Today was spent tinkering with the FM transmitter. I swapped out my initial 150cm half wave wire antenna for a 165cm solid core half wave, fashioned a crude battery pack from two D cells some wire and duct tape. After modifying the battery pack I moved the transmitter to the loft and went and did a little range check. The modifications possibly boosted the signal by 20-30 meters. In total line of sight I think roughly 200 / 250 meters reach which isn’t too shabby. FM needs a lot more power to extend range and I think the circuits good to 12v and is currently running at around 3v will do a little more reading before I start experimenting with different power supplies and voltages, also want to check the data sheet for the transistors.
Sorry for the dodgy screen capture I’m working on a better solution for the next video.
sudo apt-get install gqrx-sdr
sudo apt-get install rtl-sdr
How to install SDR# on windows …
You will need …
PC/Laptop (Recommended dual core, 4gb RAM)
(Optional antenna / adapter. *Recommended*)
.NET Framework 4.6
DO NOT PLUG IN THE DONGLE
DO NOT INSTALL ANY SOFTWARE IT CAME WITH
If you have uninstall the software, driver and unplug the dongle.
Goto airspy.com and download the ‘SDR Software Package’
Unzip the files somewhere
Plug in your dongle
Run zadig.exe (as administrator)
Make sure ‘show all devices’ is selected.
In the device drop down select ‘Bulk Interface 0’
Ensure WINUSB is selected in the other drop down.
Click OK to any warnings
Select the RTLUSB dongle
Click the play icon to start capture.
Tune to a known frequency (FM station)
Ensure WFM is selected
Open the options menu
Increase RF gain, but don’t let the signal distort.
If you can hear distortion try adjusting the volume control in SDR#
Give yourself a pat on the back and get scanning!
Moving on to gqrx and linux in the next video.
Recommended SDR shopping list for up coming content …
RTLSDR – RTL2832(u) DVB-T+DAB+FM Dongle (£10-£15)
MCX MALE TO BNC FEMALE (for connecting antennas) (Approx £2)
AIR BAND (or similar) antenna (usually with BNC male connector) (£3-£10)
What is SDR?
S.D.R. stands for Software Defined Radio.
SDR is a combination of hardware and software used to scan/monitor/demodulate/transmit electromagnetic radio signals.
Signals can be used to transmit voice or data.
The most common methods of transmission are FM and AM.
FM = Frequency modulation
AM = Amplitude modulation
FM, modulates the frequency of the carrier wave to transmit a signal.
AM, modulates the amplitude of the carrier wave to transmit a signal.
Both can be used to transmit analogue or digital data.
You will need …
PC / laptop – Laptop preferably for portability, currently running on an i5 2.4ghz 8gb ram pretty smoothly, I did try this on an older atom processor on linux using gqrx but latency was an issue.
SDR dongle – RTL2832U – If you want to follow along with the next few videos grab an RTL dongle you can always decided if you like the hobby enough to invest in more expensive equipment at a later date.
Antenna – You can use the one provided but its not recommended for the next few videos ill be using a cheap airband antenna I bought from ebay.
Realtek DVB-T+DAB+FM Dongle
RTL2832U – Notes: The dongle was never intended to be used for SDR but two researchers discovered the chip used was able to cover a wide range of frequencies (24 mhz – 1766 mhz) and decided to rewrite the drivers. (Antii Palosaari and Eric Fry of Osmocom) Since then the dongle has proved hugely successful with amateur radio enthusiasts.
So what can you do with SDR?
Voice, ADSB, ACARS, digital voice, AIS, POCSAG, FLEX, consumer devices, weather ballon data, HAM internet, DVB-T, GSM, GPS, spectrum analysis, weather satellites, ISS, radio astronomy, meteor scatter, FM/AM radio, RDS, DAB, RNG … probably much more!
Over the last few years lots of researchers and developers have started producing applications and code for the RTLSDR and hopefully many more projects to come as the community grows.
Keep tuned for more SDR fun stuff!
If you get bored in the meantime try googling some of the stuff I’ve listed above and start your own research / project / experiment / learning / hack / etc.
So it begins, late night last night, got the SDR working under windows. Todays goals, get the SDR working under linux and gqrx, look at what I managed to capture in the log and start a video showing how to setup SDR#.
Really don’t want to stop logging messages lol, but I suppose its time to start making notes. Once I can get this running on the RPi ill leave it logging 24/7 for a while so I can analyse the data. Still lots of data being sent that shouldn’t be, names, phone numbers, address information, IP addresses, email addresses, URLs … and I’m sure if I log for long enough the obligatory username and password.
So I can’t show or share any of the data I’m collecting. Hibby just pointed me to (Legal stuff) … even though I can’t share the data I can show you how to demodulate the signals yourself.
Written up notes for SDR# installation.
Executing operation tidy up for recording later also doing a few other chores.
Still tidying 🙁 b/c I’m a messy bugger.
Random picture for today …
Since I’m working on radio stuff here’s my baofeng handset its the uv-5r, a great starting handset for people looking to get in to HAM radio and start learning. I bought one relatively cheap on ebay around £20, before I got my licence so I could scan and listen a little. I’ve some other scanners and sets but ill save those for another day.
meh RL … need to script my house work or hack together some sort of roomba capable of washing up and making tea/coffee on demand.
Chilling out time for a coffee and some food. BBL
A few pages of notes written and a rough idea for an introduction to SDR. Time for a brew and to record / talk through the audio. Will report back in a while.
Captured a little extra audio for the hakology introduction too.
Woke up after a few hours sleep been doing a little radio research, too early to start the next blog entry, too late to be editing this one hmmm.
No vblog for day nine either will have to make up for it later.