RC On a Budget

And by budget, I mean cheap and cheerful. Most people that are into the hobby will tell you it can’t be done cheep, well not as cheap as we’re talking. They’ll tell you that at these prices all you can get yourself are kids toys, but what’s wrong with kids toys? It doesn’t stop them from counting as RC models does it? I go from flying my hundreds, if not thousands of pounds worth or model planes and heli’s to chucking one of these £60 machines around the air and honestly, most of the time I have more fun messing around with the little machines. But what are these mystery machines? There are two that I’m going to write about today. The Parkzone Mini Vapor, and the Hubsan X4. Lets start with the Vapor. Image This little beast will set you back a mere £60. And that’s with everything, model, transmitter, battery and charger! And believe me, it’s worth every penny!   After spending a whole day flying both the Vapor and the Hubsan around in my gliding club hanger, aswell as the clubhouse I can confidently tell you this docile little machine really is brilliant. It flies around almost silently, and very slowly. Performing gradual sweeping turns or tight spirals. Altitude adjustments are easy as it has plenty of power and elevator control. and best of all, it’s really easy to fly! Perfect for someone who has never flown before.   Out of the box all you have to do is insert the batteries into the included controller and battery charger, then charge the flight battery which only takes half an hour or so and gives you nearly 10 mins of flight time! Once the battery is charged its very simple to plug-in, and affix to the bottom of the model using Velcro. Now you’re ready to take to the skies! Half throttle will get you easily off the ground or any reasonably sized table, and this thing will just potter around gracefully. Landings just as easy too as its impossible to get this thing to stall. Now the Hubsan X4! Hubsan X4   Wow, Just Wow! I’m used to flying Quads around that are 10 times the size, and more than 10 times the cost and this thing is just better! Yes its only a “toy”, and no it can’t carry a big fancy camera and any of that stuff, but I just want one! And I want all of my friends to get one too so we can all go fly these around. Now Quadrocopters are usually rather tricky to fly, one of the main issues being the orientation of the aircraft, but these things are easy, so easy. You do of course still get the orientation problems, but all you have to do is spin the thing back round, or let go of the sticks entirely as this things on board brain is fantastic. It keeps the thing dead level, even in a rather stong breeze (of course we had to test it in more than “a breeze” and it coped amazingly well). Almost anyone can pick up the controls for the Hubsan in almost any sized space and be flying one of these around like a pro. It has 3 built-in flight modes, beginner, advanced and aerobatic. Yes you read that right, this thing will do flips! For a measly £30 you get the model, a battery, the controller and a USB battery charger. Additional batteries are easily available for a very low-cost as well as other spare parts for when you eventually break a propeller, which is nice.   I can do nothing but praise these two models, and i think anyone would be happy with either of them, or both! perfect for beginners and the wizened pros alike, these just give you a break from the hustle and bustle to just mess around with a few toys again. Now to stop boring you with words and show you a few photos! IMG_6545 IMG_6572      IMG_6808 IMG_6805

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Raspbery Jam & SDR

Inspired by a talk on Software Defined Radio (SDR) during a TinkerSoc night, and motivated by the rocketing number of hits the society’s website after their blog post about SDR was featured on Hack-A-Day. I decided to try it out for myself!

SDR works due to the RTL2832 chipset which has a very wide frequency receiver range. This chipset is used in a lot of the USB TV tuners out there, however not all of them. A list has been compiled on the Osmocom.org website where they also have a huge amount of information about SDR.

Having brought myself a USB TV Tuner off Amazon for £14 and free shipping it is clear that this is a really inexpensive way to get into amateur radio.

P1000558

The USB Tuner arrived at my house at university on the day of the fifth Raspberry Pi Jam, it seemed like an ideal opportunity to combine the two interests.

Having learnt a little bit about the different programs available during the talk at TinkerSoc, I decided to use rt-_tcp a lightweight piece of software that has the RTL (Realtek) drivers.

RTL-tcp is a sub program of RTL-sdr which is a command line interface program for controlling the TV tuner. By using RTL-tcp you are setting up a server which you can then connect to and stream the data from the Raspberry Pi to your computer. The benefit of this is that your antenna can be high up outside in the cold, meanwhile you are inside, nice and cosy.

Arriving at the Raspberry Jam I immediately set myself up with a my RPi connected to all the peripherals like the monitor and keyboard, as well as connecting it to my laptop over an Ethernet cable and I bridged the LAN to my wireless connection in order to install the software.

I was fortunate that two gents were very kind as to start helping me, teaching me my way around the command line and explaining the function of programs like aptitude and git.

Referencing a guide on hamradioscience.com I started to set up my RPi with all the software I needed.

To start with I checked that all dependencies were installed. There are programs that RTL-SDR and -TCP will need in order to work correctly. To check and/or install these dependencies I had to use the sudo apt-get install function and then install git, cmake, libusb-1.0-0.dev and build-essential.

sudo apt-get install git 
sudo apt-get install cmake
sudo apt-get install libusb-1.0-0.dev
sudo apt-get install build-essential

The next step was to download RTL-sdr and install the drivers.

git clone git://git.osmocom.org/rtl-sdr.git
cd rtl-sdr/
mkdir build
cd build
cmake ../
make
sudo make install
sudo ldconfig

The final step is to copy the rules file (rtl-sdr.rules) which can be found at /home/pi/rtl-sdr and this file should be copied into etc/udev/rules.d .

P1000557

Once the rules are in place you need to plug in the TV tuner and then you are ready to test that everything is working correctly by using the command rtl_test -t.

rtl_test

If everything is working all right, as it is in the picture above, then it is time to start the server and then set up your listening station.

To start the server type rtl_tcp -a followed by the ip address of your Pi. The ip address can be found by typing ifconfig into the command line, the ip address is the set of 4 numbers in the eth0 section. next to the lable “inet addr”.

SDR Sharp is a program written in C# that claims to be high performance with design in mind. It is also the program I decided to use with rtl-tcp.

To set SDR Sharp up with the raspberry pi, RTL-SDR / TCP must be selected from the drop down list, and then click configure.

sdrsharp1

The Raspberry Pi’s ip address should be entered into the host cell, and in the Port cell is the default value that doesn’t need to be changed. Volume can be adjusted using the RF Gain slider if you want a more permanent higher volume.

sdrsharp2When you have finished configuring, just press play. If all has gone well, then you will see the waterfall of data start to fall down the screen and hopefully hear something.  In all likely hood you won’t hear anything straight away, so you will want to change the frequency, you can do this by clicking on the top or bottom of the numbers representing the frequency at the top pf the screen, or by clicking along the activity bar.

Happy listening.

————– UPDATE ————–

April 2014

So after not using SDR for over a year I have set up my Pi to listen to the airwaves again. This was sparked by a comment below asking for help.
I followed my own walk-through and encountered the same issues as Ryan had encountered.

I managed to resolve these by adding “blacklist dvb_usb_rtl28xxu” to the file
/etc/modprobe.d/raspi-blacklist.conf by entering

sudo nano /etc/modprobe.d/raspi-blacklist.conf 

and entering the extra line at the bottom.

After rebooting everything worked well.