# CCIR System D

CCIR System D is an analog broadcast television system used in Bulgaria, Latvia, Lithuania, Poland, Romania, Slovakia, Czech Republic, Hungary, Albania and the People's Republic of China, Mongolia, Kyrgyzstan, North Korea, Tajikistan, Turkmenistan, Uzbekistan, Armenia, Azerbaijan, Georgia, Kazakhstan, Moldova, Russia, Ukraine and Belarus paired with the PAL/SECAM colour.
Initially known as the I.B.T.O. 625-line system this was the first 625-line system, developed by Mark Krivosheev in 1948, and later associated with the SECAM and PAL color systems. Used on VHF only in most countries, it usually combined with System K on UHF. In China, it is used for both VHF and UHF.

## Specifications

The general specifications for System D are listed below:
* Frame rate: 25 Hz
* Interlace: 2/1
* Field rate: 50 Hz
* Lines/frame: 625
* Line rate: 15.625 kHz
* Visual bandwidth: 6 MHz
* Vision modulation: Negative
* Preemphasis: 50 μs
* Sound modulation: FM
* Sound offset: +6.5 MHz
* Channel bandwidth: 8 MHz
Television channels were arranged as follows:
Original OIR assignments System D 625 lines :
| Channel | Video carrier (MHz) | Audio carrier (MHz) |
| I | 41.75 | 48.25 |
| II | 49.75 | 56.25 |
| III | 59.25 | 65.75 |
| IV | 77.25 | 83.75 |
| 1 | 145.25 | 151.75 |
| 2 | 153.25 | 159.75 |
| 3 | 161.25 | 167.75 |
| 4 | 169.25 | 175.75 |
| 5 | 177.25 | 183.75 |
| 6 | 185.25 | 191.75 |
| 7 | 193.25 | 199.75 |
| 8 | 201.25 | 207.75 |
| 9 | 209.25 | 215.75 |
Assignments since 1965 System D 625 lines :
| Channel | Video carrier (MHz) | Audio carrier (MHz) |
| 1 | 49.75 | 56.25 |
| 2 | 59.25 | 65.75 |
| 3 | 77.25 | 83.75 |
| 4 | 85.25 | 91.75 |
| 5 | 93.25 | 99.75 |
| 6 | 175.25 | 181.75 |
| 7 | 183.25 | 189.75 |
| 8 | 191.25 | 197.75 |
| 9 | 199.25 | 205.75 |
| 10 | 207.25 | 213.75 |
| 11 | 215.25 | 221.75 |
| 12 | 223.25 | 229.75 |
Channel arrangement for China (since 1970) :
| Channel | Frequency range (MHz) | Video carrier (MHz) | Audio carrier (MHz) | DTMB center frequency (MHz) |
| Band I |||||
| 1 | 48.5 - 56.5 | 49.75 | 56.25 | 52.5 |
| 2 | 56.5 - 64.5 | 57.75 | 64.25 | 60.5 |
| 3 | 64.5 - 72.5 | 65.75 | 72.25 | 68.5 |
| 4 | 76 - 84 | 77.25 | 83.75 | 80 |
| 5 | 84 - 92 | 85.25 | 91.75 | 88 |
| Band III |||||
| 6 | 167 - 175 | 168.25 | 174.25 | 171 |
| 7 | 175 - 183 | 176.25 | 182.75 | 179 |
| 8 | 183 - 191 | 184.25 | 190.75 | 187 |
| 9 | 191 - 199 | 192.25 | 198.75 | 195 |
| 10 | 199 - 207 | 200.25 | 206.75 | 203 |
| 11 | 207 - 215 | 208.25 | 214.75 | 211 |
| 12 | 215 - 223 | 216.25 | 222.75 | 219 |
UHF System D arrangement for China :
| Ch | Video (MHz) | DTMB (MHz) | Audio (MHz) |
| 13 | 471.25 | 474 | 477.75 |
| 14 | 479.25 | 482 | 485.75 |
| 15 | 487.25 | 490 | 493.75 |
| 16 | 495.25 | 498 | 501.75 |
| 17 | 503.25 | 506 | 509.75 |
| 18 | 511.25 | 514 | 517.75 |
| 19 | 519.25 | 522 | 525.75 |
| 20 | 527.25 | 530 | 533.75 |
| 21 | 535.25 | 538 | 541.75 |
| 22 | 543.25 | 546 | 549.75 |
| 23 | 551.25 | 554 | 557.75 |
| 24 | 559.25 | 562 | 565.75 |
| 25 | 605.25 | 610 | 611.75 |
| 26 | 613.25 | 618 | 619.75 |
| 27 | 621.25 | 626 | 627.75 |
| 28 | 629.25 | 634 | 635.75 |
| 29 | 637.25 | 642 | 643.75 |
| 30 | 645.25 | 650 | 651.75 |
| 31 | 653.25 | 658 | 659.75 |
| 32 | 661.25 | 666 | 667.75 |
| 33 | 669.25 | 674 | 675.75 |
| 34 | 677.25 | 682 | 683.75 |
| 35 | 685.25 | 690 | 691.75 |
| 36 | 693.25 | 698 | 699.75 |
| 37 | 701.25 | 706 | 707.75 |
| 38 | 709.25 | 714 | 715.75 |
| 39 | 717.25 | 722 | 723.75 |
| 40 | 725.25 | 730 | 731.75 |
| 41 | 733.25 | 738 | 739.75 |
| 42 | 741.25 | 746 | 747.75 |
| 43 | 749.25 | 754 | 755.75 |
| 44 | 757.25 | 762 | 763.75 |
| 45 | 765.25 | 770 | 771.75 |
| 46 | 773.25 | 778 | 779.75 |
| 47 | 781.25 | 786 | 787.75 |
| 48 | 789.25 | 794 | 795.75 |
| 49 | 797.25 | 802 | 803.75 |
| 50 | 805.25 | 810 | 811.75 |
| 51 | 813.25 | 818 | 819.75 |
| 52 | 821.25 | 826 | 827.75 |
| 53 | 829.25 | 834 | 835.75 |
| 54 | 837.25 | 842 | 843.75 |
| 55 | 845.25 | 850 | 851.75 |
| 56 | 853.25 | 858 | 859.75 |
| 57 | 861.25 | 866 | 867.75 |
| 58 | 871.25 | 874 | 877.75 |
| 59 | 879.25 | 882 | 885.75 |
| 60 | 887.25 | 890 | 893.75 |
| 61 | 895.25 | 898 | 901.75 |
| 62 | 903.25 | 906 | 909.75 |
* The original assignments of channels 25 to 57 were 2 MHz higher in frequency until c.1984. Channels 58 to 62 were deleted at this time.