Relevant links on this web site:
Satellite Internet access

European satellite ISPs

Bentley Walker HX VSAT hubs

Press release about HX NOC June 2007

Specification of Hughes HX50 terminal

Forum discussion: installing HX50 in Iraq

HX VSAT AM22 satellite: Afghanistan

WAFA: HX50 satellite service Middle East

Satellite internet access service W3A

Read my experience installing an HX50

Hughes HX VSAT hub in Moscow

HX satellite broadband in South America

Hughes HX50 broadband satellite internet access VSAT terminal

The HX50 modem is a high-performance satellite router designed to support high-speed data links with Quality of Service (QoS) features such as Min/Max CIR together with dynamic allocation of bandwidth.

QoS means that the various types of IP packet are queued up before transmission and sent on in according to a priority order.  The objective is to send packets containing time sensitive information, such as fragments of speech in a VoIP call with high priority while, for example, file downloads using ftp are given lower priority.

Min/Max CIR means that for a particular type of traffic (e.g. VoIP packets) that such traffic might be allocated minimum and maximum guaranteed bit rates, for example 83kbit/s minimum and 250 kbit/s maximum.  This would allow up to three G711 VoIP calls maximum.  Whether a minimum is appropriate is open to debate.  Unless you are confident that there is going to be one VoIP call is progress for most of the time then the idea of assigning 83 kbit/s is wasteful and will only cause congestion elsewhere.  The problem of setting up these parameters is one of the big difficulties of VSAT traffic management.

HX50 satellite modem
 Please contact:  for further information on this exciting new development.

Read my experience of installation of one of these HX50 VSAT terminals

Click: WAFA for HX50  satellite broadband service in the Middle East

The HX50 modem has several IP features built in including NAT/PAT, DHCP, RIPV1, RIPV2, and DNS server/relay functionality, together with TCP acceleration.  The inclusion of a DNS server means that many web page url requests from your LAN will only need to go as far as the satellite modem before finding what IP address the server is located.  This will save time downloading from web sites that someone has previously visited.   The inclusion of TCP acceleration is a great idea.  This will help speed up web page downloads by avoiding repetitive to and fro messaging between your PC and the website.  You may wait a few moments longer initially but one the page starts coming you will get the whole lot, text and pictures very quickly.

The modem which encodes and decodes the analogue satellite transmission into data is of advanced design to deal with the new DVB-S2 standard which allows for blocks of higher order modulated symbols using 8-PSK and a variety of FEC rates.  The hub knows the receive quality at the remote and adjusts the outlink transmit modulation and coding to match, thus maximising efficiency and minimising costs in the outlink direction.  On the return links the modem has several FEC options including modern turbo coding which beats every other FEC system for efficiency, being superior to the older FEC techniques.  Turbo coding is now being widely used in many competitive products.  The hub knows what is the receive quality from the remote ant is tells the remote to change modulation and coding accordingly, thus maximising efficiency and minimising costs in the return direction.

The HX50 is the ideal platform to enable high-performance IP connectivity for a variety of applications including cellular backhaul, MPLS extension services, virtual leased line services, and other high-bandwidth solutions. Target markets include SCPC/MCPC replacement links, GSM backhaul, MPLS extension services, embassy and government networks and private leased line services.

The Hughes HX system is a VSAT star network based on teleport hub.

The HX System is a star network TDM/TDMA VSAT system.   Remote HX50 and HX100 VSAT terminals connect via a central VSAT teleport hub.

The  outbound carrier from the VSAT hub to all the remotes is a DVB-S/DVB-S2 carrier supporting bit rates up to 121 Mbps.  In DVB-S2 the bit rate on the outlink can be varied by altering the number of bits per symbol.  The idea is that increases of the bit rate may be possible for large remote terminals or those in the inner contours of the downlink beam and during clear sky conditions.  It is not clear in the Hughes HX system if such variable bit rates will occur automatically, improving bit rates during clear sky and reducing them during rain.  Overall DVB-S2 will get more bits per second through he satellite for the same price so should result in lower costs to the end user.

Multiple inbound carriers supporting rates up to 3.2 Mbps are possible.  The higher return link bit rates will need more transmit power from the remote sites, requiring larger BUC power or larger dish.

Efficiency and flexibility in utilizing the satellite bandwidth have been emphasised in the design. Each link can be configured to provide a QoS tailored for the individual remote terminal. Each remote link can be independently configured with Minimum CIRs and Maximum Rates, thereby allowing a service provider to develop a service tailored to its customers' specific requirements.   If this is to work well, the default settings of the QoS parameters must be set sensibly and any tailoring of QoS to suit individual customer's traffic is going to need some careful traffic analysis, determination of parameters and then evaluation to see if the changes have made things better or worse.

The HX System bandwidth allocation scheme uses an Aloha channel for initial traffic requests, which means that remotes can be configured to de-allocate bandwidth based on inactivity. This frees up unused bandwidth and allows an operator to make more efficient use of space segment resources. Because the HX System is DVB-S conformant, the HX System can easily be multiplexed to an existing DVB outbound carrier such as the Hughes HN system, DTH system, or other DVB-based broadband systems.


 Quality of Service features include:
  On-demand constant bit rate (CBR) services
  Minimum CIR with fixed steps to maximum rate (Rate limiting)
  Minimum CIR with best effort to maximum rate (Rate limiting)
  Best effort services - weighted fair queuing
  Class-based weighted prioritization
  Multicast data delivery
  Four levels of IP traffic prioritization
  Bandwidth allocation
  Supports both pre-assigned (static) traffic assignment and dynamic traffic assignment
  Idle remotes can be configured to release all network resources

Acts as a local router

  Static and dynamic addressing, DHCP server or relay
  DNS Caching,    Full RIPV2 routing support
  Multicasts to the LAN by using IGMP
  NAT/PAT,   VLAN tagging
  Firewall support through integrated access control lists
  Supports unicast and multicast IP traffic
  Software and configuration updates via download from the HX Gateway
  Implements dynamic, self-tuning Performance Enhancement Proxy (PEP) software to accelerate the throughput performance by optimizing the TCP transmission over the satellite, delivering superior user experience and link efficiency
  Bidirectional data compression
  Configuration, status monitoring, and commissioning via the gateway
  Embedded Web interface for local status and troubleshooting
  Remote terminal management via the Hughes Unified Element Manager and SNMP agent
  User-friendly LED display indicating terminal operational status

High Availability Features

  Closed loop control between hub and remote
  Dynamic outbound coding and modulation changes based on received signal
  Dynamic inbound coding changes based on received signal
  Dynamic remote uplink power control

Technical Specifications

Physical Interfaces
  Two 10/100BaseT Ethernet LAN RJ45 ports
  One Serial port (RS-422 or RS-232)

Satellite & Antenna Specifications

Outbound transmission format: DVB-S or DVB-S2
  DVB-S2 supports adaptive coding and modulation
  Information Rate (Receive or HX System Outbound Channel): up to 121 Mbps
  Information Rate (Transmit or HX Inbound Channel): up to 3.2 Mbps
  Symbol Rate (Receive): 1-45 Msps (in 1 Msps steps)
  Symbol Rate (Transmit): 128, 256, 512, 1024 ksps
  Encoding DVB-S (Receive): Convolutional with concatenated Reed Solomon; Viterbi 7/8, 5/6, 3/4, 2/3, or 1/2
  Encoding DVB-S2 (Receive): BCH with LDPC 3/5, 2/3, 3/4, 5/6, 8/9, or 9/10 (8PSK) 1/2, 3/5, 2/3, 4/5, 5/6, 8/9, 9/10 (QPSK)
  Transmit encoding: Rate 1/2, 2/3, 4/5 TurboCode, Rate 1/2 Convolutional
  Frequency Range: C-. extended C-, Ku-, and Ka-band
  Modulation (Receive): QPSK or 8PSK
  Modulation (Transmit): OQPSK
  Bit Error Rate (Receive): 10E-10 or better
  Bit Error Rate (Transmit): 10E-7 or better
  BUC Radio:
      1 and 2 watt Ku-band
      2 watt C-band
      1, 2, and 3 1/2 watt Ka-band

HX50 Mechanical & Environmental

Mass (IDU): 4.8 lbs (2.18 kg) Dimensions (IDU): 11.5" W x 1.8" H x 11" D (29.21 cm W x 4.7 cm H x 27.94 cm D)
Operating temperature:
   IDU: +32 F (0 C) to +104 F (+40 C)
   ODU: -22 F (-30 C) to +131 F (+55 C)
Input power: 90-264 VAC; 50-60 Hz DC power supply (optional): 12-24 VDC

For more information about this new service and to pre-order your terminals for use in the Europe beam of the Eutelsat W3A satellite please click  for further information on this exciting development.

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Page started 20 June 2007, amended 5 May 2015.