{"id":47665,"date":"2021-02-07T09:26:09","date_gmt":"2021-02-07T13:26:09","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=47665"},"modified":"2021-02-07T09:26:09","modified_gmt":"2021-02-07T13:26:09","slug":"guest-post-using-carrier-sleuth-to-find-the-fine-details-of-dx","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2021\/02\/guest-post-using-carrier-sleuth-to-find-the-fine-details-of-dx\/","title":{"rendered":"Guest Post: Using Carrier Sleuth to Find the Fine Details of DX"},"content":{"rendered":"

\"\"<\/a>Many thanks to SWLing Post<\/em> contributor, Nick Hall-Patch, for sharing the following guest post:<\/strong><\/p>\n

\n

Using Carrier Sleuth to Find the Fine Details of DX<\/b><\/h1>\n

by Nick Hall-Patch<\/strong><\/p>\n

Introduction\u00a0<\/b><\/h2>\n

Medium wave DXers are not all technical experts, but most of us understand that the amplitude modulated signals that we listen to are defined by a strong carrier frequency, surrounded on either side by a band of mirror image sideband frequencies, containing the audio information in the broadcast.<\/p>\n

Most DXers\u2019 traditional\u00a0 experience of carriers has been in using the BFO of a receiver, using USB or LSB mode, and hearing the\u00a0 decreasing audio tone approaching \u201czero beat\u201d of the receiver\u2019s internal carrier compared with the DX\u2019s carrier frequency as one tuned past it.\u00a0 This was often used as a way of detecting that a signal was on the channel, but otherwise wasn\u2019t strong enough to deliver audio.\u00a0 Subaudible heterodynes,\u00a0 regular pulsations imposed on the received audio from a DX station, could indicate that there was a second station hiding there, with a slightly different carrier frequency,\u00a0 And, complex pulsations, or even outright low-pitched tones could indicate three or more stations potentially available on a single channel.<\/p>\n

With the advent of software defined radio (SDR) within the last 10 years or so, the DXer has also been able to see a graphical representation of the frequency spectrum of the carrier and its associated sidebands.\u00a0 (Figure 1<\/b>)\u00a0 Note that the carrier usually remains stable in amplitude and frequency, unless there are variations introduced by propagation, but that the sidebands are extremely variable.<\/p>\n

\"\"<\/a>

Figure 1<\/p><\/div>\n

\"\"<\/a>

Figure 2<\/p><\/div>\n

In addition, by looking at a finer resolution of the SDR\u2019s waterfall display, one might see additional carriers on a channel that are producing heterodynes (audible or sub-audible) in the received audio (Figure 2<\/b>).\u00a0 Generally speaking, a DX signal with a stronger carrier will be more likely to produce readable audio, although there are exceptions to that rule.<\/p>\n

Initially, DXers wanted to discover the exact frequency of their DX, accurate to the nearest Hertz.\u00a0 Although only a small group of enthusiasts were interested, they have produced a number of IRCA Reprints (https:\/\/www.ircaonline.org<\/a> and click the \u201cFree IRCA Reprints\u201d button) over the years under the topic of \u201cprecision frequency measurement\u201d (e.g. T-005, T-027, T-031, T-079, T-090) describing their use of some reasonably sophisticated equipment for the day, such as frequency counters.<\/p>\n

So, why would this information be at all important?\u00a0 In effect, the knowledge of the exact frequency of a carrier was used to provide a fingerprint for a specific radio station.\u00a0 \u00a0 Usually, this detail was used by DXers who were trying to track down new DX, and wanted to determine whether a noisy signal was actually something that had been heard before, so would not waste any more time with it.\u00a0 The process of finding this exact frequency has since been made much easier by being able to view the carrier graphically in SDR software, assuming that the SDR has been calibrated before being used to listen to and record the DX. \u00a0 Playing back the recorded files will also contain the details of the exact frequency observed at the time of recording.\u00a0 And, because the exact frequency of DX has become much easier to determine using SDRs, more and more DXers seem to be using this technique.<\/p>\n

At present, Jaguar software for Perseus is the one being used by many to determine frequency resolution down to 0.1Hz, both in receiving and in playback. \u00a0 But, if you have recorded SDR files from hardware other than Perseus, it is possible to get that resolution also, using software called Carrier Sleuth, from Black Cat Systems, available for both Mac and Windows, at a cost of US$20.<\/p>\n

This software will presently take as input, sets of RF I\/Q files generated by SpectraVue, SdrDx, Perseus (which includes files recorded by Jaguar), Studio One \/ SDRUno, Elad, SDR Console, and HDSDR.\u00a0 It then outputs a single file with a .fft extension, that provides the user with a set of waterfalls, similar to those displayed by SDR programs.\u00a0 The user decides ahead of time which frequency or set of frequencies (including all 9kHz or all 10kHz channels) will be output, and these will be displayed as individual waterfalls. one for each chosen frequency.\u00a0 These waterfalls can be stepped through from low frequency to high frequency, or chosen individually from a drop down menu.<\/p>\n

Let\u2019s start by looking at a couple of output waterfalls and work out what can be done with them, then step back to find out how to generate them, and what other data is available from them.\u00a0 Finally, we\u2019ll do a quick comparison with two other programs that can produce similar output, and discuss the limitations in all three programs.<\/p>\n

Example outputs from Carrier Sleuth<\/b><\/h2>\n

An example showing the original intent of Carrier Sleuth, determining precise carrier frequencies, is shown in Figure 3<\/b>, a waterfall from 1287kHz on the morning of 28 November 2020.\u00a0 At 1524UT, a woman mentions \u201cHBC\u201d and \u201cHokkaido\u201d in the original recording, so, it\u2019s JOHR, Sapporo. \u00a0 Although there are a number of vertical lines representing carriers in this graphic, only one has a strong coloration, indicating at least 25dB more strength than any other carrier at the time of the ID, and about 50dB more than the background level. \u00a0 \u00a0 The absolute values of time, signal strength, and carrier frequency precise to 0.1Hz, can be found by mousing over the desired point in the waterfall and then reading the numbers in the upper right corner of the display, (encircled in Figure 3<\/b>).\u00a0 In this case, the receiver\u2019s reference oscillator had been locked to an accurate 10MHz clock, disciplined by GPS, so the frequency indicated in the software is not just precise, but should also be accurate. \u00a0 Similar accuracy could be obtainable by the traditional method of calibrating the SDR to WWV on 10 or 15MHz.<\/p>\n

Carrier Sleuth indicates 1287.0002kHz, within 0.1Hz of that observed by a contributor to the MWoffsets list about 7 weeks earlier (https:\/\/www.mwlist.org\/mwoffset.php?khz=1287<\/a>). If you look closely, there is a slight wobble on the frequency, but the display is precise enough that it can indicate that, despite the wobble, JOHR does not wander away from that frequency of 1287.0002kHz.<\/p>\n

\"\"<\/a>

Figure 3<\/p><\/div>\n

But let\u2019s face it, tracking carriers to such accuracy is a specialist interest (though admittedly, the medium wave DXing hobby is full of specialist interests, and this one is becoming more mainstream, at least among Jaguar users).\u00a0 However, if I played back a file from another morning, and found a strong carrier on a slightly different frequency from 1287.0002kHz, it might be an indication that some new Chinese DX was turning up, and that the recorded files would be worth a closer listen at that particular time.<\/p>\n

\"\"<\/a>

Figure 4<\/p><\/div>\n

In fact, I\u2019ve found Carrier Sleuth to be useful in digging out long haul DX after it\u2019s been recorded, as both trans-Arctic and trans-Pacific DX at my location in western Canada can be spotty at the best of times.\u00a0 This means spotty as in a \u201czero to zero in 60 seconds\u201d sort of spotty, because a signal can literally fade up 10 or 15dB to a readable level in 20 seconds, perhaps with identifiable material, then disappear just as quickly. \u00a0 My best example so far this season was on 1593kHz, early in the UTC day of 16 November 2020, when a Romanian station on that channel paid a brief visit to my receiver in western Canada.\u00a0 An initial inkling of that showed up in a Carrier Sleuth waterfall, a blotch of dark red at 0358UT, and indicated by the yellow arrow in Figure 4<\/b>; that caused me to go back to the recorded SDR files that had generated these traces.<\/p>\n

The dark blotch indicates a 10dB rise and fall in signal strength including about 60 seconds of rough audio, which turned out to be the choral version of the Romanian national anthem (RCluj1593.wav<\/a>).\u00a0 That one carrier and another one both started up at 0350UT, the listed sign-on time for Radio Cluj, which does indeed begin the broadcast day with that choral anthem. \u00a0 Which one of the Radio Cluj transmitters was heard is still an open question, due to the lack of carrier sleuths (computerized or otherwise) on the ground in Romania,\u00a0 but the more powerful one listed is a mere 15kw, so I will take either.<\/p>\n

Finally, for those who have interest in radio propagation, the Carrier Sleuth displays can reveal some odd anomalies, for example, Figure 5<\/b> which displays both Radio Taiwan International (near 1557.000kHz on 28 November, but varies from day to day), and CNR2 (1557.004kHz)\u00a0 carriers as local sunrise at 1542UT approached in Victoria, BC.<\/p>\n

\"\"<\/a>

Figure 5<\/p><\/div>\n

The diffuseness of the carriers is striking, as is their tendency to shift higher in frequency at local sunrise.\u00a0 This doesn\u2019t seem to be some strangeness in the original SDR recording, as there appear to be unaffected weak carriers on the channel.\u00a0 For comparison, Figure 3<\/b> shows the same recorded time and date, but on 1287kHz, and JOHR\u2019s carrier is pretty stable, but there are others on that channel that show the shift higher in frequency around local sunrise.\u00a0 As one goes lower in frequency, these shifts became smaller and less common on each 9kHz channel, and disappear below about 1000kHz.\u00a0 \u00a0 On later mornings, however, the shifts could be found right down to the bottom of the MW band.\u00a0 Certainly, these observations are food for further thought.<\/p>\n

Many of the parameters in Carrier Sleuth are adjustable by the user, for example, the sliders at the top of the screen can allow adjustment of the color palette to be more revealing of differences in signal strength. \u00a0 The passband shown is also easily changed, and in fact, setting\u00a0 the passband width to 400Hz, instead of my usual 50Hz , and creating another run of the program on 1557kHz, shows very clearly the sidebands of the \u201cthe Rumbler\u201d, a possible jammer on the channel\u00a0 (Figure 6<\/b>).\u00a0 Incidentally, a lot of the traces around 1557.000kHz in Figure 5 <\/b>may well be part of \u201cthe Rumbler\u201d signal as well, as filtering of the audio doesn\u2019t seem to improve readability on the channel.<\/p>\n

Although the examples here are taken from DXing overseas signals from western Canada, there is no reason why similar techniques may\u00a0 not be applied to domestic DXing, particularly during the daytime, when signals can be weak, but can fade up unpredictable for brief periods.<\/p>\n

\"\"<\/a>

Figure 6<\/p><\/div>\n

How to create these waterfall displays in Carrier Sleuth?<\/b><\/h2>\n

So, how can you get these displays for yourself?\u00a0 A \u201ctry before you buy\u201d version of the program is available at http:\/\/blackcatsystems.com\/software\/medium_wave_carrier_display_app.html<\/a>\u00a0 and both the website and the program itself contain a quite detailed set of instructions.\u00a0 \u00a0 However, the 25 cent tour can be summarized this way:<\/p>\n

You start with a group of supported SDR data files, previously recorded, and use \u201cOpen I\/Q data files\u201d in the File drop down menu. Figure 7 <\/b>shows the window that will open to allow you to choose any number of the files from your stored SDR files, by clicking the Add Files button\u00a0 circled in red.\u00a0 Then choose one of the options inside the green circle in Figure 7<\/b>.\u00a0 They are explained in more detail in the help write up; note that the \u201cCustom Channel\u201d can be specified to considerably more precision than just integer kHz values, e.g. 1205.952 \u00a0 \u00a0 The rest of the settings you will probably adapt to your needs as you gain experience. \u00a0 Finally, set an output file name using the Set Output File button, and hit the \u201cProcess\u201d button at the bottom of the window. There are a couple of colored bars in the upper right hand corner of the display that indicate progress, along with number of seconds left, although these are not always visible.<\/p>\n

\"\"<\/a>

Figure 7<\/p><\/div>\n

The generation of these waterfalls takes time. \u00a0 A computer with a faster CPU and more memory will speed things up.\u00a0 There is, however, an important limitation of the program.\u00a0 It is specified for 32-bit systems, and although it will run with no problem on 64-bit systems, individual input I\/Q files are therefore restricted to 2GB or less. \u00a0 Many SDR users now choose to create larger files than this, and Carrier Sleuth will not handle them.\u00a0 Another possible limitation can occur when processing 32M FFTs, which are useful for delivering very fine frequency resolution of the carriers displayed. \u00a0 The program really requires in excess of 4GB of memory to handle the computation needed to deliver this fine a scale.\u00a0 Unfortunately, both the 2GB file size limitation and insufficient memory limitation deliver generic error messages, followed by program termination, which leaves the inexperienced user none the wiser about the true problem.<\/p>\n

This might be a good place for a word about FFT size and Resolution Bandwidth (RBW).\u00a0 The FFT is a mathematical computation that takes as its input the samples of digital data that an SDR generates (or those samples that\u00a0 have been saved in recorded files), and generates a set of \u201cbins\u201d, which are individual numbers representing signal strength at a defined number of consecutive frequencies spaced across the full bandwidth being monitored by the SDR. You could think of these bins as a series of tiny consecutive RF filters, spread across the band, each delivering its own signal strength. \u00a0 As we are trying to look at fine scale differences in frequency when using a program like Carrier Sleuth, it is important that these little \u201cRF filters\u201d, or bins, each have a very narrow bandwidth.\u00a0 This value is called \u201cResolution Band Width\u201d (RBW), and preferably should be a fraction of a Hertz to get displays such as those shown in Figures 3 through 5.<\/p>\n

The \u201cFFT Length\u201d is the number of bins that the FFT display contains, and is equal to the number of I\/Q samples (either from the SDR or recorded file) that are used for the input to its computation.\u00a0 The relationship between FFT Length, the bandwidth of the SDR or of the original recorded I\/Q file, and the RBW is fairly simple:<\/p>\n

\"\"<\/a><\/p>\n

Because the MW DXer is usually looking at data with 1MHz or more bandwidth, this equation tells us that to get a smaller than 1Hz RBW, we will need to have an FFT length of well over\u00a0 one million bins, so it would be wise to use an FFT length at least 8M(illion). \u00a0 If you are looking at a recorded file that is from an SDR using a lower bandwidth, then a lower FFT length will do the job to get a smaller RBW.<\/p>\n

A downside of using a long FFT length is that the time resolution of the FFT becomes poorer, resulting in a display in Carrier Sleuth that will appear to be compressed from top to bottom compared with what was seen when recording the SDR file, and with correspondingly less response to fast changes in signal strength. \u00a0 However, using a 16M FFT Length on a recording of the MW band results in a time resolution of about 12 seconds, so it should not be a deal breaker for most.<\/p>\n

Producing signal strength plots\u00a0<\/b><\/h2>\n

A further specialist activity for some DXers is recording signal strength on specific channels, and then displaying the progress of signal strength versus time, often to indicate when openings have occurred in the past\u00a0 (say, at transmitter sunset),\u00a0 and perhaps allowing one to predict such openings in the future.\u00a0 \u00a0 But, the world has come a long way from the noting down of S-meter readings at regular time intervals, both in deriving signal strength and in plotting the results.\u00a0 Read on for an example.<\/p>\n

\"\"<\/a>

Figure 8<\/p><\/div>\n

Carrier Sleuth recently added the capability of creating files containing signal strength versus time for specified frequencies, and, depending on the size of RBW, to deliver that signal strength as observed in a passband as narrow as 0.05Hz, or as wide as 10Hz. \u00a0 The program extracts the signal strength information from one of the FFT files that it has already generated from a selection of SDR I\/Q files. \u00a0 In Figure<\/b> 5<\/b>, two stations\u2019 signals, from Radio Taiwan International, and from CNR2, were featured in the display. \u00a0 With roughly 4Hz difference between the two signals, it is easily possible with Carrier Sleuth to derive signal strength from each one, specifying a bandwidth of, say 1.2Hz, to account for the propagation induced drifts and smearing of the carriers, not to mention any drift in either the receiver or transmitter.<\/p>\n

The program creates a .csv file (text with comma delimiters) of signal strength versus time for all the frequencies chosen from an individual FFT file, but does not plot them.\u00a0 There are several programs that can create plots from CSV files \u00a0 For example, an Excel plot generated from Figure 5<\/b> is in Figure 8<\/b>, showing peaks in those signals that occurred both before and after local sunrise at 15:42UTC. \u00a0 Note that the user is not restricted to the signals found on just one of the waterfalls that are found in the FFT file, but can pick and choose dozens of signals found anywhere in those waterfalls.\u00a0 \u00a0 (Note also that one can choose locations on any waterfall where there is no signal trace, in order to provide a \u201cbackground level versus time\u201d in the finished plots, if desired)<\/p>\n

The process used to generate this CSV file involves searching through the FFT waterfalls for signal traces that are likely candidates for adding to such a file. \u00a0 On the first candidate found, the user right clicks the mouse on the trace, at the exact frequency desired; this will bring up an editable window. \u00a0 The window will show the chosen frequency as well as any subsequent ones that will be chosen, then the overall selection is saved to a text file after editing, so that the user can move on to generating the CSV file.<\/p>\n

That file is created by going to the File drop down menu, and choosing \u201cGenerate CSV File\u201d, where the text file produced earlier can be chosen.\u00a0 Once that file is selected, the CSV file is immediately generated, and can then be manipulated separately as the user chooses.<\/p>\n

Are there comparable programs?<\/b><\/h2>\n

Displaying waterfalls in SDR programs playing back their own files is nothing new, though not that many can do it at as fine a scale as Carrier Sleuth does, and most programs are not optimized to handle such a variety of input I\/Q files.<\/p>\n

One that does read a fair number of different kinds of SDR files is the SDR Console program; this includes Data File Analyser (64-bit only) which also can display carrier tracks to a high resolution, so let\u2019s take a quick look at what Analyser does.\u00a0 If you are familiar with SDR Console, and are reasonably experienced with the way it handles your SDR or plays back files from your favored SDR software, then these online instructions https:\/\/www.sdr-radio.com\/analyser<\/a> will help you get started with Analyser<\/p>\n

This program will input a group of SDR files, then display an equivalent to a single one of the waterfalls output by Carrier Sleuth, displaying the carrier traces in reverse order, with time running from bottom to top of the display. Figure 9<\/b> shows the equivalent of Carrier Sleuth\u2019s display of the 1287kHz carrier traces shown in Figure 3<\/b>.\u00a0 \u00a0 Analyser has a convenient sliding cross hair arrangement (shown in the yellow oval) to reveal time and frequency at any point in the display, but the actual signal power available at that point must be derived from the rough RGB scale along the left hand border. Analyser is apparently capable of about 0.02Hz resolution when reading from full bandwidth medium wave SDR files, but the default is to display exact frequency only to the nearest Hertz. The \u201cCrosshairs\u201d ribbon item has a drop down of \u201cHigh-Resolution\u201d\u00a0 which displays to the nearest milliHertz however, though that will be limited by the actual RBW of the generated display. \u00a0 The graphic display can be saved as a project after the initial generation of the signal traces, which allows the user to return to the display without having to generate it all over again, equivalent to opening one of Carrier Sleuth\u2019s FFT files.<\/p>\n

A useful facility in Analyser is the ability to click \u201cStart\u201d in the Playback segment of the ribbon above an Analyser display, then mouse over and click on a signal trace; this action will play back the audio for that channel in SDR Console, at that point in time.<\/p>\n

It is possible to generate a signal strength plot of signal strength versus time for any individual frequency in the waterfall display, and to save that plot as a CSV file (\u201cSignal History\u201d). \u00a0 But, the signal strength is that found only in a +\/- 0.5Hz passband around the chosen frequency, with no other possibilities.\u00a0 If you want to generate a plot for another frequency on the same waterfall, then you will need to run the process again, and if you want a plot for another frequency in the SDR files, then you need to generate another waterfall, which, depending on your computer\u2019s capability, could take some time. \u00a0 On an i3 CPU-based netbook with 4GB of memory, it took 30 minutes to produce one frequency\u2019s worth of traces from data files scanning three hours.\u00a0 On the same machine, Carrier Sleuth could deliver all 9kHz channels in 1hr20min from the 3 hours of files.\u00a0 However, it also took 1hr20min to play back just one channel in Carrier Sleuth, which is not so efficient. (further note: \u00a0 Nils Schiffhauer has developed a technique to speed up Data Analyser processing, by first using Console\u2019s Data File Editor on full bandwidth MW recorded files; details will likely appear at https:\/\/dk8ok.org)<\/p>\n

To conclude then, SDR Console\u2019s Analyser will produce a display of a single channel faster than Carrier Sleuth will, and will play back the audio associated with that channel, while also having the capability to plot and record signal strength for a single given frequency within that display, but only on 64-bit computers.\u00a0 It can also handle SDR files larger than 2GB in size, and will run more quickly if a NVIDIA graphics card has been installed. \u00a0 Analyser is also strict about sequence of files.\u00a0 If there is the slightest gap between one file finishing, and the next file starting in time sequence, it regards that as a new set, that will need to be processed separately.<\/p>\n

Where Carrier Sleuth is more useful is that once an FFT file has been generated, it is easy to quickly check multiple channels for interesting openings during the recorded time period. It can also provide very precise frequencies of carriers, and is able to generate a file of signal strengths versus time from multiple frequencies, including those frequencies that are separated by barely more than the RBW.\u00a0 For the MW band, that can be near 0.1Hz, often beyond the capability of transmitters to be that stable.\u00a0 See Figure 10<\/b>, which shows signal strength traces from JOCB and HLQH both on 558kHz, and separated in frequency by 0.1Hz.\u00a0 \u00a0 At 1324UTC, JOCR<\/a> dominates with men in Japanese, and at 1356UTC, the familiar woman in Korean dominates, indicating HLQH<\/a>.<\/p>\n

\"\"<\/a>

Figure 9<\/p><\/div>\n

\"\"<\/a>

Figure 10<\/p><\/div>\n

Incidentally, another program that seems to offer a similar functionality to Carrier Sleuth and SDR Console\u2019s Analyser is, of course, Jaguar, which has made a point of displaying 0.1Hz readout resolution when using the Perseus SDR, and in playing back Perseus files, but\u2026only Perseus.\u00a0 There is a capability called Hi-Res in Jaguar Pro that can be applied when playing back files; this also displays fine scale traces of frequency versus the passage of time.\u00a0 Steve VE6WZ, sent the example shown in Figure 11<\/b>, zeroing in on his logging of DZAR-1026.\u00a0 As with Analyser, clicking on a certain point in the display plays back the audio at that time, but it is unclear at this point whether the display can be saved, or whether it is generated only for one individual channel, and then is lost.<\/p>\n

\"\"<\/a>

Figure 11<\/p><\/div>\n

+ \u00a0 + \u00a0 + \u00a0 + \u00a0 + \u00a0 + \u00a0 + \u00a0 + \u00a0 + \u00a0 + \u00a0 + \u00a0 +<\/p>\n

Availability<\/b><\/h1>\n

Carrier Sleuth\u00a0 <\/b>http:\/\/blackcatsystems.com\/software\/medium_wave_carrier_display_app.html<\/a><\/p>\n

Analyser (SDR Console) \u00a0 <\/b>https:\/\/www.sdr-radio.com\/download<\/a><\/p>\n

Jaguar \u00a0 <\/b>http:\/\/jaguars.kapsi.fi\/download\/<\/a> (these are the Lite versions; to unlock the Pro version, purchase is needed)<\/p>\n

(this article first appeared in International Radio Club of America\u2019s DX Monitor)<\/p>\n

\n

Many thanks, Nick. This is amazing. What a brilliant tool to find nuances of a DX signal. I can’t help but marvel at the applications we enthusiasts have available today. Thank you for sharing!<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Many thanks to SWLing Post contributor, Nick Hall-Patch, for sharing the following guest post: Using Carrier Sleuth to Find the Fine Details of DX by Nick Hall-Patch Introduction\u00a0 Medium wave DXers are not all technical experts, but most of us understand that the amplitude modulated signals that we listen to are defined by a strong […]<\/p>\n","protected":false},"author":15,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[373,5935,3194,627,433,3,43,158,1113],"tags":[9125,4342,9126,3677,5820,3678,9003,157,5808,4087],"class_list":["post-47665","post","type-post","status-publish","format-standard","hentry","category-am","category-dx","category-guest-posts","category-how-to","category-mediumwave","category-news","category-shortwave-radio","category-software-defined-radio","category-tutorials","tag-carrier-sleuth","tag-guest-posts","tag-jaguar","tag-medium-wave-dxing","tag-mediumwave-dxing","tag-mw-dx","tag-nick-hall-patch","tag-sdr","tag-sdr-console","tag-software-defined-radio"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pn3uc-coN","jetpack-related-posts":[{"id":62175,"url":"https:\/\/swling.com\/blog\/2025\/02\/beyond-dxing-analyzing-medium-wave-propagation-during-the-2023-annular-eclipse\/","url_meta":{"origin":47665,"position":0},"title":"Beyond DXing: Analyzing Medium Wave Propagation During the 2023 Annular Eclipse","author":"Thomas","date":"February 24, 2025","format":false,"excerpt":"The following article dives into medium wave (MW) radio propagation during the 2023 annular solar eclipse, building upon insights from the 2017 total solar eclipse when DXers made broadband radio recordings of the whole MW band for the first time. Unlike that previous study, the 2023 research took a methodical\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/02\/Fig-2cropped2adjustbright.png?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/02\/Fig-2cropped2adjustbright.png?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/02\/Fig-2cropped2adjustbright.png?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/02\/Fig-2cropped2adjustbright.png?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":57680,"url":"https:\/\/swling.com\/blog\/2023\/08\/how-dxers-can-contribute-to-ionospheric-research-during-the-october-14-2023-solar-eclipse\/","url_meta":{"origin":47665,"position":1},"title":"How DXers can contribute to ionospheric research during the October 14, 2023 solar eclipse!","author":"Thomas","date":"August 31, 2023","format":false,"excerpt":"Many thanks to SWling Post contributor, Nick Hall-Patch, who shares the following announcement: How DXers can contribute to ionospheric research during the 14 October 2023 solar eclipse There will be an annular solar eclipse on 14 October, 2023 when, at totality, the size of the Moon\u2019s disk will appear slightly\u2026","rel":"","context":"In "Mediumwave"","block_context":{"text":"Mediumwave","link":"https:\/\/swling.com\/blog\/category\/mediumwave\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image2.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image2.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image2.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image2.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":57954,"url":"https:\/\/swling.com\/blog\/2023\/10\/hamsci-reminder-contribute-to-ionospheric-research-during-the-october-14-2023-solar-eclipse\/","url_meta":{"origin":47665,"position":2},"title":"HamSCI Reminder: Contribute to ionospheric research during the October 14, 2023 solar eclipse!","author":"Thomas","date":"October 11, 2023","format":false,"excerpt":"Many thanks to SWling Post contributor, Nick Hall-Patch, who shares the following announcement: How DXers can contribute to ionospheric research during the 14 October 2023 solar eclipse There will be an annular solar eclipse on 14 October, 2023 when, at totality, the size of the Moon\u2019s disk will appear slightly\u2026","rel":"","context":"In "News"","block_context":{"text":"News","link":"https:\/\/swling.com\/blog\/category\/news\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image1.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image1.jpg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2023\/08\/image1.jpg?resize=1050%2C600&ssl=1 3x"},"classes":[]},{"id":64400,"url":"https:\/\/swling.com\/blog\/2025\/10\/an-introduction-to-wavviewdx-sdr-playback-software-a-totsuka-dxers-circle-article-by-kazu-gosui\/","url_meta":{"origin":47665,"position":3},"title":"An Introduction to WavViewDX SDR Playback Software (A Totsuka DXers Circle Article by Kazu Gosui)","author":"Thomas","date":"October 30, 2025","format":false,"excerpt":"Many thanks to SWLing Post contributor Nick Hall-Patch, who has kindly provided a translation of this article from the Japanese-language publication PROPAGATION by the Totsuka DXers Circle (TDXC). In this piece, Kazu Gosui introduces WavViewDX, an impressive SDR file playback and analysis tool developed by Reinhard Wei\u00df of Germany. 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In this piece, Satoshi Miyauchi explores how WavViewDX can revolutionize SDR analysis by making propagation and reception conditions instantly visible--and shares some\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/10\/image_10.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/10\/image_10.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/10\/image_10.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2025\/10\/image_10.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":39304,"url":"https:\/\/swling.com\/blog\/2019\/08\/airspy-hf-discovery-first-impressions-on-medium-wave-vs-elad-fdm-duor\/","url_meta":{"origin":47665,"position":5},"title":"AirSpy HF+ Discovery: First Impressions on Medium Wave vs. Elad FDM-DUOr","author":"Guy Atkins","date":"August 25, 2019","format":false,"excerpt":"The highly anticipated AirSpy HF+ Discovery SDR has been in the hands of early adopters for about two weeks--and I've seen nothing but positive comments! After a long run (2007-2013) with a Microtelecom Perseus, my SDR of choice became the Elad FDM-S2, and more recently an Elad FDM-DUOr \"hybrid\" SDR\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/08\/hfplus_discovery.png?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/47665","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/comments?post=47665"}],"version-history":[{"count":0,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/47665\/revisions"}],"wp:attachment":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/media?parent=47665"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/categories?post=47665"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/tags?post=47665"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}