AFEDRI SDR it is direct sampling Software Defined Receiver (see picture below)
AFEDRI SDR has next parameters:
RX frequencies:
0.1MHz-30MHz (Low Pass filter assembled (LPF) - default assembly configuration)
Special , non standard SDR revision can be assembled to provide aliased reception mode 40MHz - 80MHz or 80MHz-120MHz (In aliased mode, LPF is not assembled, external Band Pass Filter (BPF) have to be used instead)
Noise Figure: ~17dB (for 1MHz-30Mhz range)*
*input VGA (Variable Gain Amplifier) is tuned to have variable Gain from -6dB up to +44dB
Output data format: two 16-bit I/Q channels (audio stereo stream emulation)
Maximum Receiving bandwidth:
BW = up to 240kHz (for 250 ksamples/s sample rate) - 192k version (current design revision)
BW = 90kHz (96ksamples/s) - 96k version (old design revision)
RF ADC sampling rate: 76.800MHz (or alternatively 79.872MHz)
Power Supply Voltage: 5V (supplied from USB bus)
Power Supply current: 330mA
Latest news is: In new HW revision it is possible to combine two AFEDRI SDR (one fully assembled and second containing only RF Front-End) to build Dual Channel (Diversity) Receiver, that can be used together with Linrad and MAP65 applications!
AFEDRI SDR in box
The Newest High-Speed AFEDRI SDR-USB-HS revision
The SDR is designed to be connected to Personal Computer (PC) by Full Speed USB link and supplies to PC two quadrature channels I/Q with sample rate up to ~250k samples per second 16-bit each channel for latest revision on SDR design. Published on this site schematic can use STM32F105xxx processor to get maximum RX bandwidth, it needs little schematic changes, plus new firmware.
You can download recorded in Winrad audio files:
- I/Q wave files recorded with different applications
- I/Q with 192ksamples/s sample rate
- I/Q with 250ksamples/s sample rate 14Mhz band (contest)
- I/Q with 250ksamples/s sample rate 7Mhz band (contest)
From PC side of view, the SDR is presenting USB Compisite Device, that contains two USB functions:
- Generic USB Audio device - to transfer baseband I/Q signal, as audio stereo stream
- USB HID device - used to control AFEDRI SDR
The SDR doesn't need any additional driver installation on most of Operational Systems (OS) used on PC today it was successfully tested under next OS Windows XP SP2, Windows Vista 32 bit, Windows 7 32 bit, Linux Fedora 12.
The SDR compatible and working with most PC SDR software that working with PC Spund Card device, like Wirad (and its different clones), Linrad, SDR Console, Rocky etc...
Additional SDR Control software is need to control over the AFEDRI SDR frequency, RF gain/attenuation and additional parameters. SDR Control software can be used stand alone with any SDR software, or as plug-in for Winrad and/or Linrad (only Windows version yet) software, so SDR's frequency can be displayed and changed directly from Winrad GUI (please check my Download page).
The SDR Control software was written using Qt Cross-platform application framework from Nokia, so both Windows and Linux software versions can be compiled and have similar Graphical User Interface (GUI) under both OS-es.
AFEDRI SDR is based on AFEDRI8201 integrated circuit, it is Analog Front End (AFE) from Texas Instrument Company (this part obsolete now, but can be found on the market). I know two SDR-s published in the web that are using same chip:
First design from OH2NLT, was one that pointed me to this interesting Integrated Circuits – AFEDRI8201. It has nice design but it was built as stand alone receiver that does all signal processing in its "DSP like" chip dsPIC30F6014A from Microchip Company. This design has very limited usability in my opinion, due to using for RX audio output 12 bit DAC, and 40-MHz signal processing DSP.
Second design, much more robust and can use Personal Computer (PC) for signal processing, but need additional FPGA evaluation board to transfer baseband signal from front end to PC.
My target was - to use AFEDRI8201 as direct sampling receiver and connect it to PC trough USB interface. From PC’s “point of view” the SDR is looking like usual USB Audio Device, that don’t need any additional driver and bring to PC two 16-bit basebandI and Qchannels at up to 250k sample rate, like in multiple existing today Sound Card based SDR (sftrock40, Flex 1000 etc…). And this SDR can be used with existing SDR software like Linrad or/and Winrad (or any of Winrad1.32 branches, like HDSDR), running under Windows and/or Linux OS.
Please see the picture below:
There is short block diagram description:
LPF - Low Pass Filter, in default configuration is using as anti-aliasing filter for from DC to ~28MHz (or any frequency located below Nyquist limit).
Can be easily replaced by band-pass filter (BPF) for desired band in under-sampling acquisition mode when received signal is lying over Nyquist frequency (for example 50MHz, 70MHz band, 144MHz). I tested undersampling mode with this receiver on WFM band (88-108MHz) and on 144MHz band, there is some degradation in sensitivity, so it will be better to add external low noise amplifier (LNA).
VGA - Variable Gain Amplifier, it is built using AD8330 IC from Analog Devices, and adjusted in in this design to give amplification/attenuation of input signal from -6dB up to 44dB.
Direct Sampling Receiver Front End - i.e Analog Front End is built on AFEDRI8201PBF integrated circuit, it is main device of SDR, that providing Input RF signal ADC sampling, mixing and digital filtering, base-band signal data is outputs through specific serial interface, that very similar to I2S but not 100% compatible, for example used in my design CPU, need external help from CPLD, to accept data incoming data. More information about you can find in datasheet. Please pay attention that this device is obsolete on Texas Instruments, but there is many way to achieve this integrated cuicuits from different sources. And I am sure HAM radio society can use it in their applications. For example I have some quantity of AFEDRI8201PBF in my stock.
CPLD - main function of this device to convert AFEDRI8201 base-band (output data) serial protocol to SPI protocol, that can be received by used in design CPU.
CPU - it ARM Cortex-M3 architecture microprocessor - STM32F103R8, from ST Microelectronics, it controls Analog Frond End by additional SPI control channel, receive processed base-band data from Front End and transfer it to PC using USB link and software USB Audio Device and HID device emulation.
Power Supply - Whole receiver is supplied from 5V voltage of USB line, and there is three voltages +1.8V -digital, 3.3- digital and 3.3V analog, that generated from single supply voltage.
Optional UART - SDR contains also RS232 serial interface, in present firmware I am using it for additional debug command shell interfacing, filters coefficients upload and it is possible to upload firmware to CPU trough this interface.
Optional LCD - there is optional parallel LCD interface exists in SDR, LCD is not supported by current firmware yet, cause I am not sure do someone really need it, but can be easily implemented in the future on user request.
The full AFEDRI SDR schematic can be found on my Download page.
The mechanical size of the SDR PCB is 120x73mm. It was designed for installing in one two of aluminum boxes manufactured by Hammond the manufacturer part number of boxes is:
Second one has biggest size.
There is lot of files on my download page, software sources and firmware for your attention.
You can visit also Yahoo AFEDRI SDR user group
Any question? Please ask me by email. alex(*)4z5lv.net
- to really send me email - please replace (*) by @ :-) , and please put in email subject
Please check it periodically for latest version.
Further information will be later.