LCD SCOPE 400WVA

MULTI-FORMAT WAVEFORM VECTOR

AND AUDIO MONITOR

OPERATOR'S HANDBOOK

ISSUE D5

© 2008 Hamlet Video International Ltd.

All rights reserved

This handbook contains proprietary information of Hamlet Video International Limited and may not be copied in whole or in part nor its contents disclosed to any third parties without the express written consent of the company.

Corporate Head Office

Hamlet Video International Limited.

Maple House, 11 Corinium Business Centre, Raans Road, Amersham, Bucks HP6 6FB England.

Main Line: +44 (0)1494 729 728, Fax Line: +44 (0)1494 723 237, Free phone (UK): 0500 625 525

E-mail: [email protected] Web site: www.hamlet.co.uk

Hamlet USA

Sencore, Inc. 3200 W Sencore Drive, Sioux Falls SD 57107, U.S.A. Phone: (605) 339-0100 Fax: (605) 339-

7032 Toll Free: 1-800-SENCORE (736-2673) or 1-866-4-HAMLET (426-538)

Email: [email protected] Web site: www.hamlet.us.com

IN CORRESPONDENCE CONCERNING THIS INSTRUMENT

PLEASE QUOTE THE SERIAL NUMBER PRINTED ON THE

LABEL AT THE REAR OF THE UNIT

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CONTENTS

LIST OF FIGURES 5

GENERAL INFORMATION ..........................................................................

6

WARRANTY 6

SAFETY COMPLIANCE 7

PRODUCT DISPOSAL INSTRUCTIONS

FRONT .......................................................................... 8

VIEW .......................................................................... 9

OVERVIEW 10

OPERATING INSTRUCTIONS .........................................................................

INSTALLATION 11

GETTING STARTED 12

OPERATING INSTRUCTIONS .........................................................................

VIDEO SOURCE SELECTION 13

SYNC REFERENCE SOURCE SELECTION ......................................................................... 13

VIDEO WAVEFORM MEASUREMENTS .............................................................

VIDEO TIMEBASE RANGES 13

WAVEFORM PARADE 13

LINE SELECTION 13

TO MEASURE VIDEO 'OUT OF GAMUT' LEVELS ............................................................. 14

TO CHANGE THE VIDEO GAIN 14

BOWTIE DISPLAY 14

COMPOSITE DISPLAY FROM SDI SOURCE ......................................................................... 14

VIDEO VECTOR MEASUREMENTS ......................................................................... 14

TO CHANGE THE VECTOR GAIN 14

DISPLAY ADJUSTMENTS ......................................................................... 14

TO CHANGE THE DISPLAYED VIDEO

TO CHANGE THE DISPLAY PERSISTENCE ......................................................................... 15

TO FILTER THE DISPLAYED VIDEO WAVEFORM ............................................................. 15

REMOTE CONTROL

LIST OF KEY COMMANDS

LIST OF ROTARY COMMANDS

ADDITIONAL FUNCTIONS

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TO START THE UNIT IN A KNOWN STATE ............................................................. 17

TO STORE AND RECALL USER SETTINGS ............................................................. 17

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SOURCE ......................................................................... 17

BATTERY CHARGING ......................................................................... 17

AUDIO ......................................................................... 18

TO SELECT THE AUDIO SOURCE ......................................................................... 18

CALIBRATION ......................................................................... 19

TECHNICAL SPECIFICATION ......................................................................... 20

TROUBLE SHOOTING ......................................................................... 22

BASICS ......................................................................... 23

FIG 8SC-H RELATIONSHIP ......................................................................... 25

SC-H RELATIONSHIP

SERIAL DIGITAL BASICS

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DIGITAL ERROR DETECTION OVERVIEW ............................................................. 28

EMBEDDED AUDIO OVERVIEW ......................................................................... 29

USEFUL WEBSITES ......................................................................... 33

CONTACT DETAILS AND CUSTOMER SUPPORT ................................................. 33

4

Fig 1 Front View

Fig 2 Rear View

Fig 3 Getting Started

Fig 4 Getting Started - Screen

Fig 5 Audio Switch

Fig 6 Audio Scales

Fig 7 PAL Basics

Fig 8 NTSC Basics

Fig 9 Serial Digital Basics

Fig 10 625 Field Blanking

Fig 11 525 Field Blanking

LIST OF FIGURES

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5

GENERAL INFORMATION

WARRANTY

This product is manufactured by Hamlet Video International Ltd and is warranted to be free from defects in components and factory workmanship under normal use and service for a period of one year from the date of purchase.

FREE EXTENDED WARRANTY

The warranty period can be extended to two years by registering the instrument on the

Hamlet web site http://www.hamlet.co.uk/serv.html

TERMS AND CONDITIONS

During the warranty period, Hamlet Video International Ltd will undertake to repair or at its option, replace this product at no charge to its owner when failing to perform as specified, provided the unit is returned shipping prepaid, to the factory or authorised service facility.

No other warranty is expressed or implied. Warranty shall not be applicable and be void when this product is subjected to:

1. Repair work or alteration by persons other than those authorised by Hamlet Video

International Ltd in such a manner as to injure the performance, stability, reliability or safety of this product.

2. Misuse, negligence, accident, act of God, war or civil insurrection.

3. Connection, installation, adjustment or use otherwise than in accordance with the instructions in this manual.

Hamlet Video International Ltd reserves the right to alter specifications without notice.

This warranty does not affect the statutory rights of the UK customer.

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GENERAL INFORMATION

SAFETY COMPLIANCE

This product is manufactured and tested to comply with BS EN 61010-1 : 1993

Safety requirements for electrical equipment for measurement, control and laboratory use.

EMC COMPLIANCE

We, Hamlet Video International Limited, Maple House, 11 Corinium Business Centre, Raans

Road, Amersham, Bucks, HP6 6FB, England, declare under our sole responsibility that the product HAMLET LCDSCOPE 400WVA to which this declaration relates is in conformity with the following standards:

EN50081-1 Generic emissions standard for light industrial applications.

EN50082-1 Generic immunity standard for light industrial applications.

Following the provisions of EU EMC directives 89/336/EEC and 92/31/EEC.

NOTE. During the EMC certification of this product, shielded cables were used.

We recommend that they be used in operation.

PRODUCT DISPOSAL INSTRUCTIONS

The symbol shown above and on the LCDSCOPE 400WVA means the product is classed as Electrical or Electronic Equipment and should not be disposed with other commercial waste at the end of its working life. The Producer Registration Number above,

WEE/GJ0146QT proves that Hamlet are formally registered with a legally approved

Compliance Scheme. The Scheme we are registered with is called "B2B Compliance".

B2B Compliance takes on the legal responsibilities of the reporting on, and the collection and treatment of, all WEEE that Hamlet Video International Limited is obliged for - and ensures that the appropriate recycling targets are met on this WEEE

The Waste of Electrical and Electronic Equipment (WEEE) Directive (2002/96/EC) has been put in place to recycle products using best available recovery and recycling techniques to minimise the impact on the environment, treat any hazardous substances and avoid the increasing landfill.

Product disposal instructions for business users.

Business users in the EU should contact their LCDSCOPE 400WVA supplier to arrange for its return to Hamlet head office in the UK, who will safely dispose of it and ensure that this

Hamlet MS9000 is not mixed with other commercial waste for disposal.

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FRONT VIEW

Fig 1

8

REAR VIEW

Fig 2

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OVERVIEW

The Hamlet LCD SCOPE is a 3U high half width 19" rack mounting monitor designed to fit into standard rack enclosure.

The base unit accepts analogue composite (PAL/625 and NTSC/525) video, YC video and component video (YCrCb or RGB). It displays the waveforms on a quarter VGA high contrast liquid crystal display. All the standard displays are produced, including H and V

Mag, Line Select, Component Parade, Filter Parade and Bowtie. There is an additional display of RGB gamut from the component or SDI inputs and front panel warning lights and alarm for signals above peak white or below black.

Proprietary digital signal processing produces displays with the look of a CRT but without the problems of scan burn, EHT problems etc. The very low power consumption also allows it to be used in the field from external 12V or its own internal rechargeable batteries.

An additional feature is displays of composite and component vectors. There are also displays of four channels of audio and a vector audio phase display. There is a headphone monitor output jack.

A further option card provides an SDI digital component video input. This also contains an audio de-embedder, which displays on the audio bar graphs and is output to the audio monitor jack.

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OPERATING INSTRUCTIONS

INSTALLATION

UNPACKING

The LCDSCOPE is shipped from the factory in a specially constructed packing case.

Exercise caution when unpacking the unit to prevent damage to the case finish. Examine the unit carefully for damage, which may have occurred during shipment

MOUNTING INSTRUCTIONS

Hamlet can supply rack mount kits to fit the unit into a standard 19 inch equipment rack, where it occupies half the rack width and 3U of height. The unit itself generates little heat and does not need forced ventilation, but heat generated from adjacent units should not cause the case temperature to rise above 50 deg.C.

POWER REQUIREMENTS

The LCDSCOPE should be powered from the supplied adaptor or a regulated supply of

12VDC of at least 1 amp rating to 2.1mm power socket.

SIGNAL AND CONTROL CONNECTIONS

Video input and output cable connections are made to BNC sockets on the rear panel, with

YC video to 4 pin mini din sockets. All video loops should be terminated with 75 ohms.

Audio input is to 3 pin XLR sockets. To utilise all the LCDSCOPE functions, the video inputs, audio inputs and external reference (video or syncs) should all be wired.

CHECKOUT FOR INITIAL USE

After installation as above, switch on the LCDSCOPE and operate each control in turn, verifying correct response as described in the operating instructions.

PREVENTATIVE MAINTENANCE

The Hamlet LCDSCOPE should be visually inspected, cleaned and the calibration checked every one year of operation.

CAUTION.

The front panel is made from polycarbonate, which may soften if cleaned with some organic solvents. Do not allow water to get inside the equipment case.

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GETTING STARTED

1.

2.

3.

Connect the supplied 12V power adaptor output to the rear 2.1mm input jack.

Apply AC mains (100 - 250VAC) to the power adaptor.

Connect a composite video feed to the rear CST input BNC and apply a 75 ohm terminator to the CST loop BNC.

4. Hold down the front panel INPUT button whilst pressing the ON button, see fig 3.

This starts the LCDSCOPE in a pre - programmed state, see fig 4. When the unit is subsequently turned on, it will remember the panel settings used previously.

Fig 3

Fig 4

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OPERATING INSTRUCTIONS

VIDEO INPUT

Video Source Selection

Pressing the INPUT button toggles between the four input formats and the format is displayed on-screen.

Connect composite signals (PAL or NTSC) to the rear CST BNC. CST loop must be terminated with 75 ohms.

Connect component signals to the Y/Gin, Cb/Bin and Cr/R BNCs. A rear dip switch selects

YCrCb or RGB component input formats and input terminations. RGB mode should not be used with an SDI source as this is always in Y,Cb,Cr format.

If the digital video card is fitted, connect an SDI video signal to the rear SDIin BNC. An active (re-equalised) loop output is available from the rear SDI loop BNC.

Sync Reference Source Selection

To select which is to be used, press the EXT-REF key, this key toggles between the three options, INTERNAL, EXTERNAL and HFT™ (hands free timing) which alternates between internal and external every second to facilitate synching two sources. The sync source is displayed on-screen.

The reference signal can be derived from the signal being used (internal) or from an analogue reference of video or sync (external) applied to the rear BNC labelled EXT IN.

EXT loop must be terminated with 75 ohms.

Video Waveform measurements

Video Timebase Ranges

1H, 2H or H magnified are selected by pressing the H RANGE key.

1V or V magnified is selected by pressing the V RANGE key.

Waveform Parade

Pressing the PARADE key gives a 3H display of Y,Cr,Cb or RGB from component sources or Flat, Low Pass, Chroma Pass from composite sources.

To switch the unit between the standard YCrCb parade and RGB parade, switch on the unit while holding down the PARADE key.

Line selection

This mode is selected by pressing LINE SEL and shows two lines. The line number is selected by turning the horizontal shift rotary control. The line and field numbers are displayed on-screen and relate to the left line.

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OPERATING INSTRUCTIONS

To measure video 'Out of Gamut' levels

With a component input, pressing the GAMUT key produces an additional display on the right of the screen. This is a 1H display of R, G, and B superimposed. Two graticule lines indicate the black and peak white levels required for the video to remain within gamut.

The gamut alarm sounder is enabled/disabled by holding down the GAMUT key for more than one second. The letter A is displayed bottom right of the screen when enabled. The key operates when released.

Due to the predominance of 75% colour space, the 525 line gamut screen can be configured to display a Y low pass signal rather than R, G, B.

To change the Video Gain

Video gain can be changed from normal (x1) to expanded (x3.33) by pressing the video

GAIN key. The current setting is displayed on the front panel CAL and MAG lights.

Bowtie display

If a bowtie signal is available, accurate amplitude and timing measurements may be made.

Press the BOWTIE key and set the unit to MAG GAIN mode for optimum resolution.

The BOWTIE key toggles between (Y - U), (Y - V) and Bowtie OFF.

Composite display from SDI source

When viewing an SDI source, the component video signal can be viewed as a composite waveform by selecting CPASS mode.

VIDEO VECTOR MEASUREMENTS

To change the Vector gain:

PAL/625 vector gain can be toggled between 75% bars, magnified (x3.33) and 100% bars by pressing the vector GAIN key. The current setting is displayed on the front panel CAL and

MAG lights. NTSC/525 does not have the 100% option and is set up for Beta Cam levels.

The PAL SW key toggles the PAL switch defeat on and off.

DISPLAY ADJUSTMENTS

To change the displayed video

To change the overall brightness, rotate the front panel BRIGHT control.

To change the graticule intensity, rotate the front panel SCALE control.

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To change the display persistence

Pressing the front panel FRZ/STO key toggles between:

'Persistence ON', 'Persistence OFF and Freeze ON' and 'Both OFF'.

To filter the displayed video waveform

Pressing the front panel FILTER key switches between flat, low-pass and chroma pass filters.

The filter state is displayed on screen.

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REMOTE CONTROL

To remote control the unit via the RS232 interface: Data is sent on a 3 wire implementation of RS-232 ie Tx, Rx and Gnd. Data type is 8 bits, no parity, 1 stop bit. The baud rate is 9600.

All commands consist of a single byte and are equivalent to pressing a key on the front panel.

List of Key commands

--------------------------------------------------

INPUT 115

FRZ/STO 179

GAMUT 64

SEL

FILTER 113

List of Rotary commands

Key Byte value (decimal)

-----------------------------------------------------------------------------------------------

HORIZONTAL SHIFT CONTROL MOVES 1 STEP CW

HORIZONTAL SHIFT CONTROL MOVES 1 STEP ACW

1

2

VERTICAL SHIFT CONTROL MOVES 1 STEP CW

VERTICAL SHIFT CONTROL MOVES 1 STEP ACW

PHASE SHIFT CONTROL MOVES 1 STEP CW

PHASE SHIFT CONTROL MOVES 1 STEP ACW

SCALE CONTROL MOVES 1 STEP CW

SCALE CONTROL MOVES 1 STEP ACW

BRIGHT CONTROL MOVES 1 STEP CW

BRIGHT CONTROL MOVES 1 STEP ACW

3

4

5

6

7

8

9

10

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ADDITIONAL FUNCTIONS

To start the unit in a known state

Powering on the unit normally will recall the settings previously used, but if previous settings were non standard, factory set mode can be established to allow faster use.

With the power switched off, press the front panel INPUT button whilst powering up the unit.

It will then be in the following mode:

TIMEBASE: H CAL: OFF

To store and recall user settings

When the unit is switched off the current setting are stored and then recalled when the unit is switched on again. In addition, ten sets of front panel setting can be stored for later recall.

To Store Settings:

When the unit is set up as required press the front panel STR/REC key twice, then press a key

0...9 to store the settings at that location.

To Recall the settings:

Press the front panel STO/REC key once, followed by the required location number 0...9.

Power Source

The LcdScope can be powered from the supplied adaptor, providing 12V @1 amp regulated, or from the internal 1.5Ahr NiMh rechargeable batteries.

Set the rear POWER switch to the upper INT position to use the internal batteries or to the lower EXT position to use external power.

Battery Charging

When external power is supplied, and the POWER switch is in the lower EXT position, the batteries are automatically charged, whether or not the unit is switched on.

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AUDIO

Fig 5

To select the audio source

The displayed audio is taken from the rear XLR connectors, except when digital video is selected, when it is de-embedded from the video. A rear panel dip switch selects one of the four audio groups.

To select audio scales

A rear panel dip switch selects one of four audio scales:

Fig 6

Audio Vectors

Press the front panel AUD key to switch between video and audio vector display.

Audio output

A professional jack socket is provided on the rear panel, together with a volume control, to monitor the displayed audio signal.

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CALIBRATION

The unit is calibrated and tested before leaving the factory and should not normally need to be changed.

If calibration or testing is required:

On the front panel board - Set CV101 master clock frequency for 2.0V at R110

On the main bottom board - Set RV401 for 700mV waveform cal signal

Set RV407 for 100% vector cal circle

Set CV401 for flat waveform response

Set RV409 for waveform Cal gain

Set RV408 for waveform Mag gain

Set RV403 for centre null on bowtie display

Set L402 for minimum chroma on Low Pass display

Set L403 for highest chroma Pass display

Set RV404,405,406 for balanced gamut RGB display

Set RV410 for vertical position of gamut display

On the Audio board -

On the SDI board -

Set RV301, 302,303,304 for audio bar calibration

Set RV305 for bar bottom position

Set RV306,307 for audio vector centering

Set RV312, 313 for overall vector gain

Set RV311 for vector horizontal centering

Set L301 for straight lines between the vector dots

Set RV309 for composite vector gain

Set RV310 for composite vector width

Set CV301 for PAL vector lock

Set CV302 for NTSC vector lock

Set RV314 for minimum vector jitter

Set L302 for PAL 90 degree

Set CV303 for NTSC 90 degree

Set RV501, 502,503 for 700mV Y,Cb,Cr levels.

In 525 mode, the board outputs Betacam levels of 1V p/p from the Cr and Cb channels. This should be adjusted to 700mV to give correct vector and bowtie displays.

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TECHNICAL SPECIFICATION

INPUTS

Composite input. BNC connector with loop through output. Return loss better than

40dB. Zin of 22k. Max dc +/- 3 volts.

YC input. 4 pin mini din socket with loop through output. Return loss better than

40dB. Zin of 22k. Max dc +/- 3 volts.

Component input. 3 x BNC connectors with switchable terms. Return loss better than

40dB. Zin of 75R or 22k. Max dc +/- 3 volts. YCrCb or RGB.

Serial digital input. BNC connector. Input impedance 75 ohms. Max d.c. +/- 10V.

SMPTE 259M, ITU-R BT.601/656 serial component. 800mV pp

+/-10% auto equalised up to 300 metres of cable.

Serial digital output. BNC connector. Output impedance 75 ohms. Equalised version of the

External ref input. BNC connector with loop through output. Return loss better than

40dB. Zin of 22k. Max dc +/- 3 volts.

AUDIO

4 x Analog balanced inputs. Zin 22K.

AUDIO MONITORING OUTPUT

Quarter inch professional stereo jack.

REMOTE CONTROL

9 pin D socket for GPI, data up/down load and remote control. RS232 bits, no parity, 1 stop bit. Baud rate selectable to 9600, 4800, 2400, 1200.

Pin 1 GPI, closure to common.

Pin 4 Joined to pin 6.

Pin 2 RS232 output. Pin3 RS232 input.

Pin 6 Joined to pin 4.

Pin 7 Joined to pin 8. Pin 8

POWER

10 to 13V d.c. to 2.1mm jack. 1A max.

Joined to pin 7.

ENVIRONMENT

Indoor use, 5 to 45 deg.C. ambient to 2,000m.

Max humidity 80% to 31 deg.C decreasing to 50% at 40 deg.C.

Overvoltage category 2. Pollution degree 1.

Weight 2.5Kg.

Pin 9 n/c.

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DISPLAY AREAS

Display

Waveform

Audio/Gamut area

WAVEFORM MONITOR

Response

Timebase

TECHNICAL SPECIFICATION

100mm x 75.5mm viewing area.

256 pixels wide x 240 pixels high.

64 pixels wide x 240 pixels high.

Flat is +/- 0.5% 50Hz to 5.5MHz.

Low Pass is -3db @ 1.5MHz, -60db @ 6.75MHz.

H, 2H and Hmag (x5).

VECTOR MONITOR

Video

Audio

Line select is any line from the frame.

Parade is a 3H display of input or filter parade.

Traditional component or composite display.

Component accuracy 0.2%. Bandwidth 3.375MHz .

Composite accuracy 1%. Bandwidth 1.3MHz .

Stereo phase display of left or right audio pair.

Gamut

AUDIO MONITOR

Accuracy

Characteristics

Poly™ display of RGB signal shows up illegal colours.

Better than 0.1db over full scale range.

BBC, EBU, Nordic and VU.

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TROUBLE SHOOTING

Unit appears dead:

Check that the 12V supply adaptor is plugged into the unit and that this is plugged into an operational mains supply.

No display:

Turn up the BRIGHT control (clockwise).

No video displayed:

If there is no video signal connected to the selected input, the screen will display the graticules only:

Unusual display:

The unit may be set to a non-standard mode. Press STO/REC and then one of the numbered buttons to recall a stored setting. If this does not cure the display, reset the unit as follows.

Turn off, and then turn on again whilst holding down the front panel INPUT key.

Displays not locked:

May be in external reference mode. Press the front panel EXT REF key to cancel. This may need pressing twice to step through the HFT mode.

No vector display:

Audio vectors may have been selected. Press the front panel AUD button to cancel.

Distorted component vector display:

May be due to selection of the wrong input component format. Check the rear dip switch setting for RGB/YCrCb.

No audio bar graph display:

May be in video gamut mode. Press the front panel GAMUT key to cancel.

Alarm sounding:

This is the video gamut alarm. Hold down the front panel GAMUT key for one second. The letter A should disappear from the bottom right of the screen to show that the alarm is now disabled.

No Audio indication:

Check that the rear dip switch setting corresponds with the audio input applied.

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ANALOG BASICS

COMPONENT COLOUR

The colour picture can be distributed in two forms, whether in 625 or 525 line standards:

RGB

This is the basic signal produced by a camera etc and fed to a colour c.r.t. It consists of three primary signals, R ed, G reen and B lue. By convention, black level is at 0mV and peak brightness is at + 700mV.

YCrCb

As the human eye can see less resolution with colours, the video can be modified to take advantage of this to reduce the amount of information needed. The picture is separated into monochrome and colour components. The monochrome Y signal is formed from:

Y = (0.3 x Red) + (0.59 x Green) + (0.11 x Blue) approximately.

This signal has black level at 0mV and maximum white level at + 700mV.

The colour components are two colour difference signals:

Cr = (R-Y) and Cb = (B-Y)

These are weighted to give maximum values of +/- 350mV and are bandwidth restricted to half that of the Y component.

PAL

Fig 7 shows an encoded 100% colour bar signal. The two colour components of Cr and Cb are used to amplitude modulate a 4.43361875Mhz carrier signal. The two carriers are arranged to be 90 degrees apart before they are combined with the Y luminance signal, so that they can be decoded separately. The PAL system is designed to minimise hue errors by phase reversing the Cr axis on alternate lines ( P hase A lternate L ine). This reversal is copied by the decoder, so that the hue error will now alternate in phase. By combining the chrominance from two adjacent lines, the error is thus cancelled out.

NTSC

Fig 8 shows an encoded SMPTE (75%) colour bar signal. The two colour components of Cr and Cb are used to amplitude modulate a 3.579545Mhz carrier signal, but they are first modified into I and Q signals to reduce the overall maximum chrominance level when combined.

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Fig 7

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Fig 8

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SC-H RELATIONSHIP

PAL appears, at first sight, to be a four field system: field 1 being identical to field 5, and field 3 having the opposite pal switch phase. However, if a switch or edit is made between two video sources which are in the same pal sequence only, a small horizontal picture shift will often be noticed, this is due to the relationship between subcarrier and line frequencies.

In order to avoid chroma patterning on monochrome receivers the PAL subcarrier frequency was chosen to have a 90 degree offset per television line, with 25Hz added on so that any remaining patterning would run through the picture:

F (pal) = (283.75 x 15.625KHz) + 25Hz = 4.43361875MHz

The drawback of this is that after one PAL frame of four fields the subcarrier will have executed exactly 354689.50 cycles, so it will be 180 degrees shifted from its original phase at the same sync point. Hence the subcarrier to horizontal sync (SC-H) phase will only repeat every EIGHT fields.

A similar problem also exists in NTSC, except that it is a four field system rather than eight field.

F (ntsc) = (227.5 x 15.73426373KHz) = 3.579545MHz

After one NTSC frame of two fields, the subcarrier will have executed exactly 119437.50 cycles, so it will then be exactly 180 degrees shifted from its original phase at the same sync point hence the sc-h phase will only repeat every FOUR fields.

If a video edit or switch is made without regard to the above field sequence, there is a 50/50 chance of picking the wrong eight field match. This will cause an SC-H phase jump producing a picture shift of half a cycle of subcarrier. Whilst this may be acceptable if cutting to a different shot, in animation or tag-editing the shift would be very noticeable.

To produce reliable match frame edits it is therefore necessary to identify the correct field sequence. In addition, if due to misalignment, the SC-H phase was displaced from the ideal by 90 degrees, the field relationship would be uncertain.

Both these problems can be addressed by having an instrument which displays the subcarrier phase to horizontal sync phasing. Zero SC-H phase has been defined as a positive zerocrossing of subcarrier at the vertical sync point on field 1.

Systems can now be adjusted in the exactly correct SC-H phase to avoid uncertainty when near to the 90 degree point. A video signal in the exactly wrong eight-field sequence would show up as an 180 degree SC-H phase error.

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SERIAL DIGITAL BASICS

625 and 525 digital component video is produced by applying a 4:2:2 sampling structure to the analog signal. This process is defined by a sub-set of international standards ITU-R

BT.601 and BT.656. (these were formerly known as CCIR-601 and CCIR-656. The label

'CCIR601' is commonly applied to digital video coded in this manner.)

The luminance (Y) component is sampled at 13.5 MHz, and the colour difference components (U and V) are both sampled at 6.75 MHz. With 10 bit quantisation, this results in a data stream of 10 bit words at a clock frequency of 27 MHz. If the signal source uses 8 bit quantisation, 10 bit data is used with the two least significant bits of each sample code set to binary zero. This is to maintain the same data rate.

The quantizing levels employed in the analog to digital conversion are set to give 66.4mV headroom above peak white and 51.1mV below black. Coded U and V signals have 50mV above and below their normal maximum and minimum excursions.

The synchronisation pulses are discarded in the coding process, and are replaced by Timing

Reference Signals (TRS) which are inserted into the data stream to serve the same purpose.

Two TRS's are used to synchronise the data stream, EAV (End of Active Video) and SAV

(Start of Active Video). These are placed at the beginning and end of the horizontal video blanking period. see fig 9.

Each TRS consists of 4 words:

1) 3ff hex ie all '1's

2) 000 hex ie all '0's

3) 000 hex ie all '0's

4) XYZ, which determines the type of TRS pulse:

XYZ:

Bit 9: always '1'

Bit 8: 0 = frame 1 1 = frame 2

Bit 7: 0 = normal 1 = field blanking

Bit 6: 0 = SAV 1 = EAV

Bit 5: Bits used for Hamming correction.

Bit 4: Bits used for Hamming correction.

Bit 3: Bits used for Hamming correction.

Bit 2: Bits used for Hamming correction.

Bit 1: Always '0'

Bit 0: Always '0'

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SERIAL DIGITAL BASICS

The period between EAV and SAV is not used by normal video and is available for other purposes eg: error checking, timecodes or embedded audio.

Illegal Values: The values 0 and 3FF hex are used solely by TRS pulses (EAV and SAV) they must not appear anywhere in the active video area.

Out of Gamut: Values apart from the illegal values which should not be used.

Luminance is defined as being between peak white, 700mV 3AC, hex and black, 0mV 040 hex.

Chroma is defined as being between max positive, 350mV 3C0, hex and max negative, -350mV 040 hex.

The values above and below these are termed out of gamut.

The data is serialised using an NRZ (None Return to Zero) code to produce a 270 Mb/s signal. This coding method removes any low frequency component and is insensitive to polarity. The data has to be scrambled first to avoid the possible transmission of all '0's.

This data is output at 800mV p-p to normal 75 ohm video coaxial cable.

Due to the high frequencies, the cable losses are quite high, typically 10dB per 100 metres at

270 MHz. To allow acceptable cable lengths, automatic cable equalises are used at the receiver which usually allow up to 300 metres of cable to be used. It is important that standard cable is used, otherwise the equaliser will not compensate correctly.

Suitable cable is: PSF 2/3 BELDEN 8281 F&G 1.0/6.6

DIGITAL ERROR DETECTION OVERVIEW

In order to check if the digital video signal has been received correctly a Cyclic Redundancy

Check (CRC) can be made on each frame in the generating equipment, this four digit number is then placed in a 'packet' and put in the EAV-SAV space of one line of each field.

At the receiving equipment the incoming video field also has a Cyclic Redundancy Check number calculated, this value is then compared with the 4 digit number sent in the packet. If the two numbers are not identical an error has occurred between transmission and reception of the signal.

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SERIAL DIGITAL BASICS

This type of error detection is known as Error Detection and Handling or EDH and is defined by SMPTE RP165. In practice two check sums are sent per frame, one for the active video period and one for the full frame. A typical packet consists of:

The Header: (000, 3FF, 3FF) This always precedes an EDH packet.

Data ID:

Block Number:

(1F4)

(200)

Data Count: This contains the number of words that follow.

Active picture crc: 3 words

Full-field crc

Error flags:

3 words

3 words

Check Sum: This is used to test for transmission errors.

EMBEDDED AUDIO OVERVIEW

The period between the EAV and SAV markers can be used to send embedded digital audio signals. This is known as SMPTE 272M. Up to 16 separate audio signals may be sent in a single video channel. These are organised as four GROUPS of four signals, the four signals are often two stereo pairs. Typically only one group will be used, giving two stereo pairs of audio. The audio data is digitised in the sending equipment to 20 bits of resolution, usually at a 48 KHz sample rate. Often only 16 bits are used in practice. The digitised data is arranged in packets which are placed in the EAV-SAV space.

A typical packet consists of:

The Header:

Data ID:

(000, 3FF, 3FF) This always precedes an audio packet.

This contains the Audio Group number.

Block Number:

Data Count:

Audio Sample:

Audio Sample:

AES blocks have 192 'frames' of audio data

This contains the number of words that follow.

Audio Sample:

Audio Sample:

Check Sum: This is used to test for transmission errors.

Each audio sample consists of a sample of all four audio signals, eg: Channel 1 left, Channel 1 right, Channel 2 left, Channel 2 right.

Each signal requires 3 words to hold all 20 bits data, thus each audio sample has 12 words in it. Typically 3 or 4 audio samples are sent in each EAV-SAV period.

As with the video signal, words which consist of all '1's or all '0's are not allowed.

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EAV and SAV

SERIAL DIGITAL BASICS

Fig 9.

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SD SDI Field Blanking – 625

SERIAL DIGITAL BASICS

Fig 10 .

31

SD SDI Field Blanking – 525

SERIAL DIGITAL BASICS

Fig 11.

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USEFUL WEBSITES

HAMLET www.hamlet.co.uk

HAMLET (USA) www.hamlet.us.com

SMPTE www.smpte.org Society of Motion Picture Television

Engineers

DIN www.din.de

EBU www.ebu.ch

AES www.aes.org

ITU www.itu.int

CONTACT DETAILS AND CUSTOMER SUPPORT

For any form of assistance in maintaining your LCD Scope, please contact:

Corporate Head Office

Hamlet Video International Limited

Maple House 11 Corinium Business Centre Raans Road Amersham Bucks HP6 6FB England

Main Line: +44 (0)1494 729 728

Fax Line: +44 (0)1494 723 237

Free phone (UK) 0500 625 525

E-mail: [email protected] Web site: www.hamlet.co.uk

Hamlet USA

Sencore, Inc.

3200 W Sencore Drive, Sioux Falls SD 57107, U.S.A.

Phone: (605) 339-0100

Fax: (605) 339-7032

Toll Free: 1-800-SENCORE (736-2673)

Toll Free: 1-866-4-HAMLET (426-538)

Email: [email protected] Web site: www.hamlet.us.com

In correspondence concerning this instrument, please quote the serial number, which you will find printed on the label at the back of the unit.

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