rtldavis

README

rtldavis

rtldavis

About this Repository

This repository is a fork of https://github.com/lheijst/rtldavis for use with custom receiver modules. It has been modified in numerous ways.

1. Added AU frequencies
2. Used an alternative demodulator that seems to work better in noisier conditions, tested in AU
3. Made code a little more self-documenting
4. Removed an probably unnecessary buffer copy
5. Removed frequency scan code. Unnecessary regression test burden. For same function is faster to use FFT 'scan' in gqrx or equivalent.

*** THIS BUILD demodulates reasonably robustly in AU on Intel and Raspi, but requires afc disabled ***

Installation

Install packages needed for rtldavis

sudo apt-get install golang git cmake librtlsdr-dev

Setup Udev Rules

Next, you need to add some udev rules to make the dongle available for the non-root users. First you want to find the vendor id and product id for your dongle. The way I did this was to run:

lsusb

The last line was the Realtek dongle: Bus 001 Device 008: ID 0bda:2838 Realtek Semiconductor Corp. Bus 001 Device 005: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T

The important parts are "0bda" (the vendor id) and "2838" (the product id).

Create a new file as root named /etc/udev/rules.d/20.rtlsdr.rules that contains the following line: nano /etc/udev/rules.d/20.rtlsdr.rules SUBSYSTEM=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", GROUP="adm", MODE="0666", SYMLINK+="rtl_sdr"

With the vendor and product ids for your particular dongle. This should make the dongle accessible to any user in the adm group. and add a /dev/rtl_sdr symlink when the dongle is attached.

Get librtlsdr

cd /home/pi
git clone https://github.com/steve-m/librtlsdr.git
cd librtlsdr
mkdir build
cd build
cmake ../ -DINSTALL_UDEV_RULES=ON
make
sudo make install
sudo ldconfig

Change / create ~/profile

sudo nano ~/.profile
add at the end of the file:

export GOROOT=/usr/lib/go
export GOPATH=$HOME/work
export PATH=$PATH:$GOROOT/bin:$GOPATH/bin

Activate changed / new ~/profile

source ~/.profile

Get the rtldavis package

cd /home/pi
go get -v github.com/lheijst/rtldavis

Compiling GO sources

cd $GOPATH/src/github.com/lheijst/rtldavis
git submodule init
git submodule update
go install -v .

Start program rtldavis

$GOPATH/bin/rtldavis

Usage

Available command-line flags are as follows:

Usage of rtldavis:

  -tr [transmitters]
    	code of the stations to listen for: 
        tr1=1 tr2=2 tr3=4 tr4=8 tr5=16 tr6=32 tr7=64 tr8=128
        or the Davis syntax (first transmitter ID has value 0):
        ID 0=1 ID 1=2 ID 2=4 ID 3=8 ID 4=16 ID 5=32 ID 6=64 ID 7=128
        When two or more transmitters are combined, add the numbers.
        Example: ID0 and ID2 combined is 1 + 4 => -tr 5
        
        Default = -tr 1 (ID 0)

  -tf [tranceiver frequencies]
        EU, AU, NZ or US
        Default = -tf EU

  -ex [extra loop_delay in ms]
        In case a lot of messages are missed we might try to use the -ex parameter, like -ex 200
        Note: A negative value will probably lead to message loss
        Default = -ex 0
 
  -fc [frequency correction in Hz for all channels]
        Default = -fc 0
        
  -ppm [frequency correction of rtl dongle in ppm]
        Default = -ppm 0
        
  -maxmissed [max missed-packets-in-a-row before new init]
        Normally you should set this parameter to 4 (-maxmissed 4). 
        During testing of new hardware it may be handy (for US equipment) to leave the default value of 51. 
        The program hops along all channels and present information about each individual channel. 
        Default = -maxmissed 51
        
  -u [log undefined signals]
        The program can pick up (i.e. receive) messages from undefined transmitters, e.g. from a weather 
        station near-by. De messages are discarded, but you may want to see on which channels they are 
        received and how many.
        Default = -u false

License

The source of this project is licensed under GPL v3.0. According to http://choosealicense.com/licenses/gpl-3.0/ you may:

Required:

• Disclose Source: Source code must be made available when distributing the software. In the case of LGPL and OSL 3.0, the source for the library (and not the entire program) must be made available.
• License and copyright notice: Include a copy of the license and copyright notice with the code.
• State Changes: Indicate significant changes made to the code.

Permitted:

• Commercial Use: This software and derivatives may be used for commercial purposes.
• Distribution: You may distribute this software.
• Modification: This software may be modified.
• Patent Use: This license provides an express grant of patent rights from the contributor to the recipient.
• Private Use: You may use and modify the software without distributing it.

Forbidden:

• Hold Liable: Software is provided without warranty and the software author/license owner cannot be held liable for damages.

Feedback

If you have any general questions or feedback leave a comment below. For bugs, feature suggestions and anything directly relating to the program itself, submit an issue.

Documentation

Overview

rtldavis, an rtl-sdr receiver for Davis Instruments weather stations. Copyright (C) 2015 Douglas Hall

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.

Modified by Luc Heijst
- March 2019
Added: Multi-channel hopping
Added: options  -ex, -u, -fc, -ppm, -gain, -tf, -tr, -maxmissed,
                -startfreq, -endfreq, -stepfreq
Removed: options -id, -v
- May 20120
v0.14:
Added:   handling of NZ frequencies
Changed: freqErrors are now stored for the right frequencies and transmitters
v0.15:
Added:   options -d, -v, -noafc; thanks to Steve Wormley for the code
Changed: detection of freqError; thanks to Steve Wormley for the code
Changed: hopping timing (changed receiveWindow from 10 to 300 ms)