URX-1

Overview

The URX-1 is a highly compact, single-band VHF/UHF FM utility receiver engineered by Bob Simmons (WB6EYV) under the Doppler DF Instruments brand. Primarily developed as a lightweight companion receiver for automated pseudo-Doppler radio direction finding (RDF) systems, the module functions as a remotely controlled RF front-end. The receiver captures target signals and feeds recovered audio demodulation streams into direction-finding processors to extract physical signal headings.

Technical Specifications

AttributeDetails
ManufacturerDoppler DF Instruments
Product CategoryVHF / UHF FM Utility Receiver
Tuning Bandwidth Span10 MHz localized operational blocks
Frequency Spectrum Coverage100 MHz to 1000 MHz factory build options
Frequency Step Resolution1 KHz intervals via hardware synthesis
Control Interface StandardRS-232 Serial Architecture (Full Remote Control)
Native Demodulation ModeFrequency Modulation (FM) standard (AM optional)
Configuration StorageNon-Volatile Internal Memory (EEPROM)
Input Supply Voltage10 Volts to 18 Volts DC
Operational Current Draw30 milliamperes typical (squelch closed load)
Dimensions1.75 inches long by 3.78 inches wide by 0.35 inches deep
Unit Weight0.2 ounces (approx. 5.6 grams)

Physical Description

The URX-1 is produced as a miniature, low-profile single-board assembly leveraging high-density surface-mount component placement. The ultra-lightweight circuit configuration is stripped of heavy, conventional chassis controls like mechanical tuning dials, volume knobs, or dedicated speaker grilles. Instead, it features exposed connection pads for power routing, an antenna terminal node, an RS-232 logic bus interface, and analog audio outputs. Optional onboard hardware trimpots can be populated directly to the substrate to manually govern volume and squelch baseline calibrations when operating outside of an active automated control link.

History

The URX-1 was designed by Doppler DF Instruments to mitigate size, weight, and remote integration constraints associated with utilizing standard commercial transceivers in automated search and telemetry configurations. Traditional mobile pseudo-Doppler tracking installations required tapping directly into the internal discriminator circuitry of a user’s primary amateur radio transceiver to extract clean audio phase signals. This approach increased installation complexity and limited the ability to deploy direction finders inside unmanned aerial vehicles (UAVs) or remote automated listening posts due to physical space limits.

By eliminating manual user controls and relying entirely on computerized command structures, Simmons condensed a full-performance, dual-conversion FM tracking receiver onto a board weighing a fraction of an ounce. The hardware was optimized to receive serialized RS-232 frequency modification, volume adjustment, and squelch threshold commands from an external laptop terminal, a dedicated microprocessor controller, or an integrated airborne telemetry system.

The receiver’s RF design featured a highly flexible layout, allowing the factory to optimize individual boards for localized operational bands. Standard versions were frequently deployed to cover the 120–130 MHz aviation bands, the 140–150 MHz amateur and public safety sectors, or the 465–475 MHz UHF frequencies. This flexibility made the URX-1 a standard component for covert tracking systems, wildlife telemetry monitoring networks, and compact radio direction-finding equipment.

References