In late December 2018, Mike B wrote in, with the news that AOR had just released a BETA version of the firmware for the AOR AR-DV1 digital receiver, which now receives TETRA. Mike had tested it by setting up a search of the Airwave base frequencies, from 390 to 395MHz, in 12.5khz steps. Of course, the transmissions in this band are encrypted, so you will not be able to listen to content. It’s either that or, as Mike says, the Police speak Klingon! At the time of writing, the firmware is still in BETA. However, if you have an AOR AR-DV1 and would like to try this, you can read about the firmware at this URL: http://www.aorusa.com/support/firmware.html

 

Uniden Bearcat SDS-200 Base Scanner On Its Way

I hope that you have enjoyed my review of the Uniden Bearcat SDS-100 scanner in Scanning Scene last month (RadioUser, March 2019: 39-41). Meanwhile, Karl H spotted that the Uniden SDS-200 was getting ready for release. The SDS-200 is essentially a base version of the SDS-100.

Uniden says there are some enhancements. By peering at the photographs of the set, I can see there is an RJ-45 (network) connector on the back of the scanner. Reading around, it looks like there will be remote-control and remote-listening functions. Therefore, you should be able to leave your SDS-200 connected at home and listen to it on your laptop or even mobile phone, on the go.

What we know so far is that, according to Uniden, “the SDS200 incorporates the latest True I/Q receiver technology, which provides the best digital decode performance in the industry, even in challenging receive environments. Highlights include: True I/Q™ Receiver, TrunkTracker X, Direct Ethernet Connectivity for Streaming and Control, Complete USA/Canada Radio Database, Location Control for Simple Operation and 3.5" Customizable Colour Display. The SDS200 with TrunkTracker X technology supports:  APCO P25 Phase I and II, Motorola, EDACS, and LTR Trunking, MotoTRBO Capacity + and Connect +**, DMR Tier III**, Hytera XPT**, Single-Channel DMR**, NXDN 4800 and 9600** and EDACS ProVoice**.

The Sentinel database only works within North America. and digital mode updates will cost extra.

[N.B.: Additional or third-party software may be required, and the ’**’ means that paid upgrades will be required for DMR, NXDN, and ProVoice monitoring – Ed.].

All of which does sound pretty similar to the SDS-100 in a base package! If you’re looking seriously at the SDS-200, you’ll most likely want the upgrade to allow decoding of DMR, which looks likely to be an extra £50.

On January 2nd 2019, Uniden stated that the receiver was FCC-approved. Therefore, by the time you read this, it should be reaching retailers.

[We’re hoping to get hold a model to review and share more details with you very soon TK/GW.].

 

Plotting Aircraft Positions on a Map

I was idly listening to the air traffic over the West Country at the weekend – mostly commercial traffic, heading to North America or to Ireland. For me, and many others, it may be interesting to see where the aircraft you are hearing is actually located. There are some websites, which you can use to track aircraft around you, for example, Flightradar24.com. I use the 360radar site, which – although you pay a small subscription fee – does cover military and police traffic, as well as civil aviation.

Of course, you can also track aircraft by receiving ADS-B transmissions from them. You have probably read about ADS-B elsewhere, but if you need a quick catch-up, take a look at this resource:

https://en.wikipedia.org/wiki/Automatic_dependent_surveillance_–_broadcast

ADS-B transmissions are on 1090MHz. Receiving them takes a simple USB stick (Fig. 1), a small aerial, and some software for your computer. Some of the advertisers in RadioUser carry adverts for the FlightAware dongles, which work really well with a RaspberryPi computer.

Alternatively, you can search eBay for an ‘RTL-SDR dongle’ (Fig. 1). Look for ‘R820T2’ (the tuner) in the description. You can get them for around £6. Rather than fill the column up with instructions of how to set things up, I’ll point you at the Quick Start Guide on the excellent RTL-SDR.COM website. It is well worth a look for an idea of the sorts of things that you can try. There are instructions for how to set up a dongle on Windows, Linux and Macintosh computers.

A very popular option is to use a RaspberryPi as the computer to receive and decode the signals from aircraft. You can find the ‘Quick Start Guide’ here:

https://www.rtl-sdr.com/rtl-sdr-quick-start-guide

Assuming that you are using Windows, there is a tutorial on how to use the ADSB# decoder to receive data from aircraft, at this address:

https://www.rtl-sdr.com/adsb-aircraft-radar-with-rtl-sdr

Although it’s not ideal, you can easily use the aerial which comes with the dongle to receive the aircraft ADS-B transmissions. This works even indoors, although you should try and place the antenna near a window. You should be able to receive aircraft from around 50-70 miles away.

Once you get hooked – as you surely will – then there are some designs for making your own aerial. This will probably prove more effective than the basic antenna.

If like me, you use a Mac, you can easily set up an ADS-B decoder using an RTL-SDR dongle. You can install Macports and then install the rtl_sdr software. Once you have done that, you can follow instructions similar to those for the Raspberry Pi, to install the dump1090 ADS-B decoder (Fig. 2). You should look for the ‘Malcolm Robb’ version.

There are also some commercial units such as the Airspy and the SDRPlay units. these are considerably more sensitive than the simple RTL-SDR dongles.

If you install an ADS-B receiver and run it regularly, you should consider feeding your data into the various plotting networks. It’s a way of giving back to the hobby in some respects. The networks are always looking for people to run receiving stations, especially if you are in an out-of-the-way place, such as a far-flung island or coastal spot in the Highlands or on the Irish coast.

And if you are not, your data is still welcome. Although you will probably see the same high altitude aircraft as everyone else, aircraft at lower altitudes will only be detected over a fairly small area of ground.

 

It’s Not Just Aircraft Either

There’s plenty of other things that you can do with your RTL-SDR dongle once it’s installed. You can install a bit of SDR software – depending on which operating system you are using – and use it as a receiver.

For example, I installed a bit of software called rtl_433.

This allows you to monitor the unlicensed bands around 433, 868, 315 and 915MHz. I tried this out on the 433MHz band, and I was able to see data from our wireless thermometers and those of our neighbours!

There is a myriad of other sensors transmitting on 433MHz, and rtl_433 is able to decode many of them and display the data. If you want more information about this, you can obtain the software from this source:

https://github.com/merbanan/rtl_433

There is a post on using the rtl_433 software at this URL:

https://www.rtl-sdr.com/using-rtl-sdr-rtl_433-decode-various-devices

I told my friend Mike about the rtl_433 utility, and he attached the dongle to his 70cm amateur band beam, pointed at a local centre of population and received all sorts of signals including cars’ tyre pressure monitoring systems, oil tank level monitors for houses, smart electricity meters, as well as multiple types of weather stations! As he said, there is no need to buy a weather station, with all those data being transmitted.

To give you an idea of how busy the band is, Mike recorded almost 3,000 transmissions in around an hour on the 433MHz band. Intrigued by this, I popped my computer and RTL_SDR dongle in the car when I was travelling to the local supermarket. Once parked up, I started the rtl_433 program. Rather than outputting the data of the program to the screen, I saved it as a Comma Separated Variable (.csv) file. After a few minutes, I stopped the program and imported the .csv file into Microsoft Excel (you can use any spreadsheet program).

I could now see the information that I had captured. It was mostly tyre pressure management systems on Citroen, Renault, Ford and Toyota vehicles. I could see the various tyre pressure readings for different vehicles. Having the data in a spreadsheet means you can analyse it and get a good sense of what signals you are seeing. If – like one person that I saw talking about rtl_433 – you live close to a major trunk road or motorway, you will discover a lot of data on 433MHz coming from cars travelling past you.

If you have not yet had a play with one of the RTL-SDR dongles – and if you enjoy playing around the boundaries of radio and computers – I can recommend it as an interesting and rewarding experiment. In terms of ‘bang for your buck,’ there’s a lot of fun to be had, for a very small outlay, with an RTL-SDR dongle and software. If you have not tried using an SDR before, this may well enthuse you to look at the subject in some more depth – with a better quality receiver. However, the cheap dongles are a great place to start.

[Check out our monthly column on Software-Defined Radio by Andrew Barron – Ed.]. 

 

Talking Rubbish

A couple of weeks ago, there was some tropospheric enhancement on VHF/UHF, and I was delighted to be hearing marine band transmissions here in land-locked Oxfordshire. The accents were Liverpudlian; when I got home, I was searching around to see if I could get any sense of what I’d heard. Googling VHF in the Liverpool area, I found a very humorous entry on one forum, saying that all they heard on VHF was radio hams talking rubbish! Oh dear! So, a gentle reminder to all of us who have amateur licences that we are being listened to by more people than we may think!

 

Listening Post

From Gibraltar, our reader Kevin heard local air traffic control giving US Marine Osprey aircraft permission to fly over Runway 09 at a low level. Kevin reported, “The Gibraltar Broadcasting Corporation hosted an Open Day on the 12th December 2018, to raise money for local charities on the Rock. The satellite uplink truck was parked in the alleyway beside John Macintosh Hall, it was plain white, with no company logos, and the dish was not deployed. The truck was being used as an audio/video mixing suite, and also, by the director, to instruct the sound and camera crew (Fig. 3).”

https://www.gbc.gi

Russian cosmonauts conducted an EVA (Extra Vehicular Activity), commonly referred to as a ‘Spacewalk’, on the 11th December, between 1600 and 2200 UTC. Kevin monitored communications between the cosmonauts (on 121.100 and 121.275MHz FM) and the ISS (130.167MHz FM) during a 13° pass over the Rock, from the Bay of Gibraltar.

Using an Alinco DJ-X3, with a 2-element ‘rabbit-ears’ aerial, he heard nothing. However, 5 minutes later, as the pass continued over Europe, a station in Greece reported receiving one minute of audio from the ISS on 130.167MHz, using an RTL-SDR dongle with a turnstile antenna.

Roger B also received audio from the ISS on 130.167MHz, and the cosmonaut on 121.100MHz was breaking through the squelch a few times. Roger used an Icom IC-R7000 and a Diamond discone aerial.

David S from Yorkshire was listening to the downlink of the ISS when it was transmitting Slow Scan Television (SSTV). On January 31st (Fig. 4) David listened with a Uniden Bearcat UBC-125XLT scanner and a telescopic whip antenna, feeding the audio to an SSTV decoder on his iPhone.

The following day, February 1st, David listened to a schools contact between an astronaut on the ISS and a school in Portugal. David had great reception and used his Uniden UBC-125XLT scanner and a SkyScan magnetic mount antenna on his car.

If you have been thinking of getting in touch but haven’t done so, please do! It will be great to hear from you and it will ensure that I include a wide variety of topics in the column.

 

This article was featured in the April 2019 issue of Radio User