PRODUCT OVERVIEW
Inmarsat's L-band mobile satellite service relies on two distinct frequency ranges: downlink from the satellite to terminals runs from 1525 to 1559 MHz, while the uplink from terminals back to the satellite runs from 1626.5 to 1660.5 MHz.
This filter covers that uplink window precisely, centered at 1643.5 MHz with a 34 MHz passband, with less than 5 dB of insertion loss across the full band.
The 1626.5 to 1660.5 MHz uplink is the transmit path for a wide range of Inmarsat services: Fleet Broadband and IsatPhone terminals in maritime and land-mobile deployments, Inmarsat-C messaging used for Global Maritime Distress and Safety System (GMDSS) compliance, and aeronautical data links carrying ACARS and ADS-C traffic between aircraft and ground stations.
A filter placed ahead of a receiver monitoring this band rejects strong out-of-band signals from adjacent GNSS downlinks (GPS L1 at 1575.42 MHz sits just 51 MHz below the lower band edge), cellular infrastructure, and other L-band services that would otherwise compete for the receiver's dynamic range.
Operating range is -40°C to +85°C, maximum RF input is +10 dBm, and the filter is passive and draws no power.
APPLICATIONS
- Spectrum monitoring and analysis of Inmarsat mobile satellite uplink traffic
- Inmarsat terminal test and development bench setups requiring clean frequency isolation
- Maritime and GMDSS receive system front ends
- Aeronautical satellite communications monitoring (ACARS, ADS-C via Inmarsat Aero)
- Fleet management and tracking terminal development (Fleet Broadband, IsatPhone)
- SDR-based L-band satellite reception requiring interference rejection from adjacent bands
- Defence and SIGINT receive chains targeting the 1626.5–1660.5 MHz mobile satellite service allocation
FILTER PERFORMANCE
| Frequency Range | Typical Attenuation |
|---|---|
| 50–550 MHz | >60 dB |
| 550–900 MHz | >55 dB |
| 900–1590 MHz | >40 dB |
| 1626.5–1660.5 MHz (passband) | <5 dB insertion loss |
| 1750–3000 MHz | >30 dB |
The rejection above 1590 MHz rising sharply to the passband ensures GPS L1 (1575.42 MHz) and other GNSS downlink energy is substantially attenuated before it reaches your receiver, which is the most common source of front-end overload in this frequency region.
NOTES
- SMA-F PCB edge mount connectors
- Maximum RF input: +10 dBm
- Maximum DC voltage on input/output port: 3 VDC
- Passive, no power required
- For receive applications, place an LNA ahead of this filter to establish your system noise figure before the filter's insertion loss. See our wideband L-band Low Noise Amplifiers for compatible front-end options.
COMPANION PRODUCTS
If you are building a full Inmarsat L-band receive chain, both sides of the link are now covered:
- This filter covers the Inmarsat uplink
- Downlink companion covers the Inmarsat receive path: 1525–1559 MHz Bandpass Filter for Inmarsat
