leads it by 45 degrees on the odd lines and lags it by 45 degrees on the even lines. This swinging burst enables the colour decoder circuitry to distinguish the phase of the vector which reverses every line. PAL signal details For PAL-B/G the signal has these characteristics. (Total horizontal sync time 12.05 µs) After 0.9 µs a colourburst of cycles is sent. Most rise/fall times are in range. Amplitude is 100% for white level, 30% for black, and 0% for sync. The CVBS electrical amplitude is Vpp and impedance of 75 Ω. The vertical timings are: (Total vertical sync time 1.6 ms) As PAL is interlaced, every two fields are summed to make a complete picture frame. Colorimetry PAL colorimetry, as defined by the ITU on REC-BT.470, and based on CIE 1931 x,y coordinates: The assumed display gamma is defined as 2.8. PAL-N uses YDbDr instead of YUV. The PAL-M system uses color primary and gamma values similar to NTSC. Color is encoded using the YUV color space. Luma () is derived from red, green, and blue () gamma pre-corrected () primary signals: and are used to transmit chrominance. Each has a typical bandwidth of 1.3 MHz. Composite PAL signal timing where . Subcarrier frequency is 4.43361875 MHz (±5 Hz) for PAL-B/D/G/H/I/N. PAL broadcast systems The PAL colour system is usually used with a video format that has 625 lines per frame (576 visible lines, the rest being used for other information such as sync data and captioning) and a refresh rate of 50 interlaced fields per second (compatible with 25 full frames per second), such systems being B, G, H, I, and N (see broadcast television systems for the technical details of each format). This ensures video interoperability. However, as some of these standards (B/G/H, I and D/K) use different sound carriers (5.5 MHz, 6.0 MHz and 6.5 MHz respectively), it may result in a video image without audio when viewing a signal broadcast over the air or cable. Some countries in Eastern Europe which formerly used SECAM with systems D and K have switched to PAL while leaving other aspects of their video system the same, resulting in the different sound carrier. Instead, other European countries have changed completely from SECAM-D/K to PAL-B/G. The PAL-N system has a different sound carrier, and also a different colour subcarrier, and decoding on incompatible PAL systems results in a black-and-white