HF Propagation: Professional, free, and Real-time

IRTAM shows the actual state of the ionosphere – see text.

Without proper propagation, world-wide HF communications simply doesn’t exist. We, hams and SWLs, depend on the supporting power of the ionosphere and sometimes struggling with its capricious behavior. Many forecast models had been developed, VOACAP the most prominent among them. Like some far-looking weather models, they deliver broad probabilities – more the climate of the quarter than the weather in the afternoon. Even smart and processor-hungry 3D-raytracing software, taking into account more factors than just the average sunspot number of the month, do face challenges.

Here, IRTAM comes into play. The acronym means “IRI Real-Time Assimilative Mapping”, where IRI stands for the International Reference Ionosphere. This model is the base which is updated by the data of many of so-called digisondes. They are regularily probing the ionosphere at many locations of the world in time increments up to as short as five minutes.

The processed data reveal the actual space weather at this location. Experience, models and clever algorithms are used to spread (assimilate) these results over a world map, and, even more, to produce an animation of the last 24 hours – see the screenshop on the top. Click here to see the last 24 hours.

They show the frequencies, just reflected by the F2 layer under an angle of 90° (vertical sounding). You have to multiply these frequencies with a factor of about 3 to get the highest frequency, being reflected (indeed: refracted) for usual HF communications, or oblique sounding.

Additionally to this, the map will also show e.g. “deviation from climate”. By this map you can compare your VOACAP results (“climate”) to get an impression of the deviations – plus or minus, location, time.

It is a free service of a team around Prof. Bodo Reinisch, supported by world-wide data of their Lowell Digital Ionosondes, the gold standard in this field.

Medium Wave: Signals May tell sunris/Sunset at their transmitter’s site

The two stronger carriers (Romania left, Algeria right) exhibit Doppler-shifted scatter; see text for a more detailed explanation.

During my expeditions into the thicket of mediumwave offsets, I bumped into pictures like that at the top. In the lower part of the screenshot, you see two carriers mit seahorse-like structures looking to the right. In the evening, they look towards the West.

This is one of the several effects which can be seen at local sunrise/sunset. Here, the carrier gets “clouded” and show frequency changes. These effects are associated with Doppler shift (moving of ionospheric patches/layers) as well as scattering caused by irregularities of the ionosphere, most notably Travelling Ionospheric Disturbances, or TID. Whereas the Doppler shift, by vertical moving of reflecting layers like combining of F1- and F2-layer to one and lower F-layer when approaching darkness, is comparatively small, high wind speeds in these regions can cause a much faster horizontal movement of such regions. This, in turn, may cause a Doppler shift of about 1Hz or even higher in the medium wave range.

The Figure at the top demonstrates this effect at two transmitters on 1422kHz, namely SRR Radio România Actualități from Râmnicu Vâlcea/Olănești (sunrise 05:55 UTC/sunset 15:12 UTC; distance 1433km) and Radio Coran/Radio UFC/Radio Culture/Chaîne 3 from Ouled Fayet/Algeria (sunrise 06:58 UTC/sunset 17:00 UTC; distance 1840 km). Seen from midnight, sunrise first occurs at the Romanian transmitter, followed by the Algerian one with the seahorse-like pattern of the scatter towards the higher frequencies. Around each local sunset, first Romania sees darkness, followed by Algeria. Here, the scatter pattern turns towards the lower frequencies. In the insert at the right, contrast has been sharpened to additionally reveal a split-up of these carriers due to propagation into two paths.

This effect often helps to determine the local sunrise/sunset of a carrier. I marked what presumably is the carrier of MBC Radio 1 from Matiya/Malawi, sunrise 03:22 UTC; listed 02:00 to 22:00 UTC, but obviously on a 24 hours’ service this Tuesday.

Both Figures at the bottom try for some detective work without knowing specific offsets (because not available) but relying only on schedule and the above mentioned propagational effect. Crime scene takes place on 1233kHz, where we want to scrutinize two channels, one on 1232,9937 kHz, the other on 1232,9951kHz.

Distinctive scatter, associated with local sunrise at the transmitter, provides a strong hint towards the location.

The s/off- and the s/on pattern match that of Chinese National Radio #17’s Kazakh service. Incidentally, sunrise takes place in Qinghe at 01:42 UTC, and in Boertala at 02:04UTC – next Figure. Boertala is listed with 10kW (stronger signal), Qinghe with 1kW. Unfortunately, the f/out time of other CNR17 transmitters on this channel is mostly covered by phase noise from Rádio Dechovka in the Czech Republic and Absolute Radio in the United Kingdom.

Some CNR17 locations and the terminator during sunrise in Boertala, see text. Visualized with free Simon’s World Map.

Here I am indebted to Jens Mielich, Head of the ionosonde at Juliusruh/Germany, who was so kind to comment on this observation. According to him, the observed Doppler shift of 1Hz on 1422kHz should have been caused by a refracting medium, moving at an (angular) speed of roughly 105m/s. At Juliusruh, he observed e.g., an ionospheric drift of 311m/s±93m/s from East towards West on January 19, 2021 at 04:19 UTC: “You will get a positive Doppler shift during a West/North drift, and a negative one at East/South drift.” He adds that further investigations on a more longer time series are needed.


PSKOVNDB: An exciting new software for Mediumwave DXers

See the bunch of carriers on 590kHz at the left. PskovNDB shows at the right a diagram of noise, the combined signal strength of the 200Hz window and the signal strength of the carrier just picked.
Here the very carrier of VOCM/St. John’s had been clicked instead. You easily see that this signal is dominating the channel – only one of the many exciting features of free PskovNDB software!

Recently, I came across an upgraded version of Ivan Monogarov’s PskovNDB software, already having collected all laurels available as being the Gold Standard for chasing non-directional beacon, or NDBs. Recently, Ivan had expanded his tool with some as unique as exciting features for the avid medium wave DXer.

At a first view, it converts recorded WAV files (also: RF64 format, done with SDRC V3 software) into spectrograms of high resolution in which you can easily see the number of stations, measure their precise offset and see their signal strength.

A second view reveals the smart feature of producing diagrams of each signal – plus noise level and the combined power of the whole window. You can see both in the screenshots on top of this page.

A third view almost exactly helps to distinguish between signals where you can here music, listen at least to some words or phrases, or which do provide full audio.

Nothing more? Yes. Under the hood, there is much more. So, you can do automatically recordings each day and also automatically send them to PskovNDB software for showing the spectrograms, one after the other, like on a film roll. This enables you to pick the recording of the most promising day(s) for further inspection.

I wrote a short introduction to the beta version of this free software, and Ivan was so kind to add some most helping notes to this. You can download it here. It contains also some additional information, i.e. a link for downloading the software.

Spassiba, Ivan, for another software breakthrough!

Medium Wave: Offset Atlas – all 9 kHz channels Plus VLF & Longwave, 24 hours

The “Atlas” shows screenshots of all 9kHz channels on Medium Wave within a 50Hz window, sometimes better. It also shows some odd channels plus Time Signal Stations on VLF and all Broadcasting Longwave Channels. You can download it for free to determine accurate and stable offset readings over 24 hours (zoom in by e.g. 400%)

With the new Elad FDM-S3 and its OCXO/GNSS-stabilized clock, I did a 24h recording of the whole medium wave band on January 19, 2021 in Northern Germany; plus longwave on Januar 21, 2021. Free software SDRC V3 enabled me to make up a spectrogram of each channel within a window of 50Hz width, and at a frequency raster of 9kHz on medium wave. You can easily see:

  • sign-on/sign-off
  • fade-in/fade-out
  • accurate and stable frequency offset over full 24h down to a millihertz
  • frequency control of the transmitter’s oscillator (stable, drift, sinus, sawtooth …)
  • propagational effects (doppler, scatter …)

The format is PDF, DIN-A4, landscape, resolution 300dpi – see screenshot at the bottom. This allows you to zoom to a factor of about 400% to search for details and better read out of the time/frequency scale. It weighs 865MB. You can download it here, and open it with your PDF reader (you can also point your mouse cursor onto the link, click right mouse key, and choose “Save under …”). Leafing from one page to another gives an interesting overview.

A similar Atlas showing a raster of 10kHz is also available for free – just scroll to the previous post of this blog. It is also planned to publish a general article about the background, about what to do with such a tool, and how to do this by yourself.

I am sure that it will open some new horizons on Medium Wave DXing, including accurate offsets over up to 24h.

Medium Wave: Offset Atlas – all 10 kHz channels, 24 hours

The “Atlas” shows screenshots of all 10kHz channels on Medium Wave within a 50Hz window, sometimes better. You can download it for free to determine accurate and stable offset readings over 24 hours (zoom in by e.g. 400%)

With the new Elad FDM-S3 and its OCXO/GNSS-stabilized clock, I did a 24h recording of the whole medium wave band on January 19, 2021 in Northern Germany. Free software SDRC V3 enabled me to make up a spectrogram of each channel within a window of 50Hz width, and at a frequency raster of 10kHz. You can easily see:

  • sign-on/sign-off
  • fade-in/fade-out
  • accurate and stable frequency offset over full 24h down to a millihertz
  • frequency control of the transmitter’s oscillator (stable, drift, sinus, sawtooth …)
  • propagational effects (doppler, scatter …)

The format is PDF, DIN-A4, landscape, resolution 300dpi – see screenshot at the bottom. This allows you to zoom to a factor of about 400% to search for details and better read out of the time/frequency scale. It weighs 559MB. You can download it here, and open it with your PDF reader (you can also point your mouse cursor onto the link, click right mouse key, and choose “Save under …”). Leafing from one page to another gives an interesting overview.

Yes, a similar Atlas showing a raster of 9kHz is under way and will be published also here in due time. It is also planned to publish a general article about the background, about what to do with such a tool, and how to do this by yourself.

I am sure that it will open some new horizons on Medium Wave DXing, including accurate offsets over up to 24h.

Aloha: KUAU from Haiku/Hawaii, received on January 19, 2021 by DK8OK. Proofs are frequency, plus the rather unique fade-in/fade-out in the European afternoon.

Comments and suggestions are appreciated: dk8ok@gmx.net.

Millihertzing with Software “Carrier Sleuth”

24 hours on 590kHz on January 19, 2021 in Northern Germany, reveals a couple of North American signals with VOCM of St. John’s, Newfoundland being the strongest and KQNT Spokane on 590.002kHz/Washington State the most interesting with reception also in the afternoon.

“Millihertzing” seems to become “le must” of this season. The most recent software stems from smart software author Chris Smolinski, W3HFU, who over many years offers inspiring software,this new one dubbed Carrier Sleuth. It mainly analyzes I/Q-WAV files from software-defined radios at high resolution, being a perfect tool for measuring offset frequencies on mediumave. The screenshot at top shows such a spectrogram which covers 20Hz in width and 24h in length on 590kHz.

Why using “Carrier Sleuth”, when haveing SDRC V3 at hand? First, it works together with a multitude of WAV formats from many different SDR software (see Chris’ list, which is still expanding). Secondly, it let you hop from one channel (9kHz or 10kHz) to the next – if a proper part of the spectrum has already been converted from WAV to FFT. It also provides coverting spectrograms to CSV to apply some statistics on each signal. There are many more smart feature, and Chris will even add some exciting more, e.g. processing I/Q files in real time to save a lot of time.

With my bread-and-butter software being SDRC V3, recording in WAV RF64 one-file format (which sometime swells to nearly 10TB), “Carrier Sleuth” can even digest these recordings with a workaround: specify an interesting part of the medium wave, defined by upper and lower channel and time segment, and convert this into simple WAV. This is easily done with SDRC V3’s Data File Editor. It is also the way, Carrier Sleuth produced the screenshot at top of this page.

Chris published this software first on December 10, 2020. He eagerly looks for bug reports, applications and further suggestions form the users. Take a free test drive; registration code 19.99 US-$.

Magnificient FDM-S3: the Millihertz Magnifier

1340kHz, 25Hz window, resolution bandwidth 0.0061Hz: more than 100 U.S. AM stations are discernable by their frequency offset.Antenna: vertical active dipole MD300DX, 2 x 5m. Visualized with SDRC V3 software by Simon Brown, G4ELI.

With Elad’s FDM-S3 SDR now hitting the market, we have a receiver at hand which is supported by an OCXO/ GNSS frequency reference. This combines short-time accuracy with long-time stability and allows for precise frequency measurement in the millihertz range (under 30MHz). Exploiting this feature is as exciting as it is innovative. With this new tool, also a new kind of DXing is evolving. One example is propagation analysis. See below the 24h spectrogram of Radio Gotel from Jabura/Nigeria on its exclusive channel of 917kHz:

Radio Gotel transmits from 04:00 UTC to 23:00 UTC on 917kHz. In this spectrogram you clearly see sign-on, sign-off; fade-out, fade-in, plus some other feature like two short power breaks in the evening as well as some instabilities.

What surprises, is both, the late fade out at around 07:30UTC and the early fade-in as early as 15:20UTC. It is important to note that you here see the carrier with a resolution bandwidth of 0.0009Hz, roughly just one millihertz. The gain, compared to a listening bandwidth of 10 kHz, is a whopping 70dB, allowing extreme DX. Audio starts to emerge only from around 18:00UTC. As DX Atlas shows, the whole path between my location and Radio Gotel is under daylight at the palpable fade-in at around 15:20UTC, see screenshot below.

At the first visible trace of Radio Gotel at DK8OK’s location on 19JAN2021, with the whole path still is in daylight. Illustration with the help of DX Atlas software.

As with all new things: “We’ve only just begun”, Carpenters, 1970. To be continued.

Prösterchen: DARC-Funktionäre lassen ‘s krachen!

Prioritäten setzen: 2019 erhielt das “Referat HF-Technik” des DARC gerade mal drei Prozent jener Summe, mit der sich die DARC-Funktionäre für ihr Essen & Trinken von den Mitgliedern aushalten ließen – wohl bekomm ‘s!

Seit ich als junger Mensch in den Deutschen Amateur Radio-Club e.v. (DARC) eintrat, höre ich dieselbe Melodie: “Der Altersdurchschnitt unseres Vereins ist zu hoch! Wir müssen zudem mehr Technik machen!” Diese Sprüche haben selbst meinen Rausschmiss im Jahre 1992 überlebt – und doch hat sich geradezu dramatisches getan! Nein, nicht in Sachen Senioren-Überhang, auch nicht in Sachen Technik-Präferenz. Sondern im weiteren Niedergang von rund 60.000 Mitgliedern kurz vor meinem Rausschmiss bis Anfang 2021, wo es noch gerade mal 32.808 Mitglieder sind.

1.000 Mitglieder weniger je Jahr

Im Zusammenhang mit meinem Rausschmiss hatte ich die Funktionäre gewarnt, dass wegen dieser ausgepichten Art des Ham Spirit sicherlich ein paar Mitglieder den Verein verlassen würden. “Wie viele, meinst Du denn”, fragte jemand höhnisch zurück. Darauf ich: “So um die 1.000 Leute, etwa!”, und, in sein darob berstendes Lachen hinein: “Nicht insgesamt, sondern Jahr für Jahr 1.000 Leute.” Die Herren Funktionäre lachten Tränen. Nun, nach 27 Jahren, hat der DARC gut 27.000 Mitglieder weniger als zu jenem Zeitpunkt. Wer einen Dreisatz beherrscht, kann sich ausrechnen, dass meine Einschätzung halbwegs realistisch war – und die Funktionäre ihre Hanswurstereien betrieben.

Soweit, so schlecht. Aber feiern, das verstehen die Herren (und wenigen Damen) DARC-Funktionäre vorzüglich: knapp 57.000 Euro gaben sie für Essen & Trinken allein im Jahre 2019 aus: Prösterchen! Und die Jugend? Bei einem Beitrag von 31,20 Euro im selben Jahre für unter 18-Jährige mussten über 1.800 dieser Jugendlichen ihre kompletten DARC-Mitgliedsbeiträge aufwenden, um den Appetit & Durst der Funktionäre angemessen zu stillen.

Referat HF-Technik: drei Prozent der Bewirtungskosten

Aber – Technik genießt doch bei unserem technisch-wissenschaftlichen Hobby den Vorrang vor allem anderen? Follow the money: 1.842,30 Euro erhielt das “Referat HF-Technik” – die Herzkammer des Vereins – für ihre Tätigkeit. Dem Taschengeldempfänger oder dem Kleinrentner mag das angängig dünken. Doch es sind nur drei Prozent der sogenannten “Bewirtungskosten”!

Das aber ist noch lange nicht das Ende der Wohltaten. Denn für genau 10.740,63 Euro machte man “Geschenke”. Vermutlich mehr unter seinesgleichen, als dass man Jugendliche damit beglückte.

Aber die Reiselust, die ist doch bei einem Verein, in dessen Zentrum die technisch-schwere-, wie kostenlose Kommunikation steht, kein Thema, oder? Nicht ganz. Denn wiederum im Jahre 2019 finanzierten die Mitglieder 200.744,18 Euro an Reisekosten für ihre Funktionäre: “Lebe wohl, gute Reise” (Comedian Harmonists, 1934). Bei der Rechnungslegung für 2020 wird man hoffentlich sehen, welcher Anteil davon überflüssig war.

Die Kosten der vielen sind Einnahmen weniger

Doch des einen Kosten, sind des anderen Einnahmen. Seit dem Jahre 1340, als man den schönen Buchungssatz “Soll an Haben”, wohl in Genua, erfand. Nein, hier soll nicht die Rede von den angeblich rund 150.000 Euro sein, die ein Vereinskamerad ohne jede Ausschreibung für die Übersetzung eines Buches erhalten haben soll, das man seitdem vor praktisch aller Welt versteckt und das nach DARC-eigenen Maßstäben mit gerade mal rund 10 Prozent dieser Summe entlohnt worden wäre. (Dieser Fall dürfte im gesamten deutschen Verlagswesen einmalig sein. Jeder Verlagsgeschäftsführer wäre fristlos geflogen, hier aber scheint der damalige 1. DARC-Vorsitzende die Sache abgesegnet zu haben – anders ist es nicht denkbar.)

Aber bleiben wir weiter bei den Einnahmen, die ja die Kosten der Mitglieder sind. Für Rechts- und Beratungskosten kassierten Rechtsanwälte und Berater 85,475,77 Euro im Jahre 2019, wozu sich noch 5.422,99 Euro “Rechtskosten” addierten. Wie man inzwischen weiß, ist dieses Geld auch dafür ausgegeben worden, um unbotmäßige Mitglieder mit kostenträchtigen Schreiben zu zwiebeln. Von rechtlichen Durchbrüchen bei Antennengenehmigungen oder in Sachen EMV hat man hingegen nichts gehört.

Notfunk in Not

Und wie steht es um den Notfunk, der neben Jugendarbeit und Technik als heilige Dreifaltigkeit immer dann ins Schaufenster gestellt wird, wenn man die gesellschaftliche Wichtigkeit des Amateurfunks darstellen will? Macht keine 1,6 Prozent dessen, was der DARC für Rechtshändel & Co. ausgibt.

Dick loben aber wollen wir doch die 27,20 Euro, die der DARC 2019 für das UKW-Funksport-Referat springen ließ (also nicht einmal das Trinkgeld in einem Sterne-Schuppen). Denn Funksport ist ja auch wichtig! Gegenüber den Ausgaben für das, was die Funktionäre “Referat Handicap Hams” nennen, erscheint das absolut top generös – denn der Etat, mit dem der DARC unser Hobby für Menschen mit Beeinträchtigungen fördert, liegt bei exakt 0,00 Euro. “Gemeinnützigkeit” will halt verdient werden.

Nur kein Neid!

Zur Klarstellung: Ich esse, trinke und reise selbst ebenso gerne wie gut. Allerdings, Essen & Trinken, auch in der Drei-Sterne-Gastronomie, als Alleinzahler. Zu Neid besteht bei mir kein Anlass, in das DARC-eigene “Hotel Stadt Baunatal”, allerdings hat mich selbst meine sonst unstillbare Neugier noch nicht geführt. Aufmerksam machen wollte ich hier lediglich auf etwas, was man als Missverhältnis zwischen Reden und Tun auffassen kann, zwischen Dampfplauderei und den harten Fakten einer Bilanz. Damit sich was ändert. Am besten, zum besseren.

Wer die Verantwortung trägt

Die Bilanz, übrigens, sollten die Rechnungsprüfer (Kosten “Rechnungsprüfungsausschuss”: 1.016,62 Euro) nicht nur dahingehend prüfen, ob 1 und 1 richtig zusammengezählt sind, sondern auch, ob das Geld entsprechend des Vereinszwecks ausgegeben wird. Und der lautet beim DARC immer noch nicht: Essen Trinken, Reisen. Nicht zuletzt hat der Amateurrat es in der Hand, dem Finanzgebaren (von dem er allerdings unmittelbar ebenso wie mittelbar profitiert) zuzustimmen oder zu widersprechen. Und? Angenommen bei 67 Ja-Stimmen, keiner Gegenstimme sowie zwei Enthaltungen. Wenn einem so viel Gutes widerfährt, das ist schon einen Asbach Uralt wert, wie es erstmals 1955 hieß – wir sprachen ja über das Thema “Überalterung”. Vielleicht gar einen “Asbach Goethe” – ein Rollgriff ins Spesenkonto würde das lässig hergeben.

Seeing is believing: Tableau visualizing MWLIST

All medium wave stations from MWLIST, drawn with free Tableau software: the size of the circles represents the power of the stations, the colour the type of network.

Broadcasting on medium wave still is a very active part of using the electromagnetic spectrum. An unique and outstanding source of information is supplied for free by MWLIST, a team of smart DXers. They provide tons of up-to-date and precise information – down to exact locations and even offsets from the nominal channel.

By visualizing those data, you get an even better insight. Here, free Tableau Public software is (for me) the tool of choice to do just that – please see the screenshot on top of this page. You simply download the free Tableau app, and – also for free – sign up, and you are done.

For me, most striking is visualizing the spatial data, i.e. to show the transmitters at their proper place on a map. Another welcome feature is filtering the data to answer specific questions like: How are traffic broadcast stations above 1.6 MHz spread over Pennsylvania? Or: What can I expect listening on 1521kHz on a late winter afternoon in Europe? Or: Where are Chinese stations located, carrying the CNR1 programme of China National Radio? You will find screenshots illustrating these examples below.

Those are just screenshots, not active maps. If you want active maps, there is an option (WP-TAB, Tableau Public Viz Block) available for WordPress’ business version which I don’t have at hand.
But there is a simple solution: go to my Tableau Public page, download my TWBX-map “Medium Wave Station [Copyright MW List]”, and it will automatically be loaded into your Tableau Public app – after you have installed this. Then the map comes into live, and you can do all filtering, zooming etc.

[My profile photo shows a fisher’s deity in Japan, seen in October 2019 in Tokyo’s Kappabashi street. As a DXer and hobby cook, I thought location and statue being quite appropriate – thanks for asking …]

Surely, you immediately will find other ideas to realize, e.g. marking heard/verified signals by just a flag in your list and combining this with a special color on that station on your Tableau map.

Kiashahr broadcasting center of IRIB, the Iranian broadcaster, on the shores of the Caspian Sea. All three antenna sites are pinpointed on Tableau’s “Satellite” background map. Listen to the recording of IRIB Gilan (from the antennas at the left) below:
IRIB Radio Gilan, received on December 30, 2020 at 14:30 UTC in Germany.
Traffic broadcast in Pennsylvania duly follows the trail like pearls on a string, here e.g. US Highway 80 in the mid of the screenshot.
1521 kHz on a winter afternoon in Europe: What stations can be expected, and what interference should be avoided? MWLIST’s spatial data plus Tableau’s power of filtering the data and drawing it onto a map will show this at a glance.
How are transmitter, carrying the CNR1 programme, scattered over China? This screenshot will tell.

P.S.: Taking some suggestions from the fruitful discussion which follows the initial publication of this site, I like to add some more examples:

If you are looking for some challenges, a European listener may start with low-power stations in the UK (LPAM), transmitting with just 1 Watt of power, leaving 500mW from both sidebands, combined, for the audio at max. Filtering the MWLIST with Tableau Public and visualizing this by a map, leads to the screenshot below. I also attached an audio clip of Carillon Radio. Yes, reception quality of this station of the Leicester/Loughborough hospital resembles a bit the state of NHS 😉

All LAPM stations in the AM band do transmit with 1 watt of power only. They place a nice challenge for European listeners …
LPAM Carillon Radio on 1386kHz/1W, received on December 27, 2020 near Hanover/Northern Germany. Antenna: MD300DX active vertical dipole, receiver: Winradio Sigma.

A second example is even more challenging for European DXers, but not entirely impossible. The map shows some low-power Japanese service radio stations for parks, traffic, weather and harbours.

MWLIST has been filtered, so that Tableau’s map shows just the low-power Japanese service radio stations in the x-band (i.e. above 1602kHz. Reception of those stations in Europe is challenging, but possible, as …
… this recording of Tokyo Martis Radio [highlighted on the map above] on October 23, 2019 on 1663.5kHz shows at 10:00 UTC. The audio clip was extracted by DK8OK from a HF recording [WAV] at Norway’s KONG station, with sincere thanks to Bjarne Mjelde.

RX-888: 32 MHz/16bit, 200 US-$ – pricks up your ears

The RX-888 covers 32MHz @16Bit in a row. Here it comes to life with Simon Brown’s unique and indispensable software SDRC V3 at an professional active dipole antenna MD300DX.

It is the (a few weeks) younger brother to the RX-666, a brainchild of Oscar Steila, IK1XPV. And it is one of the first palm-sized SDRs in the price class of 200 US-$ which covers the whole HF band for receiving, recording and playing with 16Bit resolution, resulting in a competitive dynamic range of about 100dB. I got one from China via eBay (there are numerous sellers) within a few days. Overnight, Simon, G4ELI, made his SDRC V3 software to match also to the RX-888 with excellence. You need a PC, an i5 should do it, with USB3.0 for data streaming, controlling and power supply. Yes, there is no need for a separate 5 or 12VDC!

Much had been speculated about one obvious fact: the price of the A/D chip is, if only a medium order is placed, the same or even higher than the price tag at the RX-888. How comes? One rumor with some substantial background results in this story: the chips had been desoldered from boards of other projects which didn’t pass the quality control. These boards had been sold at a low price as a bonanza to smart people who can use all the parts which on their own will have passed the quality control, most notably the pivotal A/D chip.

This blog should give you a first impression. The biggest difference between RX-666 and RX-888 seems to be that the latter is equipped with a permanent low-noise amplifier of +20dB which perfectly balances sensitivity and dynamic range for 90% of us DXers. Sensitivity on HF is nearly on par with FDM-S2.

Two antenna sockets – the impressive cooling fins on three sides of the box will be needed after a planned update of covering 64 MHz in a row with 16Bit, and up to 10MHz (now: 8MHz) above 64MHz.

I tested the RX-888 from 10kHz to 32MHz and had a look above 32MHz – see the two following screenshots.

RJH69 on VLF 25.0kHz. This time signal from Belarus was received at 07:06 UTC on 02SEP2020 in Northern Germany and read with CW decoder MRP40.
A look onto 8MHz of the FM broadcast band.

The RX-888 also worky nicely together with decoders like DRM or (other) data, see the two following screenshots.

The very weak DRM signal of China National Radio on 9655kHz [Urumqui, 30kW, antenna direction 98°!] is duly received by the RX-888 with the data decoded with free DREAM software.
US Air Force Diego Garcia [JDG] in the Indian Ocean calling their Lajes counterpart [PLA] in the Açores on 4721kHz at 17:18UTC in MIL-STD-188-141A.

PC power: Nowadays, a “receiver” is a system, consisting of an SDR (the box), software and the PC. While world-class software SDRC V3 is for free, and an top SDR costs just about 200 US-$, you should not forget an able PC. It must be an i5 and up if you want to digest bigger bandwidth like 8 MHz, 16 MHz or even 32MHz. Even for recording 32 MHz, there is no need for internal SSDs, a fast iron disk will do the job. Furthermore: 32MHz recording for 24 hours do expect a bit more than 11TB disk space. This calls for an external HD, and a second USB3.0 card (not: hub!) is a must. As external HD, I use the WD MyBook Duo, delivering 28TB at under 750 US-$. The combination of an desktop i7 and this HD ensures stutter-free recording and playing up to bandwidth of at least 32MHz. Here simply more is more …

Last, but not least, please find below a few audio examples of broadcast as well as utility stations. They proof that the RX-888 is a serious receiver at a ridiculous low price.

4712 kHz/USB: Russian Airports with radio checks in Russian: Kazan, Rostov (net control), Saratov, Samara, Novosibirsk, Chelayabinsk. They transmit with 1kW of power to a low-hanging dipole. 02SEP2020, 17:00 UTC.
4750kHz/AM-ECSS: Bangladesh Betar with ID over an obviously defective transmitter (nominal 100kW). 02SEP2020, 17:00UTC.
4800kHz/AM-SAM: Chinese National Radio Beijing I (Geermu, 100kW) ID in Mandarin, ID. 02SEP2020, 22:00 UTC.
4920kHz/AM: Tibet People’s Broadcasting Station (Lhasa, 100kW), ID in Tibetan. 02SEP2020, 21:00 UTC.
5000kHz/CW: Chinese Time Signal Station BPM (Sha’anxi/Pucheng, 5kW), ID in CW. 02SEP2020, 22:00UTC.
6676kHz/USB: Singapore VOLMET, 5kW, ID and weather in English. 02SEP2020, 17:20UTC.
6676kHz/USB: Bangkok VOLMET, 5kW, ID and weather in English. 02SEP2020, 18:10UTC.
7240kHz/AM: Tibet People’s Broadcasting Station (Lhasa, 100kW), ID in Mandarin. 02SEP2020, 21:00 UTC.
9275kHz/AM: FEBC Philippines/Bocaue (100kW), ID in Mandarin. 02SEP2020, 14:00 UTC.
9310kHz/AM: VoA Deewa Radio (Udon Thani/Thailand, 250kHz), ID in Pashtun/Urdu. 02SEP2020, 14:00UTC.
9664,77kHz/LSB: Radio Voz Missionaria (Camboriu/Brazil, 10kW), ID in Portuguese. 02SEP2020, 22:00UTC.
10’000kHz/CW: Chinese Time Signal Station BPM (Sha’anxi/Pucheng, 5kW), ID in CW. 02SEP2020, 17:00UTC.
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