Arclight-MCP-Bot: Add comprehensive content for RGsB (sync on green) signal format page (via update-page on MediaWiki MCP Server)

2026-02-10T19:17:48Z

Add comprehensive content for RGsB (sync on green) signal format page (via update-page on MediaWiki MCP Server)

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			'''RGsB''' ('''RGB with Sync on Green''', also written '''SoG''' or '''Sync-on-Green''') is an analog video signal format that transmits the red, green, and blue color channels on three 75Ω lines, with the synchronization (sync) information embedded within the green channel rather than carried on a separate wire. This reduces the connection to three conductors total, making RGsB the most cable-efficient of the RGB signal formats.<ref name="retrorgb-sync">[https://retrorgb.com/sync.html "Sync"], RetroRGB.</ref>

			== Overview ==

			In RGsB, the composite sync signal (combined horizontal and vertical sync pulses) is added to the green channel during the blanking interval. The display must contain sync separation circuitry to extract the sync information from the green signal before processing it for display. Because the sync pulses ride below the black level of the green channel, they do not affect the visible image when properly handled.

			RGsB is one of three common analog RGB sync configurations, differing in how synchronization is delivered:<ref name="intersil">[https://www.renesas.com/en/document/apn/an9513-component-video-sync-formats "Component Video Sync Formats (EL8102)"], Renesas (Intersil) Application Note AN9513.</ref>

			{\| class="wikitable"
			! Format !! Wires !! Sync method
			\|-
			\| '''[[RGBHV]]''' \|\| 5 \|\| Separate horizontal and vertical sync
			\|-
			\| '''[[RGBS]]''' \|\| 4 \|\| Composite sync on a dedicated wire
			\|-
			\| '''RGsB''' \|\| 3 \|\| Sync embedded in the green channel
			\|}

			The three-wire nature of RGsB means it uses the same number of conductors as [[Component (YPbPr)\|YPbPr component video]], and indeed shares the same physical connectors and cabling (three 75Ω cables with [[RCA (connector)\|RCA]] or [[BNC]] connectors). This can cause confusion, as a device's three-cable "component" input might accept either YPbPr or RGsB depending on the equipment, and the two formats are not directly interchangeable without conversion.

			== Signal Characteristics ==

			{\| class="wikitable"
			! Parameter !! Value
			\|-
			\| Signal type \|\| Three-channel analog (R, G+sync, B)
			\|-
			\| R/B signal level \|\| 0.7V peak-to-peak, 75Ω impedance
			\|-
			\| G signal level \|\| 0.7V peak-to-peak video + 0.3V sync (below black level)
			\|-
			\| Sync type \|\| Bi-level (SD) or tri-level (HD) composite sync on green
			\|-
			\| Impedance \|\| 75Ω per channel
			\|-
			\| Common connectors \|\| [[BNC]] ×3 (professional), [[RCA (connector)\|RCA]] ×3
			\|}

			For standard-definition signals, bi-level sync pulses are used, with the sync tip dropping approximately 0.3V below the black level on the green channel. For high-definition progressive signals (480p and above), tri-level sync is typically used, where the sync pulse dips below black level and then rises above it, providing a more precise timing reference.

			== Use on CRT Equipment ==

			=== Sony Equipment ===

			Sony has been the most prominent proponent of sync-on-green in the consumer and professional video space. Sony professional monitors, computer workstations, and the PlayStation line of game consoles all make use of RGsB in various contexts:<ref name="retrorgb-sync" />

			* '''Sony professional monitors''' — many Sony PVM and BVM monitors with [[BNC]] RGB inputs can auto-detect and accept RGsB alongside [[RGBS]] and [[RGBHV]].
			* '''Sony computer workstations''' — Silicon Graphics (SGI) workstations and some Sun Microsystems systems output RGsB natively, often through DB13W3 connectors. Sony's high-end Trinitron computer monitors (GDM series) support sync-on-green for compatibility with these systems.
			* '''PlayStation 2''' — the PS2 is the most commonly encountered consumer device that outputs RGsB. When set to progressive scan (480p) mode over its Multi AV output, the PS2 disables its composite video and luma sync outputs and switches to sync-on-green for its RGB signal. At 480i, the PS2 uses standard [[RGBS\|composite sync or sync-on-luma]] over its RGB output.<ref name="retro-access">[https://retro-access.com/knowledge-center/sync/ "Understanding Sync"], Retro Access.</ref>

			=== Multi-Sync Professional Monitors ===

			Many multi-sync professional CRT monitors auto-detect sync type across their BNC inputs and can accept RGBHV, RGBS, or RGsB without manual configuration. This includes high-end models from Sony, Ikegami, Barco, and NEC. The monitor's sync processing circuitry detects whether sync is present on dedicated H/V lines, a separate composite sync line, or embedded in the green channel, and configures itself accordingly.

			=== Computer Workstation Monitors ===

			Before VGA's dominance, some Unix workstation environments (particularly SGI and Sun) standardized on RGsB because the three-wire approach simplified cabling in environments where long cable runs were common. The DB13W3 connector used by these systems carried three coaxial signals (R, G+sync, B) plus additional pins for identification. Monitors designed for these workstations natively support sync-on-green.

			== Compatibility Considerations ==

			A display that does not support sync-on-green will exhibit distinct symptoms when fed an RGsB signal: typically a strong green tint across the entire image (because the sync pulses are interpreted as green video data) or no image at all (because the display cannot find sync on its expected sync input). This is a common issue when connecting workstation equipment to standard VGA monitors.

			Conversely, feeding a standard RGBHV or RGBS signal to a display expecting RGsB will result in no sync lock, as the display looks for sync information in the green channel and finds none.

			Conversion between RGsB and other RGB formats requires relatively simple circuitry:

			* '''RGsB → RGBS''': A sync stripper/separator IC extracts composite sync from the green channel and outputs it on a separate wire, while passing through clean green video.
			* '''RGBHV → RGsB''': A sync combiner first merges H and V sync into composite sync, then adds (sums) the composite sync onto the green channel.

			== Retro Gaming Relevance ==

			For the retro gaming community, RGsB is primarily encountered in two contexts:

			* '''PlayStation 2 progressive scan''' — when using RGB cables with a PS2 in 480p mode, the console outputs RGsB. Most [[SCART]]-equipped displays and many scalers (RetroTINK, OSSC) can handle this, though some equipment requires explicit RGsB/sync-on-green support. For this reason, many PS2 users prefer [[Component (YPbPr)\|component video]] cables for progressive scan output, as component inputs are more universally supported.

			* '''Workstation monitor reuse''' — CRT enthusiasts who acquire SGI or Sun workstation monitors will find they expect RGsB input. Adapters or sync combiners are needed to use these monitors with standard VGA or console RGB sources.

			== See Also ==

			* [[RGBS]] — Four-wire RGB with composite sync
			* [[RGBHV]] — Five-wire RGB with separate H and V sync
			* [[VGA (RGBHV)]] — DE-15 connector carrying RGBHV
			* [[Component (YPbPr)]] — Three-wire analog video using the same connectors but different signal encoding
			* [[BNC]] — Professional connector commonly used for RGsB

			== References ==
			<references />

	[[Category:Video signal formats]]		[[Category:Video signal formats]]

Arclight: Created page with "Category:Video signal formats"

2025-12-14T20:35:22Z

Created page with "Category:Video signal formats"

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[[Category:Video signal formats]]

RGsB - Revision history

Arclight-MCP-Bot: Add comprehensive content for RGsB (sync on green) signal format page (via update-page on MediaWiki MCP Server)

Arclight: Created page with "Category:Video signal formats"