Introducing the ADSBee m1421: The World's Most Compact Dual-Band Aircraft Tracker

Pants for Birds is thrilled to unveil the latest addition to the open-source ADSBee ecosystem: the ADSBee 1421!

🌐 Background & Evolution

In the last year, the open-source aircraft tracking capabilities of the ADSBee 1090U have been integrated into a diverse array of projects, ranging from professional airport ground stations to high-altitude weather balloons and autonomous drones.

Through collaboration with our user base, we identified a specific market gap: the need for a low-cost, ultra-low-power ADS-B receiver tailored for detect and avoid (DAA) functionality, which doesn't require the exhaustive feature set of the 1090U.

The catalyst for this new design was the release of Semtech's fourth-generation LoRA IP, the LR2021 chip. This component features a high bit rate OOK (On-Off Keying) demodulator and RF frontend. By integrating an architecture that previously required discrete components, the LR2021 significantly reduces both the physical footprint and the power consumption needed to process Mode S packets.

To complement this, we selected the TI CC1314 as the RF MCU—the successor to the CC1312 used for UAT and sub-GHz tracking in the 1090U.

The Naming Logic

The name ADSBee 1421 is a simple concatenation of its primary components:

Note: The "m" prefix (as in m1421) indicates it is a solder-down module designed for seamless integration into custom PCBs.

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🛠️ Technical Specifications & Features

The ADSBee m1421 is engineered for embedded applications where every milligram and milliwatt counts.

Physical & Electrical Profile

• Weight: $< 2\text{g}$
• Power Consumption: $< 60\text{mW}$
• Dimensions: $23.4\text{mm} \times 14.5\text{mm} \times 2.7\text{mm}$

Capabilities

• Dual-Band Reception: Supports both Mode S and UAT.
• UAT Uplink Support: Includes TIS-B (traffic) and FIS-B (weather) protocols.
• Open Source: Both the schematics and firmware are released under the GPL v3 license.
• Unified Logic: Position decoding and tracking are synchronized with the popular ADSBee 1090 firmware via cloud CI.

Supported Output Protocols

• GDL90
• MAVLINK1 & MAVLINK2
• Aircraft JSON
• CSBee
• Raw Packets
• Additional protocols (Coming Soon)

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💰 Pricing and Compliance

The m1421 is available in two versions depending on your regulatory needs.

Volume Discounts (Standard Variant):

• 1–9 units: $48.00
• 10–99 units: $45.00
• 100–999 units: $42.00
• 1000+ units: $39.00

Goal: We are currently expanding US manufacturing to bring the NDAA variant cost down to $75.00 $48.00 by December 2026.

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⚖️ ADSBee m1421 vs. ADSBee 1090

A common question is whether the 1421 replaces the 1090. The answer is no; they serve different purposes due to their differing architectures.

Comparison Matrix

The Trade-offs

To maintain a high dynamic range, the LR2021 is tuned specifically for Downlink Format 17 (DF17).

• The Upside: Excellent at identifying aircraft positions.
• The Downside: You will not receive squawk codes or as many non-ADSB packets.

While the firmware allows for reception using the Mode S preamble (enabling all packet types), this significantly degrades the dynamic range, making it difficult to receive signals from aircraft in close proximity. Furthermore, the high-throughput mode of the LR2021 does not support per-packet RSSI or timestamps, which are critical for Multilateration (MLAT).

{
  "status": "MLAT_Support",
  "current_state": "Experimental",
  "out_of_box": false,
  "note": "Requires further tinkering and testing"
}

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📸 Visual Gallery

Figure 1: Front view of the m1421 module.

Figure 2: Perspective view.

Figure 3: Rear view of the PCBA.

Figure 4: High-resolution module overview.