What Is an Emission Designator?

An emission designator is a code defined by the ITU (International Telecommunication Union) that describes the characteristics of a radio signal. It usually has three main parts, like F2D or G1D.

Each character in the emission designator has a specific meaning:

• First letter: Type of modulation (e.g., F = Frequency modulation, G = Phase modulation)
• Second number: Type of signal (1 = digital without subcarrier, 2 = digital with subcarrier, 3 = analog)
• Third letter: Type of information being sent (A = Morse, D = Data, E = Voice)

For example, F2D means frequency modulation (FM), with digital data on a subcarrier.

Common Emission Types

Here’s a list of commonly used APRS and digital modes on the 2-meter and 70cm bands, and their corresponding emission types:

APRS AFSK 1200 baud

• Band: 2m (144.390 MHz, 144.800 MHz, 144.340 MHz)
• Emission: F2D
• Description: FM with digital data using AFSK tones (1200/2200 Hz). This is the most common APRS mode.

Voice repeater with CW ID

• Band: 2m / 70cm
• Emission: F2A
• Description: FM voice repeater that sends its callsign in Morse code via an audio tone.

Analog FM voice

• Band: 2m / 70cm
• Emission: F3E
• Description: Regular FM voice transmission (used on simplex or repeaters).

LoRa APRS

• Band: 70cm (commonly 433 MHz)
• Emission: G1D
• Description: LoRa uses chirp spread spectrum, which is categorized as phase modulation. Used to send APRS position/data packets.

APRS via D-STAR

• Band: 2m / 70cm
• Emission: G7D
• Description: Digital voice system with embedded GPS or APRS data.

APRS via DMR

• Band: 70cm
• Emission: G1D
• Description: Digital data over GMSK (time-division) using DMR radios with APRS capability.

APRS via Yaesu System Fusion (C4FM)

• Band: 2m / 70cm
• Emission: G7D
• Description: Digital voice and data using Yaesu’s C4FM protocol. Includes embedded GPS or APRS telemetry.

Packet 9600 baud

• Band: 2m / 70cm
• Emission: F1D
• Description: Digital data sent directly over FM (without AFSK)

Summary Table

Real-World Examples

• In Malaysia, APRS on 144.390 MHz uses F2D (AFSK 1200 baud).
• LoRa APRS is gaining popularity, using G1D.
• Voice repeaters with CW ID use F3E for voice and F2A for the Morse identifier.
• Digital APRS over DMR and C4FM would be classified as G1D and G7D, respectively.

Final Thoughts

Knowing emission type helps ensure proper and responsible operation. Whether you’re using a simple Baofeng to monitor APRS, experimenting with LoRa, or setting up a digital repeater, take a moment to understand the mode’s classification. It’s a small thing that reflects technical knowledge and practice.

The post Understanding Emission Designators for APRS and Digital Modes on 2m and 70cm Bands appeared on Hamradio.my - Amateur Radio, Tech Insights and Product Reviews by 9M2PJU.