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AbstractSDRs.jl

Purpose

This package proposes a single API to monitor different kind of Software Defined Radio. We define several SDR backends that can be piloted by the same API. With AbstractSDRs, the following SDRs can be used

  • All Universal Software Radio Peripheral USRP, based on UHDBindings package
  • RTL SDR dongle, with inclusion of RTLSDR package
  • Any device connected to a remote PC with a network connection (for instance, Exxx USRP device) on which a Julia session works and run AbstractSDRs package.
  • The ADALM Pluto SDR, through a specific package (WIP)
  • A pure simulation package usefull for testing without radio or do re-doing offline dataflow processing based on a given buffer

AbstractSDRs provides an unified API to open, transmit and received samples and close the SDRs.

For instance, in order to get 4096 samples at 868MHz with a instantaneous bandwidth of 16MHz, with a 30dB Rx Gain, assuming that a USRP is connected, the following Julia code will do the trick and returns a vector with type Complex{Cfloat} with 4096 samples.

function main()
	# ---------------------------------------------------- 
	# --- Physical layer and RF parameters 
	# ---------------------------------------------------- 

	carrierFreq		= 868e6;	# --- The carrier frequency 	
	samplingRate		= 16e6;         # --- Targeted bandwdith 
	rxGain			= 30.0;         # --- Rx gain 
	nbSamples		= 4096;         # --- Desired number of samples

	# ---------------------------------------------------- 
	# --- Getting all system with function calls  
	# ---------------------------------------------------- 
	# --- Creating the radio ressource 
	# The first parameter is to tune the Rx board
	radio	= openSDR("UHDRx",carrierFreq,samplingRate,rxGain);
	# --- Display the current radio configuration
	print(radio);
	# --- Getting a buffer from the radio 
	sig	= recv(radio,nbSamples);
	# --- Release the radio ressources
	close(radio); 
	# --- Output to signal 
	return sig;
end

Note that the SDR discrimination is done through the "UHDRx" parameter when opening the device, which states here that the UHD driver should be used, and that the radio will receive samples. To get the same functionnality with a RTL SDR dongle, the following code can be used.

function main()
	# ---------------------------------------------------- 
	# --- Physical layer and RF parameters 
	# ---------------------------------------------------- 

	carrierFreq		= 868e6;	# --- The carrier frequency 	
	samplingRate		= 16e6;         # --- Targeted bandwdith 
	rxGain			= 30.0;         # --- Rx gain 
	nbSamples		= 4096;         # --- Desired number of samples

	# ---------------------------------------------------- 
	# --- Getting all system with function calls  
	# ---------------------------------------------------- 
	# --- Creating the radio ressource 
	# The first parameter is to tune the Rx board
	radio	= openSDR("RTLRx",carrierFreq,samplingRate,rxGain);
	# --- Display the current radio configuration
	print(radio);
	# --- Getting a buffer from the radio 
	sig	= recv(radio,nbSamples);
	# --- Release the radio ressources
	close(radio); 
	# --- Output to signal 
	return sig;
end

Note that the only difference lies in the radio opening.

Installation

The package can be installed with the Julia package manager. From the Julia REPL, type ] to enter the Pkg REPL mode and run:

pkg> add AbstractSDRs

Or, equivalently, via the Pkg API:

julia> import Pkg; Pkg.add("AbstractSDRs")

Backends

AbstractSDRs wraps and implements different SDR backends that can be used when opening a radio device. The current list of supported SDR backends can be obtained via getSupportedSDR. When instantiate a radio device (with openSDR), the first argument is the radio backend and parameters associated to a specific backend can be used with keywords. Some specific functions can also be exported based in the selected backend. The list is given in the sub-backend part

UHD backend

AbstractSDRs can be used with Universal Radio Peripheral (USRP) with the use of UHDBindings.jl package. The backend is identified by the symbol :uhd. This backend supports ths following keywords

  • args="" to specify any UHD argument in initialisation. Please refer to the UHD doc. For instance, FPGA bitstream path can be specified with args="fgpa=path/to/image.bit". The IP address of the USRP can be added with args="addr=192.168.10.xx".

AbstractSDRs package also exports the following specific functions

  • NONE.

RadioSim

This backend is useful when one wants to test a processing chain without having a radio as it simulates the behaviour of a SDR (configuration and buffer management). It is also useful when you have some acquisition in a given file (or buffer) as we can give the radio device a buffer which is then used to provide samples (as recv gives chunk of this buffer based on the desired size in a circular manner). This backend supports ths following keywords

  • packetSize to specify the size of each packet given by the radio. By default the value is 1024 complex samples
  • buffer to give to the radio a buffer to be used when emulating the reception. The following rules occur
    • If packetSize is not given, the provided buffer will be buffer each time the recv command is used
    • If packetSize is higher than the size of the proposed buffer, the buffer will be circulary copied to provive packetSize complex samples
    • If packetSize is lower than the size of the proposed buffer, recv will returns packetSize samples from buffer and the buffer will be browsed cicularly
    • If no buffer is given, packetSize random data will be generated at the init of the radio and proposed each time recvis called

AbstractSDRs package also exports the following specific functions related to RadioSims

  • updatePacketSize to update the size of the radio packet.
  • updateBuffer to update the radio buffer

Pluto

This backend can be used with ADALM Pluto SDR device.

SDROverNetworks