DreamGEAR MSK 33 Constellation diagram for QAM DVB-C, Measurement of modulation error rate MER

Page 76

Const Menu

Constellation diagram for QAM (DVB-C)

For digital transmission via cables, the modulation type QAM (Quadrature Ampli- tude Modulation) is used. The MSK 33 can represent the constellation of the modula- tion types, QAM64 and QAM128. For QAM 64, every 6 information bits are put together to one symbol and modulate one carrier in its amplitude and phase. With this, 64 conditions are possible, which a receiver must recognise for correct as- sessment of a QAM signal.

A „chessboard“ with 64 or 128 clouds, which represent the possible symbols or their frequency in the fields, appears on the colour screen.

You can select the menu items by press- ing the buttons on the right of the screen. Submenus are immediately called up by

pressing the appropriate softkey. The buttons are represented in yellow for acti- vated functions. Buttons, which have multi-functions, are indicated with an arrow and are represented in yellow as well. By repeatedly pressing the same button, dif- ferent parameters can be called up and displayed.

Measurement of the bit error rate (BER)

Since it deals with transmission of binary data for DVB-C, the bit error rate can be considered as measurement for the occurring transmission error in the data stream. In the MSK 33, a BER measurement is carried out before the error correction and displayed on the screen. The bit error rate is the ratio of the number of received defective bits divided by the entire number of the received bits. The lowest bit error rate, which the MSK 33 can measure, is 1.0 e-8. If the rate is lower than this value, the display of the BER jumps to zero „0“ (no longer bit error). The highest BER, which can be displayed, is 1 e-2. Generally, it can be assumed, that picture disturbance can occur by a BER of ca. 1 e-3.

Measurement of modulation error rate (MER)

In the DVB measuring guidelines, the measurement size is determined, which are combined with the broad interfering influences. The MER is calculated to record the entirety of the signal interference, which is available on the input of this receiver. It gives instructions regarding the ability of the receiver, to decode a signal correctly. The MER is the ratio of the average signal performance divided by the error power in dB. The higher the MER value is, the better the received signal is. Measure- ments of the MER can be displayed on the upper edge of the screen.

Carrier offset

The carrier offset display shows the difference between the set receiving frequency on the MSK 33 and the transmission frequency of the digital signal in MHz.

With the help of the cursor buttons, ◄►, you can switch to the next channel.

76

Page 75 Page 77
Image 76
Page 75 Page 77
Contents Operating manual Page Preface Contents Checking the LNB supply voltage of a satellite receiver Selecting the colour standards PAL, Secam and Ntsc Mpeg transport stream interface TS-Parallel, Lvds optional Measuring an audio signal via the AV socket Scart Measurement of analogue signals in Sat operation 100 107 113General safety information Explanation of symbolsImportant Notes Validity of this manualSafety Instructions ConnectionsProper use Mechanical loadbearing capacityFunctions FunctionsFunctions overview FunctionReturn path LP DVB-S DVB-S/C/TDisplays, Operating Elements and Connections Front panelMains connection Mains switch DC socket Option / XLR-socket Rear panelHeadphone connection TS parallel Option 10 AUXObserving angle of the on screen display Side view MSKScreen Operating ConceptFrequently recurring softkeys General information for operation Menu selectionMain menu Accu CAP % I=0.00 aPlace of installation of the MSK Mains voltage / mains switchOn/Off switch Safety fuseAccumulator operation Accumulator and Battery OperationDC socket option Connections Level measurement Measurement PossibilitiesMaximal input level Sat Operation Sat menuSelecting the LO frequency Setting of the LNB voltage supplyEntering the transponder frequency Switch-over of Analog digit. Dvbs Bargraph Level range Comment DisplayIII Calling up menu LNB-CONTROLKHz control signal LNB control menuLNB supply voltage LNB current drawCalling up the DiSEqC/V SEC menu Checking the LNB supply voltage of a satellite receiverDiSEqC DiSEqC menu Submenu for entering DiSEqC commands TX display fieldDisplay field a Display field BSimple DiSEqC Example Entering and transmitting a DiSEqC commandData burst Tone burst UFOmicro DiSEqC menu General informationDisplay fields RX 0 E2 10Tx+rx Command 1390Operating the menus ModusSat Operation SEC menu Sending a V-SEC command TXEntering the hex numbers Level-dependent acoustic signal Initial ANALOG-menuCalling up the sound subcarrier MenuSecond Anlaog menu Video polarityAudio carrier setting Setting of the de-emphasisSat subcarrier menu Selecting the subcarrier recepAudio carrier tables for the satellite reception Audio carrier table for reception typeSAT Digital menu Digital Measurements27.500 SR Level measurement Digital Min./Max. levels TV Operation TV menuC10 210.25MHz A65.0dBµV Rf chanTV-DiSEqC /VSEC menu TV control menuLNB U= 0.0 V I= 0 mA Analogue menu Selecting the standardAudio carrier table for TV reception Selecting the audio carriersMeasuring the min./max. level Measuring the current levelSelecting the colour standards PAL, Secam and Ntsc Measuring audio carrier spacingSelecting demodulation for DVB-C measurement TV Digital menuMode DVB-T optional Selecting channel bandwidthsReturn Path if Menu Return path if menuAnalog menu Audio carrier table for if receptionMeasurement of the audio carrier spacing Measurement of the min./max. levelMeasurement of the current level Entering symbol rate QAM64 modeIf RP Digital Menu Radio menu Radio OperationRadio Analog menu FM Measure ALL Measuring the min/max levelAV Menu Decoder operationDecoder operation baseband Video input Video outputRGB operation Breaking voltageMpeg transport stream interface TS-Parallel, Lvds optional PAT 08 Mpeg Decoder Menu Optional3sat KiKa Phoenix Unit Setting MenuOffset 0.0 dB Screen setup Screen MenuSetting the date Setting the time Click buttonSystem Menu Calls up the SYS TEM menuSaving and calling up unit settings Saving the unit settingsCalling up saved settings Copy MenuPrinting out all measurements in TV mode Printing out all measurements in Sat modeMode Menu SpectrText Menu Enlarging the videotextHolding the videotext Original videotext sizeHorizontal zoom -Enlarging the video signal Horizontal zoom Reducing the video signalScope Menu Video scope menuMeasurement of video signals via the AV socket Scart Measurement of the amplitude of the video signalSelecting the video line Time Audio ScopePos Position and triggering of the DiSEqC signal DiSEqC ScopeSaving function Shot ContSpectral Menu Marker SpanMark AnaMarker ana Marker digMeasurement of digital signals in Sat operation Cross-polarisation measurement on signals in SAT operationZoom marker Max offConstellation diagram for Qpsk DVB-S Measurement of the bit error rate BERConst Menu Colour representation of I/Q value pairsCarrier offset Measurement of signal noise ratio SNRFrontend locked Inverting /not inverting a constellation diagram Selecting the symbol rate symbol-clockSelecting the code rate Examples for Qpsk constellation diagrams Constellation diagram for QAM DVB-C Measurement of modulation error rate MERInverting /not inverting constellation diagram ZoomExamples for QAM constellation diagram Const Menu Constellation diagram DVB-T optional Measurement of bit error rate BERMeasurement of signal noise ration SNR Carrier modeHierarchy Code rate Guard Invers Frontend locked Channel display Impulse response representation Echo representation optional Broadband Cable Analysis Measuring System MSK Measuring principleTrack MVG10 Upstream measurement Downstream measurementMSK33 MVG10 RGB MSK33Cable system With return path capable amplifiers Auto Measure Display of the check pointModem / RS 232 interface InterfacesConnection cable for modem / RS Setting baud rate Setting local echoSetting hardware handshake Modem/RS232 menuCode Password TTY modeAnsi mode Log-in procedureExample for logging-in in Ansi mode Requesting helpInterfaces List of the command abbreviations Loading and saving predefined settings STUSTU RET LDUMaintenance, Storage and Customer Service Printer paper-exchanging the ribbon Ribbon exchangeOverview of DiSEqC commands Command overview framing byteCommand overview address byte Technical AppendixCommand overview command byte Reset Reset DiSEqC minicontrollerDiSEqC commands for Kathrein matrices Command overview data byteCommand for Kathrein matrix 9xx-series Command for Kathrein matrix EXRChannel tables Channel and frequency table standard B/G frequency in MHzVHF-CCIR UHF-CCIR USB/OSB ESBChannel and frequency table standard Lfrequency in MHz VHF UHFChannel and frequency table standard D/K frequency in MHz VIIViii XIIChannel and frequency table standard I frequency in MHz Channel and frequency table standard M/N frequency in MHz Channel and frequency table standard M/Nfrequency in MHz Technical data Technical DataPower supply Qpsk BER SNRMER Scope of delivery AccessoriesAssignment of the Scart socket Assignment of RS232 socket TXD RXD RTS CTS DSR GND DCD DTRAssignment of socket TS Parallel optional Unit variants Downloading New MSK33 Operating Software General notes9986498/0206 ZWT Subject to alterations
Top Page Image Contents