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Peter Donaldson (23 August 1945 – 2 November 2015) Image source: BBC
If you live in the UK and listen to the radio, you’ve probably heard that long-time announcer/broadcaster Peter Donaldson died earlier this week. For years–decades actually–Donaldson was a prominent voice on Radio 4.
Donaldson was also well-loved by his listeners, and his colleagues at the BBC (read this touching tribute).
Donaldson had a familiar, calming voice; perhaps that’s why he was asked by the BBC to record a series of informational messages in the event of a nuclear war.
“BBC newsreader Peter Donaldson, who has died aged 70, was to have been the voice of radio bulletins in the event of a nuclear attack. What would have gone out on the UK’s airwaves if the Cold War had turned hot?
“This is the Wartime Broadcasting Service. This country has been attacked with nuclear weapons. Communications have been severely disrupted, and the number of casualties and the extent of the damage are not yet known.”
So began the script, read by Peter Donaldson, which was to go out on British airwaves in the event of nuclear war.”
Here’s an audio clip from Peter Donaldson’s pre-recorded announcement:
While I’m an avid radio listener, I should hope I never hear a similar message over the air (even though Donaldson’s voice is indeed quite calming).
If you’re curious, here is the full Wartime Broadcasting Service official post-attack statement, courtesy of Wikipedia:
This is the Wartime Broadcasting Service. This country has been attacked with nuclear weapons. Communications have been severely disrupted, and the number of casualties and the extent of the damage are not yet known. We shall bring you further information as soon as possible. Meanwhile, stay tuned to this wavelength, stay calm and stay in your own homes.
Remember there is nothing to be gained by trying to get away. By leaving your homes you could be exposing yourselves to greater danger. If you leave, you may find yourself without food, without water, without accommodation and without protection. Radioactive fall-out, which follows a nuclear explosion, is many times more dangerous if you are directly exposed to it in the open. Roofs and walls offer substantial protection. The safest place is indoors.
Make sure gas and other fuel supplies are turned off and that all fires are extinguished. If mains water is available, this can be used for fire-fighting. You should also refill all your containers for drinking water after the fires have been put out, because the mains water supply may not be available for very long.
Water must not be used for flushing lavatories: until you are told that lavatories may be used again, other toilet arrangements must be made. Use your water only for essential drinking and cooking purposes. Water means life. Don’t waste it.
Make your food stocks last: ration your supply, because it may have to last for fourteen days or more. If you have fresh food in the house, use this first to avoid wasting it: food in tins will keep.
If you live in an area where a fall-out warning has been given, stay in your fall-out room until you are told it is safe to come out. When the immediate danger has passed the sirens will sound a steady note. The “all clear” message will also be given on this wavelength. If you leave the fall-out room to go to the lavatory or replenish food or water supplies, do not remain outside the room for a minute longer than is necessary.
Do not, in any circumstances, go outside the house. Radioactive fall-out can kill. You cannot see it or feel it, but it is there. If you go outside, you will bring danger to your family and you may die. Stay in your fall-out room until you are told it is safe to come out or you hear the “all clear” on the sirens.
Here are the main points again:
Stay in your own homes, and if you live in an area where a fall-out warning has been given stay in your fall-out room, until you are told it is safe to come out. The message that the immediate danger has passed will be given by the sirens and repeated on this wavelength. Make sure that the gas and all fuel supplies are turned off and that all fires are extinguished.
Water must be rationed, and used only for essential drinking and cooking purposes. It must not be used for flushing lavatories. Ration your food supply: it may have to last for fourteen days or more.
We shall repeat this broadcast in two hours’ time. Stay tuned to this wavelength, but switch your radios off now to save your batteries until we come on the air again. That is the end of this broadcast.
PRI’s The World featured a story about Peter Donaldson as well, and it was mentioned that perhaps the US has a similar “official” post-attack statement. I’m willing to bet we do, but I’m not sure how it would be disseminated over radio. Unlike the UK, we don’t have local relays of a government broadcaster. We do have the Emergency Alert Service which is directly tied to local and national broadcasting outlets–assuming satellite feeds are still functioning, that is.
The Federal Communications Commission and the Justice Department are investigating a California firm whose U.S. radio broadcasts are backed by a subsidiary of the Chinese government, officials said.
Both investigations come in response to a Reuters report published on Monday that revealed the existence of the covert radio network, which broadcasts in more than a dozen American cities, including Washington, Philadelphia, Boston, Houston and San Francisco. (reut.rs/1Wrflt4)
“Based on reports, the FCC will initiate an inquiry into the facts surrounding the foreign ownership issues raised in the stories, including whether the Commission’s statutory foreign ownership rules have been violated,” FCC spokesman Neil Grace said.
The California firm is owned by James Su, a naturalized U.S. citizen born in Shanghai. Reuters reported Monday that Su’s company, G&E Studio Inc, is 60 percent owned by a subsidiary of Chinese state-run radio broadcaster China Radio International (CRI).
The FCC doesn’t restrict content on U.S. radio stations, except for rules covering indecency, political advertising and children’s programming.
But under U.S. law, the FCC prohibits foreign governments or their representatives from holding a radio license for a U.S. broadcast station. Foreign individuals, governments and corporations are permitted to hold up to 20 percent ownership directly in a station and up to 25 percent in the U.S. parent corporation of a station.
G&E does not own any U.S. stations, but it leases two 50,000-watt stations: WCRW in Washington for more than $720,000 a year, and WNWR in Philadelphia for more than $600,000 a year.
Through a different set of limited liability companies, Su owns, co-owns or leases virtually all the air time on at least a dozen other U.S. stations. Those stations carry G&E content, which is produced largely by his West Covina, California studios or by state-run CRI in Beijing….
Many thanks to SWLing Post contributor and noted DXer, Guy Atkins, for the following guest post:
Wellbrook 1530LNPro vs ALA1530S+ Imperium Loop Antennas
-Guy Atkins
This past weekend I found some interesting results from medium wave DXing with both models of Wellbrook Imperium loop antennas at the “fabled” Rockworks cliffs near Manzanita, Oregon USA. This location has become popular the last few years with Oregon, Washington, and British Columbia DXers due to the signal enhancement at this narrow strip of land approx. 450 feet above the Pacific ocean. The main benefit seems to be splatter reduction of “pest” stations due to the signal blockage of the rock walls blasted into the cliffs for the coastal highway 101. However, a boost of signals around local sunrise is also beneficial, and is a common occurrence near salt water beaches.
Because of the limited space along this scenic coastal highway, all antennas used for DXing need to be both compact and temporary. Wellbrook loops supported on pro-audio speaker stands are a great way to go, and can easily be set up in the pre-dawn darkness.
Comparison
Both Wellbrook loop antennas mounted on “pro-audio” tripod stands right at the cliff edge at Rockworks Cliffs. (Photo: Guy Atkins)
This is a comparison file of weak signal reception with the two models of Wellbrook Communications “Imperium” series loop antennas: the ALA1530LN “Pro” Imperium and the ALA1530S+ Imperium.
Both models of compact, 1-meter dia. active loops are excellent for reception from longwave & medium wave upwards. However, the ALA1530LN “Pro” excels at LW & MW with its low overall noise level and 9dB higher gain, engineered by Wellbrook for improved signal-to-noise ratio (S/N) of up to 10 dB. S/N on the HF bands is reportedly better also.
My laptop running HDSDR software in my SUV; the receiver is an Elad FDM-S2. (Photo: Guy Atkins)
On the weekend of October 24th, 2015 I was DXing at the “Rockworks” cliffs on the Oregon coast near Manzanita, OR. Both of these Imperium series antennas were in use and I was recording the medium wave band with an Elad FDM-S2 SDR receiver. Both antennas were fed with identical 25 ft. lengths of RG-58 coaxial cable.
The demonstration in this video begins with 10 seconds using the ALA1530LN Pro Imperium loop, alternating with 10 seconds with the ALA1530S+ Imperium loop.
https://www.youtube.com/watch?v=rbX_G0ll_kk
The first signal tuned is aviation voice beacon “SQM” from Level Island, Alaska on 529 kHz (400 watts). The signal is weak, but audible as it rises above the noise floor. The reception improvement with the ALA1530LN Pro is evident.
Half way through the recording the frequency is switched to 1710 kHz, where an unidentified station (possibly a MW pirate) is audible playing the 1967 Zombies tune “Time of the Season”. Again, the clip starts with 10 seconds with the ALA1530LN Pro alternating with 10 seconds of the ALA1530S+ Imperium.
Each antenna is a worthy, compact loop for DXing, but for chasing the weakest signals with the best readability I think the ALA1530LN Pro shows its advantages.
Many thanks, Guy, for sharing your loop research!
What I love about your portable SDR set-up, is that you can go to the cliff side, set up your antennas and equipment, record the spectrum on your SDR, then go back home to analyze and listen to what you captured. It takes some of the pressure off while you’re on-site.
This year at the Dayton Hamvention, I purchased the Pixel Technologies RF PRO-1B mag loop antenna. I used it (for the first time) at the PARI DXpedition. We were all impressed with its performance. I would love to compare it with the ALA1530LN Pro at some point in the future.
Yesterday, Tony (K3DY), shared a video (via Twitter) demonstrating his new home brew loop antenna and amplifier.
This is actually a great demonstration of how even a relatively simple, inexpensive loop antenna can improve reception in locations with heavy radio interference. Tony includes the following notes with his video:
“Testing a new receiving loop antenna that I built today. It uses a pre amplifier based on deferential setup of two 2N5109 transistors. Loop is made out of coaxial cable, only the shield is connected to the circuit.
Quick demo on 31 meters, lots of stations at sunset time. No time for further testing but I observed a pronounced directivity below 7 MHz. 75 meters is so quiet that it makes me forget I live in a townhouse. As a comparison, my noise level on 75 meters is at S8 on an end fed [antenna].
https://www.youtube.com/watch?v=bq_gKNQSVeA
I will use this loop primarily for SWLing purposes but I may use it as a separate receiving antenna with my amateur radio equipment.
A lot of fun, loops are fascinating and efficient!
Indeed, Tony! And perhaps the icing on the cake is that loop antennas are so portable, low-profile and easy to deploy. They’re ideal for those living in restricted areas and with picky home owners’ associations.
Inspired by my buddy Vlado (N3CZ), I’ve actually been collecting the pieces to build my own mag loop antenna this winter. I doubt the parts for my loop will exceed ten dollars as I plan to use the shield of some heavy coax for the primary loop and a little PVC for support (much like Tony’s loop).
Tony’s video is inspiring me to go a step further and also build a simple amplifier. Any suggestions or schematics for doing so are most welcome!
Two weeks ago, I received a mystery package in the mail: a copy of the October 2015 issue of CQ Ham Radio magazine, sent directly from the publisher in Tokyo, Japan.
Supplement magazine shipped with the October issue.
Since I can’t speak or read Japanese, I was very confused why I would receive a copy.
Out of curiosity, last week, I opened the magazine to see what sort of articles it contained.
In short: I was very impressed. While I couldn’t read the content, of course, I was able to get an idea of the scope of this magazine–it contained numerous articles, news items, reviews and photos.
I was pleased to note a section that focused on good etiquette for amateur radio exchanges in English. After all, if you are a Japanese DXer, you will need to know enough English to log DX stations around the world as English is the staple DX language. Japanese hams are well known for their excellent on-air etiquette–ask anyone who has been on a DXpedition.
The magazine is thick, too; most of the pages are black and white news print, but there are several color/glossy sections as well. This particular issue was even mailed with a separate supplement magazine containing a history of ham radio ads throughout the years. I thoroughly enjoyed the trip down memory lane.
Once I landed on the page above, I quickly realized why I had been sent a courtesy copy of the magazine: my SDRplay RSP review had been translated and published. It was then I remembered granting permission to have the article translated into Japanese for a ham radio magazine. I had completely forgotten!
I’m honored my review was printed in CQ ham radio, but most of all, it has been fascinating to browse through what appears to be an excellent radio publication. I offer my gratitude to the translator who took the time to edit my article.
Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), for the following guest post:
International Radio Broadcasts via Satellite
by Mario Filippi
I find your SWLing Post blog a constant fountain of information on the world of shortwave listening. Having been a shortwave listener since the early 1960’s, I’ve depended mainly on shortwave radios to hear foreign broadcasts. I’ve owned more shortwave radios than shoes (hi hi)–! However, there is a not-so-well known way of receiving radio broadcasts from around the world, and this is by Free To Air Satellite (FTA).
Free To Air satellite reception requires using a minimum 30 inch Ku band satellite dish, an LNB (Low Noise Block) amplifier, a Free To Air satellite receiver, and skills to aim at a satellite carrying these broadcasts.
There are several Free To Air satellites in the Clarke Belt, and the reception is cost-free as these broadcasts are for expatriates living around the world who need to tune in to stations back home. One satellite in particular that carries many foreign radio broadcasts is Galaxy 19, located at a longitude of 97 degrees, and is readily accessible from the USA.
Now let’s start on what an FTA dish set-up looks like for this type of reception. Below is an installation of mine, consisting of a 30 inch WS International satellite dish and LNB. A 30 foot length of RG/6 coax is run into the shack and hooked to an AMIKO Mini HD SE FTA receiver. Typical cost for a dish, LNB, coax is under $200.
Below is my AMIKO Mini HD SE FTA receiver, also known as an STB (Set Top Box), which can be purchased from a number of FTA vendors. This allows one to receive international television and radio broadcasts. They run about $90.
As stated earlier, Galaxy 19 is one of the best satellites to use for international radio broadcasts–currently, it has about 90 radio channels available for listening. I did a scan today of what is available, and below are three screenshots of the stations available to the listener.
Duna World radio is from Hungary. IRIB stands for Islamic Republic of Iran Broadcasting. 3 ABN is Apostolic Bible Network. TGN is Thai Global Network.
Kuwait, Syria, and the Middle East are well represented by the radio stations above. Voice of Russia, and Congo radio are good ones.
Voice of Turkey, Polski Radio found above. Not too shabby!
[Y]ou’ll find a good how-to on FTA at the following link:
[T]his is just a little introduction to the world of international listening using satellite. I hope this is something you and SWLing Post readers might find interesting.
Indeed I do, Mario! Thanks so much for taking the time to show us how to tune in a variety of international broadcasters via satellite. Each year at the Winter SWL Fest, we have demonstrations showing what can be done via FTA satellite. Perhaps I should bite the bullet and invest in one!
Many thanks to SWLing Post contributor, London Shortwave, who is kindly sharing this guest post–a brilliant article he recently posted on his own website.
I’m very grateful: one of the most common questions I’m asked by readers is how to cope with the radio interference so many listeners and amateur radio operators experience in high-density, urban areas. If this is you, you’re in for a treat–just keep reading:
Dealing with Urban Radio Interference on Shortwave
Shortwave radio listening is an exciting hobby, but for many of us city dwellers who either got back into it recently or tried it out for the first time not long ago, the first experience was a disappointing one: we could barely hear anything! Station signals, even the supposedly stronger ones, were buried in many different types of static and humming sounds. Why does this happen? The levels of urban radio frequency interference, or RFI, have increased dramatically in the last two decades and the proliferation of poorly engineered electronic gadgets is largely to blame. Plasma televisions, WiFi routers, badly designed switching power adapters and Ethernet Over Powerlines (also known as powerline network technology, or PLT) all severely pollute the shortwave part of the radio spectrum.
Does this mean we should give up trying to enjoy this fascinating medium and revert to using the TuneIn app on our smartphones? Certainly not! There are many angles from which we can attack this problem, and I shall outline a few of them below.
Get a good radio
The old adage “you get what you pay for” certainly holds true even when it comes to such “vintage” technologies as shortwave radio. Believe it or not, a poorly designed receiver can itself be the biggest source of noise on the bands. That is because many modern radios use embedded microprocessors and microcontrollers, which, if poorly installed, can generate interference. If the receiver comes with a badly designed power supply, that too can generate a lot of noise.
So how does one go about choosing a good radio? SWLing.com and eHam.net have fantastic radio review sections, which will help you choose a robust receiver that has withstood the test of time. My personal favourites in the portable category are Tecsun PL310-ET and Tecsun PL680. If you want a desktop radio, investigate the type of power supply it needs and find out whether you can get one that generates a minimal amount of noise.
It is also worth noting that indoor shortwave reception is usually best near windows with at least a partial view of the sky.
Tecsun PL310-ET and Tecsun PL680, my two favourite portable shortwave radios.
Identify and switch off noisy appliances
Many indoor electrical appliances generate significant RFI on the shortwave bands. Examples include:
Plasma televisions
Laptop, and other switching-type power supplies
Mobile phone chargers
Dimmer switches
Washing machines / dishwashers
Amplified television antennas
Halogen lighting
LED lighting
Badly constructed electrical heaters
Mains extension leads with LED lights
Identify as many of these as you can and switch them all off. Then turn them back on one by one and monitor the noise situation with your shortwave radio. You will most likely find at least a few offending devices within your home.
Install an outdoor antenna
If you have searched your home for everything you can possibly turn off to make reception less noisy but aren’t satisfied with the results, you might want to look into installing and outdoor antenna. That will be particularly effective if you live in a detached or a semi-detached property and have a garden of some sort. Of course, you will need a radio that has an external antenna input, but as for the antenna itself, a simple copper wire of several metres will do. An important trick is making sure that the noise from inside your home doesn’t travel along your antenna, thus negating the advantage of having the latter installed outside. There are many ways of achieving this, but I will suggest a configuration that has worked well for me in the past.
Fig.1 Schematic for an outdoor dipole antenna.
I have used a three-terminal balun (positioned outdoors), and connected two 6 metre copper wires to its antenna terminals to create a dipole. I then connected the balun to the radio indoors through the feed line terminal using a 50? coaxial cable. In the most general terms, the current that is generated in the antenna wires by the radio waves flows from one end of the dipole into the other, and a portion of this current flows down the feed line into your radio. The balun I have used (Wellbrook UMB130) is engineered in a way that prevents the radio noise current from inside your house flowing into the receiving part of the antenna.
Wellbrook UMB130 balun with the feed line terminal disconnected
Antenna preselectors
There is a catch with using an outdoor antenna described above — the signals coming into your radio will be a lot stronger than what would be picked up by the radio’s built-in “whip” antenna. This can overload the receiver and you will then hear many signals from different parts of the shortwave spectrum “mixing in” with the station you are trying to listen to. An antenna preselector solves this problem by allowing signals from a small yet adjustable part of the spectrum to reach your radio, while blocking the others. You can think of it as an additional tuner that helps your radio reject unwanted frequencies.
Fig.2 Schematic of a preselector inserted between the outdoor antenna and the receiver
There are many antenna preselectors available on the market but I can particularly recommend Global AT-2000. Although no longer manufactured, many used units can be found on eBay.
Global AT-2000 antenna coupler and preselector
Risk of lightning
Any outdoor antenna presents the risk of a lightning strike reaching inside your home with devastating and potentially lethal consequences. Always disconnect the antenna from the receiver and leave the feed line cable outside when not listening to the radio or when there is a chance of a thunderstorm in your area.
Get a magnetic loop antenna
A broadband loop antenna (image courtesy of wellbrook.uk.com)
The outdoor long wire antenna worked well for me when I stayed at a suburban property with access to the garden, but when I moved into an apartment well above the ground floor and without a balcony, I realised that I needed a different solution. Having googled around I found several amateur radio websites talking about the indoor use of magnetic loop receive-only active antennas (in this case, “active” means that the antenna requires an input voltage to work). The claim was that such antennas respond “primarily to the magnetic field and reject locally radiated electric field noise”[*] resulting in lower noise reception than other compact antenna designs suitable for indoor use.
Interlude: signal to noise ratio
In radio reception, the important thing is not the signal strength by itself but the signal to noise ratio, or SNR. A larger antenna (such as a longer copper wire) will pick up more of the desired signal but, if close to RFI sources, will also pick up disproportionately more of the local noise. This will reduce the SNR and make the overall signal reading poorer, which is why it is not advisable to use large antennas indoors.
The other advantage of a loop antenna is that it is directional. By rotating the loop about its vertical axis one can maximise the reception strength of one particular signal over the others, once the antenna is aligned with the direction from which the signal is coming (this is termed “peaking” the signal). Similarly, it is possible to reduce the strength of a particular local noise source, since the loop is minimally sensitive to a given signal once it is perpendicular the latter’s direction (also known as “nulling” the signal).
It is further possible to lower the effect of local noise sources by moving the antenna around. Because of the antenna’s design, the effect of radio signals is mostly confined to the loop itself as opposed to its feed line. Most local noise sources have irregular radiation patterns indoors, meaning that it is possible find a spot inside your property where their effects are minimised.
Many compact shortwave loop antennas require an additional tuning unit to be attached to the loop base (much like the preselector described above) but broadband loops do not. Wellbrook ALA1530S+ is one such antenna that is only 1m in diameter, and it was the one I chose for my current apartment. I was rather impressed with its performance, although I found that I need to use a preselector with it as the loop occasionally overloads some of my receivers when used on its own. Below is a demo video comparing using my Tecsun PL680’s built-in antenna to using the radio with the Wellbrook loop.
As you can hear, there is a significant improvement in the signal’s readability when the loop is used.
Experiment with a phaser
Although the loop antenna dramatically reduces the levels of ambient RFI getting into the radio, I also have one particular local noise source which is way too strong for the loop’s nulling capability. Ethernet Over Powerlines (PLT) transmits data across domestic electrical circuits using wall socket adapters, as an alternative to wireless networking. It uses the same frequencies as shortwave, which turns the circuits into powerful transmitting antennas, causing massive interference. One of my neighbours has PLT adapters installed at his property, which intermittently become active and transmit data. When this happens, it is not merely noise that is generated, but a very intense data signal that spreads across the entire shortwave spectrum, obliterating everything but the strongest stations underneath. Fortunately, a mature piece of radio technology called antenna phasing is available to deal with this problem.
Fig.3 The principle of antenna phaser operation (adapted from an original illustration in Timewave ANC-4’s manual)
Signal cancellation using phase difference
A phaser unit has two separate antenna inputs and provides one output to be connected to the radio’s external antenna input. The theory of phase-based signal cancellation goes roughly as follows:
The same radio signal will arrive at two different, locally separated antennas at essentially the same time.
The phase of the signal received at the first antenna will be different to the phase of the same signal received at the second antenna.
This phase difference depends on the direction from which the signal is coming, relative to the two antennas.
The phaser unit can shift the phases of all signals received at one antenna by the same variable amount.
To get rid of a particular (noise) signal using the phaser unit:
the signal’s phase at the first antenna has to be shifted by 180° relative to the signal’s phase at the second antenna (thus producing a “mirror image” of the signal received at the second antenna)
its amplitude at the first antenna has to be adjusted so that it is the same as the signal’s amplitude at the second antenna
the currents from the two antennas are then combined by the unit, and the signal and its mirror image cancel each other out at the unit’s output, while the other signals are preserved.
Noise sampling antenna considerations
To prevent the possibility of the desired signal being cancelled out together with the noise signal — which can happen if they both come from the same direction relative to the antennas — one can use the set-up illustrated in Figure 3, where one antenna is dedicated to picking up the specific noise signal, while the other is geared towards receiving the desired broadcast. That way, even if the phases of both the noise and the desired signals are offset by the same amount, their relative amplitude differences will not be the same, and thus removing the noise signal will not completely cancel out the desired signal (though it will reduce the latter’s strength to some extent).
It is possible to use any antenna combination for phase-based noise signal cancellation. However, one has to be careful that, in the pursuit of removing a specific noise source, one does not introduce more ambient RFI into the radio system by using a poorly designed noise-sampling antenna. After all, the phaser can only cancel out one signal at a time and will pass through everything else picked up by both antennas. This is particularly relevant in urban settings.
For this reason, I chose my noise sampling antenna to also be a Wellbrook ALA1530S+. The additional advantages of this set-up are:
It is possible to move both loops around to minimise the amount of ambient RFI.
By utilising the loops’ directionality property, one can rotate the noise sampling loop to maximise the strength of the noise signal relative to the desired signal picked up by the main antenna loop.
Two Wellbrook ALA1530S+ antennas combined through a phaser
And now onto the phaser units themselves.
Phaser units
DX Engineering NCC-1 (image courtesy of dxengineering.com)
I have experimented at length with two phaser units: the MFJ 1026 (manual) and DX Engineering NCC-1 (manual). Both solve the problem of the PLT noise very well, but the NCC-1 offers amplitude and phase tuning controls that are much more precise, making it a lot easier to identify the right parameter settings. Unfortunately this comes at a price, as the NCC-1 is a lot more expensive than the MFJ unit. As before, a preselector is needed between the phaser and the radio to prevent overloading.
Below is a demo of DX Engineering NCC-1 at work on my neighbour’s PLT noise. I have chosen to use my SDR’s waterfall display to illustrate the nefarious effect of this type of radio interference and to show how well the NCC-1 copes with the challenge.
Cost considerations
Fig.4 Final urban noise mitigation schematic
It would be fair to say that my final urban noise mitigation set-up, shown in Figure 4, is quite expensive: the total cost of two Wellbrook antennas ($288.38 each), a DX Engineering phaser ($599.95) and a Global AT2000 preselector ($80) comes to $1257. That seems like an astronomical price to pay for enjoying shortwave radio in the inner city! However, at this point another old saying comes to mind, “your radio is only as good as your antenna”. There are many high-end shortwave receivers that cost at least this much (e.g. AOR AR7030), but on their own they won’t be of any use in such a noisy environment. Meanwhile, technological progress has brought about many much cheaper radios that rival the older benchmark rigs in terms of performance, with Software Defined Radios (SDRs) being a particularly good example. It seems fair, then, to invest these cost savings into what makes shortwave listening possible. You may also find that your RFI situation is not as dire as mine and you only need some of the above equipment to solve your noise problems.
Filter audio with DSP
If you have implemented the above noise reduction steps but would still like a less noisy listening experience, consider using a Digital Signal Processing (DSP) solution. There are a number of different approaches and products available on the market, and I shall be reviewing some of them in my next post. Meanwhile, below are two demo videos of using DSP while listening to shortwave. The first clip shows the BHI Compact In-Line Noise Elimination Module at work together with a vintage shortwave receiver (Lowe HF-150). The second video compares using a Tecsun PL-660 portable radio indoors on its own and using the entire RFI mitigation set-up shown in Figure 4 together with a DSP noise reduction feature available in the SDR# software package, while using it with a FunCube Dongle Pro+ SDR. As a side note, it is worth remembering that while DSP approaches can make your listening experience more pleasant, they can’t recover what has been lost due to interfering signals or inadequate antenna design.
Set up a wireless audio relay from your radio shack
The above RFI mitigation techniques can result in a rather clunky set-up that is not particularly portable, confining the listener to a specific location within their home. One way to get around this is by creating a wireless audio relay from your radio shack to the other parts of your house. I did this by combining the Nikkai AV sender/receiver pair and the TaoTronics BA01 portable Bluetooth transmitter:
Head for the outdoors!
So you have tried all of the above and none of it helps? As a last resort (for some, but personally I prefer it!), you can go outside to your nearest park with your portable radio. After all, if shortwave listening is causing you more frustration than joy it’s hardly worth it. On the other hand, you might be surprised by what you’ll be able to hear with a good receiver in a noise-free zone.
Acknowledgements
Many of the above tricks and techniques were taught to me by my Twitter contacts. I am particularly grateful to @marcabbiss, @SWLingDotCom, @K7al_L3afta and@sdrsharp for their advice and assistance over the years.
Thank you–!
What I love about my buddy, London Shortwave, is that he didn’t give up SWLing just because his home is inundated with radio interference–rather, he saw it as a challenge. As you can see, over the years, he has designed a system that effectively defeats radio interference.
I also love the fact that he uses an even more simple approach to defeating RFI: he takes his radio outdoors. A kindred spirit, indeed.
I encourage all SWLing Post readers to bookmark and search London Shortwave’s website. It’s a treasure trove for the urban SWL. We thank him for allow us to post this article in its entirety.
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