Intraplex® HD Link - AV-iQ
Intraplex® HD Link™
Integrated 950 MHz Audio
and Data Gateway for Radio
Introducing the Harris® Intraplex® HD Link™ — the first digital 950 MHz STL system designed to
operate in today’s world of data communications.
The next generation of digital STL
Our challenge: to design a studio-to-transmitter (STL) link for your most demanding 950 MHz applications — one as reliable and robust as Harris
Intraplex T1 and IP audio links. Your digital STL manages much more than audio, so installation and configuration need to be straightforward
— not a “science project.” Data should not have to be an option requiring additional boxes and complexity. The 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 right.
Earlier digital STLs were not designed for IP data transport. Adding IP data to them requires 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 microwave STL, yet take less time to configure.
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 ™
Key features and benefits
Powerful, reliable RF performance
Top-notch, multichannel audio performance
Up to 5 W of RF power
One or two stereo main program channels, each available with linear
uncompressed or Enhanced apt-X® compressed audio
Harris-designed transmitter and receiver with
200, 250, 300, 375, or 500 kHz of RF bandwidth
User-selectable 32, 44.1, or 48 kHz sample rates — transports 15, 20 or
22 kHz audio
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
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
State-of-the-art modulation technology operates at 32, 64, 128 or 256
QAM, providing more than 3 Mb/s throughput under optimal conditions
Front-panel Ethernet port for access to Web GUI and diagnostics
Built-in circulator provides a high degree of isolation and VSWR
FTP access for remote software uploads
Designed for data
Integrated IP channel for HD Radio (Importer-to-Exporter or Exporter-toExciter)
USB port for saving configurations and updating software
User-configurable control input and alarm output contacts
Convenient connections and display
Intuitive front-panel interface
At least three times the nominal IP data throughput of other digital STLs
XLR AES/EBU digital and L/R analog input/output connectors
Does not require an external adapter to work with an external TCP return
path — suitable for use over private and public networks
Headphone jack on the receiver for audio monitoring
Capable of taking advantage of available IP audio paths to provide
integral backup in the event of radio link failure
LCD level displays for all audio programs at each end
AES/EBU sync port on the receiver
Two prioritized Ethernet ports — high priority for HD Radio traffic, low
priority for control data and LAN traffic
Analog level outputs for forward power and reflected power (on
transmitter unit) and for received signal level and signal-to-noise (on
receive unit)
Each main program channel includes an RS-232 asynchronous data
channel, up to 9600 b/s
Optional main/alternate interface for redundancy switching
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. This highly efficient scheme contributes to increased data
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 transport 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
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 from the high-priority HD
Radio stream.
Dual domain access control provides the
tightest, most practical security. One access
list is for control of the HD Link units.
Another manages the firewall that keeps
unwanted traffic off the transport link.
Layer 3 switching supports an
asymmetric TCP return path, allowing
integrated “plug and play” support for
TCP wherever a return path exists. Using
TCP allows quality HD Radio transport
under 30 times higher Bit Error Rate (BER)
conditions than UDP (3 x 10-4 for TCP
versus 10-5 for UDP).
Management Interface
(Front-panel display, HTTP, SNMP, FTP)
IP Layer
(Switching, tunneling, proxy ARP)
HD stream
Audio I/O
LAN stream
IP tunneling allows TCP return packets with private addresses to
traverse third-party networks like ISPs.
One or more
channels of
analog or
AES audio
HD Link IP Gateway Architecture
Revolutionary New Technologies
How HD Link Technology Improves Link Quality
Forward error correction (FEC) 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.
500 kHz RF
300 kHz RF
200 kHz RF
Like most digital microwave systems, HD Link uses
quadrature amplitude modulation (QAM) to maximize
data throughput. All other factors being equal, higherorder 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.
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
quality, 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.
QAM Order
Figure 1. Higher-order QAM levels enable greater data carrying capacity.
With HD Link, Harris has taken significant steps to
improve this situation.
Bit Error Rate (BER)
3 dB
Link Quality
Figure 2. The HD Link system’s advanced error correction handles difficult links
better than STLs using older technology.
First, HD Link uses Low-Density Parity Check (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 error 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.
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 superior
performance in the face of link deterioration.
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).
System Gain (dB)
Further, where other STLs add a fixed level of FEC regardless
of the system configuration, 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 configuration.
System Configuration
Figure 3. The combination of HD Link technology advantages can offer you
a dramatically improved STL system.
Elegantly simple installation, configuration and operation
HD Link Receiver front-panel display
HD Link Transmitter front-panel display
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-tounderstand labels. Menu hierarchies 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 active 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 Ethernet and USB ports on each unit, plus remote access via
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 compact at only two rack units per end.
Great Features, Powerful Options
HD Link Transmitter Front Panel
Main/Alt interface for
redundancy switching
High- and
Ethernet ports
GPI/O, forward
and reflected
power status
Analog and AES
inputs — program 1
Serial data
Analog and AES
inputs — program 2
Analog inputs for the
two mono aux program
speed fan
HD Link Transmitter Rear Panel
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 effect, 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.
It’s easy to choose the HD Link that is right for you
To choose the right HD Link model for your STL, all you have to decide is how many stereo audio programs you need and whether you want linear or Enhanced apt-X
compressed audio. The auxiliary audio channels, control options, selectable output power, and data handling flexibility come standard with every unit.
Choose from:
IP plus one linear stereo program
IP plus two linear stereo programs
IP plus one Enhanced apt-X stereo program
IP plus two Enhanced apt-X stereo programs
IP plus two stereo programs, one Enhanced apt-X and one linear
IP data and auxiliary audio only
HD Link Accessories
Bandpass filters
Single- and dual-cavity bandpass filters are available to attenuate interference at sites with congestion in the 950 MHz band.
Main/alternate interface
This system detects hardware and system faults in the HD Link transmitter and receiver, switching to an alternate pair should conditions fall out of normal operational
Specifications are subject to change without notice.
Frequency����������������������������944 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
Designator(s)������������������������200KD7W, 250KD7W, 300KD7W, 500KD7W
Modulation��������������������������Digital, 32/64/128/256 QAM
Antenna Connector��������������Type N (female), 50 ohms
Error Correction��������������������LDPC (Low Density Parity Check)
Error Correction Overhead����8 to 25% depending on mode
Power����������������������������������1/2/5 Watts RMS
Monitoring��������������������������Forward power, reverse power, VSWR, PLL lock
Sensitivity����������������������������-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
Monitoring��������������������������Receive lock, receive signal level, receive signalto-noise ratio, PLL lock
Delay ����������������������������������Main audio end-to-end delay is 50 to 300 mS
based on mode. HD Radio and Ethernet end-toend delay less than 20 mS
Ethernet������������������������������Three 10/100Base-T, full-duplex,
One port for monitoring and remote control
One port for high-priority data
One port for low-priority data
Ethernet Connectors������������Three RJ-45, each connector with integrated
LEDs for link and activity monitoring
Protocols������������������������������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 seven button keypad
Remote User Interface����������Monitoring and control using embedded
Web server
Network Management����������SNMP
VU Meter ����������������������������Front-panel display, six-segment audio level
indicator for all audio channels
Contacts, Output������������������Four output contacts with both normally closed
and normally open outputs
Two output contacts: normally closed
Maximum current: 120 mA
Maximum voltage: 350 VDC
Closed resistance: 23 ohms typical
Contacts, Input��������������������Two input contacts, TTL compatible
Telemetry Output������������������Two analog outputs (0 to 5 V) for RF transmit
forward and reverse power (transmitter)
Two analog outputs (0 to 5 V) for RF receive
signal level and signal/noise ratio (receiver)
Contact/Analog Connector ��26-pin D Sub and RJ-45
USB ������������������������������������One USB 2.0 port for saving settings and
software upgrade
Audio Monitoring ����������������One stereo 1/4 in. headphone jack (receiver)
Fault Detection and Logging Internal log files, SNMP traps, Syslog, and
automatic upload of log files
Audio and Serial Data
Channels������������������������������One or two stereo program channels, individually
configurable for linear or Enhanced apt-X audio
Sample Rate and Audio
Bandwidth ��������������������������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)
Coding��������������������������������Linear or Enhanced apt-X
Sample Size��������������������������16 bit (linear)
16/20/24 bit (apt-X)
Connectors��������������������������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: RJ-11
RS-232 data: RJ-11
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
Rates ����������������������������������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 RS422 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
Crosstalk������������������������������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)
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 Kohms
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 Exporter-to-Exciter)
Auxiliary Audio
Channels������������������������������Two analog
Sample Rate and Audio
Bandwidth ��������������������������16 ks/s for 7.5 kHz operation
Audio Connectors����������������Audio inputs: XLR female
Audio outputs: XLR male
Coding��������������������������������ITU G.722 mode 1
Sample Size��������������������������14 bit
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 -1 dBFS input
Dynamic Range��������������������Greater than 65 dB
Input Impedance������������������Balanced, greater than 10 Kohms
Output Impedance����������������Balanced, less than 52 ohms
Mechanical and Environmental
Dimensions (2RU)����������������Width: 19 in. (48.3 cm)
Depth: 14 in. (35.6 cm)
Height: 3.5 in. (8.9 cm)
EIA rack mountable
Weight��������������������������������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 Protection��������������������2 A AC input fuse
Cooling��������������������������������Forced air using variable-speed internal fan
Humidity������������������������������To 95% non-condensing
Operating Temperature ��������32º to 122º F (0º to 50º C)
Regulatory Compliance��������FCC Part 15
FCC Part 74, subpart E
For more information, please visit
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Broadcast Communications Division
4393 Digital Way | Mason, OH USA 45040 | Tel: (513) 459 3400
©2010 Harris Corporation
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