📡 The frequency range 1626.5 to 1660.5 MHz, centered at 1643.5 MHz, is an important slice of the L-band spectrum, used for advanced satellite communications, particularly mobile satellite services (MSS).
While it may not show up on a smartphone's spec sheet, this band plays a vital role in global connectivity—especially in remote and mobile environments.
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🛰️ What Falls Within This Frequency Band?
This 34 MHz wide band supports two-way communication between ground-based mobile terminals and satellites. It is most commonly used by mobile satellite systems like:
- Inmarsat
- Globalstar
- Thuraya
These companies deliver voice, text, and broadband data services via satellites to users on land, at sea, and in the air.
🔄 Uplink vs. Downlink: How the Band Is Divided
Here’s how the band typically breaks down in usage:
| Frequency Range | Direction | Typical Use |
|---|---|---|
| 1626.5 – 1660.5 MHz | Uplink | Mobile terminal → Satellite |
| 1525 – 1559 MHz | Downlink | Satellite → Mobile terminal |
This means devices like satellite phones, remote weather stations, and marine terminals transmit signals up to the satellite in the 1626.5–1660.5 MHz band.
Applications of the 1626.5 – 1660.5 MHz Band
This band enables reliable satellite communication in environments where traditional cellular networks don’t reach.
🚢 Maritime Communications
Ships at sea rely on this band for:
- GPS-based ship tracking
- Voice calls and email
- Safety and distress signals (GMDSS systems)
✈️ Aviation Connectivity
Airlines use mobile satellite services in this band to:
- Support inflight internet services
- Transmit real-time aircraft telemetry
- Enable pilot voice communications in remote airspace
🚙 Land Mobile Systems
Emergency responders, military personnel, and remote oil and gas crews use MSS in this band to maintain communications in areas without cell coverage.
🌪️ Disaster Response
When hurricanes, earthquakes, or wildfires take out cellular towers, satellite services operating in this band provide backup communication for first responders.
Interference Protection and Regulation
Because of its critical role, the 1626.5–1660.5 MHz band is heavily regulated and protected from interference.
- It’s licensed internationally by the ITU and national agencies like the FCC (U.S.) and ISED (Canada)
- Devices operating in or near this band must undergo stringent testing
- RF filters are often used to protect satellite receivers from adjacent band emissions
This Filter can be used for the downlink
This Filter centered at 1650 MHz can be used for the uplink
📡 Technical Considerations for Engineers
If you're designing hardware or systems using this band, keep in mind:
- Antenna design must support L-band uplink frequencies
- Low-noise amplifiers (LNAs) and bandpass filters are critical to maintaining signal quality
- DC pass filters may be used to power active antennas, especially in fixed terminal setups
Summary Table
| Parameter | Detail |
|---|---|
| Frequency Range | 1626.5 – 1660.5 MHz |
| Center Frequency | 1643.5 MHz |
| Primary Use | Mobile Satellite Service (Uplink) |
| Key Users | Inmarsat, Globalstar, Thuraya |
| Applications | Maritime, aviation, land mobile, emergency communications |
| Regulatory Body | ITU, FCC, ISED, etc. |
📍 Why This Band Matters
Even if you’ve never used a satellite phone, your safety may depend on this band. Pilots flying over the ocean, ships far from shore, and emergency teams in disaster zones all rely on this slice of the L-band to stay connected.