The RB-TGHD is an 8-channel audio tone generator that provides line identification for multi-channel audio systems, including 5.1 and 7.1 surround sound typically used in high-definition television broadcasts. Using a range of industry-standard widely accepted tone sequences such as EBU R49, GLITS and BLITS tones, channel identification and associated levels can be easily determined. The correct configuration of channels in down-mixed outputs can also be highlighted when a broadcaster needs to mix multiple audio channels to a stereo source. The RB-TGHD supports 2, 4, 6 and 8 channel configurations and all available audio tone sequences for each channel configuration can be cycled through automatically, or selected manually, and a loop mode allows tone patterns to be repeated. A set of 4 push-buttons on the front panel defines these options and associated LEDs indicate the current setting. A set of 8 LEDs on the front panel indicates which channel is currently outputting audio, with the LEDs numbered both 1 to 8 and as L, R, C, LFE, LS, RS, LR and RR. The RB-TGHD is available in two variants, each providing analogue and digital audio outputs. The RB-TGHDX offers balanced AES/EBU digital audio outputs on 3-pin XLR connectors and the RB-TGHDB has unbalanced digital audio outputs on BNC connectors. Both types provide 8 balanced analogue outputs on 3-pin XLR connectors. A wordclock sync input on BNC connector allows the digital outputs to be synchronised to an external signal. Optionally, an RB-SYA or RB-SYD video sync card can be fitted to synchronise the unit to an analogue or digital sync signal. A front panel SYNC LED indicates when the unit is synchronised to the external signal. The audio level of the RB-TGHD can be adjusted from 0dBu to +24dBu in 1dBu steps (ref. FSD) to suit different environments via front panel mounted DIP switches. Changing the audio level does not affect the gain relationship between each channel, ensuring that correct levels across the target system can be maintained. These switches also provide settings for the digital sample frequency which ranges from 32kHz to 192kHz, and the digital sample width which is either 16-bit or 24-bit. The serial port allows the RB-TGHD to be connected to a PC running SCi, the Sonifex Serial Control Interface. This allows full control of the unit and the ability to generate a user-defined audio tone sequence. Additionally, a rear panel remote port provides a simple interface to control the unit and has several outputs to indicate which tone sequence is active.