OsmoSDR Hardware

The OsmoSDR hardware consists of an oscillator, Zero-IF silicon tuner, ADC, FPGA and a USB-capable microcontroller.

The block diagram looks like this:

block diagram


  • As of 18 November 2012, an updated hardware achieves [/blog/20121018-osmosdr-update 4MS/s sample rate at 14 bits]
  • As of 28 December 2011, we have hardware verification code and detected some bugs that need a 2nd PCB revision
  • As of 13 December 2011, we had the first 5 prototypes

Major Components

Atmel AT91SAM3U Microcontroller

The SAM3U is a quite powerful but inexpensive Cortex-M3 based Microcontroller. What makes it special compared
to many other devices is its integrated USB 2.0 High-Speed device, combined with scatter-gather DMA and an internal
memory/bus architecture that can actually drive the USB 2.0 at 480Mbps without any problems.

The SAM3U Firmware will be available as Free Software / Open Source in our git repository.

Lattice XFP2 FPGA

The FPGA is mainly intended to interface the ADC with the SSC peripheral of the SAM3U. However, it is reasonable
to assume it can do some simple filtering, too.

The FPGA design will be available as Free Software / Open Source in our git repository

Analog Devices AD7357 ADC

This ADC provides two channels (I and Q) and can run at up to 4.2 Megasamples / second and provides 14 bits of resolution.

Silicon Tuner


SiLabs Si570 Oscillator

The Si570 is a 10MHz to 1.4GHz programmable oscillator. The exact frequency can be set and adjusted via an I2C interface.

Options / Extensions

OsmoSDR is prepared for a number of extensions...

GPS locked clock

There is a 1pps input on OsmoSDR. It can be used to slave the OsmoSDR clock to the 1pps output of a GPS receiver in order
to achieve high clock accuracy.


OsmoSDR is a pure Rx device. However, there are extension headers of both the SAM3U and the FPGA which permit stacking
of a future transmitter board.


There are jumpers for the differential analog I and Q baseband signals between the mixer/downconverter and the ADC. This can
be used to plug custom analog base band filters into the signal chain.

Updated by laforge almost 8 years ago · 12 revisions

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