Grant: TAPR – TangerineSDR Prototype Build

Date of Grant: June 23, 2020
Grant Amount: $42,500

TAPR, Inc. is a non-profit 501(c)(3) organization of amateur radio (“ham”) operators who are interested in advancing the state of the radio art. In this project, TAPR is working to develop TangerineSDR – a modular, direct-sampling software-defined radio (SDR).

The funding provided by ARDC goes towards developing additional prototypes for Tangerine SDR’s initial build, bringing the number that they can build from 6 to 25. These prototypes will besuitable for use as a Personal Space Weather Station (PSWS).

Project Description

The main board for TangerineSDR, or Data Engine (DE) consists of a MAX10 FPGA with modular interfaces to two RF Modules (RFM) and one Clock Module (CKM) slot. The DE includes a three-port GbE switch, a USB 3.0 device port and a USB 2.0 host port for communications interfaces. Expansion ports include a PMOD connector, a Raspberry Pi HAT connector and an enhanced RPi-compatible expansion port called a LEAF. Additional DE variants will follow, including a much more powerful Cyclone V-E based model with 301K Logic Elements (LEs).

The RFM modules contain front-end calibration and filtering circuits, plus clock and digitization circuitry. One or both slots may be populated with RFMs. The RFM for PSWS is a dual-input synchronous direct sampling receive module using a dual-channel 14-bit ADC clocked at 122.88Msps, with a receive frequency range of 100kHz to 60MHz. Other RFMs will follow, covering both receive and transmit ranges into the GHz bands.

The low-cost TangerineSDR can operate without a CKM in non-demanding applications. However, the PSWS requires a very accurate time stamp on received data, so a GPS Disciplined Oscillator (GPSDO) will be fitted to the CKM slot. The GPS selection is still in progress, but the uBlox ZED-F9 series seem to be the most promising.

All hardware will be licensed under the TAPR Open Hardware License (OHL), and all firmware and software will be licensed under GNU General Public License (GPL).

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