Home of the Jodrell Bank WebSDR

Jodrell 1 WebSDR (Active)

Note this is not affiliated with Jodrell Bank in anyway, my QTH just happens to be very close to it.

Located 70m ASL and covers numerous bands: 20m, 80m, 60m, 4m, CB, Airband, Marine.

Jodrell 2 WebSDR (Active)

Note this is not affiliated with Jodrell Bank in anyway, my QTH just happens to be very close to it.

Located 70m ASL and covers numerous bands: 2m, 70cm, PMR446, 6m, Airband.

OpenWebRX WebSDR (Active)

This is my Openwebrx version using a single RTL dongle and colinear at 7.5m AGL. Lots of bands available.

Kiwi WebSDR (Active)

This is my Kiwi using a Wellbrook Loop at 4m heigh. 0-30MHz coverage

Server 1 setup

Building the Server 2 Receivers

Inside Server 1

Contains: SDRPlay RSP1A's, RTL dongles, Duplexer, splitter and preamp

Mains filter

(Everything is powered via this)

Mains filter build

(There is one for each server)

This site supports the Pocket RXTX App by Dan YO3GGX

Download the app here


General SDR Information (to help with setup):

SDR receivers:

-converter is needed as these rtl dongles only receive down to 25MHz themselves. The upconverter converts HF up to 125MHz for the RTL to pick up. (Like a transverter but for RX only)


I use a Dell Linux PC's running Ubuntu 18.04 and Linux Mint. Each PC has 6 available USB ports. It then has numerous terminal windows open which includes instances of RTL_TCP to control the RTL dongles and rsp_tcp to control the RSP1a devices. Finally another terminal is used for the WebSDR Web server software itself (dist11 ./websdr64) from PA3FWM (www.websdr.org)

Install Guide:

sudo apt-get update

sudo apt-get install rtl-sdr

sudo apt-get install git 

sudo apt-get install cmake 

sudo apt-get install build-essential 

sudo apt-get install libusb-1.0-0-dev 

git clone git://git.osmocom.org/rtl-sdr.git 

cd rtl-sdr/ 

mkdir build 

cd build 



sudo make install 

sudo ldconfig 

sudo cp ../rtl-sdr.rules /etc/udev/rules.d/ 

  sudo add-apt-repository ppa:linuxuprising/libpng12

sudo apt update

sudo apt install libpng12-0

sudo apt install libfftw3-3


LD_LIBRARY_PATH=. ./websdr64

A. Open your /etc/modprobe.d folder as root/administrator (right click). 

B. Create a new file 'blacklist-rtl.conf' and add this one line:   blacklist dvb_usb_rtl28xxu 

C. Save the file, close the editor and restart the machine. 

SDR Configuration Guide

Websdr.cfg file:

Setup of the WebSDR is done from a config file called 'websdr.cfg' in order to set the correct parameters such as start frequency, mode, sample rate (in this case 2048KHz to cover all of the desired band), RTL dongle input settings such as port number, and the IP address to listen for the SDR on. A separate entry for use with the up converter is called 'progfreq'. This needs to be set to the frequency of your upconverter plus the desired centre freq, so for a centre freq of 14100MHz, progfreq will be set to 139100. Here is an example band config (with and without upconverter):



band 2m

device !rtlsdr

samplerate 2048000

# Center frequency in kHz:

centerfreq 145000

initial 145500 FM

gain -34

# A short description of the antenna, for listing on websdr.org:

antenna (2m) SDRPlay RSP1A and Colinear + MH Preamp, 18m AGL

noiseblanker 50


band 20m

device !rtlsdr 5

samplerate 2048000

progfreq 139100

centerfreq 14100

initial 14100 usb

gain -40

antenna Half size G5RV horizontal at 9m AGL, Yaesu FF50 low pass filter. 

noiseblanker 80


The default IP/port number if the dongle is plugged into the same PC as your software is You then need the RTL_TCP software on this PC in order for the webserver to talk to it. You'll use different terminal windows for each TCP server (1 per dongle) and a different one again for the Websdr server. I have 7 open! First start the individual TCP servers by typing 'rtl_tcp followed by device number, IP address and finally port number. e.g:

rtl_tcp -d0 -a -p 1234. (There are spaces between each parameter). 

Device number will change each time you restart the PC or unplug more than one dongle. If you have numerous dongles, you will need to assign them different serial numbers to help you determine which belongs to which device number. This is done using rtl_eeprom software (install this software if not done already:

sudo apt-get update

sudo apt-get install rtl-sdr 

Then insert a dongle and type (to change serial)

rtl_eeprom -s 00000001

To adjust gain of the RTL_SDR dongle simply add the -g parameter to your start string (any parameters left out will default to auto settings):

rtl_tcp -d0 -a -g 15 -p 1234

This will set the gain to 15db. You will need to experiment with figures for your station noise floor etc. This gain is changing the receive sensitivity of the dongle and is not related to the gain in the websdr.cfg file. If the waterfall colour is altered too much by the gain adjustment you can adjust it using the gain setting in the websdr cfg file mentioned above (which changes the colour of waterfall and s meter calibration).

If your PC is suffering with high CPU load, try changing the buffering settings of the dongle by adding these commands into your string:

rtl_tcp -d0 -a -g 15 -b 3 -n 1000 -p 1234

For the next dongle, in a new terminal window, type the same but use a different port (1235, etc...). If these fail try going the other way (1233, 1232 etc).

Once you've started the tcp for each device and it has found your devices and is listening, in a new terminal window you need to now start the websdr server. Navigate to the correct folder (where your WebsSDR Dist11 software is located) using the CD command then type ./websdr64 to run it:

cd websdr

cd dist11


the service should start and it should say (there may be some warning at the bottom you can ignore):

planning FFT's for band 0...done

planning FFT's for band 1...done

planning FFT's for band 2...done

Writing frequency axis images

Server is now running.

Labelling Terminal Windows

Since there are so many windows open, you can label them to make it easier to know which is used for which device.

open the ./bashrc file with your favourite editor:

sudo nano /.bashrc

add this function into the bottom of it and save:

function settitle(){

 if [ -z "$PS1_BACK" ];  # set backup if it is empty







Now, in your terminal window to use this function you need to first add source, then you can use the function:

source /.bashrc

settitle 2m RTL Dongle

Do the above two commands for each terminal window when you start it

Increasing USB buffer size

If you are running quite a lot of USB devices (say 5 or more) you may need to increase the usb buffer size in order to allow the SDR to work or you will get an error when starting one of the rtl tcp servers. In a terminal type:

sudo sh -c 'echo 128 > /sys/module/usbcore/parameters/usbfs_memory_mb'

enter your admin password at prompt.

Then to test your new value has been received (128mb in this case) type:

cat /sys/module/usbcore/parameters/usbfs_memory_mb

Trouble shooting

Problems with Server stopping itself?

This can happen after a 'apt-get upgrade' (it did for me and caused massive headaches!) 

netstat -nta | egrep "state|8901"

This brings up a list of tcp connections. Check everything looks ok. You shouldn't see anything other than 0 (zero) in the RECV-Q column or any CLOSE WAIT's in the state column. If you do see other than zero's it may be due to just a poor connection and may clear, or as someone first connects.

see here for more info: 


       type: sudo nano /etc/sysctl.conf

scroll to the bottom of the config file and add the following entries:

kernel.printk = 4 4 1 7

kernel.panic = 10

kernel.sysrq = 0

kernel.shmmax = 4294967296

kernel.shmall = 4194304

kernel.core_uses_pid = 1

kernel.msgmnb = 65536

kernel.msgmax = 65536

vm.swappiness = 20

vm.dirty_ratio = 80

vm.dirty_background_ratio = 5

fs.file-max = 2097152

net.core.netdev_max_backlog = 262144

net.core.rmem_default = 31457280

net.core.rmem_max = 67108864

net.core.wmem_default = 31457280

net.core.wmem_max = 67108864

net.core.somaxconn = 65535

net.core.optmem_max = 25165824

net.ipv4.neigh.default.gc_thresh1 = 4096

net.ipv4.neigh.default.gc_thresh2 = 8192

net.ipv4.neigh.default.gc_thresh3 = 16384

net.ipv4.neigh.default.gc_interval = 5

net.ipv4.neigh.default.gc_stale_time = 120

net.netfilter.nf_conntrack_max = 10000000

net.netfilter.nf_conntrack_tcp_loose = 0

net.netfilter.nf_conntrack_tcp_timeout_established = 1800

net.netfilter.nf_conntrack_tcp_timeout_close = 10

net.netfilter.nf_conntrack_tcp_timeout_close_wait = 10

net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 20

net.netfilter.nf_conntrack_tcp_timeout_last_ack = 20

net.netfilter.nf_conntrack_tcp_timeout_syn_recv = 20

net.netfilter.nf_conntrack_tcp_timeout_syn_sent = 20

net.netfilter.nf_conntrack_tcp_timeout_time_wait = 10

net.ipv4.tcp_slow_start_after_idle = 0

net.ipv4.ip_local_port_range = 1024 65000

net.ipv4.ip_no_pmtu_disc = 1

net.ipv4.route.flush = 1

net.ipv4.route.max_size = 8048576

net.ipv4.icmp_echo_ignore_broadcasts = 1

net.ipv4.icmp_ignore_bogus_error_responses = 1

net.ipv4.tcp_congestion_control = htcp

net.ipv4.tcp_mem = 65536 131072 262144

net.ipv4.udp_mem = 65536 131072 262144

net.ipv4.tcp_rmem = 4096 87380 33554432

net.ipv4.udp_rmem_min = 16384

net.ipv4.tcp_wmem = 4096 87380 33554432

net.ipv4.udp_wmem_min = 16384

net.ipv4.tcp_max_tw_buckets = 1440000

net.ipv4.tcp_tw_recycle = 0

net.ipv4.tcp_tw_reuse = 1

net.ipv4.tcp_max_orphans = 400000

net.ipv4.tcp_window_scaling = 1

net.ipv4.tcp_rfc1337 = 1

net.ipv4.tcp_syncookies = 1

net.ipv4.tcp_synack_retries = 1

net.ipv4.tcp_syn_retries = 2

net.ipv4.tcp_max_syn_backlog = 16384

net.ipv4.tcp_timestamps = 1

net.ipv4.tcp_sack = 1

net.ipv4.tcp_fack = 1

net.ipv4.tcp_ecn = 2

net.ipv4.tcp_fin_timeout = 10

net.ipv4.tcp_keepalive_time = 600

net.ipv4.tcp_keepalive_intvl = 60

net.ipv4.tcp_keepalive_probes = 10

net.ipv4.tcp_no_metrics_save = 1

net.ipv4.ip_forward = 0

net.ipv4.conf.all.accept_redirects = 0

net.ipv4.conf.all.send_redirects = 0

net.ipv4.conf.all.accept_source_route = 0

net.ipv4.conf.all.rp_filter = 1

net.ipv4.ip_nonlocal_bind = 1

use CTL+x to exit the editor and click yes to save

Then type sudo sysctl -p to activate the above parameters

No need to reboot. This should activate the parameters

To return to default, simply remove these new parameters, save the config then reboot.


Copy your Websdr folder to a root folder such as /opt

become a root user with command sudo su

then start as normal...

cd to websdr folder: 

cd opt

cd websdr

cd dist11


to view current status type:

sudo aa-status

To disable:

sudo systemctl stop apparmor

        sudo systemctl disable apparmor


        To reload all services:

        sudo service apparmor reload

net.ipv4.tcp_fin_timeout = 30

net.ipv4.tcp_max_syn_backlog = 32000

Block a rogue IP address

To block a suspect IP address from accessing the server (Input), open a terminal window and type:

    sudo iptables -I INPUT -s xxx.xxx.xxx.xxx -j DROP

       Where xxx is the rogue IP address

       then save so that it stays in place after a reboot:

       sudo service iptables save

       Verify the new rule by:

       sudo iptables -L 

Router port forwarding

Your home router will need port forwarding to allow the WebSDR server to send and receive over the internet. The default port for this is 8901, so this needs forwarding to the IP address of your Websdr server PC on your local network. Only problem with this is if your server PC is set to DHCP, your router when rebooted will assign a different IP addresses each time if you've not set a static address, meaning you’d need to adjust the Websdr config file again. You can tell the router to reserve an IP for a particular PC (using its MAC address) as a workaround, or manually set a static address. Also If you don’t have a static WAN IP (i.e the one issued by your internet service provider (ISP), then your main WAN IP may change. This has never happened to me though.

Waterfall display labels

If you want to add labels to the waterfall display, create a text file called 'stationinfo.txt' and save it into the Websdr cfg folder. Within this text file simply write the frequency, mode and label of the frequency you want, e.g:

145500fm 2m Call

add each label to a new line.

I am constantly tweaking the settings to try and improve the system and add functionality, but feel free to let me know any ideas or tips.

Note: RTL-SDR’s have a small dynamic range, so stronger signals can break through into other frequencies in that band, this happens on my station unfortunately. This can be reduced by use of band filters or by experimenting with the gain settings as described above.


These are better receivers than the RTL dongles which include built in filters. They are more expensive but have much better RX performance. To get them working you need the RSP_TCP driver from Bas, ON5HB (available on git hub) which emulates as an RTL SDR to work with the Websdr.org software. and also the linux hw/API from sdrplay. Once installed allows some extra features such as Notch filters and AGC control which is useful for removing ghosting.

How to install RSP_TCP to a linux machine: 

First update the linux package. In a terminal window type 

sudo apt-get update 


sudo apt-get upgrade

Then go to the SDRPlay website downloads page https://www.sdrplay.com/downloads/ and download the Linux 3.07.1 API. Once downloaded go back to terminal

cd to the folder you downloaded the file into (probably 'Downloads')

cd Downloads

Once in the downloads folder:

sudo chmod +x ./SDRplay_RSP_API-Linux-3.07.1.run

This makes the file executable, Then to run the file:


Accept the licence agreement, it should then install.

go back to home directory:


Install necessary tools:

sudo apt-get install git

sudo apt-get install cmake

sudo apt-get install build-essential

sudo apt-get install libusb-1.0-0-dev

If these already exist this will update them

Next we download and install the rsp_tcp.c from  ON5HB's github:

git clone https://github.com/ON5HB/rsp_tcp

cd rsp_tcp/

mkdir build

cd build

cmake ..


sudo make install

It should now be installed and ready to run. Simply connect your RSP1A then in a new terminal window to start it with default settings type:


The above command will adjust the RSP1A  AGC settings automatically using Bas's driver settings, but if you aren't happy with performance and want to start it with different settings use the list below. These settings need tweaking for your own WebSDR.

Full list of startup options here (Bas's latest driver):

-a Listen address (default:

-p Listen port (default: 1234)

-d RSP device to use (default: 1, first found)

-P Antenna Port select (0/1/2, default: 0, Port A)

-r Gain reduction (default: 40  / values 20-59) - Not set in websdr.cfg see tips

-l LNA attenuator level about -6dB each step (default: 0 / values 0-9) - See tips below

-T Bias-T enable* (default: disabled)

-f Frequency to tune center in Hertz (default: 1000000 = 1MHz) - If freq set centerfreq and progfreq are     ignored! - Normally set in websdr.cfg

-s Samplerate in samples-per-second (default: 2048000) - If sample rate is set it will be ignored from client! - Normally set in websdr.cfg

-W Wideband-pass-filter mode (default: 2 / values: 0 small (trims off each edge of the band) / 1 wide (full sample rate width) / 2 = optimised) 

-D DAB band-reject-filter* (default: enabled)

-B MW band-reject-filter* (default: enabled)

-R Refclk output* (default: disabled)

-E Edge-steep-filter enable* (default: disabled) - Beware CPU load could go high!

-A Auto Gain Control setpoint (default: -30 / values -1 to -69 / other disabled)

-G Auto Gain Control speed in Hz (default: 100 / values 0/5/50/100) - Sets overloading adjustment-speed

-n Max number of linked list buffers to keep (default: 512)

-v Verbose output (debug) enable* (default: disabled)

* Marked options are switches they toggle on/off

Tip1 - start with -l 0 level correction first, if too much signal try -l 1, -l 2 etc, most simple way start receiving correctly

Tip2 - websdr.cfg gain setting is cosmetic only, it does not impact the receivers performance!

Tip3 - if you have ghost-signals, set wideband-pass to small as it's probably too wide, mostly happens on HF!

RTL_TCP options:

-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)

I hope this helps others to get set up. Its taken me lots of time and effort to get it working. Many thanks to Bas, ON5HB for his help and excellent work with this driver which is optimised for use in websdr.org.

Please feel free to donate if you would like to help improve this Websdr service which is a free service available for anyone to use. Happy listening!