Dear OMs,
As you know, the DVB-T Receiver 820T2 can be physically modified and be able to receives low ham radio frequencies (f.ex. 1.8 – 14MHz). This is what I’m talking about :
Everything looks fine in case of Windows, but in case of Linux system and rtl_tcp service, some issue can occure.
Here you can find the youtube movie about RTL-SDR driver installation within Linux environment:
Here you can also find a short but very usefull briefly description:
installing-rtl-sdr-rtl2832u-driver
I modified the source code and equipped it with the “-i” parameter, which allow you to point out the “I” or “Q” channel of your dongle when the “rtl_tcp” deamon is started.
What is more, I also added a possibility to change the AGC mode( -c option), which is turned on by default. In case of any WebSDR, enabling the AGC could leads to unexpectable muting of weaker stations.
How to implement it? I would recommend the procedure from the link above with step 5 to be modified as following:
git clone git://git.osmocom.org/rtl-sdr.git
cd rtl-sdr/
mkdir build
cd build
{now here is the trick: please replace the
rtl-sdr/src/rtl_tcp.c with a file downloaded and unpacked
from archive available on the bottom of this site}
cmake ../ -DINSTALL_UDEV_RULES=ON
make
sudo make install
sudo ldconfig
sudo cp ../rtl-sdr.rules /etc/udev/rules.d/
When these steps are done you will be able to see the additional options within the rtl_tcp deamon(you can chek it out by typing rtl_tcp –help command:
rtl_tcp, an I/Q spectrum server for RTL2832 based DVB-T receivers
Modified by Jakub/SP5TOF on 07.02.2017 for direct sampling support
Usage: [-a listen address]
[-p listen port (default: 1234)]
[-f frequency to tune to [Hz]]
[-g gain (default: 0 for auto)]
[-s samplerate in Hz (default: 2048000 Hz)]
[-b number of buffers (default: 32, set by library)]
[-n max number of linked list buffers to keep (default: 500)]
[-d device index (default: 0)]
[-P ppm_error (default: 0)]
[-i direct sampling(1: I-ADC input enabled), 2: Q-ADC input enabled)]
[-c AGC Mode(1: ON, 0: OFF), default: 1(ON)
Example:
rtl_tcp -i 1 -c 0 -g 49.6
By typing the command above, you will be able to launch the rtl_tcp deamon with support of hardware mod for direct sampling(the RF input can be directly connected to the I pad on the dongle’s PCB).
PLEASE BE AWARE THAT IT WORKS ONLY WITH RTL-SDR-0.5.3 DRIVER!
In case of any further driver releases comes from GIT, provided file will has to be rewritten!
Please find the file : rtl_tcp
Jakub/SP5TOF