EFJohnson 7780 service manual Monitor Mode, Busy Channel Lockout, Call Guard Squelch

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TRANSCEIVER OPERATION

2.4.4 MONITOR MODE

The monitor mode temporarily disables squelch control features (such as Call Guard squelch) so that all messages are heard on the selected channel. It also overrides the Busy Channel Lockout feature (see next section) and temporarily halts scanning.

To monitor the selected transmit channel, select the monitor mode by briefly pressing the Monitor

option switch (if available). The icon is displayed and the receiver unsquelches (even if no carrier is detected). To disable the monitor mode and return to normal operation, press the Monitor switch a second time.

To monitor the selected receive channel instead of the transmit channel, press and hold the Monitor switch until the alert tone sounds (approximately 1 second). This function may be useful, for example, during weak signal conditions if intermittent squelching makes a message difficult to understand.

2.4.5 BUSY CHANNEL LOCKOUT

The Busy Channel Lockout feature (also called Transmit Disable On Busy) automatically disables the transmitter if the channel is busy when the PTT switch is pressed. When a busy condition is detected by this feature, the transmitter is disabled, “BUSY” is indi- cated in the lower part of the display, and a tone similar to a standard telephone busy tone sounds until the PTT switch is released. This feature is programmed to operate in one of the following modes on each channel:

Off - The transmitter keys even if the channel is busy. Noise - The transmitter is disabled if any signal is

detected on the channel.

Tone - The transmitter is disabled if the detected squelch coding is not correct.

If busy override is permitted by programming, it is possible to transmit even when the transmitter is disabled by this feature. Simply quickly release the PTT switch and press it again.

2.4.6 CALL GUARD SQUELCH

General

Call Guard® squelch (also called CTCSS/DCS signaling) can be programmed on conventional channels. This feature eliminates distracting messages intended for others using the channel by using a subaudible tone or digital code to control the squelch. This tone or code is unique to a user or talk group on that channel. It is transmitted by the mobile placing a call, and if Call Guard squelch is programmed in the mobile receiving the call, it must detect the correct tone or code to receive the call.

Call Guard Squelch Enable/Disable

To disable Call Guard (Selective) squelch so that all messages on the selected or scanned channels are heard, press the Normal/Selective option switch if programmed. The receiver unsquelches only if a carrier is detected. To re-enable Call Guard squelch, press the Normal/Selective switch again.

When Call Guard squelch is disabled by this switch, “SQ NORM” is flashed on the lower line of the display, and when it is enabled, “SQ SLCT” is flashed. The selected mode does not change when other channels are selected or power is cycled. Call Guard squelch can also be disabled by the monitor mode described in Section 2.4.4.

Changing the Call Guard Code

If using the full keypad (15-key) model and the ability to change Call Guard codes has been enabled by programming, the transmit and receive codes from one channel can be temporarily or permanently reas- signed to all channels of the current zone. Proceed as follows:

1.Using the number keys, enter the number of the channel that is programmed with the code you want to reassign to all channels (only channels 1-9 can be selected). See Section 2.4.2 for information on how to display channel numbers.

2.The display then briefly indicates “CODE x”, where “x” is the key that was pressed. The codes assigned

 

November 1999

2-9

Part No. 001-7780-500

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Contents 7780 Page Page Table of Contents Table of Contents CONT’D List of Figures List of TablesScope of Manual Equipment Description General InformationTransceiver Identification AccessoriesFactory Customer Service Part Number BreakdownFactory Returns AccessoriesAccessory Toll-Free 800Definitions Replacement PartsInternet Home Intrinsically Safe Information Classification of Hazardous Areas and Atmospheres Temperature Code T3CPossible Ignition Sources Intrinsically Safe and Nonincendive RatingsArea Classification Accessing PC BoardsMaterial Classification Typical Hazard Group ClassRemoving Logic Unit Removing RF UnitGeneral SpecificationsControls and Display FeaturesTransceiver Operation Low-Battery Indicator Amber TX Indicator Red Indicates when the transmitter is keyedDisplay DisplayFront Panel Keys Full Keypad Model Backlight Turning Power on and Setting VolumeOption Switches General OperationSee Option Switch FunctionsFunction Conv Scanning Tone ENABLE/DISABLEConventional and SMARTNET/ Smartzone Operation Monitoring Before Transmitting Conventional FeaturesDisplay Mode Selection Call Guard Squelch Monitor ModeBusy Channel Lockout Conventional Mode Scanning Penalty TimerConversation Timer Power Output SelectPriority Channel Sampling Standard Conventional Calls DTMF/ANI SignalingEnhanced Private Conversation Calls SMARTNET/SMARTZONE FeaturesViewing Unit ID Standard Group CallsTransceiver Operation Private Conversation II Calls Telephone Calls Call Alert Sending Status Conditions Emergency Alarm and CallMessaging Dynamic Regrouping Failsoft OperationSMARTNET/SMARTZONE Scanning Supervisory Tones Zone Change Parameter Keypad ProgrammingMenu Description Channel Parameters Channel Change ParameterSystem Parameters Computer Description Programming SetupPctrunk Software Installation Transceiver ProgrammingHelp Files Connecting RPI to Computer and TransceiverStarting and Exiting Programming File TypesCreating and Displaying Systems Screen Pop-Up Buttons and File Size IndicatorProgramming Procedure File Size IndicationMenu Bar Menu CommandsWindow Menu Radio Type MenuDownload Menu Upload Menu Systems MenuZones DefaultsRADIO-WIDE Parameter Screens BandAssign Function Buttons Radio Wide Scan ListRadio-Wide Scan List Screen Modify List ScreenHot Dtmf RADIO-WIDE Conventional ScreenRADIO-WIDE SMARTNET/SMARTZONE Screen Full Spectrum CC ScanConventional System General Screen Adjustable ParametersRADIO-WIDE Portable Options Screen Programming Conventional Systems and ChannelsScan List Button TimersConventional System Modify Scan List Screen Keypad EditingPriority Channel Selection Scan TimersSetting UP Conventional Channels Selected Channel Conventional Channel Screen ParametersTx Time-Out Transmit PowerSignaling Channel TypeSplinter Channels Restricted AccessTime-Out Timer ISW Delay TimePrivate Call SMARTNET/SMARTZONE System Other ID’S ScreenSMARTNET/SMARTZONE System Phone Interconnect Screen Phone InterconnectFailsoft Channel SMARTNET/SMARTZONE System Emergency Settings ScreenEmergency Alarm SMARTNET/SMARTZONE System Talk Groups ScreenMessage Aliasing Screen SMARTNET/SMARTZONE System Lists ScreensTrunking Phone List Screen Control Channels Screen Announcement Groups ScreenTrunking Call List Screen SMARTNET/SMARTZONE Channel Screen Parameters Setting UP SMARTNET/SMART- Zone ChannelsStatus Aliasing Screen Other Screen Parameters SMARTNET/SmartZone Channel ScreenRecommended Tone Call Guard Codes Freq Call Guard CTCSS/DCS Codes and TonesMHz Channels MHz Channels MHz Channels MHz Channels MHz Channels MHz Channels Synthesizer Description Power Switching and RegulationPower Switching Circuit DescriptionCharge Pump Q1, Q2, Loop Filter VCO and Tcxo ModulationSynthesizer Chip IC1 If Amplifier Q2, LIMITER/DETECTOR IC3 Receiver Circuit DescriptionRF Amplifier Q1, First Mixer Q2 Amplifier Q9, Driver Q8 Antenna Switch and LOW-PASS FilterSquelch Circuit IC4A/B, IC5A Transmitter DescriptionReceive Audio Processing Control Logic and DisplayPin Port Name Input or Description Active High Output Microprocessor IC306 Pin DescriptionsHvfulswlrq Receive Data FILTER/DETECTOR IC102A/B, IC107A/B Audio Amplifier IC104-IC106Receive and Transmit Data Processing Transmit Audio Processing Transmit Data Filter IC206B/ IC206ASmartnet Data Processing LOW-PASS Filter IC205A/BFunction Fahrenheit Celsius Battery Pack and Charger InformationBattery Pack Power Setting Operating TimeBattery Pack and Charger Information Test Setup Alignment Procedure and Performance TestsMm/3/32 Mm/1/8 Phone Jack Tune Software HqhudoMain Pctune Screen Preliminary SetupModulation Balance Transmit Frequency and PowerTransmit Power Adjustment Screen High Power Level = 3.0 watts Low Power Level = 1.0 wattData Deviation Squelch AdjustRssi Adjust Audio DeviationReceiver Performance Tests Performance TestsTransmit Modulation Power OutputTransmitter Performance Tests Transmit FrequencyThis page intentionally left blank Ref No Description Parts ListDisplay Assembly Chassis PartsDisplay Assembly KEY AssemblyIf Assembly If AssemblyKEY Assembly RF Unit PLL AssemblyRF Unit NJM2904V-TE1 IC RF Unit Logic Unit Logic Unit TDA7233D IC Logic Unit 200K ERJ3GE MP35 MP18 MP25 EP2 KEY Front PanelEP1 MP32 MP33 MP27 MP34 MP28 MP29 MP23 MP22 MP30 MP24 MP26 MP18 PLL Board Bottom View Schematic Diagrams and Component LayoutsPLL Board TOP View If Board Bottom View If Board TOP ViewRF Unit Transceiver Block DiagramMIC RF Board TOP ViewIf AMP RF Board SchematicHD1 Logic Board TOP ViewReceive Audio Processing Logic Board SchematicGND KEYR3 KEYR2 KEYR1 KEYR0 KEYS3 KEYS2 KEYS1 KEYS0 GND Display Board Bottom ViewDS3 DS4 DS5 Display Board SchematicKEY Board Back View KEY Board Front ViewS S R R R R KEY Board SchematicScan HC2 HC7 HC8 HC3 Schematic Diagrams and Component Layouts
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