BTS-3 Issue 2 December 1997

Home , Pilot signal, Second audio program, Stereophonic sound

Spectrum Management

Broadcast Transmission Standard

Television Broadcasting

Aussi disponible en français - NER-3 Television Broadcasting BTS-3

Table of Contents

Page

1. Scope ...... 1

2. Basic Standards ...... 1 2.1 Channel Characteristics ...... 1 2.2 Video Characteristics ...... 3 2.3 Synchronizing Signal Characteristics ...... 3 2.4 Colour TV Video Signal Characteristics ...... 5 2.5 Radiated TV Signal Characteristics ...... 8

3. Multichannel Television Sound Standards ...... 8 3.1 MTS Standards, General ...... 8 3.2 BTSC Stereophonic Sound Standards ...... 10 3.3 BTSC Second Audio Program Standards ...... 10 3.4 BTSC Sound Encoding Standards ...... 10 3.5 BTSC Subsidiary Communication Subcarrier Standards ...... 12 3.6 BTSC MTS Baseband ...... 13

4. Vertical Blanking Interval Signal Standards ...... 13 4.1 General Standards ...... 13 4.2 Line Allotment Standards ...... 13 4.3 Standards for the Ghost Cancelling Reference Signal ...... 14 4.4 Line 21 Data Signal ...... 15 4.5 Television Broadcast Videotext Data Signal ...... 16

5. Digital Data in the Video Portion of TV Transmissions ...... 16

5.1 General ...... 16 Television Broadcasting BTS-3

1. Scope

This document contains the standards governing TV broadcasting systems in Canada. The standards ensure satisfactory monochrome and colour television broadcasting services based on the 525 line NTSC colour system. The system is known as NTSC/M.

2. Basic Standards

2.1 Channel Characteristics

2.1.1 Television stations are assigned channels with numbers and frequencies as designated in Table 2.1. The width of the television broadcast channel shall be 6 MHz. The visual carrier frequency shall be nominally 1.25 MHz above the lower boundary of the channel. The aural carrier frequency shall be 4.5 MHz above the visual carrier frequency.

Table 2.1

Television Channel Frequencies

Channel No. Frequency Band (MHz) Visual Carrier (MHz) Aural Carrier (MHz)

2 54-60 55.25 59.75 3 60-66 61.25 65.75 4 66-72 67.25 71.75 5 76-82 77.25 81.75 6 82-88 83.25 87.75 7 174-180 175.25 179.75 8 180-186 181.25 185.75 9 186-192 187.25 191.75 10 192-198 193.25 197.75 11 198-204 199.25 203.75 12 204-210 205.25 209.75 13 210-216 211.25 215.75 14 470-476 471.25 475.75 15 476-482 477.25 481.75 16 482-488 483.25 487.75 17 488-494 489.25 493.75 18 494-500 495.25 499.75 19 500-506 501.25 505.75 20 506-512 507.25 511.75 21 512-518 513.25 517.75 22 518-524 519.25 523.75 23 524-530 525.25 529.75 24 530-536 531.25 535.75 25 536-542 537.25 541.75

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Channel No. Frequency Band (MHz) Visual Carrier (MHz) Aural Carrier (MHz)

26 542-548 543.25 547.75 27 548-554 549.25 553.75 28 554-560 555.25 559.75 29 560-566 561.25 565.75 30 566-572 567.25 571.75 31 572-578 573.25 577.75 32 578-584 579.25 583.75 33 584-590 585.25 589.75 34 590-596 591.25 595.75 35 596-602 597.25 601.75 36 602-608 603.25 607.75 38 614-620 615.25 619.75 39 620-626 621.25 625.75 40 626-632 627.25 631.75 41 632-638 633.25 637.75 42 638-644 639.25 643.75 43 644-650 645.25 649.75 44 650-656 651.25 655.75 45 656-662 657.25 661.75 46 662-668 663.25 667.75 47 668-674 669.25 673.75 48 674-680 675.25 679.75 49 680-686 681.25 685.75 50 686-692 687.25 691.75 51 692-698 693.25 697.75 52 698-704 699.25 703.75 53 704-710 705.25 709.75 54 710-716 711.25 715.75 55 716-722 717.25 721.75 56 722-728 723.25 727.75 57 728-734 729.25 733.75 58 734-740 735.25 739.75 59 740-746 741.25 745.75 60 746-752 747.25 751.75 61 752-758 753.25 757.75 62 758-764 759.25 763.75 63 764-770 765.25 769.75 64 770-776 771.25 775.75 65 776-782 777.25 781.75 66 782-788 783.25 787.75 67 788-794 789.25 793.75 68 794-800 795.25 799.75 69 800-806 801.25 805.75

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2.2 Video Characteristics

2.2.1 The number of scanning lines per picture (frame) shall be 525, interlaced two to one in successive fields.

2.2.2 The chrominance subcarrier frequency shall be 3.579545 MHz. The tolerance is ± 10 Hz and the rate of frequency drift shall not exceed 0.10 Hz per second.

2.2.3 The horizontal scanning frequency shall be 2/455 times the chrominance subcarrier frequency. This corresponds nominally to 15 570 Hz with an actual value of 15 734.264 ± 0.044 Hz.

2.2.4 The vertical scanning frequency is 2/525 times the horizontal scanning frequency. This corresponds nominally to 60 Hz with an actual value of 59.94 Hz.

2.2.5 The aspect ratio of the transmitted television picture shall be 4 units horizontally to 3 units vertically.

2.2.6 During active scanning intervals, the scene shall be scanned from left to right horizontally and top to bottom vertically, at uniform velocity.

2.2.7 The nominal and peak levels of the composite video signal expressed in % shall be as follows: (see Figure 1)

(a) blanking level (reference level) 0 (b) peak white level 100 (c) synchronizing level !40 (d) peak level including chrominance signal 120

2.3 Synchronizing Signals Characteristics

2.3.1 Line Synchronization. The details of the line synchronizing signal are given in Table 1, Figure 1 and Figure 5. The durations specified are measured between the half-amplitude points of the appropriate edges.

Table 1 - Details of Line Synchronization

Symbol Characteristics M NTSC/M (Fig. 1) Monochrome Colour

HNominal line period (Fs) 63.492 63.5555 aLine-blanking interval (Fs) 10.2 to 11.4 10.9 ± 0.2

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Symbol Characteristics M NTSC/M (Fig. 1) Monochrome Colour

cFront porch (Fs) 1.27 to 2.54 1.27 to 2.22 dSynchronizing pulse (Fs) 4.19 to 5.71 4.7 ± 0.1 e Built-up time (10 to 90 %) of 0.64 0.48 the edges of the line-blanking pulse (Fs) f Build-up time (10 to 90 %) of 0.25 0.25 the edges of the line-synchronizing pulses (Fs)

2.3.2 Field Synchronization. The details of the field synchronizing signal are given in Table 2, Figure 2 and Figure 5. The durations specified are measured between the half-amplitude points of the appropriate edges.

Table 2 - Details of Field Synchronization

Symbol Characteristics M NTSC/M (Fig. 2) Monochrome Colour

v Field period (ms) 16.667 16.6833 j Field-blanking interval 19 to 21H + a 19 to 21H + a (for H and a, see Table 1) - Build-up time (10 to 90 %) of 6.35 6.35 the edges of field-blanking pulses (Fs) - Interval between front edge of 1.5 ± 0.1 1.5 ± 0.1 field-blanking interval and front edge of first equalizing pulse (Fs) l Duration of first sequence of 3H 3H equalizing pulses m Duration of sequence of 3H 3H equalizing pulses n Duration of second sequence of 3H 3H equalizing pulses

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Symbol Characteristics M NTSC/M (Fig. 2) Monochrome Colour

pDuration of equalizing pulse (Fs) 2.3 ± 0.1 2.3 ± 0.1 q Duration of field-synchronizing 27.1 nominal 27.1 nominal pulse (Fs) r Interval between 4.7 ± 0.1 4.7 ± 0.1 field-synchronizing pulse (Fs) s Build-up time (10 to 90%) of 0.25 0.25 synchronizing and equalizing pulses (Fs)

2.4 Colour TV Video Signal Characteristics

2.4.1 The equation of the composite colour signal is

' ´ % ´ T % % ´ T % EM EY [EQsin( t 33°) EI cos( t 33°)]

´ ' ´ % ´ % EY 0.30ER 0.59EG 0.11EB´

´ ' ´& ´ % ´ & ´ EQ 0.41(EB EY) 0.48(ER EY)

´ '& ´ & ´ % ´ & ´ EI 0.27(EB EY) 0.74(ER EY)

The symbols in the above equations have the following significance:

EM = the total video voltage, corresponding to the scanning of a particular picture element, applied to the modulator of the visual transmitter.

3 E Y = the gamma-corrected voltage of the monochrome (black and white) portion of the colour picture signal, corresponding to the given picture element.

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3 3 E QI, E = the amplitude of the two orthogonal components of the chrominance signal corresponding respectively to narrow-band and wide-band axes.

3 3 3 E RG, E , E B = the gamma-pre-corrected primary signals corresponding to red, green and blue signals during the scanning of the given picture element.

T = the angular frequency and is 2B times the frequency of the chrominance subcarrier.

The portion of the complete equation between the brackets represents the chrominance subcarrier signal that carries the chrominance information. The o phase reference in the EM equation is the phase of the burst i.e. 180 as shown in Figure 3. The burst corresponds to amplitude modulation of a continuous sine wave.

2.4.2 The equivalent bandwidth assigned before modulation to the colour difference 3 3 signals E QI and E are as follows:

Q - channel bandwidth:

At 400 kHz, less than 2 dB attenuation At 500 kHz, less than 6 dB attenuation At 600 kHz, equal to or greater than 6 dB attenuation

I - channel bandwidth:

At 1.3 MHz, less than 2 dB attenuation At 3.6 MHz, equal to or greater than 20 dB attenuation

3 3 3 2.4.3 The gamma-corrected voltages E RG, E and E B are suitable for a colour picture tube having primary colours with the chromaticities in the CIE (Commission internationale de l'éclairage) system of specification as follows:

Colour x y

Red (R) 0.67 0.33 Green (G) 0.21 0.71 Blue (B) 0.14 0.08

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The assumed transfer gradient (gamma exponent) of the receiver for which the primary signals are pre-corrected is 2.2.

2.4.4 The radiated chrominance subcarrier vanishes on the reference white of the scene. The numerical values of the signal specification assume that this condition will be produced as CIE Illuminant C (x = 0.310, y = 0.316).

3 3 3 2.4.5 E YQI, E , E and the components of these signals shall match each other in time to 0.05 Fs.

2.4.6 The angles of the subcarrier measured with respect to the burst phase, when reproducing saturated primaries and their complements at 75% of full amplitude, shall be within ± 10 degrees and their amplitudes within 20% of the values specified above. The ratios of the measured amplitudes of the subcarrier to the luminance signal for the same saturated primaries and their complements shall fall between the limits of 0.8 and 1.2 of the values specified for their ratios.

2.4.7 The type of subcarrier modulation produced by the chrominance components shall be suppressed carrier amplitude modulation of two subcarriers in quadrature.

2.4.8 The bandwidth of the chrominance sidebands relative to the subcarrier frequency shall be:

fsc + 620 kHz ! 1300 kHz

The amplitude of the chrominance subcarrier shall be

' ´ 2 % ´ 2 ½ G [(EI ) (EQ) ]

2.4.9 The chrominance subcarrier shall be synchronized by a subcarrier burst on the horizontal blanking back porch. The start of the subcarrier burst shall be 4.71 to 5.71 Fs (5.3 Fs nominal) after the front edge of horizontal sync. and at least 0.38 Fs after the trailing edge of the horizontal sync. signal. The duration of the subcarrier burst shall be 2.23 to 3.11 Fs (9 ± 1 cycles).

2.4.10 The peak-to-peak value of the chrominance subcarrier burst shall be 4/10 of the difference between blanking level and peak white level. The phase of the o 3 ! 3 chrominance subcarrier burst shall be 180 relative to the (E BY E ) axis (see Figure 3). The chrominance subcarrier shall be blanked following each equalizing pulse during the broad synchronizing pulses in the field-blanking interval (See Figure 5).

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2.5 Radiated TV Signal Characteristics

2.5.1 The frequency spacing of the radiated signal is shown in Figure 4. The nominal radio-frequency channel bandwidth shall be 6 MHz. The sound carrier relative to the vision carrier shall be 4.5 MHz. The nearest edge of the channel relative to vision carrier shall be !1.25 MHz. The nominal width of the main sideband and the vestigial sideband shall be 4.2 and 0.75 MHz respectively.

2.5.2 The minimum attenuation of the vestigial sideband shall be:

20 dB at !1.25 MHz 42 dB at !3.58 MHz

2.5.3 The type and polarity of the vision modulation shall be C3F negative.

2.5.4 The levels in the radiated signal expressed in % of peak carrier shall be:

(i) Synchronizing pulse level 100 (ii) Blanking level 75 ± 2.5 (iii) Peak white level 12.5 ± 2.5

2.5.5 The precorrected group delay of the radiated signal shall be 0 nanosecond to 3 MHz and decreases linearly to 170 nanoseconds at 3.58 MHz. The tolerance on the group delay shall be as shown in Figure 6.

2.5.6 The type and polarity of the sound modulation shall be F3E.

2.5.7 The peak frequency deviation of the sound carrier shall be ± 25 kHz for monophonic inputs and ± 75 kHz for stereophonic or composite inputs.

2.5.8 Pre-emphasis having a time constant of 75 Fs shall be used.

2.5.9 The effective radiated power of the aural transmitter shall not be less than 10% nor more than 20% of the peak radiated power of the visual transmitter.

3. Multichannel Television Sound Standards

3.1 MTS Standards, General

3.1.1 The modulating signal for the main channel shall consist of the sum of the stereophonic (biphonic, quadraphonic, etc.) input signals.

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3.1.2 The instantaneous frequency of any baseband subcarrier shall, at all times, be within the range of 15 kHz to 120 kHz. Either amplitude or frequency modulation of the subcarrier may be used.

3.1.3 One or more pilot subcarriers between 16 kHz and 120 kHz may be used to switch a TV receiver between the stereophonic and monophonic reception modes or to activate a stereophonic mode indicator, and one or more subcarriers between 15 kHz and 120 kHz may be used for any other authorized purpose. However stations transmitting the BTSC system of stereophonic sound and audio processing shall transmit a pilot subcarrier at 15 734 Hz ± 2 Hz. Other methods of multiplex subcarrier or stereophonic aural transmission systems shall limit energy at 15 734 Hz ± 20 Hz, to no more than ± 0.125 kHz aural carrier deviation.

3.1.4 Aural baseband information above 120 kHz shall be attenuated 40 dB referenced to 25 kHz main channel deviation of the aural carrier.

3.1.5 When transmitting MTS, the main channel of the aural transmission shall meet the standards of System NTSC/M and those contained in the appropriate Radio Standards Specification for the transmitting equipment involved.

3.1.6 Multiplex subcarrier or stereophonic aural transmission systems shall be capable of producing and shall not exceed ± 25 kHz main channel deviation of the aural carrier.

3.1.7 The arithmetic sum of non-multiphonic baseband signals between 15 kHz and 120 kHz shall not exceed ± 50 kHz deviation of the aural carrier.

3.1.8 Total modulation of the aural carrier shall not exceed ± 75 kHz.

3.1.9 During any mode of transmission, monophonic, stereophonic, multiplex, the spectrum of the radiated signal or occupied bandwidth of the aural transmitter shall be within the following limits:

(a) not greater than !25 dB, when referred to the level of the unmodulated carrier, for any frequency removed from the carrier by between 120 kHz and 240 kHz;

(b) not greater than !35 dB, when referred to the level of the unmodulated carrier, for any frequency removed from the carrier by between 240 kHz and 600 kHz.

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3.2 BTSC Stereophonic Sound Standards

3.2.1 Television broadcast stations may transmit stereophonic sound by employing a subcarrier on the aural carrier. The main channel modulating signal shall be the stereophonic sum signal; the subcarrier modulation shall be the stereophonic difference encoded signal.

3.2.2 The subcarrier shall be the second harmonic of the pilot signal which is transmitted at a frequency equal to the horizontal line rate of 15 734 Hz ± 2 Hz. If the station is engaged in stereophonic sound transmission accompanied by monochrome picture transmission, this horizontal scanning frequency shall be employed.

3.2.3 The subcarrier shall be double sideband amplitude modulated with suppressed carrier and shall be capable of accepting a stereophonic difference encoded signal over a range of 50 - 15 000 Hz.

3.3 BTSC Second Audio Program Standards

3.3.1 Television broadcast stations may transmit a subcarrier carrying a second audio program.

3.3.2 The subcarrier frequency shall nominally be equal to the fifth harmonic of the horizontal line rate.

3.3.3 The second program encoded signal shall frequency modulate the subcarrier to a peak deviation of ± 10 kHz.

3.3.4 The second audio program (SAP) subchannel shall be capable of accepting second program encoded signals over a range of 50 - 10 000 Hz.

3.3.5 The modulation of the aural carrier by the second audio program subcarrier shall not exceed ± 15 kHz deviation.

3.4 BTSC Sound Encoding Standards

3.4.1 The stereophonic difference audio signal and the second program audio signal shall be encoded prior to modulating their respective subcarriers. A diagram of one method of obtaining this encoding is shown as Figure 7.

Note: When the SAP channel is used for subsidiary communications signals, encoding is not specified.

3.4.2 This encoding shall have the following characteristics, where f is expressed in kilohertz (kHz).

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3.4.2.1 Fixed pre-emphasis F(f) whose function is as follows:

jf jf [ % 1][ % 1] 0.408 2.19 F(f) ' jf jf [ % 1][ % 1] 5.23 62.5

3.4.2.2 Wide-band amplitude compression wherein:

3.4.2.2.1 The decibel gain (or loss) applied to the audio signal during encoding is equal to minus one times the decibel ERMS value of the encoded signal (the result of the encoding process), weighted by a transfer function P(f) as follows:

jf 0.0354 P(f) ' jf jf ( % 1)( % 1) 0.0354 2.09

3.4.2.2.2 The exponential time weighting period T1 of the ERMS detector is 34.7 ms.

3.4.2.2.3 The zero decibel reference ERMS value for the encoded signal is 8.99% modulation of the subcarrier at 0.300 kHz.

Note: This reference results in 0 dB gain through the encoding process at 14.1% modulation using 0.300 kHz tone, when the output band limiting filter (see 3.4.2.5) gain is 0 dB at 0.300 kHz.

3.4.2.3 Spectral compression wherein:

3.4.2.3.1 The transfer function S(f,b) applied to the audio signal during encoding is:

jf (b%51) 1 % d F b%1 S(f,b) ' , where b'10 20 jf (b%51b) 1 % F b%1

F=20.1 kHz; d=decibel rms value and b is the decibel ERMS value of the encoded signal (the result of the encoding process) weighted according to a frequency transfer function Q (f) as follows:

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jf 3 ( ) 5.86 Q(f) ' jf 2 jf jf jf [( ) % % 1]( %1)( %1) 7.66 7.31 26.9 3.92

where the exponential time weighting period T2 of the ERMS detector is 11.4 ms and the ERMS zero decibel reference for the encoded signal is 5.16 % modulation of the subcarrier at 8 kHz.

Note: This reference results in +18.4 dB gain through the encoding process at 32.0% modulation using an 8 kHz tone, when the output band limiting filter [(see 3.4.2.5)] gain is 0 dB at 8 kHz.

3.4.2.4 Overmodulation protection which functionally follows the encoding described in this section (3.4.2).

3.4.2.5 Band limiting to appropriately restrict bandwidth which functionally follows the encoding described in this section (3.4.2).

3.5 BTSC Subsidiary Communications Subcarrier Standards

3.5.1 In addition to the requirements in 3.1, when the stereophonic and second audio program subchannels are transmitted, multiplexing of the aural carrier by subsidiary communications subchannels is subject to the following requirements.

3.5.1.1 The maximum modulation of the aural carrier by the subsidiary communications subcarrier is ± 3 kHz.

3.5.1.2 The instantaneous frequency of the subsidiary communications subcarrier shall have the average value of six and one half times the horizontal scanning frequency with a tolerance of ± 500 Hz.

3.5.2 When only the stereophonic subcarrier is transmitted, the instantaneous frequency of the subsidiary communications subcarrier shall lie between 47 kHz and 120 kHz with a tolerance of ± 500 Hz.

3.6 BTSC MTS Baseband

3.6.1 The BTSC MTS baseband, Figure 8, is composed of a main channel, an AM-DSB-SC stereo channel, a second audio program (SAP) channel and a PRO channel.

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4. Vertical Blanking Interval Signal Standards

4.1 General Standards

4.1.1 The vertical blanking interval may be used for the transmission of ancillary signals.

4.1.2 Subject to certain constraints, the ancillary signals shall be inserted in the interval beginning with line 10 and continuing to line 21.

4.1.3 Any type of ancillary signal, whether program related or not, may be carried in the blanking interval provided the operation is implemented on a non-interfering basis to regular picture transmission.

4.2 Line Allotment Standards

4.2.1 Lines 10 through 20 may be used for the transmission of any ancillary signal.

4.2.2 The level of VBI transmissions should not exceed +70 IRE on lines 10-15, and +80 IRE on lines 16-20.

4.2.3 Line 19 shall be used only for the transmission of the Ghost Cancelling Reference (GCR) signal developed by Philips Laboratories.

4.2.4 Line 21 may be used for the transmission of "closed captioning" a program related data signal which, when decoded, presents visual information representative of the audio signal of the program.

4.2.5 When line 21 is not being used for the transmission of the "closed captioning" signal, other types of ancillary signals may be transmitted.

4.2.6 Line 21 will also provide rating data to the program blocking circuitry (commonly known as V-Chip). The underlying technology needed for the implementation of the program blocking system is the same as the one for close-captioning. The tentative plan for implementing the system is to add the program rating information to line 21 of field no. 2, along with the closed-captioning information. Line 21 is also being used for newer "extended data services" (XDS) which provides scheduling information and station call letters to the viewers. The complexity of the content rating system, which is presently under development, will impact on the three data signals that are to be fitted in line 21.

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4.3 Standards for the Ghost Cancelling Reference Signal

4.3.1 The Ghost Cancelling Reference (GCR) signal provides a reference signal with a group delay linearly related to frequency. This signal is transmitted in an eight field sequence of changing polarity (+,!,+,!,!,+,!,+). The GCR starts 12 Fs after the leading edge of the horizontal sync and ends 35.5 Fs later (refer to Figure 9). It allows to cancel ghosts from !3 Fs to +45 Fs relative to the main signal.

4.3.2 The GCR signal is placed on line 19 and the corresponding line in the following field. To avoid constraining the performance of the ghost cancelling device, the lines immediately preceding and following line 19 should not contain any time varying information such as teletext. Also, it is highly recommended not to have any type of eight field sequence pattern in the lines adjacent to line 19. This type of sequence will greatly affect the performance of the system.

The above constraints on the content of the lines immediately following and preceding line 19 do not apply when the GCR signal is not inserted on line 19.

4.3.3 Waveforms of the GCR signal are shown in Figure 9 and represent line A and line B respectively. Line A and line B have the same pedestal height V1=30 IRE, but GCR polarity is inverted from line A to line B. Numerical values of the reference signal as a function of time can be calculated from the following equation:

A S T f(t) ' [ [cos(bT2) % jsin(bT2)]W(T)expj tdT % 2B m0 0 [cos(bT2) & jsin(bT2)]W(T)expjTtdT] m&S

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W(T) is the window function:

B T ' c 1% 1 1 S1 j(t ( &jTt W( ) B[[ cos(ct)][ exp d ]]exp dt m& 2 2 2Bm&S1 c

Where the constants: A, b, S, c and S1 are given in the table below.

Parameters for GCR

A 3.592×10-7 Volts

b 0.53656×10-12 sec 2/radian

S 2B×4.3×106 radian/sec

c 0.917998×106 radian/sec

S12B×4.15×106 radian/sec

4.4 Line 21 Data Signal

4.4.1 The program related data signal shall conform to the format described in Figure 10a.

4.4.2 A reference pulse for a decoder associated adaptive multipath equalizer filter may replace the data signal every eighth frame. The reference pulse shall conform to the format described in Figure 10b.

4.4.3 A decoder test signal consisting of data representing a repeated series of alphanumeric characters may be transmitted at times when no program related data is being transmitted.

4.4.4 A framing code to be used by the data decoder may be transmitted during the first half of Line 21 Field 2 when data reference pulse and test signals are present. The format of the framing code is shown in Figure 10c.

4.4.5 The data signal shall be coded using a non-return-to-zero (NRZ) format and shall employ standard ASCII 7 bit plus parity character codes.

4.4.6 The signals on field 1 and 2 shall be distinct data streams, for example, to supply caption in different languages.

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Note: For more information on data formats and specific data packets, refer to EIA-608, Line 21 Data Services for NTSC available from the Electronics Industries Association.

4.5 Television Broadcast Videotext Data Signal

4.5.1 The digital data signal representing text and pictorial information shall be in accordance with the parameters outlined in Broadcast Specification No. 14.

4.5.2 The data shall be non-return-to-zero (NRZ) binary encoded.

4.5.3 The transmission bit rate shall be 5 727 272 ± 16 bits per second. The data signal shall be phase locked to the colour subcarrier when inserted into a colour television transmission and to the horizontal line scanning rate when inserted into a monochrome television transmission.

5. Digital Data in the Active Video Portion of TV Transmissions

5.1 General

Digital data may be inserted in the active video portion of the TV transmission. The insertion of the data should comply with the following conditions:

5.1.1 The data should be inserted in the active video portion of the TV transmission. The active video is defined as the portion of the TV transmission starting from line 22 and continuing through the end of each field. The active video portion does not include the portion of each line reserved for horizontal blanking.

5.1.2 A station may only use a data insertion method that has been approved in advance by Industry Canada.

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Figure 6

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Figure 9a: GCR signal lines A and B (left and right respectively)

Figure 9b: Magnitude of the spectrum of the GCR signal

GCR signal frequency limit 4.1 MHz Duration of pedestal (T3) 35.5 µsec

GCR signal frequency stop limit 4.3 MHz Start of GCR (T4) 12.0 µsec

Pedestal height (V1) 30 IRE First peak of GCR (T5) 16.7 µsec

Start of pedestal (T1) 9.5 µsec Lowest level of GCR (V2) -10 IRE

Finish of pedestal (T2) 58.5 µsec Highest level of GCR (V3) +70 IRE

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