Archive for the ‘Ham’ Category.

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’ »


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:

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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
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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.

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5GHz “WiFi” Grid antenna test

“Special offer” came out for 5GHz antenna. It was posted on Polish web store Interprojekt, where I sometimes buy some equipment for long range WiFi point-to-point links.

Gold WiFi grid antenna, price 13 EUR

The antenna came well packed in carton with additional box for the feed. The grids were separated with paper to avoid scratches during transport.

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Outdoor UV index sensor

Here are instructions for outdoor UV index and ambient light sensor.

Assembled UV index and ambient light sensor
Continue reading ‘Outdoor UV index sensor’ »

Low cost solar radiation shield

The solar radiation shield is a low cost DIY device to protect temperature, relative humidity and other sensors from the weather, while shielding them from the sun for highest accuracy. Provided here are instructions and files. It require some CNC machinig, but then it could be assembled in minutes. It is made from plant pot saucers.

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