Tag Archives: HF

Addendum: More Notes on the HF+ SDR on Medium Wave & Long Wave

In my recent post on the AirSpy HF+ vs Elad FDM-S2, I commented on medium wave reception only.

This past weekend I swapped out the Wellbrook ALA1530S+ for another Wellbrook loop, the ALA1530LN Pro. This LN Pro model is less likely to overload receivers at my suburban Tacoma, WA location. Both AirSpy and Elad radios performed admirably with the LN Pro and it was nearly impossible to find any reception differences on medium wave.

Before the antenna swap though I experimented with inline attenuation modules (“bullets”), typically used in cable TV installations. I used the same sample rates on the SDRs as described in the previous article. After some tests with different attenuation levels, I came to the following conclusions during daytime comparisons:

FDM-S2 with ALA1530S+ loop, medium wave: needs a minimum of 6 dB attenuation to avoid overloading. Anything less causes saturation of the spectrum & waterfall, “crunching” overload noises, and minimal or no received signal.

HF+ with ALA1530S+ loop, medium wave: I had to search diligently to find any signs of false signals or overloading, but finally noticed a weak image or spur of a S-9+60 dB (-13.5 dBm) local station on 1560 that was appearing very weakly on 1270 kHz, mixing with the station on that frequency. Sometimes it was there, other times the spur or image would drop down and disappear, leaving the 1270 signal alone. If I added just 3 dB of attenuation in the antenna’s feed line, the interference from the 1560 station was gone for good. The S-9+60 dB station is a very strong signal; it’s impressive that the AirSpy HF+ deals with this and similar powerhouse signals so well.

Long wave: Below are two screen captures from my local long wave reception in the evening, made moments apart with each receiver.

FDM-S2

HF+

As you can tell, there are a half dozen or so additional signals seen on the HF+ below 200 kHz that do not appear on the FDM-S2. These extra spikes are images or spurs from medium wave signals that were missing from the FDM-S2’s reception–bravo Elad! However, the remaining spikes on both radios below 200 kHz seemed to be noise or interference.

Each receiver had roughly equal performance in the bulk of the long wave spectrum, when I did A-B comparisons on the same beacon signals. I’m not a LW or NDB DXer however, so I can’t claim any expertise on these frequencies. In short, though, both radios seem neck-and-neck from about 200 to 500 kHz.

The DXer of LW frequencies may want to look elsewhere for a better performing radio than either the FDM-S2 or HF+. SWLing Post reader Tudor Vedeanu has commented that the SDRPlay RSP1A  and the Eton E1 work very well at long wave.

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

Brief Medium Wave Tests of the HF+ and FDM-S2 SDRs in a Suburban Location

The AirSpy HF+ is the new SDR on the block, but how does it compare to the Elad FDM-S2 which is more than 2-1/2 times its $199 price? My main interest is finding out how they compare in a very RF-quiet DXpedition setting, but today I compared the two briefly from my home in Puyallup, Washington (near Seattle).

The receivers were connected via a two-way antenna splitter to the output of a Wellbrook ALA1530S+ loop antenna. I monitored during mid-afternoon local time to ensure that all my MW locals in my suburban location would be at full power, for the best test of the radios’ overload performance. The Wellbrook active antenna is rather “hot” and sometimes overloads receivers during the daytime unless attenuation is added to the signal chain.

I noted there were no truly weak medium wave signals available during the session so comparing sensitivity wasn’t appropriate. However, the band was full of strong daytime MW signals.

It became apparent quickly that the upstart HF+ provides strong competition to the Elad SDR. Clearly, the AirSpy’s trade-off is bandwidth for raw performance at lower cost–approx. 660 kHz alias-free coverage versus about 6 MHz maximum for the Elad.

Using the same center L.O. (local oscillator) frequency, short recordings were made with both receivers on the same receive frequency, same bandwidth, AGC setting, etc.  To approximate the 660 kHz coverage of the HF+, I set the FDM-S2 to its 768 kHz sampling rate, the closest available setting to 660 kHz wide coverage.

Here are the results on 1540 kHz, just 10 kHz away from a strong signal on 1550:

AirSpy HF+ – 1540 kHz


Elad FDM-S2 – 1540 kHz

What’s wrong with the above audio picture? The FDM-S2 is clearly overwhelmed by the strong RF on the upper end of the MW band. Visually, the spectrum looked like this with the Elad:

Elad FDM-S2 waterfall/spectrum (1540 kHz)

The noise floor rose by approximately 20 dB due to the overloading. The HF+ showed a normal waterfall and spectrum display while tuning 1540 kHz:

AirSpy HF+ waterfall/spectrum (1540 kHz)

Let’s listen to two more audio clips, this time from 720 kHz which is adjacent to very strong 710 KIRO, the ESPN affiliate in Seattle:

AirSpy HF+ – 720 kHz


Elad FDM-S2 – 720 kHz

This time the difference is subtle, but I think you’ll agree there is a greater amount of “crunchy” background distortion noise on the FDM-S2 recording. I found this to be the case in each instance where I compared receivers on frequencies adjacent to strong locals.

I no longer own a Perseus SDR, but that receiver handles the entire MW band at this location without overload using the same Wellbrook ALA1530S+ loop.

I’d like to emphasize that these were brief, somewhat casual AirSpy HF+ vs. Elad FDM-S2 tests. I expect that in a more forgiving RF environment, both receivers will be equally adept and digging out weak weak and challenging DX signals. I plan to investigate this very scenario in a few weeks at a quiet location on the Oregon coast.

Side note: I have two HF+ units and they can operate concurrently without problems for full medium wave band coverage with HSDSR software, even when both are recording IQ WAV files.

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

Airspy HF+ SDR Now Available to Order

As reported recently on the SWLing Post that the Airspy HF+  would be available “really, really, really soon”, the rumor has become reality–this new SDR receiver is for sale on Airspy’s main sale site www.Itead.cc.

The direct link for purchase is: https://www.itead.cc/airspy-hf-plus.html.  The price in US dollars is a very reasonable $199.00, considering the high performance evident by the few test units “in the wild” recently.

There was an initial $50-off coupon code available first come, first served this morning for the first 100 orders. These were snapped up quickly; I was fortunate to make it into that limited group and I saved $50 each off a couple of HF+ units. My intent is to pair them up for full coverage of the medium wave band–while recording I/Q WAV files)–using two receiver “instances” within Studio 1 or SDR-Console software. (The alias-free bandwidth of the HF+ is a modest 660 kHz, a trade-off this receiver makes to deliver high performance at a low price.) I expect a EXTIO DLL file to be available soon for use in EXTIO software like Studio 1 (or the EXTIO version of SDRuno which I also use).

I plan to be comparing the HF+ to my current Elad FDM-S2 SDR; based on specs and early user reports, it should be a tight race.

UPDATE: I’ve learned that the shipping timeframe for the HF+ is the beginning of December (approx. three weeks). There is also a U.S. distributor who is kindly offering a similar $50-off deal: https://v3.airspy.us/product/airspy-hfplus/

Simon Brown, author of the popular SDR-Console software versions, closely compares the Airspy HF+ ($199 USD) against a RFspace NetSDR ($1449 USD w/o options): http://www.sdr-radio.com/Radios/Airspy/AirspyHF

Who else is planning on an Airspy HF+ purchase? What are your monitoring interests you plan to use it for? Please comment below and share your thoughts with other SWLing Post readers!

 

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

ITU Monitoring Programme: 2.85 to 28 MHz

Fullscreen capture 10142015 42958 PM

I’m having difficulty remembering who sent me a link to the ITU Monitoring Programme, but I am most grateful.

What is the monitoring programme? Here’s the description from the ITU website:

“The objective of this monitoring programme is to identify stations whose emissions in bands between 2 850 kHz and 28 000 kHz are not in conformity with the RR and to provide administrations that do not have monitoring facilities with information for frequency management purposes.

?The Bureau prepares a publication containing spectrum monitoring information in the frequency bands between 2 850 kHz and 28 000 kHz submitted by administrations in accordance with BR Circular-letter CR/159 of 9 May 2001.”

The data can be downloaded in spreadsheet format, organized by monitoring date. It’s an amazing amount of information–a decent survey of what can be found on the bands.

Click here to view the list of spreadsheets.

Global 24’s take on the future of the shortwave radio

Many thanks to the staff of Global 24 for the following response to my post, Does Shortwave Radio Have a Future?:


Global24

To Shortwave Listeners of the World:

Shortwave radio is not dying. In fact, we think the whole story line should just go away.

We wanted to thank Thomas Witherspoon of SWLing.com for his excellent article on this very topic and the team of Global 24 wanted to share our perspective on this question.

First,

The 5,000 of you that have written to Global 24 since November 1, 2014 attest to the fact that shortwave radio is not dying.

The 1,000 of you that have joined our Listeners Club and Insiders Club since November 1, 2014 attest to the fact that shortwave radio is not dying.

The 30,000 unique visitors that visited our website, Global24Radio.com, since November 1, 2014 attest to the fact that shortwave radio is not dying.

You can expect Global 24 to be outspoken whenever and where ever we hear the words that shortwave radio is dying.

Yes, many government broadcast operations have closed up shop. They are totally incorrect in their worldview and so-called “research”. The public diplomacy and foreign policies of governments around the world are in incoherent disarray. It’s not surprising that incoherent foreign policy equates to government shortwave broadcasting being cut back. The fact that the U.S. government thinks shortwave is a medium of the past – should be enough for us all to stand up and cast a doubtful stare.

Whether we are confronting Ebola, dwindling global natural resources,welcoming the Arab spring or dealing with the reality of more and more failed states – states based on borders and beliefs largely imposed by the West – we are living in a world that is more dangerous than ever.

Important World Events Need a Western Perspective on Shortwave

Yes, we live in a world where terrorists groups like ISIS send out thousands of tweets an hour recruiting people to their violent worldview. Yes, we live in a world where ISIS produces an “Annual Report” that visually looks as good as than anything the Voice of America (VoA) produces. Yes, we live in a world where the internet reach of terrorists far eclipses the audience of the VoA. Does shortwave have a place in this world? Of course it does. One kid in Syria – or anywhere in the Middle East – listening to a shortwave radio that gets a different perspective and doesn’t go radical makes it worth it to us. Shortwave is a place where moderate worldviews can be heard easily.

Anyone with TV access or web access has so many other choices for information gathering. Why yield the field in shortwave – the one place where an audience is guaranteed? The governments of many nations, especially the United States need to “go back to the basics” and go back to shortwave radio. VoA, Radio Free Europe, Radio Liberty, Radio Free Asia, Radio Marti and the Middle Eastern Broadcasters need to have their shortwave budgets exponentially increased immediately. It’s not just about hot button issues and unfree governments – it’s about inexpensive access to information for the world and simple “soft power”. Simply look at China Radio International or the Xinhua news agency and you will see a rapidly growing international presence – they are fighting the fights we have already largely walked away from.

The Developing World Still Need Shortwave

We live in a world where access to electricity is still limited to huge swaths of our brothers and sisters around the world. Does shortwave have a place of growing importance in this world? Of course, it does.

Shortwave radio requires no electrical mains, no internet access, no subscriptions – and of course, one radio can be shared and listened to by so many people. How can we live in a world where so many people don’t have clean water, electricity, basic medical care and access to information and think that social media, TV and the internet are the sole communication vehicles of the future? When kids in every country the world over have the water they need, the eyeglasses they need, the medical care they need, the electricity they need and the education they need, then maybe we can talk about engaging them on their smartphones and TVs exclusively and winning over their hearts and minds with 160 character “Tweets”.

Shortwave was, and is, a battle that must be won – not given up on.

The Rest of Us Still Need Shortwave

For the first time in many of our lives, we all should genuinely concerned about press freedom in the United States and in other “First World” nations – yet alone press freedom in countries driving world events like Russia, China, Saudi Arabia and Iran. Across our country more and more people are seeking a simpler lifestyle unburdened by expensive TV, internet and satellite connections. A lifestyle characterized by a lack of dependence – in terms of either information, resources or infrastructure. We are prepping, homesteading and preparing to live off the grid together. We are buying our guns, packing our bug out bags and drawing up emergency plans for our families. .

What We Plan to Do

Here at Global 24 – we are a modest operation but we will be bringing to the world a new view of shortwave radio. Together with our listeners, we can do what governments can not do alone: create a renaissance in shortwave listening in the form of commercial shortwave listening before manufacturers stop making radios and stores stop marketing and selling them. These are the real threats to shortwave radio.