1640 MHz Band Overview

The 1640 MHz frequency sits in the L-Band (1–2 GHz) of the radio spectrum and plays a critical role in satellite navigation, telemetry, surveillance systems, and space-to-Earth communication. Although not as universally known as bands used for LTE or Wi-Fi, 1640 MHz is integral to aerospace and scientific applications and is often tightly regulated.

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📶 Frequency Range and Classification

Center Frequency: 1640 MHz
Typical Range: 1610–1660.5 MHz
ITU Band: L-Band (ITU designation: Region 1, 2, and 3 compliant)
Wavelength: ~18.29 cm

This frequency range overlaps or borders bands used for satellite navigation, radionavigation-satellite services (RNSS), and space operation systems.

🌍 Regional Use Breakdown

🌐 Region	Use of 1640 MHz	Status
🌍 Region 1	Scientific and satellite services	Primary or shared
🌎 Region 2	RNSS, telemetry, spectrum surveillance	Shared, harmonized
🌏 Region 3	Satellite comms, telemetry (select areas)	Varies by country

🚀 Primary Applications

Application	Description
GNSS Downlink Channels	1640 MHz lies within ranges used by GNSS constellations like GLONASS
Telemetry (Aerospace)	Downlink for vehicle health monitoring and control systems
Spectrum Surveillance / SIGINT	Used by state and defense agencies for spectrum monitoring
Space Research & Operations	Receives data from spacecraft for scientific and observational missions
Custom Scientific Experiments	Earth-space radio signal propagation, ionospheric studies, etc.

📊 Technical Characteristics

Attribute	Value
Center Frequency	1640 MHz
Modulation Types	QPSK, BPSK, FSK, custom spread spectrum
Antenna Type	Helical, patch, directional arrays
Typical Bandwidth	Varies: 2–10 MHz allocations or narrowband
Link Type	Downlink or simplex (space-to-Earth)
Power Levels	Low-power (<10 W) to high-gain satellite class

🌐 Licensing & Governance

Organization	Role
ITU	Global coordination and regional harmonization
FCC (USA)	Regulates use within Region 2, especially for GNSS
ESA / CNES / ISRO	Space-based services using or bordering this band
Military & Intel Agencies	May reserve segments for non-public applications

🔐 Access & Restrictions

Heavily regulated due to international coordination
Not for license-free use
Subject to coordination between civil and military entities
Potential for harmful interference with GNSS and aircraft telemetry if misused

🔁 Spectrum Sharing & Interference Considerations

Shared spectrum with GLONASS signals (~1602–1616 MHz)
Adjacent to Earth Exploration Satellite Service (EESS) bands
Careful filtering and coordination required to prevent satellite downlink interference
Spectrum monitoring often enforced near this band for compliance

🛰️ Adjacent Bands Overview

Band	Frequency Range	Use
1610–1626.5 MHz	RNSS (e.g., GLONASS), Iridium uplinks
1626.5–1660.5 MHz	Mobile satellite service (MSS), telemetry, Inmarsat
1660.5–1670 MHz	Meteorological satellite, passive sensing
1670–1675 MHz	Earth Exploration Satellite Service

🧠 Summary Table

Feature	Value / Description
Center Frequency	1640 MHz
ITU Region	🌍 Region 1, 🌎 Region 2, 🌏 Region 3
Primary Use	GNSS-related downlink, aerospace telemetry
Access	Licensed only, tightly regulated
Notable Risks	GNSS interference, satellite downlink overlaps
Key Stakeholders	Space agencies, defense, spectrum authorities

🔭 Engineering Notes

Ideal for long-distance downlink from LEO/MEO spacecraft
Antenna designs require high directivity for low-EIRP signals
Filtering is critical due to proximity to sensitive navigation bands
Often used in custom SDR setups for space weather and science studies