CA2254739A1 - Automated master-slave connectivity dry loop isdn line - Google Patents
Automated master-slave connectivity dry loop isdn line Download PDFInfo
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Abstract
A BERT or a voice call ISDN communication dry loop path is automatically established between master and slave ISDN test sets by a connectivity routine that is executed with only minimal preliminary user/craftsperson participation, thereby facilitating use of the test set and minimizing the possibility of errors. Bit error rate testing is conducted by causing a prescribed master - slave message exchange sequence to be automatically executed in response to a user operating a BERT key from a test set menu. A dry loop voice communications path is established over a selected bearer channel in response to the user operating a HOOK key in a conventional POTS sense. A
dedicated bearer channel master-slave signalling sequence is then automatically conducted without further user participation to establish the call, including the generation of ringing signals and turning on respective codecs at each master and slave device.
dedicated bearer channel master-slave signalling sequence is then automatically conducted without further user participation to establish the call, including the generation of ringing signals and turning on respective codecs at each master and slave device.
Description
CA 022~4739 1998-12-01 H6562, DR183 AUTOMATED MASTER-SLAVE CONNECTIVITY FOR DRY
LOOP ISDN LINE
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of co-pending U.S. patent application Serial No. 08/855,117, filed May 13, 1997, entitled: "Test Set Using ISDN Bearer Channel for Testing Telephone Line," by R. Soto et al (hereinafter referred to as the '117 application), assigned to the assignee of the present application, and the disclosure of which is herein incorporated.
The invention disclosed in the present application also relates to subject matter disclosed in the following co-pending U.S. patent applications, each of which is filed coincident herewith, is assigned to the assignee of the present application, and the disclosures of which are herein incorporated: Serial No. _ , entitled "Testing of ISDN Line via Auxiliary Channel Signalling," by M.
Dipperstein et al, (hereinafter referred to as the ' application); Serial No. , entitled "Call Yourself BERT
Testing of ISDN Line," by M. Kennedy et al, (hereinafter referred to as the ' application); Serial No.
entitled "User Selectable Overlap and Enbloc Speed Dialing of ISDN Line," by P. Katz et al, (hereinafter referred to as the ' _ application); and Serial No. _ , entitled "Interactive Contextual-Based Assistance for Portable ISDN
CA 022~4739 1998-12-01 Test Set," by P. Katz et al, (hereinafter referred to as the ' application).
FIELD OF THE lNV~NllON
The present invention relates to telecommunication systems, and is particularly directed to a communication and testing control mechanism, that is incorporated within a craftsperson's test set having an architecture of the type described in the above-referenced '117 application, for facilitating the testing of an ISDN communication circuit.
BACKGROUND OF THE lNV~NlION
As described in the above-referenced '117 application, a variety of telecommunication test units have been proposed for testing digital signalling circuits. Such circuits may include, but are not limited to those transporting high speed data service loop (HDSL) signals, asymmetrical data service loop (ADSL) signals, digital data service (DDS) signals and integrated services digital network (ISDN) signals. Unfortunately, such conventional test units are relatively cumbersome and hardware-intensive devices, that are customarily resident in a telcom service office or other fixed system installation, affording only a single point of access to the circuit.
A non-limiting example of such a conventional test CA 022~4739 1998-12-01 unit is described in the U.S. Patent No. 5,208,846, to Hammond et al, entitled: "Subscriber Loop Tester for Telephone Switching Systems." In order to be connectable with different types of telecommunication circuits, the Hammond et al test unit contains different types of line interfaces/jacks. Determining which jack is to be used requires that the test system operator have a priori knowledge of the communication link to which the test set is to be coupled. Without this knowledge, the user does not know to which jack the line should be connected, and cannot readily configure the test unit to support a particular user interface and associated termination hardware.
As noted above, conventional test units are relatively large and fixed pieces of equipment, so that they are not readily suited for use in the field (i.e., they are not portable), so that they cannot be readily interfaced with any accessible location along a communication link. This relatively poor facility of transport and ready connection to any location of the circuit to be tested also restricts the practicality and effectiveness of such test units.
These shortcomings have become a particular concern to telecommunication service providers, especially with the continuing expansion and demand for integrated services digital network (ISDN) service~. Not only is there currently a need for a practical, portable test set that is capable of testing already installed ISDN circuits, but one CA 022~4739 1998-12-01 which can perform 'dry loop' line testing, prior to its use for ISDN service; namely, there is a need for an ISDN test device that will permit a circuit to be 'prequalified' (as ISDN-capable), before ISDN equipment is purchased and connected to a circuit for ISDN service.
Advantageously, the portable test set described in the above-referenced '117 application contains a communication architecture that is readily interfaced with virtually any location of a line/circuit to be tested, so as to allow testing of the line, irrespective of its configuration (e.g., two-wire vs. four-wire), or the type of signals that may be conveyed over the line (analog or digital). In addition to circuitry for testing the operation of a standard analog (POTS) line, the portable test set described in the '117 application contains a digital communications controller and associated digital signalling interface components, including both 'U' interface and 'S/T' interface circuits.
Thus, the test set can be interfaced with either a two-wire network link or a four-wire customer premises link, and may transmit and receive ISDN bearer channel messages. The contents of bearer channel messages may be defined to evoke prescribed responses from a companion test set coupled to another portion (relatively far end) of the communication circuit of interest, so that the circuit may be tested. When two test sets are interfaced with spaced . _ ,.~ . , CA 022~4739 1998-12-01 apart locations of the circuit/line under test, they may operate in respective master and slave modes, allowing a craftsperson using the master test set to initiate a bit error rate test (BERT) from one end of the circuit, and derive a measure of the operational performance characteristic of the in-between segment of the circuit.
SUMMARY OF THE lNv~ IoN
The present invention is directed to an enhancement of the ISDN communication and testing capability of the test set described in the '117 application, that not is only capable of performing line prequalification and post installation testing, but does so in a manner that simplifies the interaction between the user/craftsperson and the test set, thereby minimizing line testing inaccuracies (which often depend upon the skill and familiarity of the technician with ISDN communications) and improving performance. In accordance with the invention, either of a BERT or a voice call communication dry loop path is automatically established by a connectivity routine that is executed with only minimal preliminary user/craftsperson participation, thereby facilitating use of the test set and minimizing the possibility of errors.
Pursuant to a first aspect of the invention, dry loop bit error rate testing of a two-wire U-interface is conducted by causing a prescribed master - slave message CA 022~4739 1998-12-01 exchange sequence to be automatically executed between a pair of (master and slave) test sets, that are coupled to spaced apart locations (e.g., opposite ends) of the two-wire U-interface (metallic twisted pair). In a non-limiting example of the test arrangement, the master test set is coupled as a line termination (LT) unit to a central office end of the line, and a slave test set is coupled at the customer premises end of the link. There is no connection between the ISDN line and the central office switch, so that the line is not powered from the central office equipment, and all signalling is effected from the test set's two-wire 'U' interface chip, with one of the two ISDN
bearer channels employed as a slave command message channel.
To ensure that the far end test device is in slave-monitor mode, prior to the transmission of a message sequence, the craftsperson operating the master test set operates a MENU key on the test set keypad, causing the master test set's LCD display panel to display a list of test functionality options, one of which is a bit error rate test ( BERT) option. In response to a key command selecting the BERT option, a list of prescribed communication connectivity parameter options (including the data rate to be employed, the length of time the BERT is to be run, and which bearer channel is to be looped back for conducting the BERT). The test set operator then keys in CA 022~4739 1998-12-01 parameter values for the listed menu options.
Once this list of parameter options has been entered, the craftsperson need simply depress a START key on the test unit's keypad. In accordance with the automated test message exchange routine of the invention, in response to operation of the START key, a sequence of message exchanges is automatically conducted between the master and slave test sets, without the need for further craftsperson participation for testing the ISDN capability of the circuit under test. This automated sequence includes the transmission of an ACTIVATE SLAVE MONITOR message over a bearer channel to the slave test unit. This message causes the slave test unit to activate its SLAVE MONITOR function on that bearer channel and to send back a SLAVE MONITOR
ACKNOWLEDGEMENT message.
The master test set then sends a CLEAR ALL LOOPBACKS
message, causing the slave test set to clear all loopbacks on each of the bearer channels, and to return a LOOPBACKS
CLEARED message, to indicate that all loopbacks have been cleared. The master test set then transmits an ACTIVATE
LOOPBACK message, specifying which of the bearer channels is to be looped back (as previously menu-selected by the craftsperson prior to invoking the START button. In response to the ACTIVATE LOOPBACK message, the slave test unit turns off the currently active SLAVE MONITOR function, and returns a LOOPBACK ACKNOWLEDGEMENT message to the ~ ,, , CA 022~4739 1998-12-01 master test unit, informing the master test set that the loopback is ready for a BERT.
In response to receiving this LOOPBACK ACKNOWLEDGEMENT
message, the master test set routine initiates a BERT (by causing the transmission of a pseudo random bit stream over the specified bearer channel, which returned over the looped back bearer channel and compared with the contents of the transmitted pattern). The BERT derives and displays a bit error ratio (BER) and the number of errors and the number of errored seconds. The BERT continues until either the user manually intervenes by selecting a soft STOP key on the test set display, or a time-out loaded expires. To confirm proper operation of the BERT, the craftsperson may access an INJECT ERRORS option, so as to selectively cause the insertion of error bits in the pseudo random bit pattern being transmitted over the loop. If the BERT is operating properly the data displayed will indicate the injected errors.
In accordance with a second aspect of the invention, dry loop voice communications may be conducted over a (two-wire) line, by executing a prescribed master - slave message exchange sequence between a pair of equipments or devices possessing the functionality of the test sets of Figure 1, coupled to opposite ends of the two-wire pair under test. In a non-limiting example of such a test arrangement, a master test set is coupled as a line CA 022~4739 1998-12-01 termination (LT) unit to a central office end of the line, and a slave or called test set is coupled at the customer premises. Alternatively, the master test set may be coupled as a network termination (NT) at the customer premises, and the slave test set may be coupled as a line termination (LT) at the central office.
As in the first embodiment, a bearer channel is used as the slave command message channel; therefore, it is necessary to ensure that the slave device is in slave-monitor mode. For this purpose, the craftsperson operating the master test set activates a HOOK key on the test set keypad. The HOOK key is used in a conventional POTS sense, as when the user wishes to make a call to another device.
However, since the present invention uses a dedicated bearer channel master-slave signalling sequence to establish the call, a prescribed connection routine is automatically executed.
In response to activation of the HOOK key, the end-to-end call routine causes the transmission of an ACTIVATE
SLAVE MONITOR message over a selected bearer channel to the slave test unit. As in the second embodiment, upon receiving this message, the slave test unit activates its SLAVE MONITOR function on the selected bearer channel and sends back a "SLAVE MONITOR ACKNOWLEDGEMENT" message. The master test set then transmits a "PLACE CALL" message to the slave test set, which responds by generating a local CA 022~4739 1998-12-01 ringing signal and returning a "PLACE CALL ACKNOWLEDGEMENT"
message. Upon receipt of the PLACE CALL ACKNOWLEDGEMENT
message, the master test set generates its own ringing signal, so as to simulate a 'far end' ringing signal that the user would expect to hear for the placement of a POTS
call (except that no digits have been dialed).
If the HOOK key is invoked before the called test set answers, the call is terminated. If the called test set answers, it returns a "CALL ANSWERED" message, in response to which the master test set transmits a "CONNECT" message to the slave device. In response to the CONNECT message, the slave test set turns on its codec and returns a "CONNECT ACKNOWLEDGEMENT" message. Upon receipt of the CONNECT ACKNOWLEDGEMENT message, the calling test set turns on its codec, so that voice communications may be conducted over the ISDN circuit.
To terminate the call, the user at the master test set invokes the HOOK key, causing the transmission of a "TERMINATE CALL" message to the slave test unit. In response to the TERMINATE CALL message, the slave test set turns off its codec and returns a message: "TERMINATE
ACKNOWLEDGEMENT." Upon receipt of the TERMINATE
ACKNOWLEDGEMENT message, the master test unit turns off its codec, and the call is terminated. If the slave device terminates the call, it transmits a "TERMINATE CALL"
message to the master test unit and a complementary version ~.
CA 022~4739 1998-12-01 of the termination acknowledgement message exchange sequence is executed.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 diagrammatically illustrates the architecture of the ISDN test set described in the '117 application;
Figures 2 and 3 are respective front and rear isometric pictorial views of a housing configuration for the ISDN test set of Figure l;
Figure 4 diagrammatically illustrates a public switched telephone network at opposite ends of which respective master and slave ISDN test sets may be connected;
Figure 5 diagrammatically illustrates a dry loop ISDN
circuit having opposite ends connected to respective master and slave ISDN test sets;
Figure 6 is an operational flow chart associated with a master - slave bit error rate testing of a (two-wire) ISDN line, using a pair of master - slave test sets connected to the line in the manner shown in Figure 7;
Figure 7 diagrammatically illustrates a testing arrangement in which dry loop bit error rate testing of a (two-wire) line is conducted by coupling a master test set as a line termination (LT) unit to a central office end of the line and using a bearer channel to exchange messages with a slave test set at a customer premises;
.. ~ .. . . .. . .
CA 022~4739 1998-12-01 Figure 8 diagrammatically illustrates a non-limiting example of a master - slave voice call test arrangement, in which a master test set is coupled as a line termination (LT) unit to a central office and a slave test set is coupled at a customer premises; and Figure 9 is a flow chart of a communications control routine for establishing dry loop voice communication connectivity in the test arrangement of Figure 8.
DETAILED DESCRIPTION
Before describing in detail the new and improved master - slave ISDN testing mechanism of the present invention, it should be observed that the invention resides primarily in what is effectively an augmentation of the operational control software executed by the supervisory microcontroller of the test set of the '117 application.
The circuitry of the test set described in the '117 application is essentially unaffected. Consequently, the architecture of the test set per se, and the manner in which it is interfaced with communication equipment of a telephone network have been illustrated in the drawings by readily understAn~Ahle block diagrams, which show only those specific details that are pertinent to the present invention, so as not to obscure the disclosure with details which will be readily apparent to those skilled in the art having the benefit of the description herein. Thus, the CA 022~4739 1998-12-01 block diagram illustrations of the Figures are primarily intended to illustrate the major components of the system in a convenient functional grouping, whereby the present invention may be more readily understood.
The overall communication and signal processing circuit architecture of a test set of the type described in the '117 application, in which the communication and testing control mechanism of the present invention may be readily incorporated, is diagrammatically illustrated in Figure 1. To facilitate portability and ruggedized field use, the test set's circuit architecture is preferably housed within a robust protective casing physically configured as diagrammatically illustrated in the isometric pictorial views of Figures 2 and 3, and disclosed in detail in the following co-pending U.S. Patent applications:
Design Serial No. 29/061,617, entitled: "ISDN Test Set," by R. Soto et al, filed October 28, 1996, which is a continuation-in-part of U.S Design Serial No. 29/053,246, entitled: "ISDN Test Set," by R. Soto et al, filed April 18, 1996; and Utility Applications: Serial No. 08/754,077, filed Nov. 20, 1996, entitled "Telephone Test Set Keypad with Integrated Dynamic Microphone," by E. Zoiss et al;
Serial No. 08/753,101, filed Nov. 20, 1996, entitled "Telephone Test Set LCD Panel Carrier," by E. Zoiss et al;
Serial No. 08/754,075, filed Nov. 20, 1996, entitled "Line Cord Strain Relief Attachment for Telephone Test Set," by CA 022~4739 1998-12-01 E. Zoiss et al; and Serial No. 08/754,076, filed Nov. 20, 1996, entitled "Variable Geometry Battery Compartment for Accommodating Different Sized Batteries in Telephone Craftsperson's Test Set," by E. Zoiss et al. Each of the above applications is assigned to the assignee of the present application, and their disclosures are herein incorporated.
Referring now to Figure 1, the communication and signal processing circuit architecture of the test set described in the '117 application is diagrammatically illustrated as comprising a multi-pin modular jack 10, engagable by a multi-pin conductor plug terminating one end of a multi-conductor line cord, through which the test set is connectable with a circuit under test. The respective pins of the modular jack 10 are connected via multi-conductor links 11, 12 and 13, to the internal circuitry of the test set.
For this purpose, a first four-pin link 11, two leads of which are respectively associated with tip and ring lead conductors of multi-pin jack 10, is coupled to a four-pin common port 21 of a first switch 20. A first, two-pin switch port 22 of switch 20 is coupled to a two-pin common port 31 of a second switch 30. A second, four-pin switch port 23 of first switch 20 is coupled to a four conductor link 42 to a four-pin port 51 of a transformer interface 50 and to a four pin input port 61 of an 8:1 analog CA 022~4739 1998-12-01 multiplexer 60. Two-pin links 12 and 13 are coupled from modular jack 10 to respective two pin in ports 62 and 63 of 8:1 analog multiplexer 60.
The 8:1 analog multiplexer 60 has an output port 64 coupled to a first input 151 of a voltage threshold comparator 150. Voltage threshold comparator has a second input 162 coupled to receive a prescribed reference voltage V~F. The output 153 of comparator is coupled to an input/output (I/O) - control bus 140 associated with the test set's supervisory microcontroller 100. The multiplexer 60 has a multibit steering control input 65 coupled to control bus 140, for selecting which of the respective portions of multiconductor links 42, 13 and 14 is coupled to comparator 150. Should the line voltage of the selected lead exceed the threshold reference voltage V~p, the voltage comparator 150 provides an output on a voltage detect line portion 154 of the I/O control bus 140, which is read by the micro-controller 100. The states of the respective sets of leads 11-13 are mapped by an internal truth table used by the microcontroller 100 to identify the type of line to which the test set is connected.
A first, two pin port 32 of the switch 30 is coupled via link 34 to a POTS line interface module 70. Module 70 module contains conventional dial tone detector and DTMF
signalling circuitry, and is employed for conducting voice communications, DTMF and dial pulse signalling on a POTS
CA 022~4739 1998-12-01 line. A second two pin switch port 33 of switch 30 is coupled via link 35 to a controlled attenuator 80.
Attenuator 80 has a control port 81 coupled to the control bus 140, and is transformer-coupled, by way of transformer circuit 82, to a two wire port 91 of standard (two wire) 'U' interface chip 90, used for standard 2BlQ signalling.
The 'U' interface chip 90, which is coupled to and controlled by microcontroller 100, is selectively controlled via a control port 92 to function as either a line termination (LTJ or a network termination (NT). As will be described, when either bit error rate testing (BERT) of the line, or dry-loop communications are to be carried out over the line under test, the 'U' interface chip 90 is selectively placed in LT mode. A port 93 provides an interrupt link to the microcontroller 100.
Digital data communications between the two-wire 'U' interface chip 90 and the microcontroller 100 are effected by way of a first (IDL) digital serial bus digital 95 and a second (SCP) digital serial bus 96.
The four-wire transformer interface 50, to the four pin port 51 of which the four lead conductor link 42 is coupled from port 23 of switch 20, has respective pairs of two wire links 52 and 53 transformer-coupled, via transformer pairs 55 and 56, to respective two wire ports 131 and 132 of a (four wire) 'S/T' interface chip 130.
Respective controlled attenuators 57 and 58 are coupled . . . ~ ..... .
CA 022~4739 1998-12-01 across links 52 and 53, and are controlled by way of control bus 140. Like the 'U' interface chip 90, the 'S/T' interface chip 130 is coupled to microcontroller 100 by way of the first digital link IDL 95 and the second digital link SCP 96. In addition, it has an interrupt port 133 for providing an interrupt signal to the microcontroller 100.
The first (IDL) digital serial bus 95 is further coupled through a (5V-3V) logic level translation circuit 138 to a CODEC 160. CODEC 160 is coupled via a DTMF link 71 to POTS line interface module 70. The CODEC 160 has a first output port 161 coupled through a controlled gain amplifier 170 to a common/input terminal 181 of a switch 180. Switch 180 has a first output terminal 182 coupled to a speaker amplifier 190, the output of which is coupled to an audio speaker 200. Switch 180 has a second output terminal 183 coupled to link 184 which is coupled to of POTS line interface module 70. Link 184 is further coupled to an earpiece receiver transducer 210 of the test set. A
microphone (MIC) 220 is coupled to an amplifier 230, the output of which is coupled via link 231 to port 165 of CODEC 160 and to an audio input port 75 of POTS line interface module 70.
An auxiliary digital (RS 232) I/O port is provided by way of a multipin connector 240, such as an RJ-45 jack.
This connector is coupled to an RS-232 transceiver 250, which may be used to monitor externally provided bearer (B) CA 022~4739 1998-12-01 channel information or to download communication control software into the microcontroller 100. The RS-232 transceiver 250 is, in turn, ported to I/O-control bus 140.
User/craftsperson inputs for controlling operation of the test set are effected by means of a stAn~rd multi-key keypad 300, to which I/O-control bus 140 is coupled. Key depression of the keys of the keypad 300 generate input commands that are buffered in a latch 310, the contents of which are asserted onto a distributed multibit data/address bus 320. Data/address bus 320 is ported to a data/address port 105 of the microcontroller 100. Microcontroller 100 has a limited storage capacity flash memory 330, an EPROM
340 in which the operational software for the microcontroller is stored, and a random access memory 350 for storing data processed by the microcontroller's central proces~ing unit (CPU).
The data/address bus 320 is also ported to an LCD unit 360, which provides an alpha-numeric visual display of a menu of options/actions that may be selectively invoked by keypad inputs from the user, and an indication of the operation of the test set, as microcontroller 100 sequences through stored test routines, to be described. In addition to the LCD unit 360, the test set may employ one or more discrete visual indicators, such as a set of LEDs that are coupled to I/O bus 140, and selectively individually energized by the microcontroller 100 to provide an CA 022~4739 1998-12-01 indication of prescribed status or operational conditions of the line under test such as, but not limited to, ON /OFF
hook, tip/ring polarity and test set battery charging status.
As described in the above-referenced '117 application, the test set architecture of Figure 1 is able to conduct a number of analog and digital test operations of a line to it is connected. These test operations include an initial, "LINE IDENTIFICATION MODE" (in which the type of line to which the test set is connected is automatically determined), and "POTS MODE," (for testing a POTS line, in which the tip and ring line portions of the four-wire link 12 are coupled through switches 20 and 30 to the POTS line interface module 70).
Because the test set architecture of Figure 1 includes both two-wire 'U' interface chip 90 and four-wire 'S/T' interface chip 130, the test set may be used to trouble-shoot a potentially faulty digital (e.g., ISDN) circuit that is either upstream (toward the central office), or downstream (toward a remote terminal - customer premises equipment) of the location at which the craftsperson has connected the test set. Where two test sets of the type shown in Figure 1 are available, the potentially faulty circuit of interest may be tested by placing the test sets in a master-slave mode of operation. The 'master' test set may be connected to a first, test supervisory location of _.~ ....
CA 022~4739 1998-12-01 the line, from which the test is to be conducted (such as at a central office line termination location). The 'slave' test set may be connected to a second site of the line, geographically remote from the first site (such as at a network termination of a customer premises). Once a loopback path has been established between the two test sets, a BER test may be initiated from the master test set.
In addition to loopback (for bit error rate testing), an echo-back mode of operation may also be used. This mode is somewhat similar to the loopback mode in that it's purpose is to have the slave test set send back to the master test set the contents of a prescribed data sequence.
In echo-back mode, however, rather than the slave test set simply operating as a passive loopback device, the slave test set captures and then retransmits data placed on the D channel by the master test set.
Also, a voice link may be established either over a public switched network, as diagrammatically illustrated in Figure 4, or between two test sets that are connected to opposite ends of a non-powered or 'dry loop' link, as diagrammatically illustrated in Figure 5, with one of the test sets operating in LT mode as a line termination device, and the other operating in NT mode as a network termination device. Also described in the '117 application is a callback mode of operation, which allows an unmanned slave test set to return a voice call (i.e., without the . . .
CA 022~4739 1998-12-01 participation of an attendant craftsperson), and thereby determine whether a voice call can be established over the circuit under test.
As described above, the present invention is directed to an enhancement to the control software executed by the test set's supervisory processor 100, for controlling the communication and testing functionality of the test set, including the operations described in the '117 application, reviewed briefly above. As will be described below with reference to Figures 6-9, the present invention provides a prescribed master - slave testing message exchange sequence that facilitates use of the test set and minimizes errors in testing the ISDN capability of a circuit.
MASTER-SLAVE BERT (Figures 6-7) In accordance with a first aspect of the invention, dry loop bit error rate testing of a (two-wire) line is conducted by executing a prescribed master - slave message exchange sequence, shown in the flow chart of Figure 6, between a pair of (master and slave) test sets, that are coupled to opposite ends of a two-wire U-interface (metallic twisted pair). A non-limiting example of such a test arrangement is diagrammatically illustrated in Figure 7, which shows a first test set 410 coupled as a line termination (LT) unit to a central office 402 end of the two-wire interface 400, and a second test set 412 is CA 022~4739 1998-12-01 coupled as a network termination (NT) device at the customer premises 404, which may include one or more pieces of terminal equipment 432 coupled to network termination (NT-1) 406 via a four-wire S/T interface 430. There is no connection between the ISDN line 400 and the central office switch, as shown by break 405, and there is no connecton between the ISDN line 400 and a network termination NT-l 406 at the customer premises 404, as shown by line break 407. Thus, the line (e.g., metallic twisted pair) 400 is not powered from the central office equipment, and all signalling is effected from the test set's two-wire 'U' interface chip, ported to the line 400.
In the present mode of operation, a bearer channel (e.g., channel B1) is used as a slave command message channel. Consequently, it is necessary to ensure that the far end test device 412 is in slave-monitor mode, namely configured to conduct master - slave messages exchanges on the prescribed bearer channel. For this purpose, prior to the transmission of a message sequence, the user operating the master test set (here test set 410 - connected as an LT
device at the central office 402) operates a MENU key 312 on the test set keypad 300 (Figure 2). Operation of the MENU key 312 causes the master test set's LCD display panel 360 to display a list of options available to the craftsperson, as shown at step 601 in the flow chart of Figure 6.
CA 022~4739 1998-12-01 This menu includes a bit error rate test (BERT) option, which is selected by the user depressing a numeric key (e.g., '1') on the keypad 300 associated with the numerical listing ('1') in the displayed menu option~
BERT'. In response to a key command selecting the BERT
option, in step 602, the routine of Figure 6 causes the display unit 360 to display a list of prescribed parameter options (that may include the data rate to be employed (e.g., 56 Kbaud or 64 Kbaud), the length of time the test is to be run, and which bearer channel (Bl, B2 or both Bl and B2) is to be looped back for conducting the BERT).
Using the alpha-numeric keys of the test set keyboard 300, the test set operator selects and enters parameter values for the listed menu options.
Once the values for the displayed list of parameter options have been entered, the craftsperson simply depresses a START key on the test unit's keypad 300. In accordance with the test message exchange routine of the invention, in response to operation of the START key, the routine automatically conducts a sequence of message exchanges with the slave device without the need for further user participation to test the ISDN capability of the circuit under test. In particular, in step 603, the routine causes the U-chip 90 to transmit a first message:
ACTIVATE SLAVE MONITOR over the Bl channel to the far end test unit. This causes the far end test unit to activate ~, CA 022~4739 1998-12-01 its SLAVE MONITOR function on the B1 channel (if not already activated), and send back a SLAVE MONITOR
ACKNOWLEDGEMENT message on the B1 channel, which is received in step 604.
Next, in step 605, the 'LT-terminated' master test set sends a second message: CLEAR ALL LOOPBACKS, over the B1 channel, causing the far end (NT-1 terminated) test set to clear all loopbacks (on each of the B1, B2 channels), and to transmit a return message (LOOPBACKS CLEARED) on the B1 channel, which indicates that all loopbacks have been cleared. The return message is received in step 606. In step 607, the master (LT) test set transmits an ACTIVATE
LOOPBACK message to the slave (NT-1) test unit. The ACTIVATE LOOPBACK message specifies which of the bearer channels is to be looped back (as previously menu-selected by the user in step 602).
In response to the ACTIVATE LOOPBACK message, the far end or slave test unit turns off the SLAVE MONITOR function (since the loopback request message transmitted in step 607 may have requested a loopback over the B1 channel) and then returns a LOOPBACK ACKNOWLEDGEMENT message to the master test unit, informing the master test set that the loopback is complete.
In response to receiving this LOOPBACK ACKNOWLEDGEMENT
message, in step 608, the master test set routine initiates a BERT, by causing the transmission of a pseudo random bit ~ .
CA 022~4739 1998-12-01 stream over the specified bearer channel in step 609. In step 610, whatever data is returned over the looped back bearer channel i9 compared with the contents of the transmitted pattern to derive a bit error ratio (BER) and the number of errors and the number of errored seconds, which are displayed via display 360 to the user.
The BERT continues until either the user manually intervenes by selecting a soft STOP key on the test set display, or the time-out loaded in step 602 expires, as shown at termination step 611. To confirm proper operation of the BERT, the craftsperson may access an INJECT ERRORS
option of the displayed menu, selectively causing insertion of error bits in the pseudo random bit pattern being transmitted over the loop. If the BERT is operating properly the data displayed in step 610 will indicate injected errors.
MASTER-SLAVE, END-TO-END VOICE CALL (Figures 8-9) In accordance with a second aspect of the invention, the communications control routine for which is shown in Figure 9, to be described, a dry loop voice communication path is automatically established over a (two-wire) line by executing a prescribed master - slave message exchange sequence between a pair of equipments or devices possessing the functionality of, but not necessarily being the test sets of Figure 1, that are coupled to opposite ends of the .~ .. , CA 022~4739 1998-12-01 two-wire pair under test.
Figure 8 diagrammatically illustrates a non-limiting example of such a test arrangement, employing a pair of test sets 410 and 412, wherein a master or calling test set 410 is coupled as a line termination (LT) unit to a central office 402 end of the line, and a slave or called test set 412 is coupled at the customer premises 404. It should be noted, however, a reverse call exchange sequence may also be conducted, wherein the sourcing device (e.g., test set) 412 is coupled as a network termination (NT) at the customer premises 404, and operates as the master or calling unit, while the responding device (e.g., test set) 410 is coupled as a line termination (LT) at the central office 402 end of the line, and operates as the slave or called unit.
As in the first embodiment, there is no connection between the line and 400 the central office switch, so that the line is not powered from the central office equipment, and all signalling is effected from a test set's two-wire 'U' interface chip ported to the line 400. Also, the Bl bearer channel may be used as the slave command message channel; as a result, it is necessary to ensure that the far end test device is in slave-monitor mode (namely, is configured to conduct master - slave message exchanges on the Bl channel). For this purpose, the user operating the master test set (here test set 410 connected as an LT
--_ .
CA 022~4739 1998-12-01 device at the central office 402) activates a HOOK key 316 on the test unit's keypad 300 (Figure 2). In the second embodiment of the invention, the test set's HOOK key 316 is used in a conventional POTS sense, as when the user wishes to make a call to another device. However, since the present invention uses a dedicated (e.g., Bl) bearer channel master-slave signalling sequence to establish the call, some preliminary housekeeping is required.
In particular, as shown at step 901 in the flow chart of Figure 9, in response to activation of the HOOK key, the end-to-end call routine causes the transmission of an "ACTIVATE SLAVE MO~ OR" message, over the Bl channel from the (master) test set 410 to the far end (slave) test unit 412. As in the first embodiment, upon receiving this message, the slave test unit activates its SLAVE MONITOR
function on the Bl channel (if not already activated), and sends back a "SLAVE MONITOR ACKNOWLEDGEMENT" message on the Bl channel, which is received at the master test unit in step 902.
Next, in step 903, the LT test set 410 sends a second message: "PLACE CALL" to the distant test set 412. The slave/called test set 412 responds by generating a local ringing signal (that is audible at the far end test unit's receiver), and returning a "PLACE CALL ACKNOWLEDGEMENT"
message, which is received by the master test set 410 in step 904. In response to receipt of the PLACE CALL
. ._, .. . .
CA 022~4739 1998-12-01 ACKNOWLEDGEMENT message from the far end test unit, test set 410 generates its own ringing signal in step 905, so as to simulate to the craftsperson a 'far end' ringing signal that he would expect to hear for the placement of a POTS
call (except that no digits have been dialed).
If the craftsperson at the near end test set 410 reoperates the HOOK key before the called test set 412 answers (or continues to fail to answer), the call is terminated, as shown at steps 906 -907 - 908. If the called test set 412 answers (the answer to query step 906 is YES), it returns a "CALL ANSWERED" message, which is received in step 909. Upon receiving the CALL ANSWERED message, then in step 910, the calling test set 410 transmits a "CONNECT"
message to the far end device. In response to the CONNECT
message, the far end test set 412 turns on its codec and returns a "CONNECT ACKNOWLEDGEMENT" message. Upon response to receipt of the CONNECT ACKNOWLEDGEMENT message in step 911, the calling test unit 410 turns on its codec in step 912, so that a voice conversation may be conducted between the two test sets.
Either test set may terminate the call. For the non-limiting case where the technician at the originating device 410 terminates the call by operating the HOOK key, in step 913, the routine transmits a "TERMINATE CALL"
message to the far end test unit in step 914. In response to the TERMINATE CALL message, the far end test set 412 . ~ . , .
CA 022~4739 1998-12-01 -turns off its codec and returns a message: "TERMINATE
ACKNOWLEDGEMENT." Upon receipt of the TERMINATE
ACKNOWLEDGEMENT me8sage in step 915, the calling test unit 410 then turns off its codec, and the call is terminated.
If the far end test set 412 terminates the call, it transmits a "TERMINATE CALL" message to the near end test unit, and a complementary version of the termination acknowledgement message exchange sequence described above is executed between the two units, to terminate each test set's call.
As will be appreciated from the foregoing description, the present invention provides automated BERT and voice call enhancements to the ISDN test set architecture described in the '117 application, that can be executed with only minimal preliminary user/craftsperson participation, thereby facilitating use of the test set and ri ni~i zing the possibility of errors.
While we have shown and described several automated master - slave ISDN test set connectivity embodiments in accordance with the present invention, it is to be understood that the same is not limited thereto but is susceptible to numerous changes and modifications as known to a person skilled in the art, and we therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are obvious to one of ordinary skill in the art.
~ _ . .. , , . ~ . .. . . .
LOOP ISDN LINE
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of co-pending U.S. patent application Serial No. 08/855,117, filed May 13, 1997, entitled: "Test Set Using ISDN Bearer Channel for Testing Telephone Line," by R. Soto et al (hereinafter referred to as the '117 application), assigned to the assignee of the present application, and the disclosure of which is herein incorporated.
The invention disclosed in the present application also relates to subject matter disclosed in the following co-pending U.S. patent applications, each of which is filed coincident herewith, is assigned to the assignee of the present application, and the disclosures of which are herein incorporated: Serial No. _ , entitled "Testing of ISDN Line via Auxiliary Channel Signalling," by M.
Dipperstein et al, (hereinafter referred to as the ' application); Serial No. , entitled "Call Yourself BERT
Testing of ISDN Line," by M. Kennedy et al, (hereinafter referred to as the ' application); Serial No.
entitled "User Selectable Overlap and Enbloc Speed Dialing of ISDN Line," by P. Katz et al, (hereinafter referred to as the ' _ application); and Serial No. _ , entitled "Interactive Contextual-Based Assistance for Portable ISDN
CA 022~4739 1998-12-01 Test Set," by P. Katz et al, (hereinafter referred to as the ' application).
FIELD OF THE lNV~NllON
The present invention relates to telecommunication systems, and is particularly directed to a communication and testing control mechanism, that is incorporated within a craftsperson's test set having an architecture of the type described in the above-referenced '117 application, for facilitating the testing of an ISDN communication circuit.
BACKGROUND OF THE lNV~NlION
As described in the above-referenced '117 application, a variety of telecommunication test units have been proposed for testing digital signalling circuits. Such circuits may include, but are not limited to those transporting high speed data service loop (HDSL) signals, asymmetrical data service loop (ADSL) signals, digital data service (DDS) signals and integrated services digital network (ISDN) signals. Unfortunately, such conventional test units are relatively cumbersome and hardware-intensive devices, that are customarily resident in a telcom service office or other fixed system installation, affording only a single point of access to the circuit.
A non-limiting example of such a conventional test CA 022~4739 1998-12-01 unit is described in the U.S. Patent No. 5,208,846, to Hammond et al, entitled: "Subscriber Loop Tester for Telephone Switching Systems." In order to be connectable with different types of telecommunication circuits, the Hammond et al test unit contains different types of line interfaces/jacks. Determining which jack is to be used requires that the test system operator have a priori knowledge of the communication link to which the test set is to be coupled. Without this knowledge, the user does not know to which jack the line should be connected, and cannot readily configure the test unit to support a particular user interface and associated termination hardware.
As noted above, conventional test units are relatively large and fixed pieces of equipment, so that they are not readily suited for use in the field (i.e., they are not portable), so that they cannot be readily interfaced with any accessible location along a communication link. This relatively poor facility of transport and ready connection to any location of the circuit to be tested also restricts the practicality and effectiveness of such test units.
These shortcomings have become a particular concern to telecommunication service providers, especially with the continuing expansion and demand for integrated services digital network (ISDN) service~. Not only is there currently a need for a practical, portable test set that is capable of testing already installed ISDN circuits, but one CA 022~4739 1998-12-01 which can perform 'dry loop' line testing, prior to its use for ISDN service; namely, there is a need for an ISDN test device that will permit a circuit to be 'prequalified' (as ISDN-capable), before ISDN equipment is purchased and connected to a circuit for ISDN service.
Advantageously, the portable test set described in the above-referenced '117 application contains a communication architecture that is readily interfaced with virtually any location of a line/circuit to be tested, so as to allow testing of the line, irrespective of its configuration (e.g., two-wire vs. four-wire), or the type of signals that may be conveyed over the line (analog or digital). In addition to circuitry for testing the operation of a standard analog (POTS) line, the portable test set described in the '117 application contains a digital communications controller and associated digital signalling interface components, including both 'U' interface and 'S/T' interface circuits.
Thus, the test set can be interfaced with either a two-wire network link or a four-wire customer premises link, and may transmit and receive ISDN bearer channel messages. The contents of bearer channel messages may be defined to evoke prescribed responses from a companion test set coupled to another portion (relatively far end) of the communication circuit of interest, so that the circuit may be tested. When two test sets are interfaced with spaced . _ ,.~ . , CA 022~4739 1998-12-01 apart locations of the circuit/line under test, they may operate in respective master and slave modes, allowing a craftsperson using the master test set to initiate a bit error rate test (BERT) from one end of the circuit, and derive a measure of the operational performance characteristic of the in-between segment of the circuit.
SUMMARY OF THE lNv~ IoN
The present invention is directed to an enhancement of the ISDN communication and testing capability of the test set described in the '117 application, that not is only capable of performing line prequalification and post installation testing, but does so in a manner that simplifies the interaction between the user/craftsperson and the test set, thereby minimizing line testing inaccuracies (which often depend upon the skill and familiarity of the technician with ISDN communications) and improving performance. In accordance with the invention, either of a BERT or a voice call communication dry loop path is automatically established by a connectivity routine that is executed with only minimal preliminary user/craftsperson participation, thereby facilitating use of the test set and minimizing the possibility of errors.
Pursuant to a first aspect of the invention, dry loop bit error rate testing of a two-wire U-interface is conducted by causing a prescribed master - slave message CA 022~4739 1998-12-01 exchange sequence to be automatically executed between a pair of (master and slave) test sets, that are coupled to spaced apart locations (e.g., opposite ends) of the two-wire U-interface (metallic twisted pair). In a non-limiting example of the test arrangement, the master test set is coupled as a line termination (LT) unit to a central office end of the line, and a slave test set is coupled at the customer premises end of the link. There is no connection between the ISDN line and the central office switch, so that the line is not powered from the central office equipment, and all signalling is effected from the test set's two-wire 'U' interface chip, with one of the two ISDN
bearer channels employed as a slave command message channel.
To ensure that the far end test device is in slave-monitor mode, prior to the transmission of a message sequence, the craftsperson operating the master test set operates a MENU key on the test set keypad, causing the master test set's LCD display panel to display a list of test functionality options, one of which is a bit error rate test ( BERT) option. In response to a key command selecting the BERT option, a list of prescribed communication connectivity parameter options (including the data rate to be employed, the length of time the BERT is to be run, and which bearer channel is to be looped back for conducting the BERT). The test set operator then keys in CA 022~4739 1998-12-01 parameter values for the listed menu options.
Once this list of parameter options has been entered, the craftsperson need simply depress a START key on the test unit's keypad. In accordance with the automated test message exchange routine of the invention, in response to operation of the START key, a sequence of message exchanges is automatically conducted between the master and slave test sets, without the need for further craftsperson participation for testing the ISDN capability of the circuit under test. This automated sequence includes the transmission of an ACTIVATE SLAVE MONITOR message over a bearer channel to the slave test unit. This message causes the slave test unit to activate its SLAVE MONITOR function on that bearer channel and to send back a SLAVE MONITOR
ACKNOWLEDGEMENT message.
The master test set then sends a CLEAR ALL LOOPBACKS
message, causing the slave test set to clear all loopbacks on each of the bearer channels, and to return a LOOPBACKS
CLEARED message, to indicate that all loopbacks have been cleared. The master test set then transmits an ACTIVATE
LOOPBACK message, specifying which of the bearer channels is to be looped back (as previously menu-selected by the craftsperson prior to invoking the START button. In response to the ACTIVATE LOOPBACK message, the slave test unit turns off the currently active SLAVE MONITOR function, and returns a LOOPBACK ACKNOWLEDGEMENT message to the ~ ,, , CA 022~4739 1998-12-01 master test unit, informing the master test set that the loopback is ready for a BERT.
In response to receiving this LOOPBACK ACKNOWLEDGEMENT
message, the master test set routine initiates a BERT (by causing the transmission of a pseudo random bit stream over the specified bearer channel, which returned over the looped back bearer channel and compared with the contents of the transmitted pattern). The BERT derives and displays a bit error ratio (BER) and the number of errors and the number of errored seconds. The BERT continues until either the user manually intervenes by selecting a soft STOP key on the test set display, or a time-out loaded expires. To confirm proper operation of the BERT, the craftsperson may access an INJECT ERRORS option, so as to selectively cause the insertion of error bits in the pseudo random bit pattern being transmitted over the loop. If the BERT is operating properly the data displayed will indicate the injected errors.
In accordance with a second aspect of the invention, dry loop voice communications may be conducted over a (two-wire) line, by executing a prescribed master - slave message exchange sequence between a pair of equipments or devices possessing the functionality of the test sets of Figure 1, coupled to opposite ends of the two-wire pair under test. In a non-limiting example of such a test arrangement, a master test set is coupled as a line CA 022~4739 1998-12-01 termination (LT) unit to a central office end of the line, and a slave or called test set is coupled at the customer premises. Alternatively, the master test set may be coupled as a network termination (NT) at the customer premises, and the slave test set may be coupled as a line termination (LT) at the central office.
As in the first embodiment, a bearer channel is used as the slave command message channel; therefore, it is necessary to ensure that the slave device is in slave-monitor mode. For this purpose, the craftsperson operating the master test set activates a HOOK key on the test set keypad. The HOOK key is used in a conventional POTS sense, as when the user wishes to make a call to another device.
However, since the present invention uses a dedicated bearer channel master-slave signalling sequence to establish the call, a prescribed connection routine is automatically executed.
In response to activation of the HOOK key, the end-to-end call routine causes the transmission of an ACTIVATE
SLAVE MONITOR message over a selected bearer channel to the slave test unit. As in the second embodiment, upon receiving this message, the slave test unit activates its SLAVE MONITOR function on the selected bearer channel and sends back a "SLAVE MONITOR ACKNOWLEDGEMENT" message. The master test set then transmits a "PLACE CALL" message to the slave test set, which responds by generating a local CA 022~4739 1998-12-01 ringing signal and returning a "PLACE CALL ACKNOWLEDGEMENT"
message. Upon receipt of the PLACE CALL ACKNOWLEDGEMENT
message, the master test set generates its own ringing signal, so as to simulate a 'far end' ringing signal that the user would expect to hear for the placement of a POTS
call (except that no digits have been dialed).
If the HOOK key is invoked before the called test set answers, the call is terminated. If the called test set answers, it returns a "CALL ANSWERED" message, in response to which the master test set transmits a "CONNECT" message to the slave device. In response to the CONNECT message, the slave test set turns on its codec and returns a "CONNECT ACKNOWLEDGEMENT" message. Upon receipt of the CONNECT ACKNOWLEDGEMENT message, the calling test set turns on its codec, so that voice communications may be conducted over the ISDN circuit.
To terminate the call, the user at the master test set invokes the HOOK key, causing the transmission of a "TERMINATE CALL" message to the slave test unit. In response to the TERMINATE CALL message, the slave test set turns off its codec and returns a message: "TERMINATE
ACKNOWLEDGEMENT." Upon receipt of the TERMINATE
ACKNOWLEDGEMENT message, the master test unit turns off its codec, and the call is terminated. If the slave device terminates the call, it transmits a "TERMINATE CALL"
message to the master test unit and a complementary version ~.
CA 022~4739 1998-12-01 of the termination acknowledgement message exchange sequence is executed.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 diagrammatically illustrates the architecture of the ISDN test set described in the '117 application;
Figures 2 and 3 are respective front and rear isometric pictorial views of a housing configuration for the ISDN test set of Figure l;
Figure 4 diagrammatically illustrates a public switched telephone network at opposite ends of which respective master and slave ISDN test sets may be connected;
Figure 5 diagrammatically illustrates a dry loop ISDN
circuit having opposite ends connected to respective master and slave ISDN test sets;
Figure 6 is an operational flow chart associated with a master - slave bit error rate testing of a (two-wire) ISDN line, using a pair of master - slave test sets connected to the line in the manner shown in Figure 7;
Figure 7 diagrammatically illustrates a testing arrangement in which dry loop bit error rate testing of a (two-wire) line is conducted by coupling a master test set as a line termination (LT) unit to a central office end of the line and using a bearer channel to exchange messages with a slave test set at a customer premises;
.. ~ .. . . .. . .
CA 022~4739 1998-12-01 Figure 8 diagrammatically illustrates a non-limiting example of a master - slave voice call test arrangement, in which a master test set is coupled as a line termination (LT) unit to a central office and a slave test set is coupled at a customer premises; and Figure 9 is a flow chart of a communications control routine for establishing dry loop voice communication connectivity in the test arrangement of Figure 8.
DETAILED DESCRIPTION
Before describing in detail the new and improved master - slave ISDN testing mechanism of the present invention, it should be observed that the invention resides primarily in what is effectively an augmentation of the operational control software executed by the supervisory microcontroller of the test set of the '117 application.
The circuitry of the test set described in the '117 application is essentially unaffected. Consequently, the architecture of the test set per se, and the manner in which it is interfaced with communication equipment of a telephone network have been illustrated in the drawings by readily understAn~Ahle block diagrams, which show only those specific details that are pertinent to the present invention, so as not to obscure the disclosure with details which will be readily apparent to those skilled in the art having the benefit of the description herein. Thus, the CA 022~4739 1998-12-01 block diagram illustrations of the Figures are primarily intended to illustrate the major components of the system in a convenient functional grouping, whereby the present invention may be more readily understood.
The overall communication and signal processing circuit architecture of a test set of the type described in the '117 application, in which the communication and testing control mechanism of the present invention may be readily incorporated, is diagrammatically illustrated in Figure 1. To facilitate portability and ruggedized field use, the test set's circuit architecture is preferably housed within a robust protective casing physically configured as diagrammatically illustrated in the isometric pictorial views of Figures 2 and 3, and disclosed in detail in the following co-pending U.S. Patent applications:
Design Serial No. 29/061,617, entitled: "ISDN Test Set," by R. Soto et al, filed October 28, 1996, which is a continuation-in-part of U.S Design Serial No. 29/053,246, entitled: "ISDN Test Set," by R. Soto et al, filed April 18, 1996; and Utility Applications: Serial No. 08/754,077, filed Nov. 20, 1996, entitled "Telephone Test Set Keypad with Integrated Dynamic Microphone," by E. Zoiss et al;
Serial No. 08/753,101, filed Nov. 20, 1996, entitled "Telephone Test Set LCD Panel Carrier," by E. Zoiss et al;
Serial No. 08/754,075, filed Nov. 20, 1996, entitled "Line Cord Strain Relief Attachment for Telephone Test Set," by CA 022~4739 1998-12-01 E. Zoiss et al; and Serial No. 08/754,076, filed Nov. 20, 1996, entitled "Variable Geometry Battery Compartment for Accommodating Different Sized Batteries in Telephone Craftsperson's Test Set," by E. Zoiss et al. Each of the above applications is assigned to the assignee of the present application, and their disclosures are herein incorporated.
Referring now to Figure 1, the communication and signal processing circuit architecture of the test set described in the '117 application is diagrammatically illustrated as comprising a multi-pin modular jack 10, engagable by a multi-pin conductor plug terminating one end of a multi-conductor line cord, through which the test set is connectable with a circuit under test. The respective pins of the modular jack 10 are connected via multi-conductor links 11, 12 and 13, to the internal circuitry of the test set.
For this purpose, a first four-pin link 11, two leads of which are respectively associated with tip and ring lead conductors of multi-pin jack 10, is coupled to a four-pin common port 21 of a first switch 20. A first, two-pin switch port 22 of switch 20 is coupled to a two-pin common port 31 of a second switch 30. A second, four-pin switch port 23 of first switch 20 is coupled to a four conductor link 42 to a four-pin port 51 of a transformer interface 50 and to a four pin input port 61 of an 8:1 analog CA 022~4739 1998-12-01 multiplexer 60. Two-pin links 12 and 13 are coupled from modular jack 10 to respective two pin in ports 62 and 63 of 8:1 analog multiplexer 60.
The 8:1 analog multiplexer 60 has an output port 64 coupled to a first input 151 of a voltage threshold comparator 150. Voltage threshold comparator has a second input 162 coupled to receive a prescribed reference voltage V~F. The output 153 of comparator is coupled to an input/output (I/O) - control bus 140 associated with the test set's supervisory microcontroller 100. The multiplexer 60 has a multibit steering control input 65 coupled to control bus 140, for selecting which of the respective portions of multiconductor links 42, 13 and 14 is coupled to comparator 150. Should the line voltage of the selected lead exceed the threshold reference voltage V~p, the voltage comparator 150 provides an output on a voltage detect line portion 154 of the I/O control bus 140, which is read by the micro-controller 100. The states of the respective sets of leads 11-13 are mapped by an internal truth table used by the microcontroller 100 to identify the type of line to which the test set is connected.
A first, two pin port 32 of the switch 30 is coupled via link 34 to a POTS line interface module 70. Module 70 module contains conventional dial tone detector and DTMF
signalling circuitry, and is employed for conducting voice communications, DTMF and dial pulse signalling on a POTS
CA 022~4739 1998-12-01 line. A second two pin switch port 33 of switch 30 is coupled via link 35 to a controlled attenuator 80.
Attenuator 80 has a control port 81 coupled to the control bus 140, and is transformer-coupled, by way of transformer circuit 82, to a two wire port 91 of standard (two wire) 'U' interface chip 90, used for standard 2BlQ signalling.
The 'U' interface chip 90, which is coupled to and controlled by microcontroller 100, is selectively controlled via a control port 92 to function as either a line termination (LTJ or a network termination (NT). As will be described, when either bit error rate testing (BERT) of the line, or dry-loop communications are to be carried out over the line under test, the 'U' interface chip 90 is selectively placed in LT mode. A port 93 provides an interrupt link to the microcontroller 100.
Digital data communications between the two-wire 'U' interface chip 90 and the microcontroller 100 are effected by way of a first (IDL) digital serial bus digital 95 and a second (SCP) digital serial bus 96.
The four-wire transformer interface 50, to the four pin port 51 of which the four lead conductor link 42 is coupled from port 23 of switch 20, has respective pairs of two wire links 52 and 53 transformer-coupled, via transformer pairs 55 and 56, to respective two wire ports 131 and 132 of a (four wire) 'S/T' interface chip 130.
Respective controlled attenuators 57 and 58 are coupled . . . ~ ..... .
CA 022~4739 1998-12-01 across links 52 and 53, and are controlled by way of control bus 140. Like the 'U' interface chip 90, the 'S/T' interface chip 130 is coupled to microcontroller 100 by way of the first digital link IDL 95 and the second digital link SCP 96. In addition, it has an interrupt port 133 for providing an interrupt signal to the microcontroller 100.
The first (IDL) digital serial bus 95 is further coupled through a (5V-3V) logic level translation circuit 138 to a CODEC 160. CODEC 160 is coupled via a DTMF link 71 to POTS line interface module 70. The CODEC 160 has a first output port 161 coupled through a controlled gain amplifier 170 to a common/input terminal 181 of a switch 180. Switch 180 has a first output terminal 182 coupled to a speaker amplifier 190, the output of which is coupled to an audio speaker 200. Switch 180 has a second output terminal 183 coupled to link 184 which is coupled to of POTS line interface module 70. Link 184 is further coupled to an earpiece receiver transducer 210 of the test set. A
microphone (MIC) 220 is coupled to an amplifier 230, the output of which is coupled via link 231 to port 165 of CODEC 160 and to an audio input port 75 of POTS line interface module 70.
An auxiliary digital (RS 232) I/O port is provided by way of a multipin connector 240, such as an RJ-45 jack.
This connector is coupled to an RS-232 transceiver 250, which may be used to monitor externally provided bearer (B) CA 022~4739 1998-12-01 channel information or to download communication control software into the microcontroller 100. The RS-232 transceiver 250 is, in turn, ported to I/O-control bus 140.
User/craftsperson inputs for controlling operation of the test set are effected by means of a stAn~rd multi-key keypad 300, to which I/O-control bus 140 is coupled. Key depression of the keys of the keypad 300 generate input commands that are buffered in a latch 310, the contents of which are asserted onto a distributed multibit data/address bus 320. Data/address bus 320 is ported to a data/address port 105 of the microcontroller 100. Microcontroller 100 has a limited storage capacity flash memory 330, an EPROM
340 in which the operational software for the microcontroller is stored, and a random access memory 350 for storing data processed by the microcontroller's central proces~ing unit (CPU).
The data/address bus 320 is also ported to an LCD unit 360, which provides an alpha-numeric visual display of a menu of options/actions that may be selectively invoked by keypad inputs from the user, and an indication of the operation of the test set, as microcontroller 100 sequences through stored test routines, to be described. In addition to the LCD unit 360, the test set may employ one or more discrete visual indicators, such as a set of LEDs that are coupled to I/O bus 140, and selectively individually energized by the microcontroller 100 to provide an CA 022~4739 1998-12-01 indication of prescribed status or operational conditions of the line under test such as, but not limited to, ON /OFF
hook, tip/ring polarity and test set battery charging status.
As described in the above-referenced '117 application, the test set architecture of Figure 1 is able to conduct a number of analog and digital test operations of a line to it is connected. These test operations include an initial, "LINE IDENTIFICATION MODE" (in which the type of line to which the test set is connected is automatically determined), and "POTS MODE," (for testing a POTS line, in which the tip and ring line portions of the four-wire link 12 are coupled through switches 20 and 30 to the POTS line interface module 70).
Because the test set architecture of Figure 1 includes both two-wire 'U' interface chip 90 and four-wire 'S/T' interface chip 130, the test set may be used to trouble-shoot a potentially faulty digital (e.g., ISDN) circuit that is either upstream (toward the central office), or downstream (toward a remote terminal - customer premises equipment) of the location at which the craftsperson has connected the test set. Where two test sets of the type shown in Figure 1 are available, the potentially faulty circuit of interest may be tested by placing the test sets in a master-slave mode of operation. The 'master' test set may be connected to a first, test supervisory location of _.~ ....
CA 022~4739 1998-12-01 the line, from which the test is to be conducted (such as at a central office line termination location). The 'slave' test set may be connected to a second site of the line, geographically remote from the first site (such as at a network termination of a customer premises). Once a loopback path has been established between the two test sets, a BER test may be initiated from the master test set.
In addition to loopback (for bit error rate testing), an echo-back mode of operation may also be used. This mode is somewhat similar to the loopback mode in that it's purpose is to have the slave test set send back to the master test set the contents of a prescribed data sequence.
In echo-back mode, however, rather than the slave test set simply operating as a passive loopback device, the slave test set captures and then retransmits data placed on the D channel by the master test set.
Also, a voice link may be established either over a public switched network, as diagrammatically illustrated in Figure 4, or between two test sets that are connected to opposite ends of a non-powered or 'dry loop' link, as diagrammatically illustrated in Figure 5, with one of the test sets operating in LT mode as a line termination device, and the other operating in NT mode as a network termination device. Also described in the '117 application is a callback mode of operation, which allows an unmanned slave test set to return a voice call (i.e., without the . . .
CA 022~4739 1998-12-01 participation of an attendant craftsperson), and thereby determine whether a voice call can be established over the circuit under test.
As described above, the present invention is directed to an enhancement to the control software executed by the test set's supervisory processor 100, for controlling the communication and testing functionality of the test set, including the operations described in the '117 application, reviewed briefly above. As will be described below with reference to Figures 6-9, the present invention provides a prescribed master - slave testing message exchange sequence that facilitates use of the test set and minimizes errors in testing the ISDN capability of a circuit.
MASTER-SLAVE BERT (Figures 6-7) In accordance with a first aspect of the invention, dry loop bit error rate testing of a (two-wire) line is conducted by executing a prescribed master - slave message exchange sequence, shown in the flow chart of Figure 6, between a pair of (master and slave) test sets, that are coupled to opposite ends of a two-wire U-interface (metallic twisted pair). A non-limiting example of such a test arrangement is diagrammatically illustrated in Figure 7, which shows a first test set 410 coupled as a line termination (LT) unit to a central office 402 end of the two-wire interface 400, and a second test set 412 is CA 022~4739 1998-12-01 coupled as a network termination (NT) device at the customer premises 404, which may include one or more pieces of terminal equipment 432 coupled to network termination (NT-1) 406 via a four-wire S/T interface 430. There is no connection between the ISDN line 400 and the central office switch, as shown by break 405, and there is no connecton between the ISDN line 400 and a network termination NT-l 406 at the customer premises 404, as shown by line break 407. Thus, the line (e.g., metallic twisted pair) 400 is not powered from the central office equipment, and all signalling is effected from the test set's two-wire 'U' interface chip, ported to the line 400.
In the present mode of operation, a bearer channel (e.g., channel B1) is used as a slave command message channel. Consequently, it is necessary to ensure that the far end test device 412 is in slave-monitor mode, namely configured to conduct master - slave messages exchanges on the prescribed bearer channel. For this purpose, prior to the transmission of a message sequence, the user operating the master test set (here test set 410 - connected as an LT
device at the central office 402) operates a MENU key 312 on the test set keypad 300 (Figure 2). Operation of the MENU key 312 causes the master test set's LCD display panel 360 to display a list of options available to the craftsperson, as shown at step 601 in the flow chart of Figure 6.
CA 022~4739 1998-12-01 This menu includes a bit error rate test (BERT) option, which is selected by the user depressing a numeric key (e.g., '1') on the keypad 300 associated with the numerical listing ('1') in the displayed menu option~
BERT'. In response to a key command selecting the BERT
option, in step 602, the routine of Figure 6 causes the display unit 360 to display a list of prescribed parameter options (that may include the data rate to be employed (e.g., 56 Kbaud or 64 Kbaud), the length of time the test is to be run, and which bearer channel (Bl, B2 or both Bl and B2) is to be looped back for conducting the BERT).
Using the alpha-numeric keys of the test set keyboard 300, the test set operator selects and enters parameter values for the listed menu options.
Once the values for the displayed list of parameter options have been entered, the craftsperson simply depresses a START key on the test unit's keypad 300. In accordance with the test message exchange routine of the invention, in response to operation of the START key, the routine automatically conducts a sequence of message exchanges with the slave device without the need for further user participation to test the ISDN capability of the circuit under test. In particular, in step 603, the routine causes the U-chip 90 to transmit a first message:
ACTIVATE SLAVE MONITOR over the Bl channel to the far end test unit. This causes the far end test unit to activate ~, CA 022~4739 1998-12-01 its SLAVE MONITOR function on the B1 channel (if not already activated), and send back a SLAVE MONITOR
ACKNOWLEDGEMENT message on the B1 channel, which is received in step 604.
Next, in step 605, the 'LT-terminated' master test set sends a second message: CLEAR ALL LOOPBACKS, over the B1 channel, causing the far end (NT-1 terminated) test set to clear all loopbacks (on each of the B1, B2 channels), and to transmit a return message (LOOPBACKS CLEARED) on the B1 channel, which indicates that all loopbacks have been cleared. The return message is received in step 606. In step 607, the master (LT) test set transmits an ACTIVATE
LOOPBACK message to the slave (NT-1) test unit. The ACTIVATE LOOPBACK message specifies which of the bearer channels is to be looped back (as previously menu-selected by the user in step 602).
In response to the ACTIVATE LOOPBACK message, the far end or slave test unit turns off the SLAVE MONITOR function (since the loopback request message transmitted in step 607 may have requested a loopback over the B1 channel) and then returns a LOOPBACK ACKNOWLEDGEMENT message to the master test unit, informing the master test set that the loopback is complete.
In response to receiving this LOOPBACK ACKNOWLEDGEMENT
message, in step 608, the master test set routine initiates a BERT, by causing the transmission of a pseudo random bit ~ .
CA 022~4739 1998-12-01 stream over the specified bearer channel in step 609. In step 610, whatever data is returned over the looped back bearer channel i9 compared with the contents of the transmitted pattern to derive a bit error ratio (BER) and the number of errors and the number of errored seconds, which are displayed via display 360 to the user.
The BERT continues until either the user manually intervenes by selecting a soft STOP key on the test set display, or the time-out loaded in step 602 expires, as shown at termination step 611. To confirm proper operation of the BERT, the craftsperson may access an INJECT ERRORS
option of the displayed menu, selectively causing insertion of error bits in the pseudo random bit pattern being transmitted over the loop. If the BERT is operating properly the data displayed in step 610 will indicate injected errors.
MASTER-SLAVE, END-TO-END VOICE CALL (Figures 8-9) In accordance with a second aspect of the invention, the communications control routine for which is shown in Figure 9, to be described, a dry loop voice communication path is automatically established over a (two-wire) line by executing a prescribed master - slave message exchange sequence between a pair of equipments or devices possessing the functionality of, but not necessarily being the test sets of Figure 1, that are coupled to opposite ends of the .~ .. , CA 022~4739 1998-12-01 two-wire pair under test.
Figure 8 diagrammatically illustrates a non-limiting example of such a test arrangement, employing a pair of test sets 410 and 412, wherein a master or calling test set 410 is coupled as a line termination (LT) unit to a central office 402 end of the line, and a slave or called test set 412 is coupled at the customer premises 404. It should be noted, however, a reverse call exchange sequence may also be conducted, wherein the sourcing device (e.g., test set) 412 is coupled as a network termination (NT) at the customer premises 404, and operates as the master or calling unit, while the responding device (e.g., test set) 410 is coupled as a line termination (LT) at the central office 402 end of the line, and operates as the slave or called unit.
As in the first embodiment, there is no connection between the line and 400 the central office switch, so that the line is not powered from the central office equipment, and all signalling is effected from a test set's two-wire 'U' interface chip ported to the line 400. Also, the Bl bearer channel may be used as the slave command message channel; as a result, it is necessary to ensure that the far end test device is in slave-monitor mode (namely, is configured to conduct master - slave message exchanges on the Bl channel). For this purpose, the user operating the master test set (here test set 410 connected as an LT
--_ .
CA 022~4739 1998-12-01 device at the central office 402) activates a HOOK key 316 on the test unit's keypad 300 (Figure 2). In the second embodiment of the invention, the test set's HOOK key 316 is used in a conventional POTS sense, as when the user wishes to make a call to another device. However, since the present invention uses a dedicated (e.g., Bl) bearer channel master-slave signalling sequence to establish the call, some preliminary housekeeping is required.
In particular, as shown at step 901 in the flow chart of Figure 9, in response to activation of the HOOK key, the end-to-end call routine causes the transmission of an "ACTIVATE SLAVE MO~ OR" message, over the Bl channel from the (master) test set 410 to the far end (slave) test unit 412. As in the first embodiment, upon receiving this message, the slave test unit activates its SLAVE MONITOR
function on the Bl channel (if not already activated), and sends back a "SLAVE MONITOR ACKNOWLEDGEMENT" message on the Bl channel, which is received at the master test unit in step 902.
Next, in step 903, the LT test set 410 sends a second message: "PLACE CALL" to the distant test set 412. The slave/called test set 412 responds by generating a local ringing signal (that is audible at the far end test unit's receiver), and returning a "PLACE CALL ACKNOWLEDGEMENT"
message, which is received by the master test set 410 in step 904. In response to receipt of the PLACE CALL
. ._, .. . .
CA 022~4739 1998-12-01 ACKNOWLEDGEMENT message from the far end test unit, test set 410 generates its own ringing signal in step 905, so as to simulate to the craftsperson a 'far end' ringing signal that he would expect to hear for the placement of a POTS
call (except that no digits have been dialed).
If the craftsperson at the near end test set 410 reoperates the HOOK key before the called test set 412 answers (or continues to fail to answer), the call is terminated, as shown at steps 906 -907 - 908. If the called test set 412 answers (the answer to query step 906 is YES), it returns a "CALL ANSWERED" message, which is received in step 909. Upon receiving the CALL ANSWERED message, then in step 910, the calling test set 410 transmits a "CONNECT"
message to the far end device. In response to the CONNECT
message, the far end test set 412 turns on its codec and returns a "CONNECT ACKNOWLEDGEMENT" message. Upon response to receipt of the CONNECT ACKNOWLEDGEMENT message in step 911, the calling test unit 410 turns on its codec in step 912, so that a voice conversation may be conducted between the two test sets.
Either test set may terminate the call. For the non-limiting case where the technician at the originating device 410 terminates the call by operating the HOOK key, in step 913, the routine transmits a "TERMINATE CALL"
message to the far end test unit in step 914. In response to the TERMINATE CALL message, the far end test set 412 . ~ . , .
CA 022~4739 1998-12-01 -turns off its codec and returns a message: "TERMINATE
ACKNOWLEDGEMENT." Upon receipt of the TERMINATE
ACKNOWLEDGEMENT me8sage in step 915, the calling test unit 410 then turns off its codec, and the call is terminated.
If the far end test set 412 terminates the call, it transmits a "TERMINATE CALL" message to the near end test unit, and a complementary version of the termination acknowledgement message exchange sequence described above is executed between the two units, to terminate each test set's call.
As will be appreciated from the foregoing description, the present invention provides automated BERT and voice call enhancements to the ISDN test set architecture described in the '117 application, that can be executed with only minimal preliminary user/craftsperson participation, thereby facilitating use of the test set and ri ni~i zing the possibility of errors.
While we have shown and described several automated master - slave ISDN test set connectivity embodiments in accordance with the present invention, it is to be understood that the same is not limited thereto but is susceptible to numerous changes and modifications as known to a person skilled in the art, and we therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are obvious to one of ordinary skill in the art.
~ _ . .. , , . ~ . .. . . .
Claims (14)
1. A method of testing the operation of a communication link for the transport of ISDN communication signals thereover, comprising the steps of:
(a) providing a plurality of craftsperson test sets, containing test circuitry that is controllably operative to test the operation of said communication link;
(b) coupling a first location of said communication link to a first of said plurality craftsperson test sets, and coupling a second location of said communication link to a second of said plurality of craftsperson test sets;
and (c) in response to a user at one of said test sets activating an input/output element of said one of said test sets, causing said first and second test sets to automatically conduct a prescribed bearer channel message exchange sequence that is effective to establish an ISDN
communication path over said prescribed bearer channel between said test sets.
(a) providing a plurality of craftsperson test sets, containing test circuitry that is controllably operative to test the operation of said communication link;
(b) coupling a first location of said communication link to a first of said plurality craftsperson test sets, and coupling a second location of said communication link to a second of said plurality of craftsperson test sets;
and (c) in response to a user at one of said test sets activating an input/output element of said one of said test sets, causing said first and second test sets to automatically conduct a prescribed bearer channel message exchange sequence that is effective to establish an ISDN
communication path over said prescribed bearer channel between said test sets.
2. A method according to claim 1, wherein step (c) comprises causing said first and second craftsperson test sets to operate in respective master and slave modes, and automatically exchange communication messages therebetween, in response to which said first craftsperson test set derives a measure of an ISDN performance characteristic of said communication link.
3. A method according to claim 1, wherein step (c) comprises causing said first and second test sets to automatically initiate a message exchange sequence over said prescribed bearer channel that is effective to establish a voice communication path over said bearer channel between said first and second test sets.
4. A method according to claim 1, wherein step (c) comprises causing said first craftsperson test set to initiate a message exchange sequence over said prescribed bearer channel that is effective to establish a loopback path between said first and second craftsperson test sets, and to execute a bit error rate test over said loopback path.
5. A method according to claim 1, wherein said communication link comprises a dry loop.
6. A method according to claim 1, wherein said prescribed bearer channel message exchange sequence causes said second test set to clear previous loopbacks on all bearer channels, and to loopback one or more bearer channels as prescribed by said first test set, and to cause said first test set to initiate a bit error rate test over said one or more prescribed bearer channels as looped back by said second test set.
7. A method according to claim 1, wherein step (c) comprises, in response to operation of a hook key of said first test set, causing said prescribed bearer channel message exchange sequence to initiate the generation of respective local ringing signals at said first and second test sets, and to cause said first and second test sets to enable respective codecs therein for ISDN voice signal transmission and reception between said first and second test sets over said communication link.
8. A portable ISDN test set for testing the operation of a communication link for transporting ISDN
signals, said portable ISDN test set comprising diverse types of digital communication interfaces for connection with multiple communication link configurations, and a supervisory control processor which controls the operation of said diverse types of digital communication interfaces for interfacing digital communication signals with said multiple communication link configurations, said supervisory control processor being operative, in response to a user activating an input/output element, to automatically conduct a prescribed bearer channel message exchange sequence with another ISDN test set coupled to said communication link, that is effective to establish an ISDN communication path over said prescribed bearer channel.
signals, said portable ISDN test set comprising diverse types of digital communication interfaces for connection with multiple communication link configurations, and a supervisory control processor which controls the operation of said diverse types of digital communication interfaces for interfacing digital communication signals with said multiple communication link configurations, said supervisory control processor being operative, in response to a user activating an input/output element, to automatically conduct a prescribed bearer channel message exchange sequence with another ISDN test set coupled to said communication link, that is effective to establish an ISDN communication path over said prescribed bearer channel.
9. A portable ISDN test set according to claim 8, wherein said supervisory control processor is operative to automatically exchange messages over said prescribed bearer channel with said another test set, that are effective to derive a measure of an ISDN performance characteristic of said communication link.
10. A portable ISDN test set according to claim 9, wherein said supervisory control processor is operative to automatically initiate a message exchange sequence over said prescribed bearer channel that is effective to establish a loopback path at said another test set, and to execute a bit error rate test over said loopback path.
11. A portable ISDN test set according to claim 8, wherein said supervisory control processor is operative to automatically initiate a message exchange sequence over said prescribed bearer channel that is effective to establish a voice communication path over said bearer channel with said another test set.
12. A portable ISDN test set according to claim 8, wherein said communication link comprises a dry loop.
13. A portable ISDN test set according to claim 8, wherein said prescribed bearer channel message exchange sequence causes said another test set to clear previous loopbacks on all bearer channels, and to loopback one or more bearer channels, and wherein said supervisory control processor is operative to initiate a bit error rate test over said one or more bearer channels as looped back by said another test set.
14. A portable ISDN test set according to claim 8, wherein said supervisory control processor is operative, in response to operation of a hook key of said test set, to cause said prescribed bearer channel message exchange sequence to initiate the generation of respective local ringing signals at said portable ISDN test set and said another test set, and to cause said test sets to enable respective codecs therein for ISDN voice signal transmission and reception therebetween over said communication link.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US98451597A | 1997-12-03 | 1997-12-03 | |
| US08/984,515 | 1997-12-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2254739A1 true CA2254739A1 (en) | 1999-06-03 |
Family
ID=29550598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2254739 Abandoned CA2254739A1 (en) | 1997-12-03 | 1998-12-01 | Automated master-slave connectivity dry loop isdn line |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2254739A1 (en) |
-
1998
- 1998-12-01 CA CA 2254739 patent/CA2254739A1/en not_active Abandoned
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