BTS-3 — Television Broadcasting

Issue 2
December 1997
Revised: May 2023

Preface

Broadcast Transmission Standard BTS-3, Issue 2, Television Broadcasting, was issued December 1997. This editorial revision of Issue 2 of BTS-3 incorporates editorial and formatting changes to meet the Canada accessibility requirements. No modifications or changes in the content of BTS-3, issue 2, have been made.

Inquiries may be submitted by one of the following methods:

By mail to the following address:

Innovation, Science and Economic Development Canada
Engineering, Planning and Standards Branch
Attention: Regulatory Standards Directorate
235 Queen Street
Ottawa ON  K1A 0H5
Canada

By email to spectrumengineering-genieduspectre@ised-isde.gc.ca.

ISED publications related to spectrum management and broadcasting equipment technical standard are available on the Spectrum Management and Telecommunications website.

Issued under the authority of
the Minister of Innovation, Science and Industry
____________________________________
Martin Proulx
Director General
Engineering, Planning and Standards Branch

Contents

1.   Scope.
2.   Basic Standards
3.   Multichannel Television Sound Standards
4.   Vertical Blanking Interval Signal Standards
5.   Multichannel Television Sound standards

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

This section sets out the basic requirements to TV broadcasting systems subject to this standard. 

2.1 Channel characteristics

This sub-section describes the channels and frequencies assigned to television stations.

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
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

2.2 Video characteristics

This sub-section contains the video characteristics for TV broadcasting systems.

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 signal characteristics

This sub-section contains the characteristics to be met by synchronizing signals. Details of the line synchronizing and field synchronizing signals are provided in this section.

2.3.1 Line synchronization. The details of the line synchronizing signal are given in Table 2a, Figure 1 and Figure 5. The durations specified are measured between the half-amplitude points of the appropriate edges.

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

2.4 Colour TV video signal characteristics

This sub-section specifies the characteristics for the colour TV video signal.

2.4.1 The equation of the composite colour signal is:

\[ E_M - E_Y + [E_q sin(ωt+33º)] \]

\[ E_Y - 0.30E_R + 0.59E_G + 0.11E_B \]

\[ E_Q - 0.41(E_B - E_Y) + 0.48(E_R - E_Y) \]

\[ E_I - /neg0.27(E_B - E_Y) + 0.74(E_R - E_Y) \]

The symbols in the above equations have the following significance:

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

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

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

E’_R, E’_G, E’_B = the gamma-pre-corrected primary signals corresponding to
red, green and blue signals during the scanning of the given picture element.

ω = the angular frequency and is 2π 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 phase reference in the E_M equation is the phase of the burst i.e. 180º 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 signals E’_Q and E’_I are as follows:

Q - channel bandwidth:
at 400 kHz, less than 2 dB attenuation,
at 500 kHz, less than 6 dB attenuation, and
at 600 kHz, equal to or greater than 6 dB attenuation

I - channel bandwidth:
at 1.3 MHz, less than 2 dB attenuation and
at 3.6 MHz, equal to or greater than 20 dB attenuation

2.4.3 The gamma-corrected voltages E’_R, E’_G 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

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).

2.4.5 E’_Y, E’_Q, E’_I and the components of these signals shall match each other in time to 0.05 µs.

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:

\[ G - [(E_I)^2 + (E_Q)^2]^{1/2} \]

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 µs (5.3 µs nominal) after the front edge of horizontal sync. and at least 0.38 µs after the trailing edge of the horizontal sync. signal. The duration of the subcarrier burst shall be 2.23 to 3.11 µs (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 chrominance subcarrier burst shall be 180o relative to the (E’_B-E’_Y) 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).

2.5 Radiated TV signal characteristics

This sub-section sets up the requirements related to the radiated TV signal.

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 and
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:

a. Synchronizing pulse level

100

b. Blanking level

75 ± 2.5

c. Peak white level

12.5 ± 2.5

2.5.5 The pre-corrected 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 µs 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  

This section includes general and specifics standards related to multichannel television sound (MTS).

3.1 MTS standards, general    

This sub-section is related to general specifications for MTS subject to this standard.

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

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:

1. 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; and
2. 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.

3.2 BTSC stereophonic sound standards

This sub-section sets up the requirements applicable to BTSC stereophonic sound.

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

This sub-section sets up the requirements applicable to BTSC second audio program.

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  

This sub-section sets up the requirements applicable to BTSC sound encoding. 

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).

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

\[ F(f) = \frac{[\frac{jf}{0.408} + 1][\frac{jf}{2.19} + 1]}{[\frac{jf}{5.23} + 1][\frac{jf}{62.5} + 1]} \]

3.4.2.2 Wide-band amplitude compression wherein:

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: \[ P(f) = \frac{\frac{jf}{0.0354}}{(\frac{jf}{0.0354} + 1)(\frac{jf}{2.09} + 1)} \]
2. The exponential time weighting period T1 of the ERMS detector is 34.7 ms.
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:

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

\[ S(f,b) = \frac{1 + \frac{jf}{F} \frac{(b + 51)}{b + 1}}{1 + \frac{jf}{F} \frac{(b + 51b)}{b + 1}}, where \space b=10^{\frac{d}{20}} \]

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:

\[ Q(f) = \frac{ (\frac{jf}{5.86})^3}{ [(\frac{jf}{7.66})^2 + \frac{jf}{7.31} + 1](\frac{jf}{26.9} + 1)(\frac{jf}{3.92} + 1)} \]

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 communication subcarrier standards

This sub-section sets up the requirements applicable to BTSC subsidiary communications subcarrier.

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.

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

4. Vertical blanking interval signal standards

This section sets up the requirements applicable to vertical blanking interval signal subject to this standard.

4.1 General standards

This sub-section describes a feasible usage of the vertical blanking interval and provides some guidance on its operation.

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

This section describes the allocation of lines subject to this standard. It provides an allotment plan to be used according with the signal to be transmitted.

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 closed-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.

4.3 Standards for the ghost cancelling reference signal

This sub-section describes the applicable standards to 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 µs after the leading edge of the horizontal sync and ends 35.5 µs later (refer to Figure 9). It allows to cancel ghosts from - 3 µs to +45 µs 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:

\[ f(t) = \frac{A}{2\pi} [\int_{0}^{\Omega} [cos(b \omega^2) + jsin(b \omega^2)]W(\omega)exp^{j\omega t} d\omega + \int_{\neg\Omega}^{0}[cos(b\omega^2) - jsin(b \omega^2)] W(\omega)exp^{j\omega t}d \omega ] \]

W(ω) is the window function:

\[ W(ω) = \int_{-\frac{π}{c}}^{\frac{π}{c}} [[\frac{1}{2} + \frac{1}{2}cos(ct)][\frac{1}{2π}\int_{-Ω1}^{Ω1} exp^{jλt} dy]] exp^{jωt} dt \]

Where the constants: A, b, ω, c and ω1 are given in the table below.

Parameters for GCR

A	3,592×10-7 Volts
b	0,53656×10-12 sec2/radian
Ω	2π×4,3×106 radian/sec
c	0,917998×106 radian/sec
Ω1	2π×4,15×106 radian/sec

4.4 Line 21 data signal 

This sub-section sets up the requirements applicable to 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.

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

This sub-section sets up the requirements applicable to TV 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. Multichannel television sound standards

This section describes the conditions to be met by digital data when it is inserted into the TV transmission.

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:

• 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.
• A station may only use a data insertion method that has been approved in advance by Innovation, Science and Economic Development Canada.

Figure 1 – Levels in the composite signal and details of line synchronization signals

1. Blanking level
2. Peak white level
3. Synchronizing level
4. Peak-to-peak value of burst
5. Peak level including chrominance signal

Figure 2a: Signal at the beginning of each first field

Figure 2b: Signal at the beginning of each second field

Note 1: ↑ indicates an unbroken sequence of edges of line-synchronizing pulses throughout the field blanking period.
Note 2: Field-one line numbers start with first equalizing pulse in field 1, designed OE1 in Figure 2a.
Note 3: Field-one line numbers start with the second equalizing pulse in field 2, one-half-line period after OE2 in Figure 2b.

Figure 2c: Details of equalizing and synchronizing pulses

Figure 3: Phase of the reference burst

Figure 4: Idealized picture transmission amplitude characteristics

Figure 5: Burst-blanking sequence in M/NTSC system

Note: The numbering of specifics lines in accordance with new engineering practices. Line numbers in parentheses represent an alternative method of numbering.

Figure 6: Group delay requirements

Figure 7: Stereophonic difference and second program audio signal encoding

Note: f is expressed in kHz. Certain values in the figure are approximate. Exact numbers are found in the accompanying text.

Figure 8: BTSC MTS baseband

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

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

The magnitude of the spectrum of the GCR signal follows:

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

Figure 10a: Line 21 Field 1 data signal format

Figure 10b: Adaptive equalizer reference pulse

Figure 10c: Line 21 field two framing code

Horizontal dimension not to scale

1.      Data “1” = 50 IRE units, Data “0” = 0
2.      Data pulse rise time = 2T bar rise time
3.      Data time base = 32 FH (0.50349650 MHz)
4.      Data bit interval = H/32 (1.986 µs)
5.      Negative going zero crossing of clock are coherent with data transitions
6.      Data and clock run-in coherent with H.