SpaceBridge supplies the ground side of satellite connectivity: hubs, terminals and modem technology. Unlike Starlink or OneWeb, it is not presented here as an operator with its own constellation. The useful questions are how the hub shares capacity, which waveforms connect the terminals, and what RF equipment completes the link.
This note compares published product specifications and explains their practical meaning. Vendor capacity figures are not independently measured service performance. Sources checked: October 29, 2026.
Contents
- Company and Role
- Network Architecture
- Platforms and Hub Comparison
- Waveforms and Capacity Sharing
- Spectrum and RF Interfaces
- Applications and Practical Limits
- Reference
Company and Role
Separate the satellite operator from the supplier of equipment that accesses its satellites. SpaceBridge fits the equipment role, so its platform names should not be interpreted as generations of spacecraft.
A ground-segment supplier
SpaceBridge traces its origins to Advantech Wireless in 1988 and is headquartered in Montreal, Canada. Its portfolio includes VSAT hubs, terminals, SCPC equipment and broadband modems, with applications including enterprise connectivity and cellular backhaul. [1]
A service provider combines ground equipment with satellite capacity, gateway facilities and an IP network. The modem vendor and the connectivity provider may therefore be different companies. A modem alone does not provide an antenna system, a satellite subscription or a complete operational network.
GEO / NGSO support is not a constellation
The company describes support for GEO and non-geostationary networks. This is a platform-scope statement, not proof that every terminal can connect to every satellite network. [1]
A deployment still needs compatible waveforms, timing, tracking and network interfaces. ASAT II, ESTELLA and UniHUB are platform or equipment names, not orbital shells. Use the chosen satellite operator's documents for spacecraft counts, orbital planes and altitude, and use the equipment datasheet for modem interfaces and processing limits. There is consequently no SpaceBridge Gen1/Gen2 altitude table in this note.
Network Architecture
A hub-based service has two traffic directions. The forward link carries traffic from the hub to remote sites, and the return link brings their traffic back. Each direction passes through digital processing and RF equipment.
Packets, modems and RF equipment
At a remote site, the modem converts packets into a waveform. A block upconverter (BUC) translates and amplifies the transmit signal, and an antenna radiates it toward the satellite. On reception, the antenna and low-noise block downconverter (LNB) deliver a lower-frequency signal to the modem. The hub performs corresponding functions for many sites.
Figure 1. Data-path building blocks. The dashed control relationship is not a separate physical cable to the remote.
Scheduling and network control
The network control center (NCC) assigns transmission opportunities to remote terminals. Think of it as a reservation system: sites have queued packets, priorities and different achievable link qualities. The scheduler must fit their demands into available resources. Management software configures and observes this operation; it is not the RF path.
Forward and return capacity need not be symmetric. Multiple sites can receive from a common forward carrier while using separate scheduled return bursts. Uploads may therefore encounter congestion while the forward direction still has spare capacity.
Platforms and Hub Comparison
Product names describe different scopes and packaging. Read model-specific capacity tables together with the feature descriptions, because support for a feature does not establish the processing capacity of every chassis or licensed configuration.
ASAT II and access modes
ASAT II combines DVB-S2/S2X forward links with DVB-RCS/RCS2 return links. Its supported access modes include MF-TDMA, ASCPC and SCPC, with a common management and bandwidth-pool concept. [2]
MF-TDMA shares time slots across multiple carriers. SCPC assigns a carrier to a connection, which can suit sustained traffic. These are resource-sharing choices, not different orbital systems. The useful choice depends on traffic burstiness, delay requirements, available capacity and the supported terminal configuration.
ESTELLA CORE versus UniHUB CORE
The technical tables distinguish the larger return-link processor from the compact integrated hub. The following comparison follows those tables, rather than transferring a family-level maximum to every product. [3]
Parameter | ESTELLA CORE | UniHUB CORE |
|---|---|---|
Return burst-demodulator capacity | 128 MHz | 36 MHz |
Listed return carrier count | 800 | 200 |
Largest return carrier | 32 MHz | 20 MHz |
Receive tuning | 950–2400 MHz | 950–2400 MHz |
Forward modulator arrangement | External modulators | 2 × 80 MHz integrated modulators |
Chassis height | 2 RU | 3 RU |
Maximum carrier count and maximum individual carrier width are not simultaneously additive: the aggregate processing limit still applies. Licensing and configuration also matter. A wide tuning range does not mean the device processes that entire range at once.
UniHUB was announced in March 2026. Its launch article mentions up to 800 carriers, whereas the UniHUB CORE table lists 200; this note uses the model-specific table. Confirm the ordered variant with the supplier. [4]
The linked datasheet has an April 2026 filename but a DS-ESTELLA-20251008 footer. Both identifiers are recorded because a URL date alone is not a reliable specification revision date.
Waveforms and Capacity Sharing
A modem must deliver bits reliably and share limited resources between users. These problems interact, but they are different: changing modulation changes the transmission format, while changing allocations changes which resources a terminal receives.
Adaptive waveforms and return resources
ESTELLA describes 3D TDMA in terms of modulation, coding and block size, with 60 waveform choices. DRA adjusts return resources, and WaveSwitch supports movement between shared TDMA and dedicated-carrier operation. [3]
For example, rain can reduce the signal margin at one terminal. A more robust modulation and coding choice may keep that link operating, but generally carries fewer information bits per resource unit. Maintaining the same useful rate then requires more resources. If those resources are unavailable, the delivered rate must fall. Adaptation does not create free bandwidth.
Traffic demand, QoS and switching
A branch office may send short transactions most of the day and a large backup at night. Shared bursts can serve intermittent traffic without reserving a full-time carrier. A sustained transfer can justify a different allocation. Compare delivered traffic and delay under the expected load, rather than comparing only the highest supported modulation.
QoS can prioritize voice or signaling ahead of bulk traffic, but cannot give every flow its peak rate when the pool is exhausted. Test busy-hour traffic, fades and simultaneous bursts. Also distinguish switching capability from observed application continuity: packet loss, jitter and recovery time depend on the actual system and configuration.
Spectrum and RF Interfaces
Every frequency needs a location in the signal chain. The modem interface, the satellite uplink and the satellite downlink can all use different ranges while transporting the same packets through one connection.
L-band interface tuning
UniHUB lists a 950–2150 MHz modulator output range and a 950–2400 MHz receive range. These are equipment interface frequencies, not the radiated satellite service band or the bandwidth of a single carrier. [3]
Figure 2. Blue: modulator output; orange: receiver input. Bars show tuning ranges, not occupied carrier bandwidth.
From IF to satellite RF
A BUC translates the transmit signal to the required uplink frequency; an LNB translates the downlink to the modem input range. The converters, antenna, polarization, filters and payload determine whether a particular C-, Ku- or Ka-band implementation is possible. An L-band modem specification alone establishes none of those implementations.
Term | Meaning | Do not confuse with |
|---|---|---|
Tuning range | Where a carrier can be placed or received | An authorized satellite RF allocation |
Carrier bandwidth | Spectrum used by one carrier | The full tuning range |
Aggregate processing capacity | Resources processed together | Guaranteed customer IP throughput |
Satellite RF band | Actual radiated uplink / downlink frequencies | The modem IF range |
A real link budget needs both RF directions, antenna gain, conversion losses, amplifier operating point and receiver margin. The same modem settings can provide different availability with a different antenna or amplifier. A spectrum-color chart for a satellite operator therefore answers a different question from the interface-range chart here.
Applications and Practical Limits
Equipment becomes a service after integration with the satellite network and the terrestrial network. Traffic engineering, RF design and operational procedures determine whether the resulting service meets the application requirements.
Cellular backhaul versus direct-to-cell
Satellite backhaul connects a terrestrial base station to the operator network. The phone can still use an ordinary terrestrial radio link to that base station; a separate satellite terminal carries the transport behind it. This is different from the phone transmitting directly to a satellite.
A VSAT backhaul product or a statement of NGSO support is consequently not evidence of direct-to-cell service or NR-NTN air-interface compatibility. Those require specific terminal and network support. The references here describe ground platforms, not a SpaceBridge-operated direct-to-device constellation.
Integration and performance checks
Identify the hub and terminal versions, licensed features, supported payload and RF plan. For non-geostationary service, establish who provides tracking, Doppler handling and handover coordination. Generic orbit support does not answer these implementation questions.
Measure useful IP throughput, latency, jitter and loss with realistic packet sizes and traffic mixes. Repeat under congestion and reduced signal margin. Modulator bandwidth is only one limit: coding, framing, scheduling and packet processing also affect results.
Equipment capability and operational authorization are separate. Use the actual operator and earth-station documents for deployment frequencies and operating conditions. Do not borrow FCC grants, orbital planes or satellite counts from another constellation. No constellation authorization is attributed to SpaceBridge in this note.
Reference
These primary sources support the company and equipment descriptions. Product limits should be checked against the exact hardware, software and licensed configuration being purchased. The launch announcement and the model-specific specification are retained separately.