Posts

Interactive visualisation of pskreporter logs using python

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As promised in my previous post , here is a fun little code snippet to visualise logs obtained from pskreporter. Obviously the first step is to obtain logs from pskreporter, using the URL shown below. Needless to say, you have to replace my callsign (VK6JN) with yours. https://pskreporter.info/cgi-bin/pskdata.pl?callsign=VK6JN After unzipping the downloaded zip file, we obtain a psk_data.csv file that contains all the information we need. In the following gist, I demonstrate a simple code to visualise those data in an interactive world map that can be viewed in a web browser. Replace the appropriate fields (callsign, locator etc.), run the python code and you shall obtain a web interface with the reports as shown in Fig.1, where the paths have been colour coded with the reported SNR. Clicking on the pins, you will also get the callsign of the RX station. This code can be modified to analyse WSPR logs as well. Fig.1. A screenshot of the resulting webpage. Hope this is helpful ! 73, V...

Testing an Aliexpress 5.6m telescopic HF vertical antenna

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I've been searching for an easy to deploy HF vertical for quite some time. Although I have a SOTABEAMS 20/40 linked dipole, it is cumbersome to deploy, with the end result being almost always a rat's nest of wires. My MFJ1899T loaded vertical, although convenient, is after all a compromise antenna. My search led me to this antenna , something that costs about 50AUD, shipping included. For such a low price, one cannot be wrong ! I promptly purchased it and left it in my car boot. On January 27th 2025 evening, I finally decided to test it. I loaded my car with QDX and FT817ND along with a few accessories, and drove to South Perth foreshore. The location is perfect to test a vertical antenna, and also has the same gridsquare as my QTH. Also proximity to Swan river may improve the performance of a vertical antenna. From "touchdown" to key up, it took me about 10 minutes, of which a substantial amount of time was spent fixing a broken Anderson power pole contact. I chose 2...

Bias tee modification of HiLetgo RF amplifiers

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Hi folks, There are some inexpensive RF amplifiers available in the hobby market by various names. They may be called LNAs, if you consider 3 dB noise figure as low noise. I purchased two of them from Amazon from a seller called HiLetgo. However documentation is sparse and the design is not all that great. People have had frustrating experiences with this type of LNA. Information regarding power supply to this board is practically non-existent, with voltage suggestions ranging from 5V to 12V ! Some even obtained the "magic smoke". Nonetheless they are reasonably cheap and therefore modifications can be done to make them useful. Let us now take a closer look at the board. Figure 1. The amplifier without any modification. Fig.1 shows the board without any modification. There are two SMA connectors and provision to externally power the board. The active element is an MMIC, with N02 as the marking. Other users have identified the MMIC as INA-02184 from HP. It seems to m...

Digital modes with VUSDR and Quisk

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Hello all, VUSDR is a popular TxRx SDR in India. Inspired by Peaberry SDR, it can also be used in Linux machines with Quisk as the software. In this post, I won't go into the details of configuring Quisk for normal SDR. Instead, assuming that it is already done, I shall go into the details of configuring it for digital modes especially configuring for WSJT-X for Ubuntu 16.04. As for normal Quisk configuration, I might blog about it in future. A word of caution ! These steps worked for me, but I cannot guarantee that they will work for you. So let's get started ! First download and install WSJTX from the following link. https://physics.princeton.edu/pulsar/k1jt/wsjtx.html You can double click and install the .deb file or can use terminal to install. I used the following command to install it (remember to open a terminal and navigate to the folder where the .deb file is present before typing this command) sudo apt install ./wsjtx_1.8.0_amd64.deb Next step is to in...

Using FTDI USB to serial converter in Linux - Ubuntu

I recently purchased an FTDI USB to serial converter - FT232RL. However I could not use it properly in Windows. With some googling, I could find a way to use it under linux. Following are the steps to be used in Ubuntu to get it working. Open a terminal and type the following commands. sudo modprobe ftdi_sio sudo chmod 666 /sys/bus/usb-serial/drivers/ftdi_sio/new_id nano /sys/bus/usb-serial/drivers/ftdi_sio/new_id In the file that got opened, type 0403 8a8a and save it. The number can be found by typing lsusb in another terminal. Now unplug and re-plug the module. Type  ls /dev and you should see /ttyUSB0 in the list. Now use some serial terminal (like screen) to view the data ! For opening a screen session, the following command is used. Here 115200 is the baud rate. sudo screen /dev/ttyUSB0 115200

A simple guide to installing and using RTL-SDR and related software in Ubuntu

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Hello all ! In this post , let me help you install and use RTL-SDR and related software in Linux , specifically Ubuntu . The software being installed are  GNUradio and GQRX . GQRX I have tried this procedure in several systems running Ubuntu 14.04 LTS as well as Mint OS ( which is based on Ubuntu ) . The procedure assumes that you have access to root password and knows basics of Linux terminal. Moreover you need a working internet connection. If you don't know how to use the terminal , then please watch some youtube videos on the same . So let's start ! Step 0 Install Ubuntu ! This is the right decision that you can make . Linux is ideal for developers and hackers ( I mean hackers like Richard Stallman and not crackers ) . Step 1 Open a linux terminal ( Ctrl+Alt+T) and type the following command sudo apt-get update You will be prompted for the password . Give it . It won't be shown on the screen . This will update your Ubuntu installation and install th...

Some experiments with double balanced mixers and GNURadio

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Hi all, This post is all about frequency mixing , specifically double balanced mixers using diodes or ring mixers , commonly used in communication circuits . The circuit diagram of a ring mixer is given below . (Courtesy : Radio-electronics  ) Schematic of a double balanced mixer.  As you can see , this makes use of two transformers and a four diodes . For most of the HF work , switching diodes like 1N4148 suffice . However , for better performance Schottky diodes like 1N5711 can be made use of . For more information on the working of this mixer and construction aspects , I strongly recommend the excellent video by W2AEW on ring mixers given below .  So what I wish to explain in this video is a set of experiments carried out using a double balanced mixer which I shall call DB mixer for convenience :) The test gear consists of a DDS VFO , a crystal Colpitts oscillator , a variable  power supply , CRO , RTL-SDR and the PC sound card . The software tool...