The encoder card for Dolby-E

The XDEE board series is designed as Dolby-E output board for the NEXUS system. It supports all features provided in the Dolby specifications and supplements them with useful options such as auxiliary sync generation to allow limited operation even if video sync is missing. The connections are both optical as Toslink and electrical with 110 Ohm balanced and 75 Ohm unbalanced. The handling of metadata is flexible and, thanks to the functions of the NEXUS network, far beyond the usual.

The XDEE card is an encoder for Dolby E signals. Discrete signals from the entire NEXUS network can be routed to the board and encoded into a Dolby E data stream; up to 8 Dolby E-compliant audio channels in total. In parallel, the card can output two independent channels as another AES stereo signal, which is usually transmitted unencrypted as a comment or control signal. Of course, it is possible to output a Dolby-E stream that has already been encoded elsewhere in the network or to play the freshly encoded stream back into the NEXUS matrix. This can then be routed transparently and independently of the individual signals in the NEXUS network to be used elsewhere.

Via a dedicated port on the board itself, the encoded signal can be forwarded directly to an adjacent XHDI video embedder board. This direct connection guarantees the lowest possible latency as well as direct synchronization of Dolby E and HDSDI data streams to each other.

Sample rate converters are connected upstream of the Dolby encoder module and also the parallel signals that cannot be encoded, so that the signals applied internally with the NEXUS system clock can be converted to an external, possibly deviating clock before output. There is an adjustable delay for all audio signals. The metadata to be embedded into the generated signal can be transmitted over the NEXUS network from any XTI or XDEM board. They can also come from an adjacent XHDI video interface via a direct cable connection. In the simplest case, metadata can also be entered in the NEXUS control software; it can also be delayed to match the audio via an adjustable delay.

The front panel of the board offers various connections: A Toslink socket provides optical signals in S/PDIF format. The encoded Dolby E signal and the non-coded, parallel stereo signal are present on a 15-pin D-sub connector. Of course, these outputs are balanced and galvanically isolated. 110 Ohm and 75 Ohm lines are supported. There is a separate video input for synchronous signals in formats such as composite, component and HDTV. Bi- and tri-level sync are supported. In order to guarantee video frame-accurate synchronization of Dolby-E, this input should be correctly connected due to the system, but the XDED card can generate an auxiliary signal, with which limited operation is possible even in the absence of video sync. The external video sync can be fine-tuned via a line delay to compensate for the encoder's runtime, for example. In addition, the board is capable of generating an audio sync from the video clock to which the entire NEXUS network can be synchronized.

Encoding of a 5.1 audio signal including metadata

Up to eight freely selectable signals from the NEXUS network can be processed into one Dolby E data stream.

Use of metadata from any XTI interface boards in the NEXUS system

Metadata can be embedded into the data stream that has been provided system-wide by an XTI board or supplied to the XDEE card by the XDEM extension via ribbon cable.

Direct connection to XHDI cards for audio transfer for embedding in HD-SDI video signals

The encoded data can be embedded directly into an HD-SDI signal via an internal line to an SDI board XHDI.

Combined BNC connector for Bi-/Tri-Level-Sync and SDI/HD-SDI-Sync

The BNC connector can be used for both analog and digital sync signals.

XDEM expansion card with serial metadata port optionally available

The XDEM module is not a stand-alone plug-in board but an extension for the NEXUS boards XDED, XDEE, XHDI and XCPU. It provides two additional RS232- or RS422-compliant 9-pin D-Sub interfaces, which can be used to access the metadata ports of these boards. It is a simple, direct solution to pass metadata to or read metadata from these boards when none of the other higher-level solutions available with the NEXUS board are used.


XDEE_1 1 x 4TE
Toslink 1x S/PDIF Output
D-Sub 15 Socked male 1x AES/EBU Output
BNC 1x Wordclock Input

Technical specifications

Data formats

Inputs linear audio sources routed from the NEXUS network
Dolby E as specified for Dolby modules (CAT No. 559E)
Container format data stream SMPTE 337M-compliant
Audio data inputs NEXUS, 24 bit
Audio data outputs compressed Dolby E audio, 16-bit or 20-bit;
24-bit linear audio
Interface extension XDEM Expansion card XDEM with serial metadata port optionally available

Outputs AES/EBU

Outputs balanced, galvanically isolated
Impedance 110, 75 Ohm
Diff. output voltage 2…5 VPP (110-ohm output) or 1 VPP (75-ohm output)
Cable length 100 m (for lines with appropriate impedance and termination)


Wavelength 650 nm
Optical power –21…–15 dBm (APF 970/1000 μm)
Cable length 0,2…5 m (APF 970/1000 μm)

Sample rate converter

Resolution 24-bit
up/down sampling ratio 1:8 (up), 7:1 (down)
Latency typ. 1 ms, max. 2 ms (@48 kHz)
Dynamic range 140 dB (A), min. 132 dB (A) @ –60 dBu input level (typ.)
THD+N typ. –120 dB, min. 117 dB (between 20 Hz and FSOUT at 0 dBFS)
Passband ripple ±0.016 dB (max.) @ 0.4535 FSOUT
stopband attenuation –120 dB (0,5465 FSOUT min.)

Sync input

Frame rates 23.975...60 fps
Impedance 110 kohm/75 ohm (adjustable using a jumper)
Input voltage 0.5…2 VPP on RL = 75 ohm

Operation conditions

Temperature range 0° C to +50° C
Max humidity max. 90 %, non-condensing

Storage conditions

Temperature range –35° C to +70° C
Max humidity max. 90 %, non-condensing

Power supply

Voltage +4,75…5,25 V
Currrent typ. 750 mA, Dolby module equipped

Mechanical data

Weight 0.25 kg (equipped with one module)

NEXUS / NEXUS Star Technical specifications




XDEE Technical specifications