Nortel Networks RTU-292 operation manual Hybrid Balance Measurement

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RTU-292 Operations Manual

6.5.2HYBRID BALANCE MEASUREMENT

The test procedure outlined below allows measurement of the hybrid balance, or trans-hybrid loss, attainable with the RTU-292. This characteristic determines how much radio receiver input signal will leak into the transmitter output of the RTU-292. In the test set-up, the noise generator simulates the radio receiver, the audio voltmeter simulates the transmitter and the resistor simulates the telephone line. If the hybrid balance were perfect, the trans-hybrid loss would be and none of the receiver signal would leak into the transmitter (the audio voltmeter in this set-up would measure nothing except residual noise.)

The RTU-292 trans-hybrid loss specification is at least 30dB when measured with a noise source with an output bandwidth that matches the RTU-292’s bandwidth. This means that the noise output measured by the audio voltmeter should be at least 30dB below the noise input to the RTU-292’s hybrid. The test is performed with a 600 Ohm resistor simulating the phone line in order to have a repeatable standard impedance on which to base the specification. In actual use, the hybrid balance of the RTU-292 is excellent into impedances other than 600 Ohm (such as the complex impedances of the telephone lines) and is far better than any conventional hybrid under these conditions.

The procedure for this test using a noise generator is listed in paragraph 6.5.2.1. If a noise generator is not available, the alternate test method that employs an audio signal generator (see paragraph 6.5.2.2) may be used. Figure 6.1 shows equipment interconnections necessary to perform this test.

NOTE

The accuracy of the trans-hybrid loss measurement depends on the bandwidth of the noise generator used to perform the test. It is possible, however, to achieve an evaluation of the unit to within a few dB tolerance without a commercial noise generator by using the audio output of an SSB or AM receiver that has no antenna connected. This type of receiver with a 2.5 to 3.5 kHz SSB IF bandwidth makes an ideal noise generator for this measurement because the output noise is band limited by the receiver’s IF filters. (FM receivers, however, have too wide a noise bandwidth and will produce erroneous results using this procedure.) The receiver’s noise output should be between -20dBm and 0dBm so that the RTU- 292 can be adjusted for the correct hybrid input level.

JPS Communications, Inc.

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Contents JPS Communications, Inc JPS P/N Revision JulyProprietary Statement Phone 919 Fax 919Table of Contents RTU-292 Theory of Operation Front Panel Buttons and Indicators Schematic Diagrams List Of Figures List of Tables Glossary This page intentionally left blank Scope Description GeneralTelephone Interface AssembliesMain Board Radio Interface Power Supply SectionHandset/Speaker Interface DSP ModuleEquipment and Accessories Supplied Qty Part NumberOptions Optional Equipment Not SuppliedRTU-292 Specifications Reshipment of Equipment GeneralUnpacking and Inspection FCC Part 68 Regulations Installation OverviewInstallation Considerations 1RTU-292 Factory Default Settings Feature / Function Adjustment Default SettingDC Input Power Selection Power RequirementsInput Power Selection Line Voltage SelectionSetting Telephone Send and Receive Levels Configuring the RTU-292Programming Mode Setup Parameters Type of System Recommended Phone Line SettingsFactory default settings are indicated by an asterisk Telephone Send/Receive LevelsVOX Sensitivity VOX HangtimeVOX Hangtime VOX SensitivityTelephone Ring Volume Dial ModeDial Mode RX Line Input ImpedanceFull/Half Duplex Radio Control ModeSW1-3 Radio Control Off Disabled Enabled SW2-8 Full/Half Duplex Off Full Duplex11Voice Prompts Enable Password Protection10Password Protection Voice PromptsInterconnect Information 12Local Phone Enable14TX Level Set-up Mode 13 Local Phone RingthroughPin Function Telephone Connection15J1 TEL Line RJ-11C Radio Connection17J7 Handset RJ12C Jack Handset Connector16P1-RADIO DB-9 Male Terminal Block 18Terminal Block 6 PositionSetting the Transmit Level Audio Level Setup and Adjustments19P2 RS-232 Connector DB-9 Male 5 RS-232 ConnectionSetting the Receive Level 10.1.2RTU-292 Operations Manual Outline Dimensions Control and Connector Locations Location Of Internal Option Settings Internal Option Setting Details Audio Interface Wiring Diagram Interface Details Installation Checklist Installation ChecklistOptions Installation and Configuration Front Panel CONTROLS, Indicators and Connectors Keypad Speaker Volume ControlPhones Volume Control TEL Line ButtonsAudible Ring Button Speaker ButtonsAuto ANS Button KEY Pushbutton4 J2 Local Phone Connector Rear Panel Connectors1 P1 Radio Connector 7 P1 AC Power ConnectorUSE of the RTU-292 Speaker to Monitor Audio OperationOperation Overview Placing a Telephone CallReceiving a Telephone Call Using the Handset with the RadioConnecting the Radio to the Telephone Line Putting a Telephone Call on Hold8.2 Manual Phone Patch Procedure8.1 8.5 8.38.4 8.6Self Test Negative Acknowledge ErrorRemote KEY Automated OperationRadio Is Keyed Keyed Disconnecting DisconnectWaiting For Input Query Radio Is Unkeyed UnkeyedRTU-292 Adapts To The Phone Line Caller Enters The Password if enabledCaller Dials The RTU-292 Terminating a Call RTU-292 Enters the Command ModePlacing a Call in the Command Mode Dtmf Control Commands Operating the RTU-292 from the Front Panel Keypad1Standard Dtmf Operational Commands Dtmf Command Function2Programming Mode Dtmf Commands Calling Timer RTU-292 Password ProtectionInactivity Disconnect Timer Programming the Speed Dial Directory Using the RTU-292 Speed Dial FeatureUsing the Speed Dial Feature Optional 4 Wire Operation Factory ResetSpeed Dial Reset Audio BUS Arrangement Front Panel Buttons and IndicatorsMain Board Telephone Receive Circuits Telephone Interface CircuitsTelephone Send Circuits Receiver Input Amplifier Ring Detector and Tone RingerRadio Interface Circuits Transmitter Audio OutputMicrophone Circuit Dtmf DetectorFSK Modem Speaker and Headphone CircuitsNoise Generator Audio DelayAdaptive Hybrid Peak DetectorDC Power Supply Power SupplyAC Power Supply 8 CPUPrompt Tone Generator Option Interface BoardVoice Prompt Option Speech ProcessorInterface Circuitry Local Phone OptionVoice Prompt Software DIAL/BUSY GeneratorsRS-232 Remote Control Overview Commands Sent to the RTU-2921Command Summary Audible Ring Command Null CommandAuto Answer Command Date Command Dial CommandDisconnect Command Dtmf CommandHandset Phone Command Handset Radio CommandSpeaker Phone Command Speaker Radio CommandSpeed Dial Command SD nnALL num.? CRTel-Line Phone Command Tel-Line Radio CommandTime Command Software Version CommandStatus Returned from the RTU-292 Response SummaryCall Starting Response Null ResponseAuto Answer Response Dtmf Response Dial ResponseDisconnect Response Handset Radio Response Elapsed Time ResponseHandset Phone Response Speaker Phone Response Speaker Radio ResponseTel-Line Radio Response Speed Dial ResponseTel-Line Phone Response Time/Date Response Version ResponseCall Progress Responses from the RTU-292 Response Error CodesResponse Error Codes Call Progress ResponsesPerformance Testing Preventive MaintenanceRepair or Replacement AlignmentHybrid Balance Measurement Hybrid Balance Test Set-Up Main Hybrid Test Procedure Alternate Hybrid Test Procedure VOX Sensitivity Test Set-Up VOX Test Procedure VOX Sensitivity MeasurementFault Analysis Replaceable Parts List DescriptionDescription Reference Designator RTU-292 Operations Manual Reference Designator Special Software Versions RTU-292 OptionsSW1-6 Voice Prompts Off Disabled Enabled Installation and ConfigurationVoice Prompts Enable OperationVoice Prompt Option Installation SW1-7 Local Phone Off Disabled Enabled Local Phone Option Installation and ConfigurationLocal Phone Enable SW1-8 Ringthrough Off Disabled Enabled5Local Phone Dtmf Commands Local Phone Option OperationVMM-100 Analog Interface VMM-100 HardwareVMM-100 DSP Section VMR Algorithm VMM-100 Installation and ConfigurationVMM-100 Software Noise Reduction AlgorithmVMM-100 Option Installation VMM-100 Specifications EnvironmentalVMM-100 I/O Connector Information P9 VMM-100 Switch FunctionsDtmf Access Option After the Call Begins Squelch Break Access Option RTU-292 Prompts for ConfirmationCall Logging Option Setting The TimeSetting The Date Checking The Time And DateRadio Control Option Controlling the Radio VIA the RTU-292 Front Panel Keypad9DTMF Radio Control Commands Command Followed By Command DescriptionSchematic Diagrams Blank Index Environmental Self Test Speech Processor
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