X1 Encoder
MULTI-CHANNEL DIGITAL PROGRAMMING FM SUBCARRIER SYSTEM
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The FMeXtra™ X1 Encoder from Digital Radio Express, Inc., combines an industrial grade 1U height rackmount PC server with professional digital audio hardware from Lynx Studio Technologies and DRE’s innovative award-winning FMeXtra hardware and software to provide a complete multicasting digital radio broadcasting system. Simply connect your digital audio sources to the X1 Encoder via the built-in AES/EBU digital audio interface and connect the analog SCA output to the existing SCA input of your FM exciter, and you are on the air! System configuration is accomplished entirely by software control.

The X1 Encoder is responsible for combining all input data sources and generating the FM subcarrier (SCA) signal. The occupied bandwidth, peak injection, and data throughput characteristics of the generated SCA signal are determined by a user-created descriptor file. Data sources may include uncompressed AES/EBU digital audio, pre-encoded digital audio streams, and generic packet data. The X1 Encoder accepts all sources and schedules bits depending upon the SCA spectrum bandwidth occupancy.

The X1 Encoder features built-in multi-instance digital audio compression using state-of-the-art aacPlus™ also known as MPEG-4 HE AAC from Coding Technologies, including the new parametric stereo enhancement. The number of simultaneous audio streams is limited only by server CPU and SCA throughput. For pre-encoded digital audio streams, the X1 Encoder accepts RTSP /RTP MPEG-4 HE client streams such as those provided by the Orban™ Opticodec™-PC streaming audio encoder. Unlike digital radio systems based on closed, proprietary algorithms, the use of open MPEG algorithms in FMeXtra permits audio encoding at any point in the audio generation and transmission chain. We simply call it “encode anything, anywhere!” With the X1 Encoder, it is finally possible to eliminate transcoding and transfer high quality low bit rate compressed digital audio from anywhere in the world directly to the X1 encoder using the Internet and over-the-air to FMeXtra-compatible receivers, including direct streaming from 3GPP-compatible mobile phones.

The X1 Encoder is designed to maximize user flexibility. The digital audio input interface accepts any standard input sampling frequency and word length at professional or line input levels. Digital audio streams may be configured to operate at different sampling rates, stereo configurations and encoded bit rates; even supporting different compression algorithms!

The X1 Encoder makes efficient use of the available SCA spectrum. The generated FMeXtra SCA signal can be configured to use combinations of the lower subcarrier spectrum 53-76kHz, the upper subcarrier spectrum 77-99kHz, and even the stereo spectrum 20-53kHz when the main channel is operated in mono audio, all under software-control. Future upgrades include integrated RDS/RBDS signal generation with no extra equipment and no extra cost.

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Internal SCA Generator Characteristics:
External Connector: BNC-F (analog)
Bandwidth: user selectable partitions, software-controlled
20-53 kHz, 54-76 kHz, 77-99 kHz
RDS/RBDS protection optional
RDS/RBDS signal generation option (coming soon!)
Bit rates: depends on bandwidth-occupancy, 32 kbit/s - 160+ kbit/s
Injection: user-selectable, software controlled 0-30%*
Analog Output voltage: 15Vpp maximum, 10Vpp usable
Analog Load Impedance: 600 or 10K ohm
* limited by Vpp(max), end-use exciter characteristics, and current FCC regulations

Internal Digital Audio Compression:
Algorithms: AAC, aacPlus™ and aacPlus™ v2 from Coding Technologies™
Bit rates: 8-384 kbit/sec**
Channels: mono, stereo, parametric stereo, dual mono, surround (2.2, 4, 5, 5.1, 6.1, 7.1)
Sample frequencies: 8, 12, 16, 22.05, 24, 32, 44.1, 48, 64, 88.2, 96 kHz**
**not all combinations of bit rates and sample frequencies are possible

Internal Digital Audio Interface:
Lynx Studio Technology AES16-SRC 24-bit,192kHz Multichannel AES/EBU Interface
up to 8 usable channels of AES3 input with transparent sample rate conversion
includes 8 channel XLR cable (Lynx part #CBL-AES1604)
External Audio Compression Streaming Interface (coming soon!):
RTSP/RTP MPEG-4 HE AAC client (e.g. Orban Opticodec-PC)
using Internet streaming standards RFC 2326 and RFC 3016

Server Characteristics:
Chassis: 1U rack height (1.68”Hx16.7”Wx21.5”D w/o bezel), 27 lbs
Processor: 2.8GHz Intel Pentium 4, 1MB Cache, 800MHz FSB
Memory: 256MB DDR-400MHz SDRAM w/ ECC support
Graphics: on-board ATI Rage XL, 8MB
Slots: 2 PCI (none available for end-user use)
Operating Systems: Windows XP Professional
Windows 2003 Server (optional)
Red Hat Linux ES 3.1 (coming soon!)
Internal Storage: 40GB 7.2K SATA HDD
24X CD-ROM
Network Interface: on-board dual Gigabit NICs
Ports: Front: video, 1xUSB 2.0, power on/off
Rear: 9-pin serial, 2xUSB 2.0, 15 pin VGA, 2xRJ-45,
2xPS/2 mouse/keyboard
Power Supply: 1x280W (non-redundant), 110/220V auto-ranging
Operating Temperature: 10º C to 35º C (50º F to 95º F)
Operating Altitude: -50 ft to 10,000 ft
Operating Humidity: 20% to 80% (non-condensing), gradient: 10% per hour
Available options include high availability and alternate 2-4U chassis with slot expansions for additional digital audio channels and/or an analog audio interface using Lynx Studio Technology Lynx TWO/L22 (not included).