Broadcast Communications / Intraplex HD Link

Broadcast Communications / Intraplex HD Link
Intraplex® HD Link™
Digital 950 MHz STL and Data Gateway
The next generation of digital STL
Our challenge: to design a studio-to-transmitter link (STL) for your most demanding 950
MHz applications — one as reliable and robust as Harris® Intraplex® T1 and IP audio
links. Digital STL manages much more than audio, so installation and configuration need
to be straightforward, not a science project. Data should be optional requiring additional
boxes and complexity. Your STL should be ready, out of the box, for AM, FM and HD
Radio™, as well as future multimedia applications. And, of course, the price has to be
Earlier digital STLs were not designed for IP data transport. Adding IP data to them
required optional modules and external add-ons, and many engineers working on HD
Radio installations reported spending much time and money trying to eliminate glitches.
Our solution
HD Link™ is designed to manage all HD Radio™ transport scenarios, regardless of
where you place your importer and exporter. Its two prioritized Ethernet paths give
preference to HD Radio™ data over control and other LAN/WAN data. It supports both
UDP and TCP, and even handles the switching of TCP return packets over asymmetric IP
paths with plug-and-play simplicity.
HD Link offers RF power to spare, an integrated IP gateway with sophisticated data
handling capabilities, and multiple channels of great audio. The intuitive front panel and
remote interfaces tap into the most complete feature set of any micro-wave STL, yet take
less time to configure. It can even operate on both RF and IP simultaneously, and allows
automatic backup of all services from one to the other.
Intraplex is broadcasting’s first choice for rock-solid, full-time operation of T1 STLs. With
HD Link, you can now count on the same dependable performance, superior support and
long-term value for your microwave links.
Intraplex HD Link
Powerful, reliable RF performance
• Up to 5 W of RF power
• Harris-designed transmitter and receiver with 200, 250, 300, 375 or 500 kHz of RF bandwidth
• Low-density parity check (LDPC) Coding advanced error correction — requires less receive signal
than Reed-Solomon to achieve an equivalent bit error rate (BER), a critical parameter for glitch-free
HD Radio performance
• State-of-the-art modulation technology operates at 32, 64, 128 or 256 QAM, providing more than 3
Mb/s throughput under optimal conditions
• Built-in circulator provides a high degree of isolation and VSWR protection
Designed for data
• Integrated IP channel for HD Radio (importer-to-exporter or exporter-to-exciter)
• At least three times the nominal IP data throughput of other digital STLs
• Does not require an external adapter to work with an external TCP return path — suitable for use
over private and public networks
• Capable of taking advantage of available IP audio paths to provide integral backup in the event of
radio link failure
• Two prioritized Ethernet ports — high priority for HD Radio traffic, low priority for control data and
LAN traffic
• Each main program channel includes an RS-232 asynchronous data channel, up to 9600 b/s
Top-notch, multichannel audio performance
• One or two stereo main program channels, each available with linear uncompressed or Enhanced
apt-X® compressed audio
• User-selectable 32, 44.1, or 48 kHz sample rates—transports 15, 20 or 22 kHz audio
• Two monaural, 7 kHz audio channels with G.722 coding available for AM, radio reading services,
SCA, EAS and other auxiliary audio applications
Easy setup and reliable operation
• Advanced Web browser user interface and SNMP remote control
• Front-panel Ethernet port for access to Web GUI and diagnostics
• USB port for saving configurations and updating software
• FTP access for remote software uploads
• User-configurable control input and alarm output contacts
Convenient connections and display
• Intuitive front-panel interface
• XLR AES/EBU digital and L/R analog input/output connectors
• Headphone jack on the receiver for audio monitoring
• AES/EBU sync port on the receiver
• LCD level displays for all audio programs at each end
• Analog level outputs for forward power and reflected power (on transmitter unit) and for received
signal level and signal-to-noise (on receive unit)
• Optional main/alternate interface for redundancy switching
Intraplex HD Link
The ability to do more
Our RF and audio engineering teams designed HD Link for maximum reliability and to carry
higher-quality audio and more data over the STL path than was possible with earlier 950 MHz STLs.
• More power
Sometimes you just need a little more RF power to get the job done. Out of the box, HD Link can
operate at 1 W, 2 W, or 5 W, selectable in the field. It’s the most powerful 950 MHz digital STL you
can buy.
• Advanced error correction
HD Link is the only radio STL using LDPC coding for forward error correction (FEC). This highly
efficient scheme contributes to increased data throughput.
• 21st-century design
By applying Harris know-how to the technologies not available when legacy STLs were designed, we
optimized HD Link for state-of-the-art performance with minimal circuit noise.
The advantages to you
The combined benefits of more transmitter power, LDPC error correction and enhanced circuit design
add up to as much as 10 dB signal improvement over older digital STLs. Depending on your
requirements, this can enable any or all of the following:
• Use of smaller antennas, for less tower load and lower costs
• Increased path distance
• Improved fade margin
• Operation at higher quadrature amplitude modulation (QAM) orders for increased carrying capacity
Sounds great
As with any Intraplex product, audio quality is a top priority. Uncompressed audio trans-port is fully
transparent. In the event bandwidth limitations require audio compression, HD Link offers Enhanced
apt-X® coding to prevent the occurrence of audio artifacts that can occur with multiple generations of
MPEG compression in the air chain.
Audio and data. And more data.
The architecture of HD Link starts with an integrated IP gateway, the first in a radio STL. This provides
you with options for nearly every practical combination of audio, data, control and status used by radio
stations — as well as future media applications. With the HD Link system’s 1536 kb/s of allocatable IP
data, you’ll no longer consider your STL to be merely an audio transport system that happens to provide
some data options. In addition, an asynchronous RS-232 serial data channel accompanies each main
program audio channel for use with legacy control systems.
IP done right — the Intraplex way
If you like what Intraplex has done for you with T1 and IP audio and data codecs, you’ll love our
implementation in HD Link. The integrated IP gateway includes numerous features:
IP prioritization allows it to carry other IP data, such as control signals and LAN traffic, separately f
the high-priority HD Radio stream.
Dual domain access control provides the tightest, most practical security. One access list is for co
of the HD Link units. Another manages the firewall that keeps unwanted traffic off the transport link.
Layer three switching supports an asymmetric TCP return path, allowing integrated • “plug and pla
support for TCP wherever a return path exists. Using TCP allows quality HD Radio transport under 3
times higher bit error rate (BER) conditions than UDP (3x10-4 for TCP versus 10-5 for UDP).
Intraplex HD Link
IP tunneling allows TCP return packets with private addresses to traverse third-party networks like
HD Link IP Gateway Architecture
How HD Link Technology Improves Link Quality
Like most digital microwave systems, HD Link uses quadrature amplitude modulation to maximize data
throughput. All other factors being equal, higher-order QAM can deliver more data using the same RF
bandwidth than lower-order QAM (Figure 1), but each step up in QAM order requires about 3 dB to 4 dB
better signal-to-noise ratio on the RF link to maintain the same level of quality. RF link quality is thus a
critical factor in determining the amount of data that any given 950 MHz STL can carry.
Forward error correction is a useful tool for improving link quality in digital transmission. Essentially, it
involves adding redundant data to the transmission stream to allow the detection and reconstruction of
missing information. All digital RF STLs use some form of FEC, typically using either the Reed-Solomon
or the Viterbi coding method.
However, adding FEC increases the bit rate of the STL. Adding enough extra bits may require the use of
a higher QAM order, which places greater demands on the link qual-ity, thereby creating a Catch-22
situation — adding FEC to improve link quality may cause an increase in QAM order, which requires yet
higher link quality.
Intraplex HD Link
Figure 1. Higher-order QAM levels enable greater data carrying capacity
With HD Link, Harris has taken significant steps to improve this situation.
First, HD Link uses LDPC to do its FEC coding. LDPC is more efficient than either Reed-Solomon or
Viterbi, requiring less overhead data to provide the same level of er-ror correction; given the same
overhead, it typically provides about 3 dB improvement in link performance over traditional FEC methods
(Figure 2). While the mathematical principles underlying LDPC have been understood for some time,
only recently have DSP chips become available with the speed and processing power to run LDPC on
digital STL signals in real time.
Intraplex HD Link
Figure 2. The HD Link system’s advanced error correction handles difficult links
better than STLs using older technology
In addition, whereas the performance of Reed-Solomon FEC falls off directly if the link quality is
degraded due to environmental or other interference, LDPC maintains supe-rior performance in the face
of link deterioration.
Further, where other STLs add a fixed level of FEC regardless of the system configura-tion, HD Link
uses adjustable amounts of FEC and employs a sophisticated algorithm to calculate the optimum
balance between QAM order and FEC overhead to achieve the maximum data throughput for any given
The result? Combined with the increased performance afforded by its 5 W amplifier, HD Link can provide
up to 10 dB of system enhancement, right out of the box, compared with older digital STL systems
(Figure 3).
Intraplex HD Link
Figure 3. The combination of HD Link technology advantages can offer you
a dramatically improved STL system.
Elegantly simple installation, configuration and operation
Your time is valuable, so HD Link is designed to make setup quick and painless. The front-panel display
is bright and clear, with easy-to-understand labels. Menu hierar-chies are shallow, so accessing most
functions takes only a few steps.
Modem settings automatically synchronize between the transmitter and receiver units. With both units
set for the same frequency and RF bandwidth, changes to QAM, IP bandwidth, etc., on the transmitter
automatically sync to the receiver.
HD Link has tools to help you in planning your overall STL system. Select the ac-tive audio channels and
IP bandwidth you want it to carry, and HD Link automatically calculates the optimum settings for QAM
and forward error correction, along with the receive signal strength necessary to achieve the desired
level of throughput. These auto-calculated values enable you to prepare a reliable path calculation and
determine the requisite transmitter power, antenna size and other variables.
HD Link provides numerous interfaces for setup, diagnostics and updates, with Ether-net and USB ports
on each unit, plus remote access via HTTP, FTP and SNMP.
Additional convenience features include a headphone jack and AES/EBU sync port on the receiver, and
variable-speed fans to minimize noise. And HD Link is physically com-pact at only two rack units per
Built-in backup
When your HD Link is connected to a bidirectional IP network with sufficient bandwidth, the program
channels will automatically switch to IP should the 950 MHz link fail. In ef-fect, HD Link is both a 950
MHz RF STL and an IP audio STL in one box, with automatic fallback from one to the other.
Intraplex HD Link
HD Link Transmitter Rear Panel
Specifications and designs are subject to change without notice.
935 to 960 MHz fully synthesized
Step Size
25 kHz
Frequency Accuracy
+/-4 PPM (+/-0.0004%)
Occupied Bandwidth
200/250/300/375/500 kHz
FCC Emission Type
200KD7W, 250KD7W, 300KD7W, 500KD7W
Digital, 32/64/128/256 QAM
Antenna Connector
Type N (female), 50 ohms
Error Correction
LDPC Error Correction Overhead
8 to 25% depending on mode
1/2/5 W RMS
Forward power, reverse power, VSWR, PLL lock
-95 to -82 dBm depending on mode
Dynamic Range
0 to -95 dBm
Spurious and Harmonic Equalizer
24-tap feed-forward filter and 3-tap decision feedback filter
Receive lock, receive signal level, receive signal-to-noise ratio, PLL lock
Intraplex HD Link
Main audio end-to-end delay is 50 to 300 mS based on mode. HD Radio™ and
Ethernet end-to-end delay less than 20 mS
Three 10/100Base-T, full-duplex, auto-negotiation
1 port for monitoring and remote control
1 port for high-priority data
1 port for low-priority data
Ethernet Connectors
3 RJ45, each connector with integrated LEDs for link and activity monitoring
IP, TCP, UDP, HTTP, FTP, NTP, Syslog, and SNMP v2c
IP Gateway
Port or IP based prioritization, static routing, proxy ARP, policing, firewall, public or
private network for return path
Control and Monitoring
Front Panel
Intuitive, graphical front-panel user interface 4.3 in. display, 480x272, TFT Color
LCD with LED backlight and 7 button keypad
Remote User Interface
Monitoring and control using embedded Web server
Network Management
VU Meter
Front-panel display, 6 segment audio level indicator for all audio channels
Contacts, Output
4 output contacts with both normally closed and normally open outputs
2 output contacts: normally closed
Maximum current: 120 mA
Maximum voltage: 350 VDC
Closed resistance: 23 ohms typical
Contacts, Input
2 input contacts, TTL compatible
Telemetry Output
2 analog outputs (0 to 5 V) for RF transmit forward and reverse power
2 analog outputs (0 to 5 V) for RF receive signal level and signal/noise ratio
Contact/Analog Connector
26-pin D Sub and RJ45
1 USB 2.0 port for saving settings and software upgrade
Audio Monitoring
1 stereo 1/4 in. headphone jack (receiver)
Fault Detection and Logging
Internal log files, SNMP traps, syslog, and automatic upload of log files
Intraplex HD Link
1 or 2 stereo program channels, individually configurable for linear or Enhanced
apt-X® audio
Sample Rate and Audio
48 ks/s for 22.5 kHz operation
44.1 ks/s for 20 kHz operation
32 ks/s for 15 kHz operation
24 ks/s for 12 kHz operation (apt-X®)
16 ks/s for 7.5 kHz operation (apt-X®)
Linear or Enhanced apt-X®
Sample Size
16-bit (linear)
16/20/24-bit (apt-X®)
Audio Inputs: XLR female on left, right, and digital AES/EBU
Audio Outputs: XLR male on left, right, and digital AES/EBU
External AES/EBU Input Clock: RJ11
RS-232 Data: RJ11
Digital/Analog Operation
For input, digital/analog auto-detection
For output, digital and analog simultaneous
Data Channel
RS-232 data transport 9.6 kb/s (linear)
RS-232 data transport 1.2, 2.4, 4.8 and 9.6 kb/s, mode dependent (apt-X®)
Main Digital Audio
Accepted Audio Sampling
Accepts any AES/EBU rate between 32 and 48 ks/s (linear)
Accepts any AES/EBU rate between 24 and 48 ks/s (apt-X®)
Rate Conversion
Rate converts any AES/EBU input rate to 48, 44.1 or 32 ks/s. In addition, for
apt-X®, rate conversion includes 24 and 16 ks/s
External Sync (Receive Only)
Accepts external AES/EBU reference signal or RS-422 clock to synchronize
output to facility timing
Input/Output Impedance
Balanced, 110 ohms ±20%
AES/EBU Channel Status
A&B channel status bits are transported
Main Analog Audio
Audio Frequency Response
±0.5 dB
48 ks/s: 1 Hz to 22 kHz
44.1 ks/s: 1 Hz to 20.5 kHz
32 ks/s: 1 Hz to 15 kHz
Audio Full Load Level
9 to +24 dBu
Better than –80 dB
Total Distortion
THD+N, less than 0.003% at 1 kHz – 1 dBFS input (linear)
THD+N, less than 0.004% at 1 kHz – 1 dBFS input (apt-X®)
Intraplex HD Link
Dynamic Range
Greater than 91 dB (for linear)
Greater than 92 dB (16-bit apt-X®)
Greater than 105 dB (20-bit apt-X®)
Greater than 110 dB (24-bit apt-X®)
Input Impedance
Balanced, greater than 10 K ohms
Output Impedance
Balanced, less than 52 ohms
Main Diagnostics
Test Tone Generator
1004 Hz test tone at -12 dBFS, which is equivalent to +8 dBm input
HD Audio
Integrated IP channel for UDP or TCP HD Radio (importer-to-exporter or
Auxiliary Audio
2 analog
Sample Rate and Audio Bandwidth 16 ks/s for 7.5 kHz operation
Audio Connectors
Audio Inputs: XLR female
Audio Outputs: XLR male
ITU G.722 mode 1
Sample Size
Audio Frequency Response
100 to 6400 Hz ±1 dB
Data Rate
64 kb/s per active channel
Total Distortion
THD+N, less than 0.1% at 1 kHz to 1 dBFS input
Dynamic Range
Greater than 65 dB
Input Impedance
Balanced, greater than 10 K ohms
Output Impedance
Balanced, less than 52 ohms
Mechanical and Environmental
Dimensions (2RU) (W X D x H)
19 x 14 x 3.5 in. (48.3 x 35.6 x 8.9 cm)
EIA rack mountable
Transmitter: 18.5 lbs (8.4 kg)
Receiver: 14.5 lbs (6.6 kg)
Power Requirements
Universal AC 100 to 240 VAC, 50/60 Hz
Power Consumption
Transmitter: 104 W maximum
Receiver: 34 W maximum
Fuse Protections
2A AC input fuse
Forced air using variable-speed internal fan
To 95% non-condensing
Intraplex HD Link
Operating Temperature
32º to 122º F (0º to 50º C)
Regulatory Compliance
FCC Part 15
FCC Part 74, subpart E
Contact your Harris sales representative for information on ordering these products.
Intraplex HD Link
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