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Televes MTD 120, User Manual

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TV & SAT Level Meter   MTD 120

User Manual

4.9.1.4.-  Measuring the Power of Digital Channels (Channel power)

The MTD 120 offers two different methods to measure digital channels power, according to the active operation mode: Automatic method

in TV mode and Integration method in Spectrum mode. The Automatic method measures digital channel power in the measurement filter
bandwidth and estimates total channel power assuming that spectral density is uniform throughout channel bandwidth. On the other hand, the
Integration method takes into account signal spectral distribution so measurement is more accurate (see 4.10.2 Selecting the
Measurements Mode). The obtained readouts using these methods may differ some dBs, specially when the digital signal is degraded.

Figure 9.- Measuring digital power.

On selecting the CHANNEL POWER measurement mode, the screen displays the following information:

Figure 10.- Digital channel power measurement.

In addition to the power of the digital channel (45.8 dBµV in previous figure) this also shows the tuning frequency or channel, depending

on the tuning mode selected, and the parameters regarding bandwidth: Channel BW and measuring filter bandwidth (Measure BW).

For the power measurement of a digital channel to be correct it is essential to have previously defined the channel bandwidth using the

Channel BW function, in the TV mode functions menu (see section '4.9.2.11 Channel Bandwidth’).

CHANNEL POWER

45.8 dBuV

DIGITAL CARRIER:

Frequency 

= 

538.00 MHz

BANDWIDTH PARAMETERS:

Channel BW 

= 

8.00 MHz

Measure BW

=

230      KHz

TV mode

Channel BW

Marker

Spectrum

Channel BW

Marker

Power measurement by integration method

Digital channel power

Mesure BW

Power measurement by the automatic method

Summary of Contents for MTD 120

Page 1: ...TV SAT Level Meter User s manual MTD 120 Ref 4202 Color Ref 4207 B N Bit Error Rate BER ...

Page 2: ...easurement Information 119 4 9 1 1 2 Selecting TV Mode TV LV SY TV MODE 119 4 9 1 2 Measuring the Video Audio Ratio V A 120 4 9 1 3 Measuring the Carrier Noise Ratio C N 121 4 9 1 4 Measuring the Power of Digital Channels Channel power 122 4 9 2 TV Mode Functions Menu 123 4 9 2 1 Selection of the RF Band Band switching 123 4 9 2 2 Selection of the TV System and Standard System Standard 123 4 9 2 3...

Page 3: ...5 4 10 2 2 Measuring the Carrier Noise ratio C N Referenced 135 4 10 2 3 Measuring the Power of Digital Channels Channel Power 136 4 11 Selecting the Sound Mode Sound 137 4 12 Measurement Configuration Memories 138 4 12 1 Storing a Measurement Configuration STORE 138 4 12 2 Retrieving a Configuration RECALL 138 4 13 Direct Access to Functions 139 4 14 Printing Measurements and Memories 139 4 14 1 ...

Page 4: ...annels level C N ratio referenced to a noise frequency defined by the user and digital channels power using an integration method The bandwidth of the measuring filter can be modified to improve frequency resolution This is an indispensable feature as high channel density is present on all transmission systems today Spectrum display can be varied between full span the entire band and 8 MHz terrest...

Page 5: ...OSD window Digital Absolute value calibrated in dBµV dBmV or dBm Analogue Relative value through an analogue bar on the screen Measurement bandwidth 230 kHz Terrestrial band 4 MHz Satellite band maximum band ripple 1 dB Audible indicator LV audio A tone with pitch proportional to signal strength Accuracy Sub band 2 5 dB 50 120 dBµV 5 45 MHz 22ºC 5ºC Terrestrial bands 1 5 dB 30 120 dBµV 48 25 861 M...

Page 6: ...Hierarchy FEC Reed Solomon 204 188 and Viterbi MEASUREMENTS IN TV MODE Terrestrial bands Analogue channels Level Video Audio ratio and Carrier Noise ratio Auto and Referenced Digital channels Channel power Auto and Carrier Noise ratio Auto and Referenced Satellite band Analogue channels Level and Carrier Noise ratio Auto and Referenced Digital channels Channel power Auto and Carrier Noise ratio Au...

Page 7: ...e standard 4 50 5 50 5 80 6 00 6 50 6 65 5 74 AM FM LV OFF Satellite 6 65 5 80 6 50 7 02 LV OFF TELETEXT Decodes at 1 5 level RS 232C INTERFACE EXTERNAL UNITS POWER SUPPLY Through the RF input connector Terrestrial External or 13 15 18 V Satellite External or 13 15 18 V 22 kHz signal Selectable Voltage 0 6 V 0 2 V Frequency 22 kHz 4 kHz Maximum power 5 W DiSEqC GENERATOR According to DiSEqC 1 2 st...

Page 8: ...280 W x 95 H x 250 D mm Weight 5 2 kg INCLUDED ACCESSORIES Rechargeable battery 6 V 3 3 Ah F F BNC F adapter F F DIN F adapter F F F F adapter External DC adapter Carrying bag NOTE BER measurement options of QPSK QAM or COFDM modulated signals vary based on the model of used Measurer ...

Page 9: ...nditions The user is only authorized to carry out the following maintenance operations Batteries replacement On the Maintenance paragraph the proper instructions are given Any other change on the equipment should be carried out by qualified personnel When using the power adaptor the negative of measurement is at ground potential Do not obstruct the ventilation system of the instrument Use for the ...

Page 10: ...ounds 3 1 2 1 Battery Charging To fully charge the batteries connect the instrument to the external DC adapter without pressing the on off key 2 The length of time it takes to recharge it depends on the condition of the battery If they are very low the recharging period is about 12 hours The CHARGER 7 indicator should remain lit IMPORTANT If batteries are completely discharged it is advisable to r...

Page 11: ...ons and entering numeric data Figure 2 Main keyboard 5 ENTER Validation of the different options In TV mode press the ENTER 5 key to display a menu containing different functions some are dependent on the band and the standard Band switching Permits to change from terrestrial 5 862 MHz to satellite band 920 2150 MHz and vice versa A D 0 SHIFT CH F SPECT 1 7 LEVEL 2 FA 8 MODE 3 FB 9 SEARCH 4 MEMORY...

Page 12: ...ol software options installed etc Exit Exits from the function menu In Spectrum Analyser mode the menu displays the following functions Band switching Permits to switch from terrestrial 5 862 MHz to satellite band 920 2150 MHz and vice versa Span Defines the frequency range displayed between Full the entire band 500 MHz 200 MHz 100 MHz 50 MHz 32 MHz 16 MHz and 8 MHz the latter two only for terrest...

Page 13: ... 2 to enter numeric data 23 MODE Selects the information displayed on screen in TV operation mode LV measurement Key number 3 to enter numeric data 24 SEARCH This is the function for automatic station search Starting at the present frequency or channel it searches until finds a station with an adequate level The threshold level search level can be defined by means of the TV mode functions menu bet...

Page 14: ... key for moving across different fields on some screens Figure 3 Side panel connections 35 RF RF signal input Maximum level 130 dBµV Universal connector for F F or F BNC adapter with input impedance of 75Ω ATTENTION Note the importance to protect the RF 35 input signal with an accessory to block the AC voltages used in CATV cables needed to feed the amplifiers and remote mode 36 RESET button Enabl...

Page 15: ...memory with a tuning frequency belonging to the band you wish to access See section 4 12 Measurement Configuration Memories 4 5 Channel Tuning Frequency Tuning Pressing key CH F 30 the MTD 120 switches from frequency tuning to channel tuning and back again In channel tuning mode pressing keys 6 sequentially tunes the channels defined in the active channels table see the Channel set function in the...

Page 16: ... mode the unit powering the amplifiers before the antenna terrestrial television or the satellite TV receiver house hold or community also powers the external units The DRAIN 9 indicator lights when current is flowing to the external unit If any kind of problem occurs e g a short circuit an error message appears on the monitor SUPPLY SHORT the acoustic indicator will be heard and the instrument wi...

Page 17: ...h To measure it correctly it is indispensable to define the Channel BW C N Two methods selectable through the C N setup function Auto Out channel measurement Noise level is measured at fnoise ftuning 1 2 Channel BW To measure it correctly digital channel must be tuned at its central frequency Referenced The user defines the frequency where noise level will be measured by means of the Reference noi...

Page 18: ... dBµV their equivalent level will be 90 dBµV 10 log 10 100 dBµV Observe that in this case loss of tuning by overload of the RF input may occur besides other effects such as tuner saturation and generation of intermodulation products that may mask the spectrum visualization 4 9 1 1 1 On screen Measurement Information In TV operation mode the measurement information to be displayed on screen is sele...

Page 19: ...ars which indicates the level of the signal received 79 dBµV in figure 6 example On the left side the line synchronising pulse is represented as it would appear on the screen of an oscilloscope On the lower side the TV picture is shown Figure 6 Line synchronism level TV TV LV SY Starting from the line synchronism representation it is possible to perform a qualitative analysis of the TV picture del...

Page 20: ...ith an average detector and corrected to refer it to channel bandwidth according to the standard in use B Terrestrial band digital carrier Both measurements are done with an average detector 230 kHz and the same corrections are introduced on them bandwidth corrections C Satellite band analogue carrier Carrier level is measured using a quasi peak detector 4 MHz BW Noise level is measured with an av...

Page 21: ...egraded Figure 9 Measuring digital power On selecting the CHANNEL POWER measurement mode the screen displays the following information Figure 10 Digital channel power measurement In addition to the power of the digital channel 45 8 dBµV in previous figure this also shows the tuning frequency or channel depending on the tuning mode selected and the parameters regarding bandwidth Channel BW and meas...

Page 22: ...d standard to be changed The standards which can be selected depend on the band in use terrestrial or satellite channels To change the standard access the TV mode functions menu then use keys 6 to select the System Standard function and press key ENTER 5 A fold down menu will appear listing the following options Terrestrial bands Satellite band PAL B G PAL PAL D K SECAM PAL I NTSC PAL M Digital PA...

Page 23: ...ion allows the user to carry out store and or print out up to 9801 measurements in a fully automatic way It may be understood as a measurement matrix whose columns address the 99 measuring configurations defined in the 99 memories of the equipment and whose lines permit to store 99 measurements for every measuring configuration conducted in different points of the system or in the same point on di...

Page 24: ... logger function main screen 1 TO MEASURE PRINT OR MEASURE AND PRINT First of all the user must indicate whether he wants to take measurements or to print them or to do both at the same time To do this press key SHIFT 31 repeatedly until positioned in the Measure field Then use keys 6 to activate On or deactivate Off the measurement function and press key SHIFT 31 The next step is to activate or d...

Page 25: ...he Data logger configuration screen repeatedly press key SHIFT 31 until the section dealing with time in the Measure interval field has been activated define the hours by using keys 6 then press key SHIFT 31 again to go to the minutes field and define these in the same way Finally press key SHIFT 31 again to validate the defined time interval You can make as many acquisitions as there are activate...

Page 26: ...asurement matrix row has been previously activated the bottom of the screen will show the error message NOT CELLS SEL No cells selected b Acquisition of different measurements at the same moment Multiple measurements in a row will be taken as specified by the measurement configurations defined in all the activated columns Process place the cursor on the row you want and press key ENTER 5 until the...

Page 27: ...e monitor will show a screen labelled INPUT VIDEO displaying the three available options as well as the Exit option Press keys 6 to select the mode you require then press key ENTER 5 to activate it 4 9 2 7 Selecting the Channels Table Channel set The MTD 120 comes with twelve stored channel tables as standard four for terrestrial television and eight for satellite for greater adaptability to the s...

Page 28: ... be entered using the keyboard The frequency of the LNB local oscillator is expressed in MHz with 5 figures for the whole part a decimal point and a decimal figure which acts as confirmation For example to select 9 GHz the number 9000 0 has to be entered Values must be defined between 8000 0 and 12000 0 4 9 2 13 Video Polarity This option affects reception of SAT satellite band signals It allows s...

Page 29: ...utomatically at its right to change it press keys 6 and to validate it press key ENTER 5 see DiSEqC commands table Once the DiSEqC command is defined the cursor will pass to the following line if you want to define a new command proceed as for the first one if you do not want to add any command press key SHIFT 31 After the commands sequence is created it is possible to modify it To modify the sequ...

Page 30: ...ss keys 6 to select the Equipment Info function and press key ENTER 5 The monitor will show the EQUIPMENT INFO screen listing several informations such as the instrument serial number Serial Number the version of the control program Version etc To exit the function press key ENTER 5 4 9 2 20 Exit Exits from the TV functions menu Character Command Associated parameter General Sat A B A B Reset Powe...

Page 31: ...or the best orientation and position of the receiving antenna This is particularly important in UHF Because such frequencies are involved with wavelengths ranging from 35 cm to 65 cm if the antenna is shifted only a few centimetres the relationship between the picture chrominance and sound carrier frequencies change affecting the quality of the picture in the receiver If there is an excess of soun...

Page 32: ...rence level is 70 dBµV To alter the value of the reference level select the Spectrum Analyser mode functions menu press keys 6 to select the Reference level function and press key ENTER 5 The screen will show a window with the values which can be selected Press keys 6 to select the desired reference level and activate it by pressing key ENTER 5 again 4 10 1 4 Dual Marker Single Marker Only for lev...

Page 33: ...r defining the Reference noise Permits to change the tuning frequency by means of keys 6 4 10 1 10 Bandwidth of the Spectrum Measuring Filter Measure bandwidth The frequency resolution of the Spectrum Analyser mode is determined by the bandwidth of the measuring filter when displaying the spectrum This parameter is fundamental given the increasing density of channels present in all TV transmission...

Page 34: ...oise function Like in the TV mode to select the type of measure press key LEVEL 22 then press keys 6 until desired mode is marked and finally press key ENTER 5 or key LEVEL 22 to activate the new measurement mode 4 10 2 1 Measuring Carrier Levels Level Only for analogue channels When selecting this mode on the lower part of the image appears the tuned frequency or channel and the signal level at t...

Page 35: ...llowing figure channel bandwidth is 8 MHz defined by the markers If channel power is measured in TV operation mode different readouts will be obtained depending on the tuned frequency measurement filter bandwidth is 230 kHz if tuning is shifted from 759 MHz to 762 MHz reading will increase in several dB Figure 21 Channel power measurement in Spectrum Mode When measuring Channel power on the lower ...

Page 36: ...nt information displayed on the screen name assigned to memory power supply to external units sound colour system TV standard level and frequency channel In the position relative to the type of Sound will appear the information about the type of NICAM according to Sound Type Error Type NICAM type no NICAM is detected du dual NICAM st stereo NICAM mo mono NICAM Error indication of the bit error rat...

Page 37: ... corresponds to the column headings of the Data Logger function If a configuration is stored in a memory location already containing information that data will be lost 3 Optional If you wish to assign a name to a memory position press key SHIFT 31 the first character of the name will blink press keys 6 and the different characters will appear in the first position of the configuration name When yo...

Page 38: ...s for analysis purposes The installation process consists of simply using the data transfer cable to connect the printer to the RS 232C connector 37 on the MTD 120 see section 4 14 1 Handshake and control lines Switch off the power to both instruments before connecting To print measurements select the Data logger function on the functions menu see section 4 9 2 4 Data Logger function access the co...

Page 39: ...ine is permanently active in order to indicate the establishment of the communication Connections The cable between the MTD 120 and the printer must have the following connections Figure 25 Connector RS 232C MTD 120 Pins numbering 12345 6789 140 TV SAT Level Meter MTD 120 User Manual PC CONNECTOR LEVEL METER CONNECTOR Type D 25 female Type D 9 female SHIELD GROUND 1 DATA TRANSMIT 2 2 DATA RECEIVE ...

Page 40: ...appear on the screen 1 Modulations It defines the modulation type When selecting this function and pressing key ENTER 5 a multiple choice menu will appear on the screen this menu permits to choose one of the following modulations 16 32 64 128 and 256 2 Symbol Rate When selecting this function and pressing key ENTER 5 a multiple choice menu will appear on the screen this menu permits to choose one ...

Page 41: ...packets received wrong packets up to a maximum of 126 in the time detailed on its right A packet is considered wrong when one at least non corrigible bit is detected To reset this measurement just modify the measurement conditions for example change the tuned frequency Finally it is shown a status line which displays information about the detected signal The possible messages that can appear and i...

Page 42: ...s to select attenuation between 0 and 30 dB It is advisable to activate the 30 dB attenuator under that measurement conditions where the signal level is near to the maximum input level approximately starting from 20 dB under the maximum level and it is possible that the tuner becomes saturated Under no saturation conditions when increasing the attenuation value the BER measure must to maintain or ...

Page 43: ...n appear and its meaning are shown in the following list The messages are exposed from less to more fulfilment of the MPEG 2 standard No signal received Any signal has been detected Signal received A signal is detected but it can not be decoded Carrier recovered A digital carrier has been detected but it can not be decoded Viterbi synchronized A digital carrier has been detected and the Viterbi al...

Page 44: ...nes the ratio between the data bits number and the total number of bits transmitted the difference corresponds to the number of control bits for the error detection and recovery Modulations Carriers modulation It also defines the system noise immunity QPSK 16 QAM and 64 QAM Spectral Inv Defines the state of the spectral inversion Hierarchy The DVB T norm contemplates the possibility to make a DTT ...

Page 45: ...in it will activate with no reset When during any measuring time interval the counter has been deactivated in other words the signal has not satisfied the MPEG 2 requi rements the presentation of this counter will alternate with another counter titled FAIL This second counter shows the time that the detected signal has not fulfilled the MPEG 2 standard requirements 12 seconds in the example of the...

Page 46: ...ation related to the transmission modulation and codification Modulation type QPSK 16 QAM 64 QAM Hierarchy Guard Interval Viterbi Code Rate Transmission mode 2k or 8k and Number of the received frame MPEG 2 Correct detection of a MPEG 2 signal In case of detecting a DVB signal message MPEG 2 DVB T will appear and the DVB Channel Identifier function will be automatically activated See section 5 6 D...

Page 47: ...are not transmitted at the same time but they appear alternatively in different packets Besides the cadence of presentation of each one of these packets may vary from one operator to another When tuning a DVB compatible transponder the DCI function DVB Channels Identifier detects those data packets including service information relative to these three fields and shows on the lower line on the scre...

Page 48: ...for data exchange with a PC a serial printer or to other devices The signals in this connector are described in Table 5 Figure 34 RS 232C connector External view PIN No SIGNAL CHARACTERISTICS 1 Carrier Detect not connected 2 Data Request RxD 3 Data Transmit TxD 4 Data Transmission Ready DTR Fixed at 12 V 5 Ground GND 6 Data Send Ready DSR not connected 7 Request To Send RTS 8 Clear To Send CTS 9 R...

Page 49: ...eft channel audio output 14 Digital bus reserved not connected 4 Audio grounding 15 Red output R 5 Blue grounding B 16 Blanked signal not connected 6 Left channel audio input 17 Composite video grounding 7 Blue output B 18 Blanked return not connected 8 Switching voltage 19 Composite video output 9 Green grounding G 20 Video input 10 Digital bus interface not connected 21 Connector shield groundin...

Page 50: ...nal fuses which user cannot replace The following fuses are found on the base board Their location identifier and characteristics are the following F4 F5 5 A F 63 V SMD F3 1 A F 63 V SMD 7 3 Replacing the Batteries Batteries must be replaced whenever the capacity of the fully charged batteries is noticeably diminished To change the batteries follow next procedure Figure 37 Battery compartment Remo...

Page 51: ... battery compartment into the back of the MTD 120 and secure with the five screws A If you wish replace the holster 7 4 Cleaning Recommendations The cover should be cleaned by means of a light solution of detergent and water applied with a soft cloth Dry thoroughly before using the system again CAUTION Do not use for the cleaning of the front panel and particularly the viewfinders alcohol or its d...

Page 52: ... 847 25 69 855 25 Ch Freq 1 49 75 2 59 25 3 77 25 4 85 25 5 93 25 SK1 111 25 SK2 119 25 SK3 127 25 SK4 135 25 SK5 143 25 SK6 151 25 SK7 159 25 SK8 167 25 6 175 25 7 183 25 Ch Freq 8 191 25 9 199 25 10 207 25 11 215 25 12 223 25 SK11 231 25 SK12 239 25 SK13 247 25 SK14 255 25 SK15 263 25 SK16 271 25 SK17 279 25 SK18 287 25 S19 295 25 S20 303 25 Ch Freq S21 311 25 S22 319 25 S23 327 25 S24 335 25 S2...

Page 53: ...12051 84 12090 86 12129 88 12168 Ch Freq 90 12207 92 12246 94 12285 96 12324 Ch Freq 98 12363 100 12402 102 12441 104 12480 Ch Freq 106 12522 108 12552 110 12581 112 12610 Ch Freq 114 12640 116 12670 118 12699 120 12728 EUT13 HL Ch Freq 111 10722 113 10775 115 10815 117 10853 Ch Freq 119 10892 121D 10914 121A 10933 123 10974 Ch Freq 125 11009 127 11054 129 11095 131 11148 Ch Freq 131b 11178 1D 112...

Page 54: ...RONICA PORTUGUESA MAIA OPORTO Via Dr Francisco Sa Carneiro Lote 17 ZONA Ind MAIA 1 Sector X MAIA C P 4470 BARCA Tfno 351 2 9418313 Fax 351 2 9488719 9416180 E mail televes pt televes com LISBOA C P 1000 Rua Augusto Gil 21 A Tfno 351 1 7932537 Fax 351 1 7932418 E mail televes lisboa pt televes com TELEVES UNITED KINGDOM LTD Unit 11 Hill Street Industrial State CWMBRAN GWENT NP44 7PG United Kingdom ...

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