MicroBeacon

Overview

The MicroBeacon is a specialized, compact Automatic Packet Reporting System (APRS) position beacon transmitter designed by Bob Simmons (WB6EYV) under the Doppler DF Instruments brand. Engineered specifically for weight-sensitive applications such as radio direction finding tracking, high-altitude weather balloons, and unmanned aerial vehicle (UAV) telemetry, the module automatically parses raw global positioning data and converts it into standard AX.25 packet strings to broadcast real-time location, altitude, and tracking telemetry over amateur radio bands.

Technical Specifications

AttributeDetails
ManufacturerDoppler DF Instruments / WB6EYV
Product CategoryAPRS Telemetry Beacon Transmitter
RF Power Output2 Watts minimum at 12 Volts DC
Primary Frequency Band2-Meter Amateur Radio Band (144 MHz to 148 MHz)
Frequency Step Tuning1 KHz intervals via hardware synthesizer
System Control LogicMicrochip PIC 18F442 Microcomputer Hardware
Radio Frequency ChipsetAnalog Devices ADF7012 Transmitter Integrated Circuit
RF Output Amplifier StagePhilips PD85004 RF Field-Effect Transistor (FET)
Telemetry Interface ProtocolRS-232 Serial Port (NMEA-0183 Standard Inputs)
Monitored NMEA Strings$GPRMC and $GPGGA Sentences
Input Operating Voltage7 Volts to 14 Volts DC
Current Consumption Profiles10 milliamperes (Idle State)
Dimensions1.20 inches by 2.20 inches by 0.13 inches
Unit Weight0.25 ounces (7 grams)

Physical Description

The MicroBeacon is built on an ultra-lightweight, miniature single-board profile using surface-mount technology (SMT) component layouts to optimize balance for aerospace deployments. The layout features an integrated 5-Volt DC regulated power terminal line dedicated to powering external serial GPS puck receivers without adding peripheral voltage step-down transformers. Peripheral interfaces include a main power feed track, an RS-232 terminal connector for raw NMEA ingestion, an RF coaxial output node, and uncommitted processing pins exposed specifically for localized hardware experimentation and testing.

History

The MicroBeacon was engineered by Bob Simmons to address a growing demand for miniaturized telemetry trackers within the high-altitude amateur ballooning and remote model aviation communities. Standard packet radio setups and mobile APRS installations required a heavy combination of a standalone global positioning system, a separate terminal node controller (TNC), and a standard commercial transceiver. This multi-device footprint added too much bulk and weight for specialized airborne search and recovery research payloads.

Simmons consolidated the functions of a data frame packet generator, a frequency synthesizer, and a 2-Watt RF amplifier onto a single quarter-ounce circuit outline. The system logic removed the need for a separate hardware TNC by using an onboard PIC microcontroller to decode raw GPS data, calculate checksum variations, and compile the final coordinates directly into standard AX.25 audio frequency shift keying (AFSK) packets.

Configuration parameters—including station call signs, automated repeat intervals, transmitter frequencies, and target APRS map tracking icons—were set by operators via an RS-232 link using the brand’s proprietary WinBeacon configuration utility and stored directly into the non-volatile internal EEPROM memory blocks. The tiny tracking transmitter achieved a prominent reputation for reliability during high-altitude tracking missions, successfully maintaining coherent telemetry streams at flight elevations exceeding 100,000 feet and through severe temperature drops down to minus 70 degrees Celsius.

References