start date and time  605  and the end date and time  610  of the connection. Also specified are origin  615  and destination  620  ports (cities). Upon submission  640  of the reservation order the web page is updated with the computed duration  625  of the connection, a reservation status of Confirmed  630  and a unique reservation ID  650  with which to reference the reservation in future transactions. 
     Returning to FIG. 4, the network resource manager  410  creates new video connections at the requested time and destroy connections when the reservation expires in addition to accepting new reservations. The network resource manager issues commands to a set of control programs that control the ATM switches  430 , analog/digital video switches  432 , audio and video test sets  434  and MPEG-2 equipment  436 . The control programs, in turn, issue hardware specific commands to the slave equipment over a wide area network  445  that is accessed through an IP router  440 . The commands are sent using Simple Network Management Protocol (SNMP) which is a well-known IP protocol used to control network hardware. Alternatively, the test equipment controller  434  can control the POP test equipment over dial backup line. Each controller runs in a separate computer with a user interface that permits network operators to take manual control of the POP equipment if operator intervention is deemed necessary, however control of the entire IVS network is fully automated under the control of the network resource manager  410 . As each controller issues commands and detects POP alarms conditions, network status is updated at the operator&#39;s console  438  and printer  425  which are continuously monitored by the network operators. 
     The network test manager  431  is the platform on which the video feed monitor (VFM), in-service (IS) and out-of-service (OOS) test executives reside. All network testing is automated and controlled from this workstation  431 . The manual test console  435  facilitates the manual testing of network resources for in-depth troubleshooting and ad-hoc problem isolation. The CAC POP  439  enables the video feed monitor (VFM) to route active video feeds to a bank of video  433  and waveform monitor/vectorscopes  437  for quality assurance. A video tape recorder  441  optionally records the snapshot of each feed under control of the VFM in network test manager  443 . 
     Each POP is configured with an IP hub  490  that is the gateway to the wide area network. From the hub, Ethernet lines  495  are connected to each set of networking equipment and the terminal server  462 . The terminal server permits the test equipment controller  434  to remotely control and monitor all test signal generators and measurement sets via an RS-232 control interface from a wide area IP network. 
     In FIG. 6, the network test manager  431  is further illustrated. Three (3) executives: in-service test  802 , out-of-service test  804  and the video feed monitor  806  run continuously controlling all aspects of network testing and monitoring. Each of the executives is manually controllable via a manual test console  809 . A test controller  808  serializes access to the network resources which are directly controlled by a analog/digital switch  822 , ATM switch  824 , test equipment  826  and MPEG-2 equipment  828  controllers. A video feed monitor (VFM)  806  routes active video feeds into the CAC in a round robin fashion through requests to the connection manager  814 . The VFM also responds to alarm conditions reported by an alarm monitor  812  which fields all alarms reported from the POPs. The VFM immediately switches to feeds that are directly affected by the hardware signaling the alarms. A connection manager  814  interfaces with an Out-Of-Service (OOS) test executive  804  to have new connections tested before being released to the subscriber. All connections are established by the connection manager  814  at the reservation start time by a resource manager  816  which maintains a database  818  of all resources to be used to establish all future video connections. A reservation manager  834  ensures resources are available before confirming the reservation. 
     The preferred embodiment of the present invention is incorporated in a communications network using real-time MPEG-2 video and audio compression. MPEG-2 is described in detail in the Moving Pictures Expert&#39;s Group (MPEG) standard, Coding of Moving Pictures and Associated Audio ITU Recommendation H.262 which is incorporated herein by reference. However as the details of MPEG-2 encoding/decoding are not essential to the understanding of the invention and are generally well understood in the art no description will be offered here. 
     In FIG. 7A, an active video area  700  of an NTSC broadcast of 525 video lines comprises 2 interlaced fields of 262.5 lines each (not shown). A vertical blanking interval  702  area is made up of video lines  1  through  21 . Line  22  is the start of the active video area and it continues to video line  262 . Lines  22  through  33  and lines  250  through  262  of each field lay in an overscanned area  715 . The size of the overscan will vary for each television and even within the same television due to fluctuations in the voltage regulation of the power supply. To prevent viewers from seeing the non-picture areas of the horizontal and vertical scans, the overscan is typically set for 5% of the active video which effectively renders unviewable approximately 12 lines of each field at the top and bottom of the screen. The active video fuher comprises an action safe  710  and title safe  705  areas. These areas serve as boundaries that guide producers in the framing of a scene or placement of title text. 
     FIG. 7B illustrates a few of the well-known television test signals used to test video performance and quality over transmission systems. Shown are NTC 7  Combination  750  for frequency response and distortion testing, FCC color bars  760  for amplitude and timing measurements, FCC multiburst  770  for frequency response and NTC 7  Composite  780  allowing amplitude and phase measurements. One or more of these signals may be placed into VBI lines  10  through  20  of either field for in-service testing. For OOS testing, these signals may be placed anywhere in the active video area. 
     In FIG. 8, the full complement of test equipment needed at each POP to test in both the analog and digital domains and the ATM network is illustrated. An analog  2480  and digital  2470  VITS insert test signals into the VBI for in-service testing. A picture quality generator  2430  and analyzer  2420  are long term tests, approximately 15 minutes each, that objectively measure picture quality in terms of Just Noticeable Differences (JND) scores. These tests are run off-line against newly installed hardware at encode rates ranging from 8 to 40 Mbps. Video  2440  and analog  2450  signal generators produce signals used in OOS testing as they are service affecting. All of the audio and video test signals are measured and analyzed by an analog/digital measurement set  2410 . A downstream VITS  2415  is used during in-service testing to remove any test signals inserted by the upstream VITS  2470   2480 . 
     ATM switch and network trunks are evaluated using an ATM test generator  2486  and analyzer  2484 . The ATM specific test sets facilitate separate testing of the ATM network and provide problem isolation capabilities that cannot be achieved using television test signals. All test equipment is remotely controllable via well known RS-232 control interfaces. The command and control of the test equipment is accomplished under program control from a test equipment controller  2495  in the CAC. The RS-232 control signals are transmitted and received over an IP network  2485  via terminal servers  2475 ,  2490  which packetize and depacketize the RS-232 control information. The terminal server  2475  has a dial-up line  2477  which allows the CAC  2497  to control the test equipment during a Wide Area Network (WAN) IP network outage. 
     Under program control, several tests may be run concurrently by programming the VITS to insert simultaneously multiple test signals into VBI lines  10  through  20 . A measurement set  2410  is pre-instructed to test each pattern at its assigned line and the results of all the tests are read out in a single operation. The test signals are inserted for less than a second. 
     In-Service Software Test Executive 
     In-service testing measures the analog video performance of active feeds by running EIA/TIA 250 C tests. EIA/TIA 250 C is the National Association of Broadcasters&#39; (NAB) test specification of choice. Digital video is tested in accordance with ITU-R601 General Digital Video. In order to perform in-service testing without adversely affecting the broadcast, test signals are injected into the VBI at lines  10  through  20  inclusive. Since signals in the VBI are filtered out prior to MPEG-2 encoding, the present invention relies heavily on the techniques for in-service testing taught in the co-pending application entitled ‘METHOD AND APPARATUS OF IN-SERVICE TESTING OF A COMPRESSED DIGITAL BROADCAST VIDEO NETWORK’, supra which moves test signals from the VBI into the active viewing area. The test signals are removed from the active video area at the decoder and the lines used to carry the test signals are concealed from the viewer. Also relied upon is co-pending application entitled ‘SYSTEM AND METHOD OF IN-SERVICE AUDIO/VIDEO SYNCHRONIZATION TESTING’, supra, which teaches a transparent, non-service affecting method of audio/video synchronization. The test has traditionally used a very objectionable audio tone to test audio synchronousness. 
     Analog in-service testing is accomplished using such signals such as NTC7 Composite  730  which enables many tests from the EIA/TIA 250 C test suite to be run including: 
     Line time distortion 
     Chroma burst amplitude 
     Audio/video synchronization 
     Y/C gain delay 
     Luminance non-linearity 
     Differential gain 
     Differential phase 
     The foregoing seven (7) tests provide an excellent indication of video quality. Two additional signals, FCC Multiburst  720  for frequency response testing and NTC7 Combination  710  for chroma non-linearity enable a further and more complete analysis of video performance. All of the above tests can be run in sub-second time which allows each active connection to be tested more frequently. Digital video tests include jitter, signal amplitude and legal color palette. Such analog and digital tests are well-known to those skilled in the art of broadcast television testing and no further discussion of these tests is deemed necessary as the teachings of the present invention do not involve the test procedures or results analysis. 
     FIGS. 9 and 10 illustrate in-service testing at a POP and the logic flow of VBI in such testing. The VBI of the video signal received from the subscriber may contain signals inserted by the subscriber so an unused or black VBI must be chosen for in-service testing in order not to interfere with the subscriber&#39;s VBI data. An idle VBI line is found by searching VBI lines  10  through  20  in block  2600  using a measurement test set  558  to analyze the line in block  2605 . When an idle line is found in block  2610 , a VITS  532  on the transmit side is configured in block  2630  to insert the in-service test signal on that line, a downstream VITS  557  is configured in block  2635  to insert black on the same line, and the measurement set  558  is configured in block  2640  with the VBI line ID and the test signal type. After 3 unused VBI lines have been found in block  2650  or all of the VBI lines have been searched in block  2600 , execution falls to block  2655  where a test is made to see if any black lines were found. If not, the routine in block  2670  returns without conducting the test. Otherwise, both VITS are activated to insert the test signal and black concealment line for a period of 15 frames in block  2660 . 
     In-service tests are initiated by: 
     1. Periodic testing of active feeds. 
     2. Test requests generated from alarm activity. 
     3. Test requests from the manual test console. 
     FIG. 9 illustrates in-service-tests from an origin POP  500  to a receiving POP  505 . A subscriber&#39;s video feed  528  is routed through a analog/digital video switch  582  into the vertical interval test signal (VITS) equipment  532  which inserts a test signal into the chosen VBI line without affecting the active video. The analog/digital switch then routes the output of the VITS into an MPEG-2 encoder  536  for encoding and transmission. An injector  534  moves the test signal from the VBI into the active video area before the video is encoded. At the receive end  505 , an extractor  584  moves the test signal from the active area into the VBI and a decoded signal  585  is routed into two output ports by an analog/digital switch  556 . One port is connected to a VITS  557  and the other to a measurement set  558  that performs analysis and measurement of the video test signals in block  2665  (See FIG.  10 ). The VITS  557  receives the video signal  546  and inserts black into the line that contains the in-service test signal, effectively removing the test signal from the broadcast. The video is then routed back into a analog/digital switch  556  where is it switched into the subscriber&#39;s egress line  562 . In this manner, the IVS network is tested end-to-end affecting neither the viewed broadcast nor the subscriber&#39;s VBI signals or data. 
     In FIG. 11, the logic flow diagram of the in-service (IS) test executive  802  (See FIG. 6) will be described in conjunction with FIG.  11 . The IS test executive runs continuously testing active video feeds and responding to test requests from an alarm monitor  812  at a manual test console  809 . At each invocation, a test is performed in block  900  to determine the cause of invocation. The test(s) is run against specified hardware in block  920 , otherwise the executive is run due to the expiration of the timer (not shown) that initiates IS testing of the active feeds. A list of all active connections is queried in block  905  and a loop is entered where for each active and untested connection identified in block  910 , IS testing is performed in block  920  and the results are logged in block  925 . The results of the IS tests are queried in block  930  and if successful and the completed test was a periodic IS test identified in block  962 , the loop iterates to the next video feed. Otherwise the results are returned in block  964  to the caller, either the alarm monitor or manual test console. The elapsed time is checked in block  965  to determine whether it is time for periodic IS testing to start again. If so, the main loop is reentered. If not, a timer is set for the remaining time in block  970  and the IS executive enters a wait state in block  975  that will be satisfied by either the expiration of the timer or a request to run IS tests. 
     A test failure causes the executive to alert the network operators in block  935  via an audible alarm and operator&#39;s console message and a test is made to see whether the failing circuit should be automatically reconfigured in block  940 . If auto-reconfiguration has been disabled, the loop iterates. Else a new, unscheduled connection is requested of the resource manager in block  945  (to be described in FIG.  12 ). If the resource manager is able to establish a new connection in block  950 , the subscriber ingress/egress lines are switched into it in block  958 . If the new connection was not provisioned in block  950 , the network operator is given a second and higher priority alert message in block  955  to handle the circuit outage. The failed circuit is then scheduled for isolation by the out-of-service test executive in block  960 . The problematic circuit is left in a connected state to because the resources cannot be released until the failed component has been identified. If the IS test executive was not processing a test request in block  962 , the loop iterates to the next connection. 
     FIG. 12 illustrates a request to make an unscheduled connection. The connection parameters are validated in block  1000  and the resources are requested of the resource manager  810  (See FIG. 6) in block  1005 . If the resources are not available  1010 , a check is made to see if the calling routine specified usurpation in block  1020 . Generally, committed resources are only usurped to restore a failed video feed. If the resources were not allocated, the connection is denied and the routine returns with error in block  1075 . Else, the resource is taken from a future reservation in block  1025  and the connection is established in block  1040 . If the connection is successful in block  1040  and a resource was usurped to provision it in block  1042 , a Check Resources Commitments is called in block  1045  to mark any affected reservations as ‘non-viable’. The routine then returns without error in block  1070 . 
     In FIG. 13, an Establish Connection routine is run by the connection manager  814  (See FIG. 6) which is part of the resource manager  810 . Establishing a connection involves configuring the transmit and receive MPEG-2 components in blocks  1220  and  1230  and issuing the ATM connect and add party commands in block  1235  to setup a switched virtual circuit to the destination POP(s). A set of OOS pre/post-service video and audio tests is then run in block  1245  by the OOS test executive  804  (See FIG.  6 ). If the tests are successful in block  1250 , a color bars test pattern is removed from the subscriber&#39;s egress line in block  1255 . The ingress and egress lines are switched in blocks  1260  and  1265 , respectively into the connection giving the subscriber end-to-end connectivity and the routine returns a successful result in block  1290 . If the tests fail in block  1250 , the CAC operators are alerted in block  1270  and OOS isolation testing is scheduled in block  1275  to troubleshoot the failed connection. Thereafter, the routine returns an error code to the caller in block  1280 . 
     Out-Of-Service Software Test Executive 
     Now turning to the OOS software test executive, all out-of-service diagnostic tests, problem isolation, acceptance testing and any probative procedure of a disruptive nature are automated and controlled by the executive. In contrast to IS testing, OOS testing permits a full range of audio testing and long duration video tests such as objective picture quality analysis. Invasive audio signals, long term video tests using the active video area and ATM testing differentiate OOS testing from in-service testing, in particular tests such as: 
     Audio unity gain 
     Audio signal/noise 
     Audio noise floor 
     Audio harmonic distortion 
     ATM jitter 
     ATM Cell loss 
     ATM trunk bit error rate 
     ATM signaling 
     Zone plates video test pattern 
     The OOS test executive is divided into five (5) testing sub-components: 
     1. Idle resource 
     2. Problem isolation 
     3. Pre/post service 
     4. Manual console 
     5. Acceptance/maintenance 
     Idle resource testing is timer driven and is invoked a minimum of 4 times a day. Isolation testing, which isolates faults to the component level, is scheduled by the connection manager  814  and the IS test executive  802  as circuit failures are detected shown in FIG.  6 . Pre/post-service testing is a limited set of OOS tests that is run when a connection is established and broken. 
     Requests from the manual test console  809  are generated by ad-hoc operator testing or troubleshooting, which is commonly in response to subscriber complaints. Acceptance and maintenance testing are scheduled whenever new hardware resources are added to expand the network or faulty components are removed and replaced. Although installation is often accomplished during normal business hours, the testing is generally deferred to off-peak hours. 
     When scheduling acceptance and maintenance tests, automatic reconfiguration may be enabled which causes the new resource(s) to be automatically added to the network database and placed on-line. 
     FIG. 14 illustrates the high level logic flow of the OOS test executive shown in FIG.  6 . The main processing loop of the executive enters a wait state in block  1505  until a test request is received. In block  1510 , if the request is for testing subsequent to a new installation or a maintenance action in the field, the full OOS acceptance test suite is run to validate the new hardware in block  1545 . Any failures that occur in block  1550  result in notification to the network operator in block  1570 . If the hardware passes diagnostics, the resource is added to the network database in block  1555 . If the resource had been previously removed from the database in block  1560 , reservations are checked in block  1565  to see if any connections are scheduled to use the repaired resource. The lists of tests run and the results are logged to the operator console in block  1570 . If the OOS test request is from the manual test console in block  1515 , the requested tests are executed in block  1535  and the results are returned to the requester in block  1540 . Continuing with the OOS test request processing, if problem isolation is scheduled in block  1520 , the isolation routine is invoked in block  1525 . 
     FIG. 15 illustrates the task of automatically isolating failed components anywhere in the network. The automation of this process eliminates the need for network engineers to issue numerous commands from multiple consoles to a set of heterogeneous components procured from multiple vendors. IVS Network operations are automated and the setup and removal of connections occur continuously and given that subscriber reservations are accepted for as soon as 15 seconds in the future, network engineers cannot know with certainty what resources can be safely used to aid in troubleshooting without jeopardizing network availability. Isolation commences by obtaining the ID of all the resources used in the failed connection information in block  1600  and requesting an unscheduled (multipoint) connection in block  1601 . The connection adds a leaf to the faulty connection so that a third POP can participate in the troubleshooting in order to isolate the problem to either the transmit or receive chain. The third POP is almost always the CAC POP which has subscriber service. If the connection is denied due to lack of resources in block  1602 , the isolation testing is rescheduled and the routine returns in block  1604  to block  1600 . Otherwise, the test generator and test analyzers (See FIG. 9) are switched into the connection to test for continuity in block  1603 . If the connection is restored in block  1605 , the fault lies somewhere in the receive path and problem is further isolated by configuring in blocks  1645 , 1655 , and  1665  a different decoder, demultiplexer and ATM switch port and trunk, respectively. If any of these changes restores the circuit, the field engineer is paged in block  1675  with the failure data, the failed resource is removed from the network database in block  1685  and a check is made in the Check Resource Commitment in block  1690  to see if any future reservations are contingent on this resource. If the connection is still active in block  1692 , the multipoint connection is disconnected in block  1694 , bypassing the post-service testing that is normally done prior to freeing the resources. In block  1698 , the routine then returns to block  1600 . If the multipoint circuit at the third POP received neither video or audio in block  1605 , isolation proceeds at the transmitting POP. In blocks  1610 ,  1620  and  1630 , the encoder, multiplexer, and ATM switch port and trunk, respectively are reconfigured in serial order. If the circuit still is not restored, the problem is isolated to the analog/digital switch port in block  1642 . 
     FIG. 16 illustrates a Check Resource Commitment (CRC) routine which is necessitated whenever network resources are unexpectedly allocated or removed from the network database due to failure. The invocation of the CRC ensures all subscriber reservations within the next 72 hours will be honored. The network mean time to repair is 24 hours. Reservations 72 hours in the future are processed in case an extended outage is experienced. All reservations for the next 72 hours are examined in block  1710  to see if the resource being removed from service had been committed to the connection in block  1720 . If not, the loop iterates. Otherwise an attempt is made to replace the failed resource with another of the same type in block  1740 . If another resource can be committed, the reservation is updated to reflect the ID of the replacement resource in block  1745 . If no spares exist, the over-committed global flag is set in block  1750  and the reservation is updated with the type of resource needed in block  1755  and a status of ‘non-viable’ is indicated in block  1760 . An alert is generated in block  1765 . In block  1779  the reservation owner is e-mailed with the updated reservation information and an expected time of restoration. After all reservations have been checked in block  1710 , the routine returns in block  1790  to the block  1710 . 
     FIG. 17 illustrates a Break Connection routine used by the connection manager  814  to switch the subscriber&#39;s ingress and egress lines in blocks  1300  and  1310 , respectively out of the circuit and tests to determine if the calling routine requested in block  1320  that the tests not be run. If tests were requested (the default) post-service tests are run in block  1325  to validate the quality of the circuit at the time of disconnect. In blocks  1330 ,  1345 , and  1350 , if the tests passed, the transmit and receive MPEG-2 hardware, respectively are reset to a quiesced state and the ATM switched virtual circuit connection is released in block  1360 . A color bar test pattern  760  (See FIG. 7B) is switched in block  1370  into the egress line to allow the subscriber to test the access lines into the subscriber&#39;s premises. The resources used in make the connections are freed in block  1375  and a Check Over-Committed Reservations (to be described in FIG. 18) is called in block  1385  in case an over-committed reservation is waiting on resources. The routine then returns in block  1390  to block  1300 . If the tests failed in block  1330 , the network operator is alerted in block  1340 , isolation testing is scheduled in block  1355  and an error code is returned in block  1380  to the caller. 
     In FIG. 18, a Check Over-Committed Reservations routine is called anytime resources are added to the network database  412  (See FIG. 4) by the OOS test executive  804  (See FIG. 6) or connections resources are freed. In block  1800 , if there over-committed reservations, the over committed flag is reset in block  1805  and the routine falls into a loop to check the next 72 hours of reservations in block  1810  for non-viable status. If the status is non-viable in block  1820 , then a check is made to see if the resource currently being returned satisfies the reservation in block  1840 . If the reservation was waiting on the resource, the reservation is updated in block  1845  to use the resource and its status is modified to ‘confirmed’ in block  1850 . The network operators are alerted in block  1860  and the subscriber is e-mailed in block  1870  with the reinstated confirmation. After processing all of the scheduled connections, the loop exits in block  1810  and in block the routine returns to the start block  1800 . If reservations are found that are contingent on other resources in block  1840 , an over-committed flag is set in block  1830  to ensure the A reservation gets automatically updated when the awaited resource becomes available. 
     Returning to FIG.  14  and OOS test request processing if isolation testing has not been scheduled in block  1520 , the request by default is for Test Idle Resource routine which will now be described hereinafter. 
     FIG. 19 illustrates the Test Idle Resources routine which assures the availability of network resources. Periodically invoked a minimum of 4 times a day, the logic queries the list of all resources not currently in use in block  1100  and determines the reason for invocation in block  1102 . If an idle testing timeout occurred, all idle resources are marked as untested in block  1104 . Otherwise, a processing thread is dispatched by the alarm monitor  812  (See FIG. 6) in block  1102  and all resources with newly reported alarms are marked as untested in block  1106  and the logic falls into the main loop in block  1108  to initiate idle resource testing. In block  1110  a Select Resources subroutine is repeatedly called to provide a unique list of resource IDs that form an end-to-end video connection. 
     Transferring to FIG. 20, the selection of idle resources begins with establishment of a set of known good resources, an encoder/mux, decoder/demux and analog/digital switch ports  1405  in blocks  1400 ,  1402 , and  1405 , respectively. The most recently idled hardware is selected as trusted resources. The trusted resources are used on every subsequent invocation of the OOS idle resource testing until they are no longer available because they have either malfunctioned or they are in use. At that time, the unavailable resource will replaced again by the last idled resource of its type. Once a functioning set of resources has been provisioned, all idle ATM switch ports are tested in block  1445  using the trusted encoder/decoder pair identified in block  1410 . After looping through all of the idle ATM switch ports, all of the idle ATM trunk lines identified in block  1450  are likewise tested in block  1415 . In block  1420 , again using the same encoder/decoder pair, all of receive and transmit analog/digital switch ports are tested in serial fashion in blocks  1460  and  1470  using the trusted transmit and receive analog/digital switch ports. Then all idle decoders are tested in block  1480  using the known good transmit chain in block  1430 . Idle resource testing concludes by checking the in block  1485  the encoders the trusted decoders in block  1440 . 
     Returning to FIG.  19  and block  1115 , an unscheduled connection request may fail if the resources that were selected for test were not available. Failures are not uncommon given that connections are continuously being established during idle testing. Network resources are not usurped during idle resource testing. If the requested unscheduled connection in the block  1115  is allocated in block  1120 , the OOS idle resource test suite is run against that chain of resources in block  1125  and the results are logged in block  1130 . Each resource provisioned in the connection is marked as tested in block  1135 . If the OOS tests were successful in block  1140 , the loop iterates to the next set of idle components. Otherwise, the network operators are alerted in block  1   145  and a test is made in block  1   165  to see if the resources selected for this test included just one previously untested component. If so, the failed component can be identified and if auto-reconfiguration is enabled in block  1150 , the failed resource is removed from the network database  412  (See FIG. 4) in block  1155 . Reservations are checked in block  1160  in case the resource had been committed. If a test in block  1145  involved more than one previously untested component, isolation testing is scheduled in block  1170  to determine the failing resource. The unscheduled connection is left intact to speed isolation and prevent the faulty resource from being used. The loop terminates when all idle resources have been tested. If more than 4 hours elapsed during the testing of idle resources in block  1175 , the routine is once again invoked. Otherwise, a timeout is set for the balance of the remaining time in block  1180  and a processing thread of execution waits in block  1185  for either a timeout or a request from the alarm monitor to test idle resources in the alarm state. No attempt is made to test network resources that were freed after the idle test cycle had begun. Those freed resources were tested before the connection was broken. 
     In FIG. 21, a pre/post-service test component of the OOS test executive  804  (See FIG. 8) executes as a separate task in a detached processing thread of execution in order to respond rapidly to test requests prior to releasing a circuit to a subscriber. The thread runs a series of OOS video and audio tests to validate the connection. Subscribers may add other tests to this pre-service test suite to better assure circuit quality for their particular requirements. The task is halted in a wait state in block  1900  until dispatched with a test request. When the wait is satisfied, a loop is entered in block  1902  where each enqueued test request is processed. In blocks  1905  and  1915 , a video test signal generator and an audio tone generator, respectively are switched into the connection by the analog/digital switch at the origin POP. Downstream, in blocks  1910  and  1920 , video and audio analyzers, respectively are switched in to receive the generated test signals. In block  1930 , a loop is initiated to execute the pre/post-service test suite. The test generators  112  and test analyzers  114  (See FIG. 1) are serially commanded in block  1935  to run each test in block  1938  and any failure that occurs in block  1940  results in the logging of the error data in block  1950 , the normalization of the circuit in block  1960  and the appropriate error data are passed back to the caller in block  1970 . In block  1930 , if the test suite runs to completion without failure, the test equipment is removed from the circuit in block  1980  and an indication of success is returned. 
     Video Feed Monitor (VFM) Executive 
     Regardless of video test results, many engineers and operators insist on judging video quality subjectively by direct viewing of the live broadcast on a studio monitor at the receiving location. Viewing flesh tone, for example, gives an engineer a good idea of relative video quality. This is not possible in the IVS network since the POPs are unmanned. To enable the monitoring of live video of all active circuits, the VFM splits the signal off in the analog/digital switch at the receiving POP and routes it back through the network to the CAC where it is viewed by an operator. Fixed circuits are established from each POP to the CAC for monitoring purposes. The VFM cycles through each connection in the network, routing each one back to the CAC for viewing on a single studio monitor for a period of 15 seconds, allowing CAC personnel to quality assure 4 connections per minute per monitor. 
     In FIG. 22A, using a character generator, the origin and destination port ID, reservation ID and subscriber name are overlaid in small characters into the lower portion of the video and viewed on the studio monitor  2220  to identify the feed. In addition, the VFM output can be recorded for later review. The VFM stops and starts VTR recording of the video feed by commands from either the operator or alarm monitor. 
     The video is also routed to a companion waveform monitor/vectorscope  2030  to perform an analysis of the live video. The vectorscope measures phase over amplitude and amplitude over time to indicate the relative quality of the color and black/white components. The network operators can assess the health of the circuit at a glance using this device. 
     FIG. 22B is a vectorscope display output of a well-known vector generated by the color bar test pattern  760  (See FIG.  7 B). Display outputs are continuously logged. The video seen at the CAC is of a lower quality than what is seen at the customer&#39;s location since it transverses the network twice and therefore undergoes cascaded compression. However the monitored signal does give the operator a relative indication of video and audio quality. If video problems are detected, the operator can instruct the VFM to switch the feed through a vector test set configured at the POP that overlays a vector of the video and the audio levels onto the video feed shown in the monitor screen  2010  (See FIG.  22 A). Alternatively, the operator can instruct the VFM to add a multipoint drop to the switched ATM connection to decode the original signal. This effectively isolates the problem to the either the transmitting POP or the receiving POP. 
     FIG. 23 contains a network diagram of a video feed monitored by the VFM. The feed originates in Los Angeles  2100  and terminates in Washington DC  2105 . At the analog/digital switch  2156  in the Washington DC CAC, the received video signal  2185  is split off in the analog/digital switch  2198  to feed an encoder  2154  assigned to a fixed VFM circuit for monitoring. Inside the CAC POP  2110 , the analog/digital switch  2157  splits the received video signal  2187  into two outbound ports  2185   2183  to route the video/audio to a studio monitor  2190  and a waveform monitor/vectorscope  2191 . The character generates  2192  provides on-screen text to identify the feed being monitored. The video tape recorder (VTR)  2193  permits operators to record the snapshots of each feed. The VTR is controlled via a VTR controller  2194  that is attached to the network test manager  431 . To view the vector waveform of the video as received at the destination POP, a normal return path  2198  is broken and a vector test set  2170  is switched into a circuit  2178 . The vector test set overlays the vector waveform and a graphic of the received audio levels onto the video feed and the test set then injects a signal  2176  back into the analog/digital switch  2156  where it is routed to the CAC. 
     In FIG. 24, each studio monitor and waveform monitor/vectorscope set has its own dedicated processing thread of execution inside the VFM. The thread remains active in a block  2200  of a loop until the monitors are unconfigured at which time the thread is ended in block  2205 . The next video feed to monitor is queried in block  2210  and if fixed monitoring circuits are not being used in block  2215 , an unscheduled connection is established to route the video in block  2220  into the CAC. The default is to use fixed connections unless the network is low on resources. If the connection is made in block  2225 , the switch at the receiving POP is commanded in block  2230  to route the video back into the VFM circuit. The analog/digital switch inside the CAC&#39;s POP  439  (See FIG. 4) splits the video signal in block  2235  into two paths to feed the pair of monitors. If the vector waveform is to be inserted into the feed in block  2245 , the video is switched into the vector test set in block  2238 . The subscriber&#39;s name, reservation ID and ingress/egress ports are displayed at the bottom of the screen (See FIG. 22A) in block  2240  using the character generator. If the alarm monitor  812  is reporting an alarm on any resource used in this circuit and the video tape recorder is not recording in block  2245 , the VTR is put into record mode in block  2250  for the duration of this feed. The waveform monitor then captures the waveform and in block  2255  logs it and the processing thread in block  2260  halts execution for 15 seconds to give the operators time to view the feed. If the network operator commands the VFM to freeze the feed in block  2265 , the thread is halted until an unfreeze command is received in block  2270 . Otherwise, the VFM connection is removed in block  2280  if it was not fixed in block  2270  and the loop iterates to the next video feed. 
     In FIG. 25, the VFM is controlled through the manual test console  435  (see FIG.  4 ). After decoding the command in block  2305 , if the command is to freeze in block  2310  or unfreeze in block  2315 , an appropriate freeze flag is set in blocks  2345  and  2350 . A multipoint request in block  2320  is used to isolate quality problems results in an additional circuit being added by an unscheduled connection in block  2360  to monitor the feed directly. When using fixed connections in block  2325  a unscheduled request for a fixed VFM circuit is created in block  2370  and the fixed flag is set in block  2375 . Reverting to dynamic connections in block  2330 , the fixed VFM connection is broken in block  2380  and the fixed flag is reset in block  2385 . Creating a new processing thread to configure an extra waveform monitor/vectorscope in block  2340  causes a new VFM monitor thread to be spawned in block  2390 . Removing a monitor in block  2345  resets the active flag in block  2395  which will cause the VFM thread to end. If the operator starts or stops VTR recording of the feeds in blocks  2332  and  2334 , respectively, the VTR is commanded to start or stop recording in blocks  2397  and  2399 , respectively via the VTR controller. The command to embed the vector waveform of the received video signal into the feed in block  2346  results in the embed flag being set in block  2398 . 
     FIG. 26 shows the logic flow of the alarm monitor  812  (See FIG. 8) which invokes the VFM, OOS and IS test executives in response to alarms received from the POPs. In block  2500 , the alarm monitor thread waits on alarms which are reported over the IP WAN network as SNMP traps messages. If the alarm message indicates an alarm condition was cleared in block  2505 , the resource alarm indication is cleared in block  2515 , the information is logged in block  2525  and a message is sent to the operator console to inform the network operator in block  2435 . In block  2505 , if the message was a new alarm, the resource is marked as alarmed in block  2510  and the pertinent information is logged in block  2520 . Then each active connection is examined in block  2530  to determine in block  2540  if the alarmed resource is being used in the connection. If so, the video feed is scheduled for VFM monitoring in block  2550  and in-service testing in block  2560 . The operator is notified in block  2570  and the loop iterates. When the loop exits in block  2530 , a test in block  2580  is made to see if any of the active connections were affected by the alarming resource. If not, the test means that the alarm occurred on an idle resource so idle resource testing is scheduled in block  2590 , the operator is alerted in block  2595 , and the processing thread then reenters the wait state in block  2500 . 
     Although the preferred embodiment has been disclosed, it will be understood by those skilled in the art that changes can be made to this specific embodiment without departing from the spirit and scope of the invention. Furthermore, this embodiment is for the purpose of example and illustration only and is not to be taken to limit the scope of the invention or narrow the scope of the appended claims.