Tuesday, April 3 2018

Setting up the Raspberry Zero W for the Wobbulator (1)

To start with, you need an image of the RPI operating system (Rasbian, based on Debian Linux). At the time of writing this blogpost, the actual version is Debian Stretch. Visit raspberrypi.org for the latest version.
Write the image on an empty micro SD card (4GB is big enough, bigger is OK, as small cards are harder to get nowadays). Instructions how to do this can be found on the Rasberrypi website. Since we don't want to hook up keyboard, mouse, monitor to the RPI, we have to use some tricks. First of all, we have to tell the RPI to accept SSH connections (explained further on) and instruct the RPI to automatically connect to your wifi network (Note: this is a prerequisite for this procedure, if you don't have this, please hook up keyboard, mouse and monitor).
Once this is done, you see two volumes in your PC that you have used to write the SD card (you might need to remove and re-instert the SD card in some cases). One is called Boot, and can be read, the other is unreadable by windows. By now, you probably have seen a pop-up asking you to format the volume. Of course you have to say no. In the root of the Boot volume, you have to create two new text files:

  • ssh
  • wpa_supplicant.conf

(make sure the names are exactly like this, the trailing .txt should be removed)

The ssh file should remain empty, the wpa_supplicant.conf should contain the following:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev


This example assume you are located in the Netherlands, and your wifi network's SSID is mywifinetwork, with passphrase 1234567890. You have to replace these values with your own country code and wifi network details (note: the quotes should remain)

Save the file and unmount the SD card. Insert in your RPI and power up.

If everything went according to plan, the RPI should now be connected to your wifi router. You have to check your routers homepage to find out how to reach it. It can be identified by the name raspberrypi. Note the IP address down.

You need an SSH client to be able to reach the RPI to set it up further. A good one is PuTTY. You can download it here:

PuTTY is very easy to use. You can start the program, and follow the help. But just as easy, use a cmd window and type the following command:

putty -ssh pi@raspberrypi
(you may need to change 'raspberrypi' with the name you will give it later on, or use the IP address)

You can also make a text file with this command, and name it ssh.bat (or some other name you fancy).

If everything is working, you will be presented with a text window, which asks you for the credentials of user 'pi'. By default, the password is 'raspberry'. Once logged in, you will be prompted to change the password. I recommend you to do this right away.
It is allways a good idea to update the software to the latest version. This is done by the following commands:
sudo apt-get update
sudo apt-get upgrade

You have to adjust some of the default settings now. This can be done by the program raspi-config. Type:
sudo raspi-config

You are presented with the following window: raspi-config_1.PNG
If you haven't changed your password, you can do it here. The other changes to be done are:

  1. Change the network name. Every RPI will by default be called raspberrypi. You may want to change it into a little bit more descriptive, e.g. wobbulator. You can change this with option 2: Network Options. Choose sub-option N1: Hostname to change this. raspi-config_2.PNG
  2. Boot options. You want your wobbulator to start with the graphical interface. Choose option 3: Boot Options. Choose submenu B1 Desktop/CLI and finally choose option B4 Desktop Autologin.raspi-config_3.PNG
  3. EnableVNC. To be able to take control of your wobbulator from remote, you need the VNC server to be switched on. You can do this through menu option 5. Interfacing Options. Select P3 VNC and enable it:raspi-config_4.PNG
  4. Expand filesystem. By default, the file system is as big as the image that has been downloaded. You want to use all the available memory on the SD card, so choose menu 7: Advanced Options, and then A1 Expand Filesystem.raspi-config_5.PNG
  5. Resolution. In the same menu, you can set a new default resolution. You can set it to match the resolution of the PC you will use to view the Wobbulator screen. Minimum size should be 1024x768, otherwise the wobbulator graphic window is not displayed completely, and you will not be able to control it, as the buttons are at the bottom of the window.

Monday, April 2 2018

A little side project


One of the things that is still unfinished business is the final amplifier and LPF. To be able to check and adjust the LPF, some measurement equipment would come in handy. I stumbled across the following project by Tom, MI0IOU:

Continue reading

Thursday, November 16 2017

More on the Raspberry PI

One of the last comments on the entry where I described the installation of quisk on the RPI was that it was up to the user if he/she wanted to add a nice desktop icon. The point is that I upgraded my RPI to model 3B, and therefore had to reconfigure the RPI with quisk from scratch. I followed my

Continue reading

Sunday, January 10 2016

A little bit of progress


Today I found some time to do a little soldering. I needed to add an audio amplifier to drive a speaker, so I don't need to use headphones all the time. This was not needed when I used computers as frontend, but now I have decided to use the Raspberry PI this became an issue. With the Raspberry, I

Continue reading

Saturday, January 2 2016

Raspberry Pi 2 with touch panel


I have purchased a touch panel for the RPI. This makes a very nice compact unit, and I am quite happy with it. I shot a short video, which can be seen HERE

Continue reading

Sunday, December 27 2015

Raspberry PI2 as coding/decoding computer hardware


The Raspberry PI2 (RPI2) is a very nice, small and powerful little computer. It is capable of doing all the DSP tasks to decode and code the audio signals to and from the SDR hardware. I managed to install QUISK on the RPI2 and it runs very nicely. I am thinking of adding a touch screen display, to

Continue reading

Saturday, April 25 2015

The control board


The construction of the control board is underway. It is mainly the Arduino Micro fitted on a prototyping PCB, with some additional hardware (switching transistors, resistors, etc.) and pin headers for connecting it to other parts of the transceiver later on. Here is a picture of the current state:

Continue reading

Monday, April 6 2015

The Sound card


One of the nice things of this setup is that it uses a soundcard embedded in the unit itself. First of all, it is a good idea to use an external soundcard. The soundcards usually found in laptops are not very good. I did some comparison between the laptop's internal card and this one, and it made a

Continue reading

Sunday, April 5 2015

Stage 4. The control electronics


The control electronics have to perform the following tasks: Decode the band data from the Lima SDR Switch the relays for the low pass filters for the various bands Measure the output power and VSWR, and protect against high VSWR Measure the temperature of the PA and control the fan Provide bias

Continue reading

Block diagram


Here is the block diagram of the complete system (click on it to enlarge):

Continue reading

Saturday, April 4 2015

Stage 3. Boxing it


The shopping list for the complete transceiver is quite long: Case - reused from the old power supply project Power supply - Meanwell switch mode module bought at a radio rally USB sound card - Behringer card, bought at a music store USB hub - found one lying around somewhere Controller & LCD -

Continue reading

Friday, April 3 2015

Stage 2: Working, and now what?


I built the kit according to the very well written (German) description. Since it describes tests during the various stages it is very easy to verify the correct working of the unit during the building process. In the end, it worked almost instantly. The biggest challenge was the software. I tried a

Continue reading

Thursday, April 2 2015

Stage 1. Building the unit


Back in 2010, there was no kit available, at least not in the Netherlands. You could order the PCB's directly with Bernd, and Reichelt in Germany did have a kit with all the electronics available. Unfortunately, at that time Reichelt would not deliver to the Netherlands. So I had to order all the

Continue reading

Tuesday, March 31 2015



This blog will show the progress of my Lima SDR project. For those of you who are not familiar with this kit, here is some background info. Lima SDR is a Software Defined Radio transceiver for the HF bands, designed by Bernd Wehner, DL9WB. It uses a sound card as radio interface to code and decode

Continue reading

Haut de page