jpoirier / gortlsdr

A Go wrapper for librtlsdr (a driver for Realtek RTL2832U based SDR's)

Description

gortlsdr is a simple Go interface to devices supported by the RTL-SDR project, which turns certain USB DVB-T dongles employing the Realtek RTL2832U chipset into a low-cost, general purpose software-defined radio receiver. It wraps all the functions in the librtlsdr library (including asynchronous read support).

Supported Platforms:

• Linux
• OS X
• Windows (with a little work)

Installation

Dependencies

• Go tools
• librtlsdr - builds dated after 5/5/12
• libusb
• git

Usage

All functions in librtlsdr are accessible from the gortlsdr package:

go get -u github.com/jpoirier/gortlsdr

Example

See the eample.go file:

go run example.go

Windows

If you don't want to build the librtlsdr and libusb dependencies from source you can use the librtlsdr pre-built package, which includes libusb, but you're restricted to building a 32-bit gortlsdr library.

Building gortlsdr on Windows:

• Download and install git.

• Download and install the Go tools. Create a "go-pkgs" directory-your user folder is a good location-and add a GOPATH variable to your system environment, where GOPATH is set to the go-pkgs path, e.g. GOPATH=c:\users\jpoirier\go-pkgs.

• Download the pre-built rtl-sdr library and unzip it, e.g. to your user folder. Note the path to the header files and the *.dll files in the x32 folder.

• Download gortlsdr, but don't install the package:

      go get -d github.com/jpoirier/gortlsdr
  

• Set CFLAGS and LDFLAGS in rtlsdr.go. Open the rtlsdr.go file in an editor, it'll be in go-pkgs\src\github.com\jpoirier\gortlsdr, and set the following two windows specific flags shown below, but with the correct paths from your system. CFLAGS points to the header files and LDFLAGS to the *.dll files:

      cgo windows CFLAGS: -IC:/Users/jpoirier/rtlsdr
      cgo windows LDFLAGS: -lrtlsdr -LC:/Users/jpoirier/rtlsdr/x32
  

• Build gortlsdr:

      go install github.com/jpoirier/gortlsdr
  

• Insert the DVB-T/DAB/FM dongle into a USB port, open a shell window in go-pkgs\src\github.com\jpoirier\gortlsdr and run the example program: go run example.go. Note, the pre-built rtl-sdr package contains several test executables as well.

Credit

• pyrtlsdr for the great read-me description, which I copied.
• osmoconSDR for the rtl-sdr library.
• Antti Palosaari for sharing!

Todo

-joe

gortlsdr's Issues

test and agc modes are backwards

Go errors

It would be nice to hide the C-isms as much as possible e.g. rather than returning ints, return Go errors

To this end I've created a branch which includes:

• return Go error type where appropriate.
• Tidy up function comments. Hide C function signatures
• Use bool instead of int 0/1

Possibly a candidate for v2.0 😀

cgo question

I'm trying to understand how gortlsdr uses cgo to interface with the C library, in particular the callback function used in the async read. clientCb is set inside ReadAsync() yet doesn't get passed to a C function or referenced from the C preamble!?

The Go docs http://golang.org/cmd/cgo/ talk about using //export before the Go function to be exported...yet gortlsdr doesn't do this. Could you explain how this works?

rtlsdr_set_tuner_bandwidth

function rtlsdr_set_tuner_bandwidth() is not present in Linux distro releases of rtl-sdr package. Go packages that have gortlsdr as a depencency will fail to compile when using distro packaged librtlsdr.

I've confirmed this on Fedora 23 and Ubuntu 14.04.

Could SetTunerBw() be modified to return an error if rtlsdr_set_tuner_bandwidth() can't be found?

libusb

-lusb here appears to be redundant and removing it makes no difference to compilation on Linux.

I found that having the flag there actually causes compilation to fail if legacy libusb is not installed. For example Arch linux uses the current 1.0 library which is referenced by -lusb-1.0

@jpoirier do you foresee see any issues in removing this flag?

Support for older versions of rtl-sdr

gortlsdr/rtlsdr.go

Line 32 in 8185285

Please add here:

#ifdef rtlsdr_set_bias_tee
static int rtlsdr_set_bias_tee_wrap(rtlsdr_dev_t* d, int i) { return rtlsdr_set_bias_tee(d,i); }
#else
static int rtlsdr_set_bias_tee_wrap(rtlsdr_dev_t* d, int i) { return -12; }
#endif

And call rtlsdr_set_bias_tee_wrap instead of rtlsdr_set_bias_tee
Thanks.

"gcc": executable file not found in %PATH%

I get

exec: "gcc": executable file not found in %PATH%
message after go install github.com/jpoirier/gortlsdr command

OS: Windows 7 64 bit

error

when i run "go get -u github.com/jpoirier/gortlsdr" i get this error does anyone know how to fix it?

# github.com/jpoirier/gortlsdr /tmp/go-build505426775/github.com/jpoirier/gortlsdr/_obj/rtlsdr.cgo2.o: In function _cgo_1debe9789e24_Cfunc_rtlsdr_set_bias_tee':
go/src/github.com/jpoirier/gortlsdr/rtlsdr.go:355: undefined reference to rtlsdr_set_bias_tee' /tmp/go-build505426775/github.com/jpoirier/gortlsdr/_obj/rtlsdr.cgo2.o: In function _cgo_1debe9789e24_Cfunc_rtlsdr_set_tuner_bandwidth':
go/src/github.com/jpoirier/gortlsdr/rtlsdr.go:446: undefined reference to rtlsdr_set_tuner_bandwidth' collect2: error: ld returned 1 exit status