ST Engineering iDirect MDM3315 Satellite Modem

by Hamid Bagheri  |  March 4, 2026

The ST Engineering iDirect MDM3315 Satellite Modem is a powerful and highly flexible next-generation VSAT modem designed to support a wide range of satellite networks including enterprise connectivity, cellular backhaul, maritime communications, broadcast distribution, and government networks.

Built to operate on both Dialog and Velocity satellite platforms, the MDM3315 offers exceptional flexibility by supporting multiple return technologies such as ATDMA, MF-TDMA, SCPC, and Mx-DMA. This multi-waveform capability allows operators to design highly efficient satellite networks that adapt to changing bandwidth requirements while maintaining optimal spectral efficiency.

At VSATplus, we supply the MDM3315 Satellite Modem with full technical consultation, configuration support, and global delivery. Customers looking to deploy high-capacity satellite broadband networks can order this modem directly from VSATplus to build scalable and reliable VSAT infrastructures.


Modern satellite networks require high throughput, advanced waveform support, and the ability to integrate seamlessly with both fixed and mobility environments. The MDM3315 modem addresses these requirements with its high-speed architecture and flexible waveform support.

The modem is engineered to operate efficiently across a wide variety of networks and supports high throughput rates of up to 150 Mbps downstream and 70 Mbps upstream, enabling service providers to deliver reliable broadband connectivity for demanding applications. 

One of the most important capabilities of the MDM3315 is its wideband forward channel support up to 500 Msps, which makes it suitable for use with modern HTS (High Throughput Satellite) and VHTS systems. This capability allows operators to deploy high-capacity networks that maximize satellite spectrum utilization.

The modem can also operate seamlessly within mixed networks alongside other iDirect terminals, allowing network operators to scale deployments gradually without requiring large infrastructure changes.


The MDM3315 supports both major satellite networking platforms used by iDirect systems:

Dialog Platform

The Dialog platform enables operators to deploy advanced satellite services using multiple access technologies.

Supported waveforms include:

  • DVB-S2 / DVB-S2X outbound
  • MF-TDMA return
  • Mx-DMA HRC
  • Mx-DMA MRC
  • SCPC return

These technologies allow the modem to dynamically allocate bandwidth depending on network conditions and traffic demands.

Velocity Platform

On the Velocity platform, the modem supports:

  • DVB-S2 outbound transmission
  • Adaptive TDMA return

This architecture allows efficient bandwidth sharing across large numbers of terminals while maintaining high service quality.

By supporting multiple platforms and waveforms, the MDM3315 provides unmatched network design flexibility for satellite operators. 


3.1 DVB-S2 and DVB-S2X Forward Channel

The modem supports advanced forward link modulation including:

  • QPSK
  • 8PSK
  • 16APSK
  • 32APSK
  • 64APSK

DVB-S2X provides higher spectral efficiency and improved throughput compared to traditional DVB-S2 networks.

The forward channel can operate at symbol rates up to 500 Msps, enabling extremely high capacity satellite links. 


3.2 Multiple Return Waveform Technologies

The modem supports several return channel technologies that allow operators to optimize network performance.

ATDMA

Adaptive Time Division Multiple Access allows multiple remotes to share bandwidth dynamically.

MF-TDMA

Multi-frequency TDMA supports efficient multi-carrier operation across multiple frequencies.

SCPC

Single Carrier Per Channel mode enables dedicated high-throughput connections.

Mx-DMA

Mx-DMA combines TDMA flexibility with SCPC performance, delivering both bandwidth efficiency and guaranteed throughput.

These waveform technologies allow the MDM3315 to operate efficiently across both small enterprise networks and large service provider infrastructures.


3.3 High Throughput Capability

The MDM3315 supports high data rates suitable for modern satellite broadband applications.

Maximum throughput:

  • Up to 150 Mbps downstream
  • Up to 70 Mbps upstream

These speeds make the modem suitable for high-bandwidth applications such as enterprise networking, video streaming, and cellular backhaul. 


3.4 TCP and GTP Acceleration

Satellite networks typically suffer from latency due to the distance between earth stations and satellites. To mitigate this effect, the MDM3315 integrates advanced acceleration technologies.

Key acceleration features include:

  • TCP acceleration
  • GTP acceleration
  • Header compression

These technologies reduce protocol overhead and significantly improve application performance across satellite links.


3.5 Security and Authentication

Security is critical for enterprise and government networks. The modem includes:

  • Optional AES-256 encryption
  • Hardware authentication using an ATMEL security chip

These features ensure secure communication across satellite networks while protecting sensitive data from unauthorized access. 


4.1 RF Interfaces

ParameterSpecification
TX Frequency Range950 – 2400 MHz 
RX Frequency Range950 – 2150 MHz 
TX Power Level-55 dBm to +5 dBm (Dialog) 
TX Power Level-45 dBm to +5 dBm (Velocity) 
Connector TypeF-Type 75 Ohm 

4.2 BUC and LNB Support

FeatureSpecification
BUC Power Supply24V / 4A or 43–44V / 3.5A 
BUC Reference10 MHz or 50 MHz 
LNB Voltage13V / 18V selectable 
LNB Current500 mA 
Polarization Control13/18V or 22 kHz tone 

4.3 Network Interfaces

InterfaceSpecification
LAN Ports4 × 10/100/1000 Mbps Ethernet 
Auto MDI/MDIXSupported 
Network ProtocolsIPv4, IPv6, TCP, UDP, ICMP, ARP, DHCP, DNS, NTP, BGP 

4.4 Modulation and Symbol Rates

TechnologySymbol RateModulation
DVB-S2/S2X1 Msps – 500 Msps QPSK, 8PSK, 16APSK, 32APSK, 64APSK
MF-TDMAUp to 7.6 Msps QPSK, 8PSK
Mx-DMA MRCUp to 25 Msps QPSK, 8PSK, 16APSK
SCPCUp to 64 Msps QPSK – 64APSK

4.5 Physical Specifications

ParameterSpecification
Dimensions22 × 33 × 4 cm 
Weight1.7 kg 
Operating Temperature0° to 55°C 
Storage Temperature-30° to 60°C 
Humidity5–95% non-condensing 
Power Consumption60 W max 

The MDM3315 modem supports a wide variety of satellite communication applications.

Enterprise Connectivity

Provides reliable broadband connectivity for corporate offices, remote branches, and enterprise WAN networks.

Cellular Backhaul

Supports mobile network operators by providing high-capacity satellite backhaul links for remote cellular towers.

Maritime Communications

Delivers broadband connectivity for ships, offshore platforms, and maritime operations.

Broadcast Distribution

Enables reliable multicast distribution of video and media content.


The modem offers several advantages that make it a strong choice for modern satellite networks.

High Throughput Performance

Supports up to 150 Mbps downstream capacity.

Wideband Forward Channel

Up to 500 Msps operation for HTS and VHTS satellite networks.

Multi-Waveform Support

Flexible return technologies including TDMA, SCPC, and Mx-DMA.

Integrated Acceleration Technologies

TCP acceleration and header compression improve application performance.

Strong Security Architecture

AES-256 encryption and hardware authentication.

Ease of Deployment

Multilingual web-based GUI and Point&Play installation tools simplify network setup. 


VSATplus provides a complete solution for satellite communication equipment procurement and deployment.

When ordering the MDM3315 from VSATplus, customers receive:

  • Genuine ST Engineering iDirect hardware
  • Expert network design consultation
  • Integration support with existing VSAT systems
  • Competitive global pricing
  • Fast international shipping
  • After-sales technical support

Our experienced team ensures that your satellite network is designed and configured for maximum performance and reliability.


The ST Engineering iDirect MDM3315 Satellite Modem is a powerful and versatile VSAT modem designed to meet the evolving needs of modern satellite communications networks. With support for DVB-S2X wideband channels, advanced multi-waveform return technologies, high throughput rates, integrated acceleration, and strong security features, the MDM3315 is ideal for enterprise connectivity, cellular backhaul, maritime communications, and government networks.

By combining performance, flexibility, and reliability, the MDM3315 enables satellite operators and service providers to build scalable broadband networks capable of supporting the next generation of satellite services.

Organizations seeking to deploy high-capacity VSAT networks can order the MDM3315 Satellite Modem directly from VSATplus, where it is available with full technical support, configuration assistance, and global delivery.

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