Tim Kirby meets Charlie Brown in London, introduces the DropBoxer for WTR Browser feature, assesses satellite prediction tools and appreciates the wider range of signals resolvable with new scanner models.

 

As I was listening to a conversation on one of the Zello Network Radio channels recently, I heard someone mention that they were quite close to one of the major airports, that they spent some time listening to the civilian airband frequency of 121.500MHz, and that they had never heard anything.

I reflected quietly that this was, perhaps, a good thing! However, someone else commented that they sometimes heard test calls on the channel.

This reminded me of a recent lunchtime conversation I had when I was walking around the Science Museum in London. I had decided to go and have a look at the Space Gallery, which I had not visited in some years. I felt the need to go – as you do – and stand by some of the hardware, which had travelled to the Moon and back. This is an inspiring thought, to me at least, if ever there was one.

After I had enjoyed looking at Charlie Brown, the Apollo 10 command module (Fig. 1), I went on to examine the Apollo Lunar Module exhibit. In one of the cabinets, which surround the display, I spotted a very interesting-looking device called the Apollo Survival Radio (Fig. 2).

I began to wonder in what kind of situations and scenarios it might have been anticipated to be used.

I posted a picture on Twitter and this generated numerous interesting responses, including one from Patrick Stoddard in Phoenix, Arizona. Patrick included a link to the Apollo Experience Report – Development and Use of Specialized Radio Equipment for Apollo Recovery Operations. The document makes interesting reading:

https://tinyurl.com/ycgp2dup

Among other subjects, the document covers the Apollo Survival Radio and a similar radio for the swimmers who would go out on the Apollo recovery missions, once ‘splashdown’ had occurred. The radios featured voice operation, but also a ‘beacon’, which consisted of the transmission of a tone.

In tests, the range of the radio was found to be around 195nm miles for the beacon and 120nm for voice operation, with the other end of the link on an aircraft flying at 25,000ft.

The Apollo Experience Report also details some of the challenges encountered in the design of the equipment, including battery life (the requirement was specified as 24 hours) and maintaining a low VSWR when the radio was in close proximity to various metal objects.

The Apollo Survival Radio used a frequency of 243MHz, which is the military air distress frequency (twice the civilian distress frequency of 121.5MHz).

This, of course, is useful from an antenna-design point of view.

 

Scanning from Difficult Locations

Many thanks to Martin Rolls, who kindly emailed me. Martin lives in a flat in an urban area with only an outside balcony and finds many signals weak. He wonders what advice I, or other readers, might have, for getting the most out of the hobby in such a situation.

Martin says that drilling holes through the window frame would not be permitted.

This is a challenge indeed; in most urban locations, noise levels have risen hugely over the last 20 years. Apart from noise, the second challenge, of course, is ‘screening’ by other buildings, including the one you are in. Of course, there is often little you can do about this.

However, perhaps this is something that you can make the best of: In good weather, a window can be opened to allow a coax through, from a magnetically mounted whip (or scanner-type wideband aerial) on some sort of metal surface for a ground plane – a tin tray will often suffice!

In cooler weather, of course, having the window open will not be acceptable or pleasant. In one property that I rented, there was a cat flap, and, at that time, I did not have a cat, so I was able to press that into action for getting cables in and out.

Sometimes, airbricks might afford some possibilities for passing cables through the wall. Some flat dwellers are lucky enough to have access to the roof; good relations with the building management can help here.

When none of those things is possible, why not try cutting a dipole for the frequency of interest – maybe air band or marine – and try taping it on the inside of the window.

Of course, listening on air band, or undertaking VHF/UHF, satellite reception is often a good possibility from most locations, as you can normally see some sky.

If you tape a dipole to the inside of a window, you can try varying its orientation; vertical or horizontal, or even somewhere in between. This may help you ‘null-out’ some of the local noise.

During the time I have been interested in radio, I learned that any antenna you have is better than the one you don’t have! What do I mean by that?

Really, it’s just a case of you don’t need to have the perfect antenna. Try and put something together, and, hopefully, you will hear something. You will certainly hear more than you would if you had no antenna at all.

If the antenna works well, great – if it is not so good, then this can all be a part of the experimentation involved in trying something different to improve your results.

A possible benefit of scanning from an urban location is that there may be many more signals available to you in the UHF spectrum, both analogue and digital, such as ShopWatch, buses, railway stations and so on.

The other option, when your home location is a dreadful RF spot, is to take your portable scanning receiver to a more favourable location. In good weather, it is always pleasant to carry a receiver up a hill or to a location of interest, such as a harbour, shopping mall, sports stadium or airport.

Sadly, there are no ‘magic solutions’ to the problems of noise and poor location, but there are always some possibilities for improvement, which will allow you to enjoy and expand the hobby.

Thank you, Martin, for a great question, which I think will apply to very many people.

If you have any experience in scanning from a difficult location that you would like to share with readers, please drop me a line – it would be great to hear from you.

 

WTR Browser and DropBoxer

Wayne Richards’ WTR Browser frequency database has got some interesting new functionality for those people who want to use the program from a mobile device. This is courtesy of a feature called the DropBoxer.

This functionality allows you to search on your mobile device and get the results back from WTR Browser, running on your machine at home.

The results will upload to your Dropbox account (you will need to set up one if you don’t have one). You can then view them on your smartphone or tablet. You can alter the filter and search by all the methods you would use if you were at home.

When you first set it up, WTR Browser will create some files in your Dropbox account.

One of them is help.txt.

There will also be some other files, which define the various filters that WTR Browser can use.

You run WTR Browser on your machine at home, with DropBoxer open and running. On your mobile device, you open the Dropbox application and choose the folder used by WTR Browser.

Use the search.txt file to enter the frequency you want information about. Save and escape out of it. Wait for a few seconds, and you will shortly see a file called results.txt appear in the folder. This will contain the details of the frequency that you searched for. It will provide information about the licence holder, the licence date, the frequency and the location, just as it would in WTR Browser.

Wayne Richards, the author of the program, says that, when you first read this, it sounds complicated. However, it really is not, and it works very smoothly.

To make things even easier, Wayne has provided a video, so you can see the new features in action.

To learn more about DropBoxer and the WTR Browser program in general, take a look in the WTR Browser Group on Facebook.

 

Listening Post

Kevin Hewitt from Gibraltar had an interesting time during the Gibraltar Calling Music Festival, held at the Victoria Stadium on September 21st and 22nd (Fig. 3).

Kevin used his Alinco DJ-X3 from two locations, Princess Caroline Battery on the Rock, and a multi-storey car park opposite the stadium.

Kevin found around 65 active frequencies, the majority of which were used by media directors to facilitate communication with camera operators and sound engineers. In addition to this, wireless microphones were used on stage and could be heard.

The local radio station, Radio Gibraltar, had a number of engineering frequencies in operation.

https://www.gbc.gi/radio/listen-live

The band from 441 to 457MHz was particularly busy, including PMR frequencies around 446MHz. Kevin was interested to hear prompting for the Scouting for Girls set on 444.437MHz. There was also a lot of activity from 821MHz up to around 885MHz, and a couple of frequencies were used at around 911 and 912MHz.

Very interesting Kevin. I am sure it was fascinating to get a sense of what goes on behind the scenes at a major event like this. What’s striking to me is the very wide range of frequencies that are in use from around 150MHz all the way up to 912MHz – that's a lot of spectrum for you to scan, so the tools on the various scanners which provide an indication of active frequencies will be very useful indeed.

During one of the recent Slow Scan TV (SSTV)  transmission periods from the International Space Station (ISS), Bob Houlston attempted to decode some pictures. Bob wrote, “I find SatPC32 by Erich Eichmann, DK1TB to be a most useful program to predict satellite passes. The basic version is free at:

www.dk1tb.de

“I used it to help me detect SSTV from the ISS, using a 2m radio and an aerial in the loft. I piped the audio from the rig into the PC, using the free RX-SSTV software to decode the image.

“I have a precautionary (but not essential) 1:1 600Ω audio isolating transformer from RX to PC. They're £5 for two from eBay.”

Bob is right: The SatPC32 software is excellent, and, should you wish to use it on a regular basis, you can register it. This obviates the need to enter your latitude and longitude each time you start up the program.

Among the other satellite prediction programs, you might want to try, there is also GPredict. This works across platforms such as Raspberry Pi. With the latter, you can have a nice big screen in your shack displaying the position of various satellites. It works well too, on a Windows (or Linux) PC.

Howard Parker, of the Radio Radio Facebook Group, posted an interesting video recently, of a reception event that puzzled him: He used his handheld Yupiteru scanner and had picked up what he thought were Spanish-sounding voices around 261.795MHz.

I realised that these were the signals from the Brazilian pirate operators using one of the MILCOM satellites. What I was unaware of, however, was that the signals could be received on a simple handheld scanner. I had rather hoped that they might be heard with such a system, but most people reporting reception of these signals have been using a pair of crossed dipoles or even a small Yagi.

You will probably hear mostly foreign languages on these channels, but I gather there is some English-speaking activity too. Thanks, Howard for your interesting report!

That’s really brilliant news, and I think will constitute an interesting challenge for me – perhaps for you too!

Can we hear signals from satellites on simple handheld equipment? If you have read the column last month, (RadioUser, November 2018: 66-68), you might remember that Paul Beaumont kindly included details of some of the frequencies, which might be worth listening on.

Please let me know if you have any success in listening to these frequencies.

Karl Hobson contacted me and said that he was enjoying using a Whistler TRX-1 digital scanner, in conjunction with the excellent WTR Browser software. Karl said that he was amazed by the diversity of things to listen to, including the local Air Ambulance.

Having dipped his toe in the water, Karl is considering buying a base station scanner like the AOR DV-1, in order to increase the range of signals he can listen to.

Thanks for the email Karl and please keep me posted on your activities and results.

That’s all for this month. Thanks to those of you who have emailed. Please keep your news, thoughts and questions coming; I will do my best to have some answers.

Happy scanning!

 

This article was featured in the December 2018 issue of Practical Wireless