Tag Archives: SDR

Mario shares a short review of the Airspy HF+ Discovery SDR

10 Replies

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who shares the following guest post:

Author’s Airspy HF+ Discovery (small black box to the left of the laptop)

A Short Review of the Airspy HF+ Discovery SDR

by Mario Filippi (N2HUN)

I recently purchased an AirSpy HF+ Discovery.  As a SWL for over 60 years who’s owned many shortwave radios by manufacturers such as Drake, Yaesu, Icom, Zenith, Kenwood, Panasonic, Sony, Radio Shack, Grundig, CountyComm, MFJ, Sears, AOR and have used a number of different SDRs such as the RTL-SDR.com, HackRF, NooElec and many other rudimentary inexpensive first generation SDR dongles, I feel the AirSpy was an excellent choice. It cost $169 plus shipping.

For LW/MW/HF reception, I use a 30’ ground mounted vertical with about 50 buried radials in different stages of decomposition hihi. For VHF, a roof mounted 2m/70cm SlimJim antenna is used, but I haven’t done much listening in that portion of the spectrum yet except for occasional foray into the aero, 2m ham, NOAA satellite and public service bands.  Note that the AirSpy also covers 60 – 260MHz.

An older Dell Inspiron laptop and SDR# are used in conjunction with the AirSpy.  For decoding, MultiPSK, FLDigi, MTTY, Yand (for NAVTEX), along with VB cable are the accompanying software to make the digital modes intelligible.

So far I’ve logged a few local LF aeronautical beacons and some DGPS beacons on longwave but will be in a better position to judge its performance when winter sets in.  As for the medium (520 – 1710 kHz) wave AM broadcast band, the AirSpy easily brings in both local stations during daytime and distant stations at night with no adjacent channel interference whatsoever.  Even low powered community Emergency Alert Stations in the 1600 – 1710 kHz portion of the band can be heard daily from this QTH. A rotatable loop would certainly improve reception though.

As for shortwave listening the AirSpy HF+Discovery is, in my opinion, great for listening to both shortwave broadcasts and utility stations though I tend to concentrate on UTES mostly such as VOLMET, WEFAX, RTTY (the few that remain unencrypted), CW marker stations (e.g. XSG and XSQ from China) NAVTEX (519 kHz), aero/maritime SSB, time signal stations (WWV, CHU) and many of the other esoteric digital utility signals populating the band.  As for SW broadcast stations, WRMI, Radio Exterior, RFI, R. Marti,  BBC, WWCR and Radio Algerienne, to mention a few have been received.  The Frequency Manager (memory storage) in SDR# has quickly filled up with intercepts using the AirSpy.

As a ham and CB operator (yes, the two can mutually coexist in the same human body), I’ve found the AirSpy HF+ Discovery to be a trouper on all the HF ham and CB bands. One of my favorite hangouts is the 28.100 – 28.300 MHz slice of 10m where domestic and international low power CW beacons transmit their callsigns (and at times their grid squares and power output) into the ionosphere and achieve great distances.  Recently, beacons from 5, 6 and 7 land in the US along with DX prefixes ED4, PY4 and XE1 were logged.  If you’re into 10m FM operation you can also tune the AirSpy to hear local and distant repeaters on 29.62 – 29.68 MHz.  When the band is open, .62 and .64 seem to be the most active here in Central NJ.

If you’re a CB (aptly named the Citizen’s Band) op, the AirSpy HF+ Discovery does a stellar job on Channels 1 – 40 which is especially exciting when the band’s open.  While domestic (USA)  CB’ers are limited to frequencies from 26.965 – 27.405 MHz you’ll nonetheless hear DX ops below our (USA) channel 1 and above channel 40 conversing in French, Spanish and German in LSB/USB.  Add to this mix the fact that the FCC dropped the 150 mile limit for US ops a few years back and now the advent of the FM mode operation in the US, you’ll find the AirSpy won’t disappoint.  In my opinion the AirSpy HF+Discovery was an excellent choice and I’m more than satisfied with its performance.

In the matter of honesty and full disclosure, I purchased the AirSpy HF+ Discovery completely on my own in an effort to upgrade my station.  My choice was based on information gathered from the Internet and YouTube video reviews.  The performance of this receiver was based on my experience using the vertical antenna described earlier, the hours spent at my QTH (location) listening to stations of interest to me and my six decades experience as a SWL.  No test equipment to assess sensitivity, selectivity or other empirical methods to measure performance was used. That information can be found on the Airspy website.  The main purpose of this article was to craft a rudimentary review for those interested with the caveat that reception will vary depending on many factors such as location, antenna, ionospheric conditions, feedline quality, computer/software variations, QRN, QRM, and operator experience.  The results presented in this article are typical for my location; others may experience different results.  Thanks very much.

Spread the radio love

Radio Waves: Insomnia-Fueled Pirate, Cold War & High-Tech Tactics for Russia, PL-660 Panadapter, Women-Run Radio in Somalia, and Building an SDR Transceiver

3 Replies

Radio Waves:  Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Meet the 68-year-old ‘bad-boy nerd’ behind this North Side pirate radio station (WBEZ)

If you’re driving through the greater Ravenswood area and tune your radio dial to 87.9 FM, you might just enter a sort of radio twilight zone. On tap? Old timey, crime-thriller radio dramas, complete with sleuthy melodramatic music, damsels in distress and classic radio sound effects – footsteps, doors slamming, the gun going off.

There are no call letters or DJs, just “audio noir” floating out over a two-square-mile sweet spot on Chicago’s North Side.

It’s all broadcast illegally out of a nondescript two-flat on a residential block. There’s a spindly antenna on the roof, visible mainly from the alley, and a 50-watt transmitter in the upstairs apartment. And there’s Bill, a retired computer and audio engineer who’s been operating this illegal station for some 15 years. He asked us not to use his last name for fear of “FCC prison.”

“People on the lakefront up in the high rises can hear it,” said Bill. “And they used to listen at Lane Tech somewhere on an upper floor. So it gets out a little ways, but not that far.”

Bill got into noir not because it’s gripping radio, but rather because it’s not. He has insomnia, and the plot lines from Dragnet and Yours Truly, Johnny Dollar help him fall asleep. [Continue reading and listen to this piece at WBEZ.]

U.S. and Ukrainian Groups Pierce Putin’s Propaganda Bubble (NY Times)

U.S.-backed news outlets and Ukrainian activists use Cold War techniques and high-tech tactics to get news about the war to Russians.

WASHINGTON — Using a mix of high-tech and Cold War tactics, Ukrainian activists and Western institutions have begun to pierce the propaganda bubble in Russia, circulating information about the Ukraine war among Russian citizens to sow doubt about the Kremlin’s accounts.

The efforts come at a particularly urgent moment: Moscow appears to be preparing for a new assault in eastern Ukraine that could prove devastatingly bloody to both sides, while mounting reports of atrocities make plain the brutality of the Kremlin’s tactics.

As Russia presents a sanitized version of the war, Ukrainian activists have been sending messages highlighting government corruption and incompetence in an effort to undermine faith in the Kremlin.

Radio Free Europe/Radio Liberty, a U.S.-funded but independent news organization founded decades ago, is trying to push its broadcasts deeper into Russia. Its Russian-language articles are published on copies of its websites called “mirrors,” which Russian censors seek out in a high-stakes game of whack-a-mole. Audience numbers have surged during the war despite the censorship. Continue reading →

Spread the radio love

Guest Post: An Introduction to DXing the MF Marine Bands

15 Replies

Many thanks to SWLing Post contributor, Don Moore–author of  Following Ghosts in Northern Peru–for the following guest post:

Monitoring the MF Marine Bands

By Don Moore

For me, DXing has always been about the challenge of receiving difficult-to-hear radio stations, regardless of the type of station or frequency range. In my five decades in the radio hobby I’ve logged a lot of different kinds of stations – shortwave broadcast, medium wave, shortwave utility, longwave beacons, etc. But some of my favorite catches have been in the upper end of the medium frequency range.

Technically speaking, medium frequency (MF) is the range from 300 to 3000 kHz and includes the standard medium wave (AM) broadcast band. The upper end of the MF band, from 1600 to 3000 kHz (except for a small portion reserved for amateur radio),  has always been assigned to various types of utility uses including broadcasts and other voice communications from regional maritime stations. And while digital modes and satellites have done a lot to change the nature of communication with ships at sea, there is still a lot of good human-voice DX to be heard.

Several dozen stations, mostly in Europe and North America, broadcast regularly scheduled marine information broadcasts in the MF range. These broadcasts are usually between five to ten minutes in length and include weather forecasts, navigational warnings, and other notices to keep ships at sea safe. On occasion it’s possible to hear two-way voice communication here between ships and shore stations, although that’s much less common today.

The Equipment

Nothing special is needed to DX the marine MF band other than a receiver that covers the frequency range and can receive USB mode (which all these broadcasts are in). However, for reasons explained below, I highly recommend using an SDR to make spectrum recordings of the entire band to go through later. Continue reading →

Spread the radio love

HFDY vs. Fire Brothers: Dan compares two Chinese Malahit SDR clones

10 Replies

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post and review:

Two Chinese Clones:   A Look at Noise Levels

Arriving recently here in the radio shack, were a Chinese clone under the name of “Fire Brothers” and another under the name HFDY.  I thought it would be constructive to note the key differences between these two clones, both of which are running Malahit 1.10c firmware, and post some video of a brief comparison.

A note in advance of any comments – I am primarily a HF listener so these comparisons do not cover frequencies above 30 MHz.  For those whose focus is on higher frequencies I recommend looking through the many comments on the Malahit Facebook group and Telegram by those who use these receivers in those ranges.

HFDY

  • Constructed of metal-like material (a correction from my previous articles that this is fiberglass of the kind used in printed circuit boards – thanks to Georgiy of Malahiteam for pointing this out)
  • Front speaker grille is gold color and appears to be metal but may be fiberglass as well – audio is quite good
  • Two top-mounted antenna jacks, one 50 ohm, the other Hi-Z (makes switching between HF and FM/VHF reception easier) with in-use LED indicators
  • Two high quality right side mounted black metal encoder knobs with large power button (clear printed Frequency/STDBY/Volume printed on panel)
  • Cabinet held together with TORX screws
  • 1.10c firmware
  • Receiver is elongated left to right to accommodate left side front-firing speaker, but is thinner overall and could be easily placed in a pocket though not recommended to prevent damage
  • Like every one of these SDRs, suffers from body sensitivity to touch which reduces signal levels unless some sort of additional ground is attached to cabinet
  • Internal flat-type Lithium battery of 3300 mAh though apparently capable of fitting up to 8000 mAh

Continue reading →

Spread the radio love

Dan adds updates to his Malahit SDR and variant reviews

2 Replies

Many thanks to SWLing Post contributor, Dan Robinson, for the following update to his previous post regard the DSP-2 and HFDY Malahit SDRs:

HFDY clone of the Russian-made Malahit SDR

Malahit and HFDY Updates

by Dan Robinson

HFDY CLONE:  As noted by a reader in comments, the Chinese-made HFDY leaves out a large portion of the military AIR band, with no coverage from 250MHz to 400MHz, or about 150MHz, whereas the Russian-made DSP2 only loses 20MHz from 380MHz to 400MHz.  This may be of concern for some readers, others not.

RUSSIAN DSP-2:  As users of the Russia-made DSP-2 may or may not have noticed, the current firmware shows SIX memory bank pages when there are only 5.  This appears not to have been discussed much on the Malahiteam Telegram group or elsewhere.  In response on this, Georgiy of Malahiteam says this “is normal and for our future features” so clearly there are future plans that we are not aware of.

CHINESE-MADE FIRE BROTHERS CLONE:  On September 21st, I took delivery of another China-manufactured clone, with a heavy metal cabinet, a vertical format with controls on top, and twin front-firing speakers.  Obtained via Alibaba, and branded as “Fire Brothers” this has a thick built-in telescopic antenna and a separate SMA jack which the maker describes as “[supporting] a better external shortwave antenna”

On Alibaba, prospective buyers of this receiver are given two options:  Type 1: 50KHz-2GHz without firmware updates supported, and Type 2 with support for updates.   The unit did arrive with 1.10c Malahit firmware with a 160 kHz bandscope width.

As noted above, this China-manufactured clone also blocks 200 mHz – 400 mHz and shows the Msi001 chip and STM32h743 and a claimed blocking figure of 85dB and  sensitivity up to 250MHz of 0.3?V = 10dB.  The battery is described as 5000 mAh and presumed to be flat type Lithium Ion.

The only thing included with this clone, which arrives in a plain black box marked “Fire Bros.Radio” is a USB-C cable.  That’s in stark contrast with the HFDY clone which comes in a high quality fabric zipper case, flexible whip antenna, USB-C cable, and a small metal stand.

The Fire Brothers manufacturer highlights the “high quality speakers” which not only fire out the front of the receiver, but also wrap around with openings on left and right sides of the radio.  My first tests show that audio is indeed quite nice, certainly equal to the Russia-made DSP-2, possibly an improvement on the HFDY clone which has a single front-firing speaker.

I’ll have more on this Chinese clone and some comparisons with the DSP-2, HFDY, and Afedri SDRs, in future articles here on SWLing Post.

Spread the radio love

Malahit DSP-2 versus Chinese Clone: Taking the Gloves Off

20 Replies

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post:

Malahit 2 versus Chinese Clone: Taking the Gloves Off

New DDC (Direct Digital Conversion) Version in Development

by Dan Robinson

It’s been a few weeks since my last commentary on the Malahit/Malachite, which as of this writing remains at the DSP-2 level, though there are continuing hints from the Malahiteam in Russia about future changes, including a DDC version.

All of the observations I made in previous articles are unchanged.  As of today in mid-September, the latest test firmware version posted by the Malahiteam remains M2_FW2_10D.  This includes a widening of the waterfall bandwidth from 160 kHz to 192 kHz.  See my previous articles for more information.

Recently, I obtained a Chinese clone, one which will be familiar to anyone who has taken a dive into the clone market.  This one is by HFDY and is immediately recognizable for its front speaker and longer slim rectangular form factor.

The HFDY (Malahit SDR V 3) has two high quality black metal encoder knobs on the right, with a large power button between, and USB-C and a headphone jack on the left side.  On the bottom are two OFF/ON slide switches, one marked for 3.3 volts and the other BOOT(O).

Continue reading →

Spread the radio love

Malahit DSP-2: Dan’s thoughts on external antennas, firmware, and purchase decisions

7 Replies

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post:

Additional Thoughts on the Malahit DSP-2 

  • Potential for Noise Reduction Using Non-Whip Antennas
  • Latest Firmware Changes

by Dan Robinson

After my last update on the Russia-made Malahit DSP-2, I thought it important to add something about the receiver, as it could well influence those who may be on the fence about purchasing one.

In a series of communications, Georgiy at Malahit team has stressed steps taken to attempt to deal with internal interference seen across the bands.  And he has asserted

that noise spikes lessen if the receiver is connected to a non-whip antenna.

Most of my tests have used whip antennas of various lengths, in various locations indoors and outdoors, because it’s my view that portability is a major attraction of these small SDR receivers.

Continue reading →

Spread the radio love