Rec. ITU-R BT.

601-5 1

SECTION 11B: DIGITAL TELEVISION

RECOMMENDATION ITU-R BT.601-5

STUDIO ENCODING PARAMETERS OF DIGITAL TELEVISION FOR STANDARD 4:3

AND WIDE-SCREEN 16:9 ASPECT RATIOS

(Question ITU-R 206/11)

(1982-1986-1990-1992-1994-1995)
Rec. ITU-R BT.601-5

The ITU Radiocommunication Assembly,

considering

a) that there are clear advantages for television broadcasters and programme producers in digital studio standards
which have the greatest number of significant parameter values common to 525-line and 625-line systems;

b) that a worldwide compatible digital approach will permit the development of equipment with many common
features, permit operating economies and facilitate the international exchange of programmes;

c) that an extensible family of compatible digital coding standards is desirable. Members of such a family could
correspond to different quality levels, different aspect ratios, facilitate additional processing required by present
production techniques, and cater for future needs;

d) that a system based on the coding of components is able to meet these desirable objectives;

e) that the co-siting of samples representing luminance and colour-difference signals (or, if used, the red, green
and blue signals) facilitates the processing of digital component signals, required by present production techniques,

recommends

that the following be used as a basis for digital coding standards for television studios in countries using the
525-line system as well as in those using the 625-line system:

1 Introduction
This Recommendation specifies methods for digitally coding video signals. It includes a 13.5 MHz sampling rate for
both 4:3 and 16:9 aspect ratios with performance adequate for present transmission systems. An alternative 18 MHz
sampling rate for those 16:9 systems which require proportionately higher horizontal resolution is also specified.

Specifications applicable to any member of this family of standards are presented first. Then follows in Part A the
specific characteristics for 13.5 MHz sampling and in Part B the specific characteristics for 18 MHz sampling.

2 Extensible family of compatible digital coding standards

2.1 The digital coding should allow the establishment and evolution of an extensible family of compatible digital
coding standards. It should be possible to interface simply between any two members of the family.

2.2 The digital coding should be based on the use of one luminance and two colour-difference signals (or, if used,
the red, green and blue signals).
2 Rec. ITU-R BT.601-5

2.3 The spectral characteristics of the signals must be controlled to avoid aliasing whilst preserving the passband
response. Filter specifications are shown in Appendix 2 to Part A and Appendix 2 to Part B.

3 Specifications applicable to any member of the family

3.1 Sampling structures should be spatially static. This is the case, for example, for the orthogonal sampling
structures specified in Part A and Part B.

3.2 If the samples represent luminance and two simultaneous colour-difference signals, each pair of colour-
difference samples should be spatially co-sited. If samples representing red, green and blue signals are used they should
be co-sited.

3.3 The digital standard adopted for each member of the family should permit worldwide acceptance and
application in operation; one condition to achieve this goal is that, for each member of the family, the number of samples
per line specified for 525-line and 625-line systems shall be compatible (preferably the same number of samples per
line).

3.4 In applications of these specifications, the contents of digital words are expressed in both decimal and
hexadecimal forms, denoted by the suffixes “d” and “h” respectively.

To avoid confusion between 8-bit and 10-bit representations, the eight most-significant bits are considered to be an
integer part while the two additional bits, if present, are considered to be fractional parts.

For example, the bit pattern 10010001 would be expressed as 145d or 91h, whereas the pattern 1001000101 would be
expressed as 145.25d or 91.4h.

Where no fractional part is shown, it should be assumed to have the binary value 00.

3.5 Definition of the digital signals Y, CR, CB, from the primary (analogue) signals ER′ , EG′ and EB′

This section describes, with a view to defining the signals Y, CR, C B, the rules for construction of these signals from the
primary analogue signals ER′ , EG′ and EB′ . The signals are constructed by following the three stages described in §
3.5.1, 3.5.2 and 3.5.3. The method is given as an example, and in practice other methods of construction from these
primary signals or other analogue or digital signals may produce identical results. An example is given in § 3.5.4.

3.5.1 Construction of luminance (E Y′ ) and colour-difference (E R′ – EY′ ) and (E B′ – EY′ ) signals

The construction of luminance and colour-difference signals is as follows:

E′Y = 0.299 E′R + 0.587 E′G + 0.114 E′B

whence:

(E′R – E′Y ) = E′R – 0.299 E′R – 0.587 E′G – 0.114 E′B

= 0.701 E′R – 0.587 E′G – 0.114 E′B

and:

(E′B – E′Y ) = E′B – 0.299 E′R – 0.587 E′G – 0.114 E′B

= – 0.299 E′R – 0.587 E′G + 0.886 E′B

Taking the signal values as normalized to unity (e.g. 1.0 V maximum levels), the values obtained for white, black and the
saturated primary and complementary colours are shown in Table 1.
 Rec. ITU-R BT.601-5 3

TABLE 1

Normalized signal values

Condition ER′ EG′ EB′ EY′ ER′ – EY′ EB′ – EY′

White 1.0 1.0 1.0 1.0 0 0

Black 0 0 0 0 0 0

Red 1.0 0 0 0.299 – 0.701 – 0.299

Green 0 1.0 0 0.587 – 0.587 – 0.587
Blue 0 0 1.0 0.114 – 0.114 0.886

Yellow 1.0 1.0 0 0.886 0.114 – 0.886

Cyan 0 1.0 1.0 0.701 – 0.701 0.299
Magenta 1.0 0 1.0 0.413 0.587 0.587

3.5.2 Construction of re-normalized colour-difference signals (EC′ R and EC′ B )

Whilst the values for E′Y have a range of 1.0 to 0, those for (ER′ – E′Y) have a range of + 0.701 to – 0.701 and for (EB′ –
E′Y) a range of + 0.886 to – 0.886. To restore the signal excursion of the colour-difference signals to unity (i.e. + 0.5 to –
0.5), coefficients can be calculated as follows:

0.5 0.5
KR = = 0.713;mmmmmmKB = = 0.564
0.701 0.886

Then:

E′CR = 0.713 (E′R – E′Y ) = 0.500 E′R – 0.419 E′G – 0.081 E′B

and:

E′CB = 0.564 (E′B – E′Y ) = – 0.169 E′R – 0.331 E′G + 0.500 E′B

where EC′ R and EC′ B are the re-normalized red and blue colour-difference signals respectively (see Notes 1 and 2).
NOTE 1 – The symbols EC ′ R and EC′ B will be used only to designate re-normalized colour-difference signals, i.e. having
the same nominal peak-to-peak amplitude as the luminance signal E′Y thus selected as the reference amplitude.
NOTE 2 – In the circumstances when the component signals are not normalized to a range of 1 to 0, for example, when
converting from analogue component signals with unequal luminance and colour-difference amplitudes, an additional
gain factor will be necessary and the gain factors K R, K B should be modified accordingly.

3.5.3 Quantization

In the case of a uniformly-quantized 8-bit binary encoding, 2 8, i.e. 256, equally spaced quantization levels are specified,
so that the range of the binary numbers available is from 0000 0000 to 1111 1111 (00 to FF in hexadecimal notation), the
equivalent decimal numbers being 0 to 255, inclusive.

In the case of the 4:2:2 systems described in this Recommendation, levels 0 and 255 are reserved for synchronization
data, while levels 1 to 254 are available for video.

Given that the luminance signal is to occupy only 220 levels, to provide working margins, and that black is to be at level
−
16, the decimal value of the luminance signal, Y , prior to quantization, is:

−
Y = 219 (E′Y ) + 16

and the corresponding level number after quantization is the nearest integer value.
4 Rec. ITU-R BT.601-5

Similarly, given that the colour-difference signals are to occupy 225 levels and that the zero level is to be level 128, the
− −
decimal values of the colour-difference signals, C R and C B, prior to quantization are:

−
C R = 224 [0.713 (E′R – E′Y )] + 128

and:

−
C B = 224 [0.564 (E′B – E′Y )] + 128

which simplify to the following:

−
C R = 160 (E′R – E′Y ) + 128

and:

−
C B = 126 (E′B – E′Y ) + 128

and the corresponding level number, after quantization, is the nearest integer value.

The digital equivalents are termed Y, CR and CB.

3.5.4 Construction of Y, CR , C B via quantization of E R′ , EG′ , EB′

In the case where the components are derived directly from the gamma pre-corrected component signals ER′ , EG′ , E B′ ,
or directly generated in digital form, then the quantization and encoding shall be equivalent to:

E′RD (in digital form) = int (219 E′R) + 16

EG′ D (in digital form) = int (219 E′G) + 16

E′BD (in digital form) = int (219 E′B) + 16

Then:

77 150 29
Y = E′RD + EG′ D + E′
256 256 256 BD

131 110 21
CR = E′RD – EG′ D – E′ + 128
256 256 256 BD

44 87 131
CB = – E′RD – EG′ D + E′ + 128
256 256 256 BD

taking the nearest integer coefficients, base 256. To obtain the 4:2:2 components Y, CR, CB, low-pass filtering and sub-
sampling must be performed on the 4:4:4 CR, C B signals described above. Note should be taken that slight differences
could exist between CR, CB components derived in this way and those derived by analogue filtering prior to sampling.

3.5.5 Limiting of Y, CR , C B signals

Digital coding in the form of Y, C R, CB signals can represent a substantially greater gamut of signal values than can be
supported by the corresponding ranges of R, G, B signals. Because of this it is possible, as a result of electronic picture
generation or signal processing, to produce Y, C R, CB signals which, although valid individually, would result in out-of-
range values when converted to R, G, B. It is both more convenient and more effective to prevent this by applying
limiting to the Y, CR, C B signals than to wait until the signals are in R, G, B form. Also, limiting can be applied in a way
that maintains the luminance and hue values, minimizing the subjective impairment by sacrificing only saturation.
 Rec. ITU-R BT.601-5 5

4 13 MHz family members

The following family members are defined in Part A:

– 4:2:2, 13.5 MHz for 4:3 aspect ratio, and for wide-screen 16:9 aspect ratio systems when it is necessary to keep the
same analogue signal bandwidth and digital rates for both aspect ratios.

– 4:4:4, 13.5 MHz 4:3 and 16:9 aspect ratio systems with higher colour resolution.

5 18 MHz family members

The following family members are defined in Part B:

– 4:2:2, 18 MHz, for 16:9 aspect ratio systems with higher horizontal resolution compared with systems sampled
at 13.5 MHz.

– 4:4:4, 18 MHz for 16:9 aspect ratio systems with higher colour resolution.

NOTE 1 – In the 4:4:4 members of the family the sampled signals may be luminance and colour difference signals (or, if
used, red, green and blue signals).

ANNEX 1

Some guidance on the practical implementation of the filters

specified in Appendix 2 to Part A and Appendix 2 to Part B

In the proposals for the filters used in the encoding and decoding processes, it has been assumed that, in the post-filters
which follow digital-to-analogue conversion, correction for the (sin x / x) characteristic is provided. The passband
tolerances of the filter plus (sin x / x) corrector plus the theoretical (sin x / x) characteristic should be the same as given for
the filters alone. This is most easily achieved if, in the design process, the filter, (sin x / x) corrector and delay equalizer
are treated as a single unit.

The total delays due to filtering and encoding the luminance and colour-difference components should be the same. The
delay in the colour-difference filter (Figs. 4a) and 4b)) is double that of the luminance filter (Figs. 3a) and 3b)). As it is
difficult to equalize these delays using analogue delay networks without exceeding the passband tolerances, it is
recommended that the bulk of the delay differences (in integral multiples of the sampling period) should be equalized in
the digital domain. In correcting for any remainder, it should be noted that the sample-and-hold circuit in the decoder
introduces a flat delay of one half a sampling period.

The passband tolerances for amplitude ripple and group delay are recognized to be very tight. Present studies indicate
that it is necessary so that a significant number of coding and decoding operations in cascade may be carried out without
sacrifice of the potentially high quality of the 4:2:2 coding standard. Due to limitations in the performance of currently
available measuring equipment, manufacturers may have difficulty in economically verifying compliance with the
tolerances of individual filters on a production basis. Nevertheless, it is possible to design filters so that the specified
characteristics are met in practice, and manufacturers are required to make every effort in the production environment to
align each filter to meet the given templates.

The specifications given in Appendix 2 to Part A and Appendix 2 to Part B were devised to preserve as far as possible
the spectral content of the Y, C R, C B signals throughout the component signal chain. It is recognized, however, that the
colour-difference spectral characteristic must be shaped by a slow roll-off filter inserted at picture monitors, or at the end
of the component signal chain.
6 Rec. ITU-R BT.601-5

PART A

TO ANNEX 1

The 13.5 MHz members of the family

1 Encoding parameter values for the 4:2:2, 13.5 MHz member of the family

The specification (see Table 2) applies to the 4:2:2 member of the family, to be used for the standard digital interface
between main digital studio equipment and for international programme exchange of 4:3 aspect ratio digital television or
wide-screen 16:9 aspect ratio digital television when it is necessary to keep the same analogue signal bandwidth and
digital rates.

TABLE 2

525-line, 60 field/s 625-line, 50 field/s

Parameters
systems systems

1. Coded signals: Y, CR, CB These signals are obtained from gamma pre-corrected signals, namely:
EY′ , ER′ – EY′ , EB′ – EY′ (see § 3.5)

2. Number of samples per total line:

– luminance signal (Y) 858 864
– each colour-difference signal 429 432
(CR, CB)
3. Sampling structure Orthogonal, line, field and frame repetitive. CR and CB samples co-sited with odd
(1st, 3rd, 5th, etc.) Y samples in each line
4. Sampling frequency:
– luminance signal 13.5 MHz
– each colour-difference signal 1 6.75 MHz
The tolerance for the sampling frequencies should coincide with the tolerance for the
line frequency of the relevant colour television standard
5. Form of coding Uniformly quantized PCM, 8 (optionally 10) bits per sample, for the luminance signal
and each colour-difference signal
6. Number of samples per digital active
line:
– luminance signal 720
– each colour-difference signal 360
7. Analogue-to-digital horizontal
timing relationship:
– from end of digital active line 16 luminance clock periods 12 luminance clock periods
to OH
8. Correspondence between video (See § 3.4) (Values are decimal)
signal levels and quantization levels:
– scale 0 to 255
– luminance signal 220 quantization levels with the black level corresponding to level 16 and the peak
white level corresponding to level 235. The signal level may occasionally excurse
beyond level 235
– each colour-difference signal 225 quantization levels in the centre part of the quantization scale with zero signal
corresponding to level 128
9. Code-word usage Code words corresponding to quantization levels 0 and 255 are used exclusively for
synchronization. Levels 1 to 254 are available for video
 Rec. ITU-R BT.601-5 7

2 Encoding parameter values for the 4:4:4, 13.5 MHz member of the family
The specifications given in Table 3 apply to the 4:4:4 member of the family suitable for television source equipment and
high-quality video signal processing applications.

TABLE 3

525-line, 60 field/s 625-line, 50 field/s

Parameters
systems systems

1. Coded signals: Y, CR, CB or R, G, B These signals are obtained from gamma pre-corrected signals, namely:
EY′ , ER′ – EY′ , EB′ – EY′ or ER′ , EG′ , EB′
2. Number of samples per total line for 858 864
each signal
3. Sampling structure Orthogonal, line, field and frame repetitive. The three sampling structures to be
coincident and coincident also with the luminance sampling structure of the
4:2:2 member
4. Sampling frequency for each signal 13.5 MHz

5. Form of coding Uniformly quantized PCM, 8 (optionally 10) bits per sample

6. Duration of the digital active line 720

expressed in number of samples
7. Correspondence between video (See § 3.4) (Values are decimal)
signal levels and the 8 most
significant bits (MSB) of the
quantization level for each sample:
– scale 0 to 255
– R, G, B or luminance signal(1) 220 quantization levels with the black level corresponding to level 16 and the peak
white level corresponding to level 235. The signal level may occasionally excurse
beyond level 235
– each colour-difference signal (1) 225 quantization levels in the centre part of the quantization scale with zero signal
corresponding to level 128
(1) If used.

APPENDIX 1
TO PART A

Definition of signals used in the digital coding standards

1 Relationship of digital active line to analogue sync reference

The relationship between the digital active line luminance samples and the analogue synchronizing reference is shown in:
– Fig. 1 for 625-line 13.5 MHz (see Table 2);
– Fig. 2 for 525-line 13.5 MHz (see Table 3).

In the figures, the sampling point occurs at the commencement of each block.

The respective numbers of colour-difference samples can be obtained by dividing the number of luminance samples by
two. The (12,132), and (16,122) were chosen symmetrically to dispose the digital active line about the permitted
variations. They do not form part of the digital line specification and relate only to the analogue interface.
8 Rec. ITU-R BT.601-5

FIGURE 1

16:9 or 4:3 at 13.5 MHz

625
OH
Analogue line n – 1 Analogue line n

Digital line n – 1 Digital line n

Digital blanking
12 T 132 T
Luminance samples
717 718 719 720 721 730 731 732 733 862 863 0 1 2

4:2:2, chromo
CR samples

359 360 365 366 431 0 1

4:2:2, chromo
CB samples
359 360 365 366 491 0 1

T : luminance sampling period

FIGURE 2

16:9 or 4:3 at 13.5 MHz

525
OH
Analogue line n – 1 Analogue line n

Digital line n – 1 Digital line n

Digital blanking
16 T 122 T
Luminance samples
717 718 719 720 721 734 735 736 737 856 857 0 1 2

4:2:2, chromo
CR samples

359 360 367 368 428 0 1

4:2:2, chromo
CB samples
359 360 367 368 428 0 1

T : luminance sampling period D01

FIGURE 1...[D01] = 11 CM ET FIGURE 2...[D02] = 10 CM

 Rec. ITU-R BT.601-5 9

APPENDIX 2
TO PART A

Filtering characteristics

F IGURE 3
Specification for a luminance or RGB signal filter
used when sampling at 13.5 MHz
50

40 dB
40

30
)
B
d
( 20
12 dB
10

0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
5.75 6.7 5 13.5
F requency (MHz)
a) Templa te for inserti on loss/frequency character istic

0.05

) 0 0.01 0.05 0.1 dB

B
d
(

– 0.05
0 1 2 3 4 5 6
Frequency (MHz) 5.5
5.75
b) Passband ripple tole rance

s)
(n

sn 0 4 n s 6 ns
2

–5
0 1 2 3 4 5 6
Frequency (MHz) 5.75

c) Passband group-delay tole rance

Note 1 – The lowest indicated values in b) and c) are for 1 kHz ( instead of 0 MHz). D02

IFIGURE 3...[D02] = 21 CM = PAGE PLEINE

10 Rec. ITU-R BT.601-5

FIGURE 4
Specification for a colour-difference signal filter
used when sampling at 6.75 MHz

50

40 dB
40

30
)
B
d(
20

10
6 dB

0
0 1 2 3 4 5 6 7
2.75 3.375 6.75
Frequency ( MHz)
a) Template for insertion loss/frequency chara cteristic

0.1

0.05

) 0 0.02 0.1 dB
B
d(

– 0.05

– 0.1
1 2 3
Fr equency (MHz) 2.75

b) Passband r ipple tolera nce

20

)s 10
n(

s 0 8 ns 12 ns 24 ns
n
4
– 10

– 20
0 1 2 3
Frequency (M Hz) 2.75 3 dB loss frequency
c) Passband group-delay tole rance

N ote 1 – The lowest indicated values in b) and c) are for 1 kHz (instea d of 0 MHz). D 03

FIGURE 4...[D03] = 21 CM = PAGE PLEINE

 Rec. ITU-R BT.601-5 11

FIGURE 5
Specification for a digital filter for sampli ng-rate conversion
from 4:4:4 to 4:2:2 colour-difference signals

60
55 dB

50

40
See Note 3
) 30
B
d(

20

10
6 dB

0
0 1 2 3 4 5 6 7
2.75 3.375 6.25 6.75
Frequency (MHz)
a) Templa te for insertion loss/f requency cha racteristic
0.1

0.5

) 0 0.1 dB
B
d(
– 0.5

– 0.1
0 1 2 3
Fr equency ( MHz) 2.75

b) Passband ripple tolerance

Notes to Figs. 3, 4 and 5:

Note 1 – Ripple and group dela y are specified relative to their values at 1 kHz. The full lines a re practical limits and the
dashed lines give suggeste d limits for the theoretical design.
Note 2 – In the digital filter, the practical a nd design limits are the same. The delay distortion is zero, by design.
Note 3 – In the digital filter ( Fig. 5), t he amplitude/frequency characte ristic (on linear scales) should be skew-symmetr ical
about the half-amplitude point, which is indicate d on the figure.
Note 4 – In the proposals for the filters used in the encoding and decoding processe s, it has been a ssumed that, in the
post-filter s which follow digital-to-analogue conversion, corr ection for the (sin x/x) characte ristic of the sa mple-and-hold
circuits is provide d.
D04

FIGURE 5...[D04] = 21 CM = PAGE PLEINE

12 Rec. ITU-R BT.601-5

PART B

TO ANNEX 1

The 18 MHz members of the family

1 Encoding parameter values for the 4:2:2, 18 MHz member of the family

The specification (see Table 4) applies to the 4:2:2 member of the family used for the standard digital interface between
main digital studio equipment and for international programme exchange of 16:9 aspect ratio television with higher
horizontal resolution compared with 16:9 systems sampled at 13.5 MHz.

TABLE 4

525-line, 60 field/s 625-line, 50 field/s

Parameters
systems systems

1. Coded signals: Y, CR, CB These signals are obtained from gamma pre-corrected signals, namely:
EY′ , ER′ – EY′ , EB′ – EY′ (see Annex § 3.5)

2. Number of samples per total line:

– luminance signal (Y) 1144 1152
– each colour-difference signal 572 576
(CR, CB)
3. Sampling structure Orthogonal, line, field and frame repetitive. CR and CB samples co-sited with odd
(1st, 3rd, 5th, etc.) Y samples in each line
4. Sampling frequency:
– luminance signal 18 MHz
– each colour-difference signal 1 9 MHz
The tolerance for the sampling frequencies should coincide with the tolerance for the
line frequency of the relevant colour television standard
5. Form of coding Uniformly quantized PCM, 8 (optionally 10) bits per sample, for the luminance signal
and each colour-difference signal
6. Number of samples per digital active
line:
– luminance signal 960
– each colour-difference signal 480
7. Analogue-to-digital horizontal
timing relationship:
– from end of digital active line To be determined (see Appendix 1 to Part B)
to OH
8. Correspondence between video (See § 3.4) (Values are decimal)
signal levels and quantization levels:
– scale 0 to 255
– luminance signal 220 quantization levels with the black level corresponding to level 16 and the peak
white level corresponding to level 235. The signal level may occasionally excurse
beyond level 235
– each colour-difference signal 225 quantization levels in the centre part of the quantization scale with zero signal
corresponding to level 128
9. Code-word usage Code words corresponding to quantization levels 0 and 255 are used exclusively for
synchronization. Levels 1 to 254 are available for video
 Rec. ITU-R BT.601-5 13

2 Encoding parameter values for the 4:4:4, 18 MHz member of the family

The specifications given in Table 5 apply to the 4:4:4 member of the family suitable for television source equipment and
high-quality video signal processing applications.

TABLE 5

525-line, 60 field/s 625-line, 50 field/s

Parameters
systems systems

1. Coded signals: Y, CR, CB or R, G, B These signals are obtained from gamma pre-corrected signals, namely:
EY′ , ER′ – EY′ , EB′ – EY′ or ER′ , EG′ , EB′

2. Number of samples per total line for

1144 1152
each signal

3. Sampling structure Orthogonal, line, field and frame repetitive. The three sampling structures to be
coincident and coincident also with the luminance sampling structure of the
4:2:2 member

4. Sampling frequency for each signal 18 MHz

5. Form of coding Uniformly quantized PCM, 8 (optionally 10) bits per sample

6. Duration of the digital active line

960
expressed in number of samples

7. Correspondence between video (See § 3.4) (Values are decimal)

signal levels and the 8 most
significant bits (MSB) of the
quantization level for each sample:
– scale 0 to 255

– R, G, B or luminance signal(1) 220 quantization levels with the black level corresponding to level 16 and the peak
white level corresponding to level 235. The signal level may occasionally excurse
beyond level 235

– each colour-difference signal (1) 225 quantization levels in the centre part of the quantization scale with zero signal
corresponding to level 128
(1) If used.

APPENDIX 1

TO PART B

Definition of signals used in the digital coding standards

1 Relationship of digital active line to analogue sync reference

Further study is required to specify absolute values for these parameters, while ensuring consistent picture positioning
and geometry across different standards. For practical application, the correct relationship is achieved when the picture to
sync relationship in the analogue domain is identical for images converted from 13.5 and 18 MHz sampled digital
representations.
14 Rec. ITU-R BT.601-5

APPENDIX 2
TO PART B
Filtering characteristics
FIGURE 6
Sp ecification for a luminance or RG B signal filter used when sampling at 18 MHz

50

40 dB
40

30
)
B
(d 20
12 dB
10

0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
7.67 10.67
Frequency (MHz)

a) Template for insertion loss/frequency characteristic

0.05

) 0 0.01 0.05 0.1 dB

B
d
(

– 0.05
0 1 2 3 4 5 6 7 8
Frequency (MHz) 7.33
7.67

b) Passband ripple tolerance

)s
(n

2 ns 0 4 ns 6 ns

–5
0 1 2 3 4 5 6 7 8
Frequency (MHz) 7.67

c) Passband group-delay tolerance

Note 1 – The lowest indicated values in b) and c) are for 1 kHz (instead of 0 MHz).
D05
 Rec. ITU-R BT.601-5 15

FIGURE 7
Specification for a colo ur-difference signal filter used when sampli ng at 9 MHz

50

40 dB
40

30
)
B
(d 20

10
6 dB

0
0 1 2 3 4 5 6 7 8 9 10
3.67 4.60 5.33
Frequency (MHz)

a) Template for insertion loss/frequency characteristic

0.1

0.05

) 0 0.02 0.1 dB
B
d(

– 0.05

– 0.1
0 1 2 3 4
3.67
Frequency (MHz)

b) Passband ripple tolerance

20

s)
(n 10

4 ns 0 8 ns 12 ns 24 ns

– 10

– 20
0 1 2 3 4
3 dB loss frequency
3.67
Frequency (MHz)

c) Pa ssband group-delay tolerance

Note 1 – The lowest indicated values in b) and c) are for 1 kHz (instead of 0 MHz).
D 06

FIGURE 7...[D06] = 21 CM = PAGE PLEINE

16 Rec. ITU-R BT.601-5

FIGURE 8
Specification for a digital f ilter for sampling-rate conversion
from 4:4:4 to 4:2:2 colour-dif ference signals

60
55 dB

50

40
See Note 3
) 30
B
d
(
20

10
6 dB

0
0 1 2 3 4 5 6 7 8 9 10
3.67 4.5 5.33 8.33
Freque ncy (MHz)

a) Template for insertion loss/frequency characteristic

0.1

0.5

) 0 0.1 dB
B
d
(
– 0.5

– 0.1
0 1 2 3 4
Frequency (MHz) 3.67

b) Passband ripple tolerance

Notes to Figs. 6, 7 and 8:

Note 1 – Ripple and group delay are specified relative to their values at 1 kHz. The full lines are practical limits and the dashed
lines give suggested limits for the theoretical design.

Note 2 – In the digital filter, the practical and design limits are the same. The delay distortion is zero, by design.

Note 3 – In the digital filter (Fig. 8), the amplitude/frequency characteristic (on linear scales) should be skew-symmetrical about
the half-amplitude point, which is indicated on the figure.
Note 4 – In the proposals for the filters used in the encoding a nd decoding processes, it has been assumed that, in the post-filters
which follow digital-to-analogue conversion, correction for th e (sin x/x) characteristic of the sample-and-hold circuits is provided.

D07

FIGURE 8...[D07] = 21 CM = PAGE PLEINE

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Characteristics of television systems CCIR Report 624-4

CHARACTERISTICS OF TELEVISION SYSTEMS

(Question 1/11)

Section 11A: Characteristics of systems for monochrome and colour television

Report 624-4

(1974-1987-1982-1986-1990)

The tables in this document are given for information purposes and contain details of a number of different television
systems in use at the time of the XVIIth Plenary Assembly of the CCIR, Duesseldorf, 1990.

Information on the results of the comparative laboratory tests carried out on the various colour television systems in the
period 1963-1966 by broadcasting authorities, administrations and industrial organizations, together with the main
parameter of systems may be found in Reports 406 and 407, XXIIth Plenary Assembly, New Delhi, 1970

All television systems listed in the Report employ an aspect ratio of the picture display (width/height) of 4/3, a scanning
sequence from left to right and from top to bottom and an interlace ratio of 2/1, resulting in a picture (frame) frequency
of half the field frequency. All systems are capable of operating independently of the power supply frequency.

The full report can be obtained from:

The International Radio Consultative Committee
International Telecommunications Union
Place des Nations
CH-1211 Geneva
20 Switzerland
Telephone: (011) 4122 730 5800

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(ALSO RESOLUTIONS AND OPINIONS) VOLUME XI — PART 1

BROADCASTING SERVICE (TELEVISION)
CCIR
1. The International Radio Consultative Committee (CCIR) is the permanent organ of the International Telecommunication Union responsible
under the International Telecommunication Convention “...to study technical and operating questions relating specifically to
radiocommunications without limit of frequency range, and to issue recommendations on them...” (International Telecommunication
Convention, Nairobi 1982, First Part, Chapter I, Art. 11, No. 83).1
2. The objectives of the CCIR are in particular:
a. to provide the technical bases for use by administrative radio conferences and radiocommunication services for efficient utilization of the
radio-frequency spectrum and the geostationary-satellite orbit, bearing in mind the needs of the various radio services;
b. to recommend performance standards for radio systems and technical arrangements which assure their effective and compatible
interworking in international telecommunications;
c. to collect, exchange, analyze and disseminate technical information resulting from studies by the CCIR, and other information available, for
the development, planning and operation of radio systems, including any necessary special measures required to facilitate the use of such
information in developing countries.

1. See also the Constitution of the ITU, Nice, 1989, Chapter 1, Art. 11, No. 84.

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RECOMMENDATION 656

INTERFACES FOR DIGITAL COMPONENT VIDEO SIGNALS

IN 525-LINE AND 625-LINE TELEVISION SYSTEMS
(1986)
The CCIR,

CONSIDERING

a. that there are clear advantages for television broadcasting organizations and programme producers in digital studio standards which have
the greatest number of significant parameter values common to 525-line and 625-line systems;
b. that a world-wide compatible digital approach will permit the development of equipment with many common features, permit operating
economies and facilitate the international exchange of programmes;
c. that to implement the above objectives, agreement has been reached on the fundamental encoding parameters of digital television for
studios in the form of Recommendation 601;
d. that the practical implementation of Recommendation 601 requires definition of details of interfaces and the data streams traversing them;
e. that such interfaces should have a maximum of commonality between 525-line and 625-line versions;
f. that in the practical implementation of Recommendation 601 it is desirable that interfaces be defined in both serial and parallel forms;
g. that digital television signals produced by these interfaces may be a potential source of interference to other services, and due notice must
be taken of No. 964 of the Radio Regulations,

UNANIMOUSLY RECOMMENDS

that where interfaces are required for component-coded digital video signals in television studios, the interfaces and the data streams
that will traverse them should be in accordance with the following description, defining both bit-parallel and bit-serial implementations.

1. Introduction

This Recommendation describes the means of interconnecting digital television equipment operating on the 525-line or 625-line
standards and complying with the 4 : 2 : 2 encoding parameters as defined in Recommendation 601.
Part I describes the signal format common to both interfaces.
Part II describes the particular characteristics of the bit-parallel interface.
Part III describes the particular characteristics of the bit-serial interface.

PART I

COMMON SIGNAL FORMAT OF THE INTERFACES

1. General description of the interfaces

The interfaces provide a unidirectional interconnection between a single source and a single destination.
A signal format common to both parallel and serial interfaces is described in § 2 below.

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The data signal are in the form of binary information coded in 8-bit words. These signals are:
– video data;
– timing reference codes;
– ancillary data;
– identification codes.

2. Video data

2.1 Coding characteristics

The video data is in compliance with Recommendation 601, and with the field-blanking definition shown in Table 1.

TABLE I — Field interval definitions

625 525

V-digital field blanking

Start
(V = 1) Line 624 Line 1
Field 1
Finish
Line 23 Line 10
(V = 0)
Start
Line 311 Line 264
Field 2 (V = 1)
Finish
Line 336 Line 273
(V = 0)
F-digital field identification

Field 1 F=0 Line 1 Line 4

Field 2 F=1 Line 313 Line 266

Note 1 — Signals F and V change state synchronously with the end of active
video timing reference code at the beginning of the digital line.

Note 2 — Definition of line numbers is to be found in Report 624. Note that

digital line number changes state prior to 0H as shown in Fig. 1.

2.2 Video data format

The data words 0 and 255 (00 and FF in hexadecimal notation) are reserved for data identification purposes and consequently only 254
of the possible 256 words may be used to express a signal value.
The video data words are conveyed as a 27 Mwords/s multiplex in the following order:
CB , Y, CR , Y, CB , Y, CR , etc.
where the word sequence CB , Y, CR , refers to co-sited luminance and colour-difference samples and the following word, Y, corresponds to the
next luminance sample.

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2.3 Timing relationship between video data and the analogue synchronizing waveform

2.3.1 Line interval

The digital active line begins at 244 words (in the 525-line standard) or at 264 words (in the 625-line standard) after the leading
edge of the analogue line synchronization pulse, this time being specified between half-amplitude points.
Figure 1 shows the timing relationship between video and the analogue line synchronization.

Analogue line blinking

OH OH

TV line 64 µs (625)
63.5 µs (525)
16T (625) Nom.
8T (525) 20T (625) Nom.
10T (525)

24T (625) Video data block

32T (525) 1448T

Multiplexed video data

CB Y CR Y CB Y ...

4T 4T

Digital line blanking Digital active line

288T (625) 1440T (625)
276T (525)
Digital line
1728T (625)
1716T (525)

FIGURE 1 – Data format and timing relationship with the analogue video signal

T: clock period 37 ns nom.

SAV: start of active video timing reference code
EAV: end of active video timing reference code

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2.3.2 Field interval

The start of the digital field is fixed by the position specified for the start of the digital line: the digital field starts 32 words (in
the 525-line systems) and 24 words (in the 625-line systems) prior to the lines indicated in Table I.

2.4 Video timing reference codes (SAV, EAV)

There are two timing reference codes, one at the beginning of each video data block (Start of Active Video, SAV) and one at the end of
each video data block (End of Active Video, EAV) as shown in Fig. 1.
Each timing reference code consists of a four word sequence in the following format: FF 00 00 XY. (Values are expressed in
hexadecimal notation. Codes FF, 00 are reserved for use in timing reference codes.) The first three words are a fixed preamble. The fourth
word contains information defining field 2 identification, the state of field blanking, and the state of line blanking. The assignment of bits within
the timing reference code is shown below in Table II.

TABLE II — Video timing reference codes

Bit No.

Word
7 (MSB) 6 5 4 3 2 1 0 (MSB)

First 1 1 1 1 1 1 1 1

Second 0 0 0 0 0 0 0 0

Third 0 0 0 0 0 0 0 0

Fourth 1 F V H P3 P2 P1 P0

0 during field 1
F=
1 during field 2

V = 0 elsewhere
1 during field blanking

0 in SAV
H=
1 in EAV

P0, P1, P2, P3 : protection bits (see Table III).

MSB: most significant bit
LSB: least significant bit

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Table I defines the state of the V and F bits.
Bits P0, P1, P2, P3, have states dependent on the states of the bits F, V and H as shown in Table III. At the receiver this arrangement
permits one-bit errors to be corrected and two-bit errors to be detected.

TABLE III — Protection bits

Bit No. 7 6 5 4 3 2 1 0

Function Fixed 1 F V H P3 P2 P1 P0

0 1 0 0 0 0 0 0 0

1 1 0 0 1 1 1 0 1

2 1 0 1 0 1 0 1 1

3 1 0 1 1 0 1 1 0

4 1 1 0 0 0 1 1 1

5 1 1 0 1 1 0 1 0

6 1 1 1 0 1 1 0 0

7 1 1 1 1 0 0 0 1

2.5 Ancillary data

Provision is made for ancillary data to be inserted synchronously into the multiplex during the blanking intervals at a rate of 27 Mwords/s.
Such data is conveyed by one or more 7-bit words, each with an additional parity bit (LSB) giving odd parity.
Each ancillary data block, when used, should be constructed as shown in Table IV from the timing reference code ANC and a data field.

2.6 Data words during blanking

The data words occurring during digital blanking intervals that are not used for the timing reference code ANC or for ancillary data are
filled with the sequence 80, 10, 80, 10, etc. (values are expressed in hexadecimal notation) corresponding to the blanking level of the CB , Y, CR ,
Y signals respectively, appropriately placed in the multiplexed data.

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TABLE IV — Ancillary data block

ANC code Data field
Word 0 1 2 3 4 5 0 N

00 FF FF TT MM LL XX XX

Data words
(00, FF excluded)

Word count or line number (Note 1)

Bit 7 6 5 4 3 2 1 0
Word MM 0 D11 D10 D9 D8 D7 D6 P

Word LL 0 D 5 D4 D3 D2 D1 D0 P

Odd word parity

Data type (Note 1)

Fixed pattern

“Word count” specifies the length of the data field and lies in the range 1 to 1434. If word TT
specifies a line number then D11 to D0 contain the binary equivalent of the line number and
the word count is assumed to be zero. The ancillary data block(s) may be transmitted when
time is available during horizontal or vertical blanking following the EAV timing reference
signal.

Note 1 — The precise location of the ancillary data blocks and the coding of words 3, 4 and 5 require
further study.

PART II

BIT-PARALLEL INTERFACE

1. General description of the interface

The bits of the digital code words that describe the video signal are transmitted in parallel by means of eight conductor pairs, where each
carries a multiplexed stream of bits (of the same significance) of each of the component signals, CB , Y, CR , Y. The eight pairs also carry
ancillary data that is time-multiplexed into the data stream during video blanking intervals. A ninth pair provides a synchronous clock at 27MHz.
The signals on the interface are transmitted using balanced conductor pairs. Cable lengths of up to 50 m (≅ 160 feet) without
equalization and up to 200 m (≅ 650 feet) with appropriate equalization (see § 6) may be employed.
The interconnection employs a twenty-five pin D-subminiature connector equipped with a locking mechanism (see § 5).
For convenience, the eight bits of the data word are assigned the names DATA 0 to DATA 7. The entire word is designated as DATA
(0-7). DATA 7 is the most significant bit.
Video data is transmitted in NRZ form in real time (unbuffered) in blocks, each comprising one active television line.

2. Data signal format

The interface carries data in the form of 8 parallel data bits and a separate synchronous clock. Data is coded in NRZ form. The
recommended data format is described in Part I.

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3. Clock signal

3.1 General

The clock signal is a 27 MHz square wave where the 0-1 transition represents the data transfer time. This signal has the following
characteristics:
Width: 18.5 ± 3 ns
Jitter: Less than 3 ns from the average period over one field.

3.2 Clock-to-data timing relationship

The positive transition of the clock signal shall occur midway between data transitions as shown in Fig. 2.

Timing reference
for data and clock

Data

td

Clock

FIGURE 2 — Clock-to-data timing (at source)

1
Clock period (625): T  37ns
1728 f
H

1
Clock period (525): T  37ns
1716 f
H

Clock pulse width: t  18.5
3ns

Data timing – sending end: t d  18.5
3ns
fH : line frequency

4. Electrical characteristics of the interface

4.1 General

The interface employs nine line drivers and nine line receivers.
Each line driver (source) has a balanced output and the corresponding line receiver (destination) a balanced input (see Fig. 3).
Although the use of ECL technology is not specified, the line driver and receiver must be ECL-compatible, i.e. they must permit the use of
ECL for either drivers or receivers.
All digital signal time intervals are measured between the half-amplitude points.

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Source Transmission Destination

line
A

Line Line
driver receiver

FIGURE 3 — Line driver and line receiver interconnection

4.2 Logic convention

The A terminal of the line driver is positive with respect to the B terminal for a binary 1 and a negative for a binary 0 (see Fig. 3).

4.3 Line driver characteristics (source)

4.3.1 Output impedance: 110 Ω maximum

4.3.2 Common mode voltage: –1.29 V ± 15% (both terminals relative to ground).

4.3.3 Signal amplitude: 0.8 to 2.0 V peak-to-peak, measured across a 110 Ω resistive load.

4.3.4 Rise and fall times: less than 5 ns, measured between the 30% and 80% amplitude points, with a
110 Ω resistive load. The difference between rise and fall times must not exceed 2 ns.

4.4 Line receiver characteristics

4.4.1 Input impedance: 110 Ω ± 10 Ω.

4.4.2 Maximum input signal: 2.0 V peak-to-peak.

4.4.3 Minimum input signal: 185 mV peak-to-peak.

However, the line receiver must sense correctly the binary data when a random data signal produces the conditions
represented by the eye diagram in Fig. 4 at the data detection point.

4.4.4 Maximum common mode signal: ± 0.5 V, comprising interference in the range 0 to 15 kHz (both
terminals to ground).

4.4.5 Differential delay: Data must be correctly sensed when the clock-to-data differential delay is in the
range between ± 11 ns (see Fig. 4).

5. Mechanical details of the connector

The interface uses the 25 contact type D subminiature connector specified in ISO Document 2110-1980, with contact assignment shown
in Table V.
Connectors are locked together by a one-piece slide lock on the cable connectors and locking posts on the equipment connectors.
Connectors employ pin contacts and equipment connectors employ socket contacts. Shielding of the interconnecting cable and its connectors
must be employed (see Note).
Note — It should be noted that the ninth and eighteenth harmonics of the 13.5 MHz sampling frequency (nominal value) specified in
Recommendation 601 fall at the 121.5 and 243 MHz aeronautical emergency channels. Appropriate precautions must therefore be taken in the
design ad operation of interfaces to ensure that no interference is caused at these frequencies. Emission levels for related equipment are given
in CISPR Recommendation: “Information technology equipment – limits of interference and measuring methods” Document CISPR/B (Central
Office) 16. Nevertheless, No. 964 of the Radio Regulations prohibits any harmful interference on the emergency frequencies.

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Tmin Tmin

Vmin

Reference transition
of clock

FIGURE 4 — Idealized eye diagram corresponding to the minimum input signal level

Tmin = 11 ns
Vmin = 100 mV

Note — The width of the window in the eye diagram, within which data must be
correctly detected comprises ±3 ns clock jitter, ±3 ns data timing (see § 3.2),
and ±5 ns available for differences in delay between pairs of the cable.

TABLE V — Contact assignments

Contact Signal line Contact Signal line

1 Clock A 14 Clock B

2 System ground 15 System ground

3 Data 7A (MSB) 16 Data 7B

4 Data 6A 17 Data 6B

5 Data 5A 18 Data 5B

6 Data 4A 19 Data 4B

7 Data 3A 20 Data 3B

8 Data 2A 21 Data 2B

9 Data 1A 22 Data 1B

10 Data 0A 23 Data 0B

11 Spare A-A 24 Spare A-B

12 Spare B-A 25 Spare B-B

13 Cable shield — —

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Any spare pairs connected to contacts 11,24 or 12,25 are reserved for bits of lower significance than those carried on contacts 10,23.

6. Line receiver equalization

To permit correct operation with longer interconnection links, the line receiver may incorporate equalization.
When equalization is used, it should conform to the nominal characteristics of Fig. 5. This characteristic permits operation with a range of
cable lengths down to zero. The line receiver must satisfy the maximum input signal condition of § 4.4

20

18

16

14
Relative gain (dB)

12

Luminance sampling frequency

10

Multiple clock frequency

8

0
0.1 0.2 0.5 1 2 5 10 20 50
Frequency (MHz)

FIGURE 5 — Line receiver equalization characteristic for small signals

PART III

BIT-SERIAL INTERFACE

1. General description of the interface

The multiplexed data stream of 8-bit words (as described in Part I) is transmitted over a single channel in bit-serial form. Prior to
transmission, additional coding takes place to provide spectral shaping, word synchronization and to facilitate clock recovery.

2. Coding

The 8-bit data words are encoded for transmission into 9-bit words as shown in Table VI.
For some 8-bit data words alternative 9-bit transmission words exist, as shown in columns 9B and 9B, each 9-bit word being the
complement of the other. In such cases, the 9-bit word will be selected alternately from columns 9B and 9B on each successive occasion that
any such 8-bit word is conveyed. In the decoder, either word must be converted to the corresponding 8-bit data word.

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TABLE VI — Encoding table

Input Output Input Output Input Output Input Output Input Output Input Output

8B 9B 9B 8B 9B 9B 8B 9B 9B 8B 9B 9B 8B 9B 9B 8B 9B 9B

00 0FE 101 2B 053 56 097 81 0AA AC 12C D7 0CC

01 027 2C 1AC 57 168 82 055 AD 0D9 D8 139
02 1D8 2D 057 58 099 83 1AA AE 126 D9 0CE
03 033 2E 1A8 59 166 84 0D5 AF 0E5 DA 133
04 1CC 2F 059 5A 09B 85 12A B0 11A DB 0D8
05 037 30 1A6 5B 164 86 095 B1 0E9 DC 131
06 1CB 31 05B 5C 09D 87 16A B2 116 DD 0DC
07 039 32 05D 5D 162 88 0B5 B3 02E DE 127
08 1C6 33 1A4 5E 0A3 89 14A B4 1D1 DF 0E2
09 03B 34 065 5F 15C 8A 09A B5 036 E0 123
0A 1C4 35 19A 60 0A7 8B 165 B6 1C9 E1 0E4
0B 03D 36 069 61 158 8C 0A6 B7 03A E2 11D
0C 1C2 37 196 62 025 1DA 8D 159 B8 1C5 E3 0E6
0D 14D 38 026 1D9 63 0A1 15E 8E 0AC B9 04E E4 11B
0E 0B4 39 08C 173 64 029 1D6 8F 153 BA 1B1 E5 0E8
0F 14B 3A 02C 1D3 65 091 16E 90 0AE BB 05C E6 119
10 1A2 3B 098 167 66 045 1BA 91 151 BC 1A3 E7 0EC
11 0B6 3C 032 1CD 67 089 176 92 02A 1D5 BD 05E E8 117
12 149 3D 0BE 141 68 049 1B6 93 092 16D BE 1A1 E9 0F2
13 0BA 3E 034 1CB 69 085 17A 94 04A 1B5 BF 066 EA 113
14 145 3F 0C2 13D 6A 051 1AE 95 094 16B C0 199 EB 0F4
15 0CA 40 046 1B9 6B 08A 175 96 0A8 157 C1 06C EC 10D
16 135 41 0C4 13B 6C 0A4 15B 97 0B7 148 C2 193 ED 076
17 0D2 42 04C 1B3 6D 054 1AB 98 0F5 10A C3 06E EE 10B
18 12D 43 0C8 137 6E 0A2 15D 99 0BB 144 C4 191 EF 0C7
19 0D4 44 058 1A7 6F 052 1AD 9A 0ED 112 C5 072 F0 13C
1A 129 45 0B1 70 056 9B 0BD 142 C6 18D F1 047
1B 0D6 46 14E 71 1A9 9C 0EB 114 C7 074 F2 1B8
1C 125 47 0B3 72 05A 9D 0D7 128 C8 18B F3 067
1D 0DA 48 14C 73 1A5 9E 0DD 122 C9 07A F4 19C
1E 115 49 0B9 74 06A 9F 0DB 124 CA 189 F5 071
1F 0EA 4A 06B 75 195 A0 146 CB 08E F6 198
20 0B2 4B 194 76 096 A1 0C5 CC 185 F7 073
21 02B 4C 06D 77 169 A2 13A CD 09C F8 18E
22 1D4 4D 192 78 0A9 A3 0C9 CE 171 F9 079
23 02D 4E 075 79 156 A4 136 CF 09E FA 18C
24 1D2 4F 18A 7A 0AB A5 0CB D0 163 FB 087
25 035 50 08B 7B 154 A6 134 D1 0B8 FC 186
26 1CA 51 174 7C 0A5 A7 0CD D2 161 FD 0C3
27 04B 52 08D 7D 15A A8 132 D3 0BC FE 178
28 1B4 53 172 7E 0AD A9 0D1 D4 147 FF 062 19D
29 04D 54 093 7F 152 AA 12E D5 0C6
2A 1B2 55 16C 80 155 AB 0D3 D6 143

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3. Order of transmission
The least significant bit of each 9-bit word shall be transmitted first.

4. Logic convention
The signal is conveyed in NRZ form. The voltage at the output terminal of the line driver shall increase on a transition from 0 to 1
(positive logic).

5. Transmission medium
The bit-serial data stream can be conveyed using either a coaxial cable (§ 6) or fibre optic bearer (§ 7).

6. Characteristics of the electrical interface

6.1 Line driver characteristics (source)
6.1.1 Output impedance
The line driver has an unbalanced output with a source impedance of 75 Ω and a return loss of at least 15 dB over a frequency
range of 10 to 243 MHz.

6.1.2 Signal impedance

The peak-to-peak signal amplitude lies between 400 mV and 700 mV measured across a 75 Ω resistive load directly
connected to the output terminals without any transmission line.

6.1.3 DC offset
The DC offset with reference to the mid amplitude point of the signal lies between +1.0V and –1.0 V.

6.1.4 Rise and fall times

The rise and fall times, determined between the 20% and 80% amplitude points and measured across a 75 Ω resistive load
connected directly to the output terminals, shall lie between 0.75 and 1.5 ns and shall not differ by more than 0.40 ns.

6.1.5 Jitter
The timing of the rising edges of the data signal shall be within ± 0.10 ns of the average timing of rising edges, as determined
over a period of one line.

6.2 Line receiver characteristics (destination)

6.2.1 Terminating impedance
The cable is terminated by 75 Ω with a return loss of at least 15 dB over a frequency range of 10 to 243 MHz.

6.2.2 Receiver sensitivity

The line receiver must sense correctly random binary data either when connected directly to a line driver operating at the
extreme voltage limits permitted by § 6.1.2, or when connected via a cable having loss of 40 dB at 243 MHz and a loss characteristic of
1ń Ǹf .
Over the range 0 to 12 dB no equalization adjustment is required; beyond this range adjustment is permitted.

6.2.3 Interference rejection

When connected directly to a line driver operating at the lower limit specified in § 6.1.2, the line receiver must correctly sense
the binary data in the presence of a superimposed interfering signal at the following levels:
d.c. ± 2.5 V
Below 1 kHz: 2.5 V peak-to-peak
1 kHz to 5 MHz: 100 mV peak-to-peak
Above 5 MHz: 40 mV peak-to-peak

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6.3 Cables and connectors

6.3.1 Cable

It is recommended that the cable chosen should meet any relevant national standards on electro-magnetic radiation.
Note — It should be noted that the ninth and eighteenth harmonics of the 13.5 MHz sampling frequency (nominal value) specified in
Recommendation 601 fall at the 121.5 and 243 MHz aeronautical emergency channels. Appropriate precautions must therefore be taken
in the design and operation of interfaces to ensure that no interference is caused at these frequencies. Emission levels for related
equipment are given in CISPR Recommendation: “Information technology equipment – limits of interference and measuring methods”
(Document CISPR/B (Central Office) 16). Nevertheless, No. 964 of the Radio Regulations prohibits any harmful interference on the
emergency frequencies.

6.3.2 Characteristic impedance

The cable used shall have a nominal characteristic impedance of 75 Ω.

6.3.3 Connector characteristics

The connector shall have mechanical characteristics conforming to the standard BNC type (IEC Publication 169-8), and its electrical
characteristics should permit it to be used at frequencies up to 500 MHz in 75 Ω circuits.

7. Characteristics

To be defined.

_________________________

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