Remote SDRs – update

This is short update on my post about seting up the Multiband WEB SDR with remote receivers:

The update is based on Armbian, Linux for ARM development boards. First download and write image (CLI) for your preffered board. After first boot, enter default credentials for Armbian (root/1234) and follow some basic setup:

create new password
select bash (1)
enter your new username
create pass for new user
enter real name
Set user language based on your location? Yes

Now enter following commands:

apt update
sudo apt install soapyremote-server
sudo apt install soapysdr-tools
sudo apt install rtl-sdr
sudo apt-get install soapysdr-module-rtlsdr

edit the file /etc/modprobe.d/blacklist.conf and add following lines:

sudo nano /etc/modprobe.d/blacklist.conf 
blacklist dvb_usb_rtl28xxu
blacklist rtl2832
blacklist rtl2830

reboot with


Now plug RTL SDR (could be more than one) and check if everything works with:

SoapySDRUtil --probe="driver=rtlsdr"

The output should be something like this:

Soapy SDR -- the SDR abstraction library
Probe device driver=rtlsdr
Found Rafael Micro R820T tuner
Found Rafael Micro R820T tuner

-- Device identification

-- Peripheral summary
Channels: 1 Rx, 0 Tx
Timestamps: NO
Other Settings:
* Direct Sampling - RTL-SDR Direct Sampling Mode
[key=direct_samp, default=0, type=string, options=(0, 1, 2)]
* Offset Tune - RTL-SDR Offset Tuning Mode
[key=offset_tune, default=false, type=bool]
* I/Q Swap - RTL-SDR I/Q Swap Mode
[key=iq_swap, default=false, type=bool]
* Digital AGC - RTL-SDR digital AGC Mode
[key=digital_agc, default=false, type=bool]

-- RX Channel 0
Full-duplex: YES
Supports AGC: YES
Stream formats: CS8, CS16, CF32
Native format: CS8 [full-scale=128]
Stream args:
* Buffer Size - Number of bytes per buffer, multiples of 512 only.
[key=bufflen, units=bytes, default=262144, type=int]
* Ring buffers - Number of buffers in the ring.
[key=buffers, units=buffers, default=15, type=int]
* Async buffers - Number of async usb buffers (advanced).
[key=asyncBuffs, units=buffers, default=0, type=int]
Antennas: RX
Full gain range: [0, 49.6] dB
TUNER gain range: [0, 49.6] dB
Full freq range: [23.999, 1764] MHz
RF freq range: [24, 1764] MHz
CORR freq range: [-0.001, 0.001] MHz
Sample rates: 0.25, 1.024, 1.536, 1.792, 1.92, 2.048, 2.16, 2.56, 2.88, 3.2 MSps

Finally, use rtl_eeprom to change serial numbers and add newly created receivers to your WEB SDR.

Optionally: add firewall rule for the Soapy remote:

ufw allow 55132

1 to 4 power splitter

This is small module for splitting 1 signal to 4 receivers. It is part of the multiband SDR receiver, but it can be used standalone for any similar application.

Finished splitter with four SMA connectors
Continue reading ‘1 to 4 power splitter’ »

Multiband SDR with remote receivers

In past I assembled small SDR receiver based on Raspberry Pi and SDR USB dongle based on software developed by PA3FWM. The problem was with limited usability by multiple clients connected to the Raspberry pi at the same time. The old SDR was retired and put aside for few years.

Then András Retzler ha7ilm developed (and stopped developing) OpenWebRx, which was the base for now regulry maintained and further developed

I recently built homelab server based on “proper” server infrastructure with plenty of RAM and lots of processing cores. I decided to setup OpenWebRx in one linux virtual machine with raspberry pi only as remote receivers serving single user (server itself).

Continue reading ‘Multiband SDR with remote receivers’ »

GoPro Session 3D printed housing

I broke the original housing for GoPro Session (the smallest GoPro). Then I designed more bulky one, suitable for 3D printing.

Here is the OnShape project.

and 3D printed part…

Please send email for STL files.

Final version with holder for quick release gooseneck:


Yaesu FT-991A Frontend has nasty hidden fault. It is not normal from €1000 radio to stop working just because you use it in a pileup situation or when your close OM is beaming toward you with QRO.

New, out-of-the box radio receive performance of the FT-991(A) was normal, but after other station(s) had transmitted at a higher power levels, the FT-991(A) receiver failed. The failure mode was as follows:

  • Receiver operation is normal when the Attenuator feature is disabled.
  • Receiver operation fails (no receive and a very quiet noise-floor) when the Attenuator feature is enabled.
  • IPO operation enables the Attenuator and results in the same receiver failure mentioned immediately above.

Same issues are reported elsewhere:

Patient with exactly the same simptoms got to the operation table in my lab today. The owner is OM S52W, very successfull contester and member of the famous contest club.

Continue reading ‘FT991 IPO/ATT FAULT’ »

Multi-Service Flight Tracker

(Photo by Dan Gitwood/Getty Images)

There are many flight tracking services around the web and most of them are based on ADS-B receivers placed by individuals. Few months ago I put together simple GP antenna, RTL-SDR and installed Pi-Aware software. It fed data to FlightAware. Soon after one of my mod-school friends asked if I could do the same for FLightRadar24. After some search I found this github repo: Balena ADS-B Multi-Service Flight Tracker. I had good experience with balena (for LoRa gateways) and followed the really excellent step-by-step instructons. Below are some details about my installation of this Multi-Service Flight Tracker.

The plane tracker is now feeding online (with short outages) since August 2019.

Here are links:

Continue reading ‘Multi-Service Flight Tracker’ »

Tiny cable tester for UTP and other cables

I developed simple cable tester. The complete project is in my GitHUB repository:

This is simple cable testing tool for checking your cables (e.g. ethernet patch cables or house installation). Complete tester consists of two modules and tested cable. Master (left) module is on the left. It is connected to the power supply (battery or wall adapter). Slave (right) is passive and has only LEDs.

Cable tester

Outdoor housing for Telraam Traffic counting camera

I recently found interesting project It’s an open source project where a Raspberry Pi with camera counts traffic passing by (pedestrians, bicycles, cars and other heavy vehicles). The device is (as stated by authorts) “mounted on the inside of an upper-floor window with a view over the street. To send the traffic count data straight to the central database, the device needs a continuous Wi-Fi connection to the internet.”
I placed one in my home on the window and it started counting some day after installation.

Next I wanted to install one in my remote location, where I have internet for other IoT purposes. There is no “upper-floor window”, which means I should place my raspberry and camera outside. Here is how I did it…

Continue reading ‘Outdoor housing for Telraam Traffic counting camera’ »

Convert TTIG to TTOG

I bought used outdoor WiFi access point for couple of coffees. At first I wanted to use only the housing for conversion of the TTN Indoor gateway to outdoor gateway. But after some testing and factory reset of the AP I found out it is working and could be configured as stand-alone WiFi MIMO AP. Usually such APs require infrastructure, or at least some management server.

Aruba networks AP175
Continue reading ‘Convert TTIG to TTOG’ »

How to Integrate LoRa sensor to Weather Underground

This is short tutorial how to send data from sensor connected to The Things Network via LoRaWAN to Weather Underground. I will use Scidrom air quality sensor whic I developed for students in local school. Just a quick reminder the “AQ” sensor detects PM10, PM2,5 particles, air pressure, temperature and humidity and solar radiation in visible in UV spectrum. More details are available in older post.

Read mor