[Discuss-gnuradio] Prototype Hardware for gnuradio

[jschwack]

All,

I am new to gnuradio but so far am very impressed with the design, organization, and functionality of the software. Recently, I developed a prototype of a small, relatively low cost, hardware platform for SDR experimentation and wanted to make that information and my efforts available to the gnuradio community. I've posted some basic information and my initial efforts to integrate the hardware into the gnuradio framework on the web at http://sdrtrack.drupalcafe.com.

Hardware summary:

Single input, receive-only.

27 MHz LPF and -5 to 43 db LNA.

Switchable LPF-LNA Bypass.

80 Msps 12 bit ADC/DDC (TI AFEDRI8201), 2.5 Msps IQ at minimum decimation.

Connector plugs directly into PMOD Ports on Digilent Nexys2 FPGA Board.

Approximate construction cost (single/small quantities) ~$80.

Construction possible using mylar solder paste stencil, “skillet” reflow, a pair of tweezers, and a steady hand.

FPGA/USB Board – Nexys2 from Digilent ($99+$20 for 1.2M gate Spartan III).

Software (so far):

FPGA code (verilog) including FIFOs, Digilent USB-to-FPGA protocol, SPI Master for AFEDRI8201.

nexsdr_source_c() block patterned after usrp_source_c().

Converted version of usrp_wfm_rcv.py.

Converted version of usrp_nbfm_rcv.py.

Results:

WFM works great with antenna connected directly to input (no amplifier or filter) with bandpass sampling (tune to f-80MHz), sounds better than my car radio.

NBFM works great listening to several amateur repeaters on 2 meters (~147 MHz) with antenna connected via 4 MHz wide BPF to input (no amplifier) with bandpass sampling (tune to 160 Mhz-f).

The hardware is not Universal (USRP) or High Performance (HPSDR) or super cheap (Softrock + sound card) but I've found it quite useful as a platform for experimenting with gnuradio.

I'll continue to document my efforts at the site listed above and, again, thanks for a great open source framework for SDR. Your comments and suggestions are welcome.

John