SECAM Video Format Explained
Table of Content
What does SECAM stand for?
SECAM is an abbreviation for Sequential Color and Memory or Séquentiel couleur à mémoire in French.
What is SECAM?
SECAM is an analog color television system first used in France. A team led by Henri de France working at Compagnie Française de Télévision (later bought by Thomson) invented SECAM. SECAM uses the same resolution as PAL (625 lines) but transmits the color information sequentially: R-Y on one line and B-Y on the next.
SECAM is used sparingly around the world and can be found in France, parts of Greece, Eastern Europe, Russia, and Africa. It is, historically, the first European color television standard.
Because of its great similarities with PAL, including the same framerate and Active Area, all of the modern video systems, such as DVD, VCD, and SuperVHS use PAL internally (for storing the data in the storage media, etc) and just change the color encoding to SECAM when outputting the signal back to SECAM TV.
Sequential Couleur Avec Memoire
or Sequential Color with Memory
|SYSTEM||SECAM B,G,H||SECAM D,K,K1,L|
|Horizontal Frequency||15.625 kHz||15.625 kHz|
|Vertical Frequency||50 Hz||50 Hz|
|Video Bandwidth||5.0 MHz||6.0 MHz|
|Sound Carrier||5.5 MHz||6.5 MHz|
What bandwidth uses SECAM?
SECAM is a 625 line 50 field system with a channel bandwidth of 8 MHz.
How does the SECAM video standard work?
Like PAL, SECAM also has 625 scan lines and is based on 50 Hz. SECAM uses two color difference signals and modulates them onto alternate lines, and through a built-in delay, both are available simultaneously. That eliminates phasing, and with FM transmission and color recovery so good, saturation was unnecessary.
While NTSC and PAL transmit the luminance and chrominance signals simultaneously, SECAM transmits luminance continuously and generates only one of the two chrominance signals on any given line. The frame rate is 25 frames per second (It has a field rate of fifty fields per second) to provide compatibility with the European electrical supply frequency, and the number of scanning lines is 625 as in PAL. SECAM employs a 15.625 kHz horizontal rate. Also, SECAM suffers from the visibility of the sub-carrier signals. That visibility detracts from its black and white compatibility, particularly in the mid-gray and white colors.
SECAM is not compatible with PAL or NTSC.
What are the SECAM variants?
There are five varieties of SECAM:
- French SECAM (SECAM-L)
- SECAM D/K
Which countries use the SECAM system?
The following countries use the SECAM system for television broadcasting.
- Burkina Faso
- The central African Republic
- Ce´te d’Ivoire
- Equatorial Guinea
- Egypt (Simulcast in PAL-B/G)
- Libya (Simulcast in PAL-B/G)
- Reunion (France)
- Afghanistan (Simulcast in PAL-B)
- Cambodia (Kampuchea) (Simulcast in PAL-B/G)
- Iran (Simulcast in PAL-B/G)
- North Korea (Simulcast in PAL-D/K)
- Saudi Arabia (Simulcast in PAL-B)
- Syria (Simulcast in PAL-G)
- Vietnam (Simulcast in NTSC-M)
- French Polynesia (incl. Tahiti)
- New Caledonia
- Wallis and Futuna
- Andorra (Simulcast in PAL)
- France (SECAM broadcast to be abandoned by 2011, simulcast in IPTV/ADSL and DVB-T)
- Luxembourg (Simulcast in PAL-B/G)
- Monaco (Simulcast in PAL-G)
Due to some slight differences in the type of SECAM adopted by the former USSR, the former USSR states that adopted SECAM are listed separately.
- French Guiana
- Saint-Pierre and Miquelon
Migration from SECAM to PAL
- Some former SECAM countries are in the process of migrating to PAL or have already finished doing so.
- Bulgaria (migrated 1994 – 1996)
- Czech Republic (migrated 1992 – 1994)
- Estonia (migrated 1995 – 1999)
- East Germany (switchover on December 14, 1990, because of German reunification)
- Greece (migrated in ca. 1992)
- Hungary (migrated 1995 – 1996)
- Latvia (migrated 1997 – 1999)
- Lithuania (migrated 1997 – 1999)
- Poland (migrated 1993 – 1995)
- Slovakia (migrated 1993 – 1996)
What is MESECAM?
MESECAM, Middle Eastern SECAM, is not a broadcast standard. It uses an AM subcarrier and SECAM uses FM subcarrier. It is a VCR standard by which the color under process in VCR’s is done by subcarrier shift instead of by frequency division. This means that an original SECAM recording (frequency division) does not playback in a MESECAM player.