ANALYSIS | NORTH AMERICAN SPORADIC ES SEASONS 2017-2024
ANALYSIS | NORTH AMERICAN SPORADIC ES SEASONS 2017-2024
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POWERED BY DATA FROM: FMLIST.ORG
POWERED BY DATA FROM: FMLIST.ORG
TABLE OF CONTENTS
TABLE OF CONTENTS
PREFACE
PREFACE
For years, analysis of Sporadic Es receptions on the FM band has been largely a siloed effort.
Historically, this has meant DXers analyzing the data of receptions from their specific location, comparing season-over-season and gauging quality of seasons based on total logs or number of events. What if some locations are just more prone to Sporadic Es than others? What if some DXers just have better setups or have more time to DX?
Clearly, we need more data.
Further, we have seen over the past decade or two an explosion in the amount of resources available to DXers. Sites such as FMList.org that provide real-time maps of receptions and email alerts for possible Sporadic Es propagation in a specific location. Sites such as Rabbitears and the RDS autologging maps that allow for unattended RDS decode logging of receptions through always-on receivers.
We haven't even mentioned the explosion of the use of Software-Defined Radio (SDR) technology that provides DXers with not only visual representations of their FM band, but the ability to record a portion or even the entire FM band for later review and logging of every single station received during an opening. Even online receivers through sources such as FMDX.org that allow DXers to hear "first hand" the FM band in various locations all around the world!
So, It is in that spirit that here at DX Central we decided it was time to collect all of that newly created data from the tens of thousands of FM Sporadic Es logs over the past decade or so. We decided to start with North America, as that was the data that was most easily digestible and available to us from our partners at FMlist.org.
To our knowledge, this represents the first widespread and collective analysis of Sporadic Es logs from a large enough sample size to be able to spot trends and provide what we hope is a directionally accurate analysis.
We hope it helps provide insight for you not only into the historical performance of Sporadic Es seasons, but also a barometer to use for future seasons to gauge their overall quality.
SPECIAL THANKS TO...
SPECIAL THANKS TO...
Gunter Lorenz at FMList.org, the Worldwide TV-FM DX Association and their detailed station database, and Mike Jeziorski for their partnership in obtaining the data needed for this analysis.
METHODOLOGY & DISCLAIMERS
METHODOLOGY & DISCLAIMERS
Data analyzed is for North American Sporadic Es receptions reported by DXers to FMlist.org from 2017-2024
No other form of reported propagation is included in this analysis (Tropo, Meteor Scatter, etc.)
Only the months of May-August were analyzed
To the degree that it is possible, we are keeping this data anonymous, with no names of DXers shown in the analysis.
Calculations were performed through a combination of spreadsheet formulas and Google Apps Scripts. Where needed for coding, ChatGPT AI assistance was used (thanks, Skip!). The analysis of the data was 100% a human effort, though.
Many times, the data doesn't lead to conclusions, but questions. It can be hard to use data to make absolute certainty statements without additional context. So, we have tried to ask those remaining questions, where applicable.
Data accuracy is entirely dependent on the accuracy of the DXer submission. As such, a small degree of error must be assumed due to possible bad data (Tropo receptions reported as Es, etc.) but the data should maintain directional accuracy
Other factors to consider for changes in data over time include the influx of RDS autologging through RabbitEars.info, the expanded use of SDR technology for reviewing of IQ recordings after live DX during the Sporadic Es event, an increase of DXers utilizing and submitting logs to FMlist.org, and a much higher saturation of the FM band in the United States with FM translators and LPFM stations (though this can both help and hurt DXers ability to receive Sporadic Es DX).
We try to acknowledge impacts of these influences, where appropritate, in our analysis.
TOTALS
TOTALS
2017-2024 SEASONAL ANALYSIS
2017-2024 SEASONAL ANALYSIS
TOTAL LOGS BY SEASON
TOTAL LOGS BY SEASON
On an individual level, comparisons of total logs of one season versus another can give that person a very rudimentary gauge on the quality of the Sporadic Es season.
However, when trying to compare a much broader population of DXers that span an entire continent, this metric is not as helpful.
I do include it here though as this can be one of the initial indicators of an overall trend. It can also give us an indication of the performance of individual months during the analysis period.
One interesting note is that despite a general increase in the number of reporting DXers (which we will see in a bit) over the past several seasons, 2024 still had a dramatic drop in production. Remember that, as it will be a consistent theme throughout this analysis.
This metric can be influenced by an increase in the use of RDS autologgers in North America and by the general increase in use in the FM DX community of SDRs and recording DX events for later review.
UNIQUE LOGS BY SEASON
UNIQUE LOGS BY SEASON
For a twist, what if we looked at "unique" logs? What we mean in this analysis is that we created a "helper" field within our data that concatenated the frequency and location of each station received. This allowed us to bypass any issues in the data due to call letter changes. From there, we did a count of unique receptions per month and year. It is important to note this is not unique to an individual DXer. Let's say DXer A logs Station A. That station will no longer count towards the logs no matter how many times that DXer or any other DXer reports it for the rest of that month/year combination.
Overall, the trends were nearly identical to those from the overall logs. The overall log count definitely dropped, as you would expect, but the impact to seasonal trending was small.
But it wasn't zero. If anything, it nearly flattened the volume between 2021-2023.
DAYS WITH ES REPORTED
DAYS WITH ES REPORTED
So, if total logs isn't helpful, where can we start to find metrics that can provide some context? For a start, the number of days with Es reported can be an indicator. For this one, any date within a month where at least 1 Es log was reported in the data is counted.
This brings up an interesting element to this metric, in that there are openings that are hyper-isolated to a small number of DXers or a specific geographic region. There is still value in including these events in our data analysis as they show the overall tendencies of the ionosphere to be able to produce Es clouds.
There is 123 total available days between May 1 and August 31 during the peak of Es season in the Northern Hemisphere. This and the monthly calendar allows us to assign a percentage of the month to produce Es openings.
PERCENTAGE OF MONTH WITH ES
PERCENTAGE OF MONTH WITH ES
LOGS REPORTED PER DAY
LOGS REPORTED PER DAY
So, now armed with those two metrics, we can normalize the volume a bit by calculating the number of logs received per day (=total logs per month/days producting Es per month).
This can be a fantastic way to get a clear picture of the performance of a season. A season with a lot of logs but a small number of producing days indicates a smaller number of large openings. Vice versa, a high number of producing days with fewer logs means that the openings were primarily shorter in duration and not widespread to be received by DXers over a large geographic region.
This pans out perfectly with July 2021, as this month had fewer days (28) producing Es than July of 2022 (31) or 2023 (29) but had significantly higher logs per day (359) than either of those years. This means that with fewer openings, more logs were produced. One can infer, then, that either there were longer duration, stronger openings in 2021 or more DXers received the openings than in 2022 or 2023. We will explore that next.
DXERS REPORTING LOGS
DXERS REPORTING LOGS
How do we know that the increases in volume seen from 2021-2023 compared to previous years isn't just because there are more DXers reporting logs?
Well, actually, that is one of the reasons that we see increased log volume in that period. This chart shows that the increase in DXers reporting is very similar to the volume increases we saw in the Total Logs chart.
Another consideration is the proliferation of SDR usage amongst DXers, and the ability for DXers to record Sporadic Es openings for later review and extraction of station loggings.
It also stands to reason that a DXer in a more geographically favorable location for Sporadic Es (even if just for certain seasons) would result in a higher log count than DXers that see fewer openings.
Going back to July 2021, we see that the number of reporting DXers was actually lower than 2022 or 2023. We already saw that July had a lower Es producing day count, so this actually provides additional validation that July 2021 contained long duration events that were decently widespread and produced a large number of logs.
Looking at 2024, the drop in season volume also coincided with a drop in number of reporting DXers. Anecdotally, East Coast DXers have stated that 2024 was a largely absent year for them. Given the number of stations on the East Coast and the saturation of East Coast DXers, a lack of openings for them would lead to both a drop in log volume and drop in reporting DXers.
One final note on this chart is that these are unique DXers reporting. As such, you can't just total each month to get the total DXers reporting for the season, because some of those in reporting in June are also reporting in July, etc. Because of this, I am including a small table here with the total number of unique DXers reporting for each season.
LOGS BY DXER
LOGS BY DXER
So, let's bring it all home by looking at the number of logs per each DXer.
Like the number of logs per day, looking at logs per DXer is a great way to normalize the volume and more equitably compare the volume of one year to another.
This gets us pretty close to the original scope of an individual DXer comparing one season against another in their own logbook.
So, for instance, looking at 2018 tells us the season was actually a lot better performing than the other metrics were letting on. The log volume looked low because there was a smaller number of reporting DXers. Likewise, there was a smaller number of days producing DX, which points to a fewer number of openings.
But when we look at the volume by DXer, we see that the DXers that did report logs were treated with sizeable openings that were likely long duration and widespread. Especially in June, with an average of 169 logs per DXer.
Likewise, this shows just how rough the 2024 season actually was. Many of the other metrics have pointed to 2020 being a strong analogous season for 2024. However, this metric shows 2024 was actually a bit closer to the famously-bad 2019 season.
Anecdotally, DXers reported 2024 was a season filled with short-lived, geographically limited openings. My own experience was very similar, with many openings ending before I even realized they were underway.
This metric shows exactly that. This shows that the number of logs per DXer was among the lowest year of any in the analysis. A harbinger of an overall poorly performing season.
MONTHLY HEATMAPS
MONTHLY HEATMAPS
(All days shown are local to the DXer)
First a quick note on how we classify the productivity of Sporadic Es days. First, it is important to note the difference between a "day" and an "opening". An opening refers to a single event or Es cloud. This single event can be experienced by a single DXer or many at a time. You can have multiple openings in a day, including the usual morning/afternoon openings. There can also be smaller openings that occur throughout the day and multiple openings occurring at the same time.
To classify the days, we break them into four categories:
Isolated | Less than 100 logs reported for the day - This can still have multiple openings in over the course of the day, but usually there are just 1-2 openings and they are experienced by a limited number of DXers (often, only 1).
Moderate | Between 100 and 500 logs reported for the day - These are usually experienced by more DXers, meaning the Es cloud is reflective in multiple directions. This can also be openings that are experienced by a small number of DXers but the events are long-lasting and highly productive.
Widespread | Between 500 and 1000 logs reported for the day - These are usually defined by large scale openings, where the Es cloud allows for multiple paths. These are typically longer lasting events or at the very least, these are good candidates for the "double dip" of a morning and evening event with strong performance in each. There can also be multiple openings during these types of days, though, often dominated by 1-2 events.
Extreme | More than 1000 logs reported for the day - These are long-lasting events with numerous paths and paired with a morning and evening "double dip" with the evening event lasting well into the night. These days also produce multiple openings and sometimes even double-hop Es
What we have tried to do with these heatmaps is to try to identify any overall trends in a day-to-day view. Are there any days in particular that stand out as more productive? Any date ranges? When can we expect activity to start heating up in May? When can we expect activity to start dying off in late July/early August? Where are the "BIG" openings hiding?
Let's see what the data says:
MAY - DAILY LOG HEAT MAP
MAY - DAILY LOG HEAT MAP
MAY HEATMAP ANALYSIS
MAY HEATMAP ANALYSIS
May comes in very quietly, according to the historical heatmaps. In the first 15 days of the month, no day has more than 4 years of activity out of the 8 years in this analysis. Further, only two days in the first two weeks produced any 100-or-more log days: May 7th and 8th. May 7 of the 2022 season stands out as one of the lone bright spots in the early season with 296 logs reported on that day.
May 4th is the only day in May without any logs reported during the 8 years included in this analysis. May the 4th be with you? Not so much for Sporadic Es!
Things begin to slowly pick up in the second half of the month. We see more days with 5 or more years of activity between May 16th and May 31st. We also see May 25th as our first day to really start taking shape with 3 years reported with more than 100 logs in the day.
May 31, 2023 stands out as the peak of activity in May with 1,651 stations logged. May 30th and May 31st also have logs reported in 7 out of the 8 years in this analysis.
For active days, the most recent four years from 2021-2024 have the highest counts at 18 days (2021 and 2022) and 19 days (2023 and 2024). Could this be related to more DXers reporting to FMList? Could this be more early-season openings being spotted by autologgers and FMList users subcribed to Es alerts? Very possible.
May had 111 total active days over the eight years of the analysis out of 248 total "May days". This equates to 48% of available days in May producing at least some Spoardic Es on the FM band. This puts May solidly at third place among Es Season months for total activity. The average active May day has 3.59 years of activity behind it, which is at the bottom of the rankings for months in our analysis.
In terms of overall productivity, May has 23 days that were "Moderate" days or better. While this is far behind June and July, it is certainly better than August. Additionally, May has two days of "Widespread" or better and one "Extreme" day (May 31, 2023).
Only one day in May, May 31st, has more than 1000 total logs reported and that is driven almost entirely by 2023. The next highest producing day in May is May 30th with 885 total logs.
So, for those that wait for any signs of life from the Ionosphere in this early part of the season, be patient. A quiet May is fairly typical. If you want large, massive openings...look no further than June!
JUNE - DAILY LOG HEAT MAP
JUNE - DAILY LOG HEAT MAP
JUNE HEATMAP ANALYSIS
JUNE HEATMAP ANALYSIS
June is historically viewed as the peak of the FM Sporadic Es season, but what does the data tell us?
Certainly, June hits the high mark in our analysis for active days over the span of the eight years in the analysis with 212 active days out of 240 total possible "June days" of activity. This equates to a staggering 88% of all June days producing Es). This edges out July by 17 days.
In the span from 2021-2024, the productivity of June was even higher, with 117 out of 120 total available June days producing Es, or 98%!
Additionally, we see that June is consistently generating active days over the majority of the eight-year span of this analysis. In fact, the average number of active years for a day in June is 7.03, which is higher than any other month.
But kind of productivity does June provide for us in those active days?
To start, June had 69 days in the analysis period with 100 or more logs - more than any other month. These "moderate" days are very much the bread and butter of a Sporadic Es season and even in the absence of much more productive days, a large number of these - especially when spread out over a wide geographic area - can produce a strong season.
Many DXers felt that 2024 was a "letdown" season and the data backs that up, with 22 days out of 30 falling in the "Isolated" category. That was the highest number of those in June since 2019. We will come back to this topic in July.
A bit higher in our scale, we see June had 16 "Widespread" days over the period of the analysis, just barely nudging out July for the top spot. Finally, June carried five "Extreme" days during the analysis period, which actually tied July for the top spot. That shows that - on this side of the pond at least - these Extreme days are rather rare.
How rare? Well, for the analysis period there was a total of 605 active days across all months. There was a total of 11 days that produced 1000 or more logs. That means that a mere 1.8% of all active days qualified as "Extreme" and produced more than 1000 logs for the day.
If we dive into this a bit deeper, we see that certain days are a little more likely to produce a minimum of a "Widespread" day than others. In particular, June 20-22 is a very productive time span in our analysis. The 20th and 22nd in particular had two years falling in the "Widespread" category. June 21st had one year landing in this category. This also shows back up again on June 27-28 with each of those days having a Widespread day in two out of the eight years. Both of these spans also had between 3-4 years of being a "Moderate" day. If you are looking for the most productive period in the most productive month of the season, those two ranges are it. Interestingly, none of the days between these two ranges - June 23 through 26 - produced a Widespread day. Though, June 25th was the most likely day to produce "Moderate" productivity with five of the eight years falling in this category (the highest day in all of June).
In terms of pure loggings, June has the two top spots as well. June 11 has more logs reported in it than any other date in the analysis at 3520. Though, this is largely pushed by June 11, 2023 which saw 2686 logs reported which is the most productive single day of any in the entire analysis (this was the only year this day ended up being anything more than "Moderate", as well). June 26th comes in just behind in second place with 3194 logs reported and a little more consistency (with two moderate days, one Widespread and one Extreme day reported).
In all, June has three days that have total logs over eight years of 2000 or more.
So, I think we can safely say that June is the peak of Sporadic Es in North America. How does July measure up?
JULY - DAILY LOG HEAT MAP
JULY - DAILY LOG HEAT MAP
JULY HEATMAP ANALYSIS
JULY HEATMAP ANALYSIS
With June holding the title for "most productive month" in the Sporadic Es season, what does July hold for us? Well, actually quite a bit, especially early in the month.
Starting with active days, July held 195 active days over the span of the eight years in this analysis, just behind June. With 248 total "July days" available, this means that 79% of July days produced Sporadic Es. Additionally, a typical June day has an average of 6.38 years worth of production behind it. While just a little behind June, that is still a pretty high average.
In terms of productivity, July is actually really close to June. July had 64 days that fell into the "Moderate" category with July 1st through 17th producing the vast majority of these. July was just barely beat out by June in terms of "Widespread" days, with 15. Again, majority of these could be found early in the month, mostly between July 1st and 14th. July has five "Extreme" days in this analysis, equal with June.
If you want to find the single most productive day in the entire Es season, you will find it on July 9th. What makes July 9th so special? Well, for one, it produced activity in each of the eight years of this analysis. Lots of days did that, but none had the productivity that July 9th has. In three consecutive years (2021-2023) this day produced one "Extreme" and two "Widespread" days. It also had three additional years of producing "Moderate" days. That means in six out of the eight years in this analysis, July 9th had openings experienced by more than a handful of DXers. That is pretty consistent. Even in the much maligned 2024, this day produced 221 logs. Considering that season's max day (June 22nd) had 688 logs reported, 221 is actually a fairly productive day for that season.
Just like June, July has three days (July 9th, July 13th and July 14th) with more than 2000 total logs reported over the span of the eight years.
Going back to 2024, to demonstrate how far behind this season was, 25 out of the 31 days in July 2024 were "Isolated" producing days. Between June and July, the active days in these months produced an "Isolated' day 89% of the time. That is the highest percentage of any year in this analysis, beating out even 2017 (85%) and 2019 (79%). So, while 2024 had a total active day rate of 86% between June and July (which was much higher than both 2017 and 2019) the openings produced were largely unproductive.
While there are days in late July that do show some signs of life (July 17th through 20th and July 29th, in particular), in a typical year one can fairly accurately gauge the quality of their season by July 15th. So, to put all of that productivity into mostly the next 15 days means it is a busy first couple of weeks for DXers!
Having said that, August can hold some surprises!
AUGUST - DAILY LOG HEAT MAP
AUGUST - DAILY LOG HEAT MAP
AUGUST - HEATMAP ANALYSIS
AUGUST - HEATMAP ANALYSIS
If July shows signs of the season winding down, August can constitute the last gasps of a dying season.
With a grand total of 87 active days over the span of the analysis out of 248 total "August days" (35% of August days producing Sporadic Es), August ranks last amongst the Sporadic Es season, with 7 of the month's 31 days not having any reported loggings over the entire eight year span of this analysis (August 22nd-23rd, 26th-29th and 31st). A typical August day (of those that have reported activity) has an average of 3.8 years of reported loggings with it. This just barely nudges out May to keep them from the bottom spot.
Indeed, after August 6th, activity becomes very hit or miss. Those first six days of the month all have five or more years of activity on each of them - with August 4th having seven years of production (remember that date, we will mention it again in a minute).
In terms of productivity, August is largely on the low side. What openings do occur are mostly experienced by a limited number of DXers and tend to be rather short lived.
In all, there were 10 days in this analysis in August that fell into the "Moderate" category with only one single day in 2021 (August 4th) providing a "Widespread" opening.
While that one day of logs (810 total reported for that day) was nice, no other year for August 4th produced anything beyond an "Isolated" day.
Only one August day (August 13th) had more than one "Moderate" or higher day reported (163 logs in 2018 and 195 in 2022). Only 2020 (August 15th with 217 and August 17th with 148) and 2022 (August 6th with 348, August 7th with 205, August 11th with 250, August 13th with 195 and August 18th with 100) had multiple days that were "Moderate" or above. 2022 was far and away the best August of this analysis, with a total of 1420 logs reported.
SEASONAL FREQUENCY (MUF) ANALYSIS
SEASONAL FREQUENCY (MUF) ANALYSIS
Looking at logs per day over time is one way to gauge the productivity of a season. But what about if we look at the proclivity for days to produce strong openings with high maximum usable frequency (MUF)? In theory, the higher the MUF, the stronger the opening (though this doesn't necessarily equate to a large number of DXers expriencing the event. We have seen plenty of examples over the years of solitary openings, relatively brief, that shoot to a very high MUF before disappearing.
In fact, I would say that MUF is definitely the single most impacted metric by the use of software-defined radios (SDRs). During live DX events, it may not always be possible to ascertain the accurate MUF. But having a recorded file to sift through and thoroughly scrub of all captured DX during the life of the event, that means that we are more likely than ever to determine the true MUF of each event.
Still, the higher the MUF, the more possible stations there are to receive. That should count for something in our analysis.
As such, we will still examine the likelihood of each day, broken down by month and year, to produce a high MUF event. Perhaps we can see some either correlation to other metrics or other trends that stand out.
MAY- DAILY MUF HEAT MAP
MAY- DAILY MUF HEAT MAP
MAY - MUF HEATMAP ANALYSIS
MAY - MUF HEATMAP ANALYSIS
Starting with May, we see that just as the other metrics such as number of active years and logs per day begins slowly, so too does the MUF. We don't see our first day producing an opening all the way to 107.9 until the 7th (once, in 2022).
In all, there are 14 days out of 31 that produced a highest MUF of 107.9 during the day (45%). 2021 in particular had a year of strong MUF activity, with 10 days producing events with MUF between 104.3 and 107.9 (out of 18 total active days, or 55%) and 5 of those days climbing all the way to 107.9 (out of 18 active days or 28%). 2022 was right behind with 9 days of 104.3 to 107.9 MUF (out of 18 days, or 50%) and 4 days at the highest 107.9 MUF (out of 18 active days of 22%).
In all, 2020. 2021 and 2022 all had roughly 50% of May days producing a 104.3-107.9 MUF event.
May 25th stands out as the day with the most consistency in producing high MUF events, with 6 out of the 8 years of this date having an MUF between 104.3 and 107.9. In addition, May 25, along with May 31, were the only days to produce more than 1 year of MUF of 107.9 for the day.
In fact, after May 25th, every day for the rest of May produced at least one year with an MUF of 107.9. with each of these days having between 2 and 3 years of producing a 104.3-107.9 MUF event.
Further, every day after May 14th had an event with an MUF of 107.5 or higher. Only 7 days out of 31 failed to produce an event with MUF rising at or above 107.1. This lends further credence to the statement we made earlier that the second half of May is when thinks really begin to heat up.
Looking back at 2024, it is interesting to note that this year produced the highest number of low-MUF days (below 98.3 MHz). This is especially true after May 22nd, with 3 days in 2024 between May 22-May 31 producing an MUF no higher than 88.5! May of 2024 had the lowest number of high MUF (104.3-107.9) post-May 22nd of any year outside of 2018-2019!
JUNE - DAILY MUF HEAT MAP
JUNE - DAILY MUF HEAT MAP
JUNE - MUF HEATMAP ANALYSIS
JUNE - MUF HEATMAP ANALYSIS
As you might expect, June leads the way when it comes to MUF.
A full 27 days in June (out of 30, or 90%) have produced at least one opening in eight years with the highest MUF of 107.9. Not one single day had a maximum MUF over 8 years that was less than 107.5!
Several years stand out as particularly productive MUF generators. 2023 leads the way with 23 days (out of 30 for 77%) producing an event with an MUF of 104.3 or higher. 13 of those days (out of 30, or 43%) produced events with the highest MUF of 107.9. 2022 was close behind with 21 days (out of 30 , or 70%) producing events with MUF of 104.3 or higher and 13 of those days (43%) producing a 107.9 MUF event.
June 17th stands out with a total of 7 years out of 8 producing an event with a high MUF of 104.3 or higher. It also had 4 years where events produced the max MUF of 107.9. June 18th was close behind with 6 years of high MUF of 104.3 or higher and 5 days with a max 107.9 MUF.
Our big day from the log analysis, June 22nd, shows up as well with 6 years of producing an MUF of 104.3 or higher and 2 years of max 107.9 MUF.
In all, only 7 days in June had less than 4 years of producing an event with an MUF of 104.3 or higher (June 1, 2, 10, 14, 16, 23 and 26th).
Looking again at 2024, we see another example of the lack of production. In all, only 14 days (out of 29 active June days, or 48%) produced a high MUF of 104.3 or higher. This was the lowest since 2019. Additionally, only 9 days produced the max MUF of 107.9 (31%) which is the lowest since 2020. In addition, 2024 was one of three years to have a day in June producing an event with an MUF of 92.1 or lower, and it had two of them! Only 2019 (3 days of 92.1 or lower) had more.
JULY - DAILY MUF HEAT MAP
JULY - DAILY MUF HEAT MAP
JULY - MUF HEATMAP ANALYSIS
JULY - MUF HEATMAP ANALYSIS
We see a lot of the same trends when looking at July's daily MUF breakdown that we do in other metrics for July.
To start, July has 26 days that have produced a max MUF of 107.9 at some point in the analysis period (this equals 84% of July producing max MUF). Two days had an MUF below 107.1 (July 3 at 106.9 and July 28 with 103.1).
Interestingly enough, July actually outpaces June with regards to the number of days in a single year that produced max MUF of 107.9. 2021's 16 days (out of 29 active July days or 55%) as well as 16 in 2022 (out of 30 active days, or 53%) outpace June's max of 13 days with max MUF. 2021 and 2022 also each shared 21 days with an MUF of 104.3 or higher (72% and 70%, respectively).
Our champion for logs also comes through in MUF with July 9th outpacing all other days in the analysis with 7 out of 8 years with an event producing an MUF of 104.3 or higher and 5 out of 8 years producing an event with a max 107.9 MUF. The lowest MUF on this day was in 2017 with an MUF of 92.7. Every year starting with 2020 had an MUF event pushing to 107.9.
July 14th though was neck-and-neck with the same 7 out of 8 years of 104.3 or higher MUF and 5 years of max 107.9 MUF. The lowest MUF on this day came also in 2017 at 100.5.
Things begin to sharply drop off after July 20th, with 10 out of those last 12 days having less than 4 years of producing a high MUF event of 104.3 or higher. Only 7 days in the first 20 had less than 4 years of high MUF production. There definitely seems to be a peak in MUF production in July between July 8th and July 19th.
Looking again at 2024 we find 3 days that produced events with an MUF below 92.1. That is the highest total of any year in the analysis for the month of July. When we include this with the rest of our seasonal metrics from logs, unique DXers, daily counts of logs, daily MUF, etc.....this further cements that 2024 was a notoriously bad year (but it isn't done telling us that!)
AUGUST - DAILY MUF HEAT MAP
AUGUST - DAILY MUF HEAT MAP
AUGUST - MUF HEATMAP ANALYSIS
AUGUST - MUF HEATMAP ANALYSIS
Just as in every other seasonal metric we have explored so far, August's MUF performance shows the signs of a season with one foot out of the door.
11 days (out of 31, or 35%) produced a maximum MUF of 107.9 at some point in the 8 years of this analysis. There were 6 days in August that never had an MUF cross 104.3: August 10, 12, 16, 19 (with an MUF of 90.3!), 24, and 30th.
2022 had the most days in August with 104.3 or higher MUF with 8 days (out of 21 active days, or 38%). It also had the highest number of max MUF days of any year, with 6 (out of 21 active days, or 29%). Considering 2022 had the most active August of any in our analysis, this stands to reason.
No single day in August has produced more than 1 year of max MUF at 107.9, with most days producing none. No day in August produced more than 2 years of 104.3 or higher MUF, with some days producing as low as 90.3 (August 19, 2022) or 93.7 (August 30, 2023).
Even in August, we find more evidence of a lackluster season in 2024. There were 4 days in August of 2024 that had an MUF below 92.1 - more than any other year in the analysis. It also had no days with a max MUF of 107.9, which was the worst season since 2019.
After all of the analysis we have looked at, any activity received in August should really be considered bonus/extra and not relied upon to make/break the season (honestly, that is what we were doing here in 2024....holding on to hope that August would come through!).
The chart above represents receptions of US stations only
There is nothing Earth shattering when we look at the total number of loggings broken out by frequency. Lower frequencies have more logs since not every opening has a high MUF. That is what we expect to see and what the overall trend does show.
What is interesting though is to get a bit more granular and try to determine which frequencies produce the most logs.
Interestingly, the top spot is not at the bottom of the band, but is in-fact within the commercial portion of it: 92.9 with 2.6% of all loggings. 88.7 and 92.1 are not too far behind at 2.2% of logs. 89.5 and 93.9 (both at 2.1%) round out the top 5 productive frequencies.
At first, this was surprising to me to see so many frequencies out of the 88.1-91.9 portion of the band at the top of the logs. In fact, we don't see any frequencies in the 90 or 91 MHz range until we get to the 15th and 16th spot.
The more I thought about it, though, it makes sense. These are stations that identify much more frequently than those stations in the non-commercial portion of the band. It is a fact that there is a greater percentage of stations using RDS PI codes above 92.1 MHz. (more on RDS decodes, including the available stations on each frequency/state that are known to have RDS PI Codes, will be coming in a bit in this analysis).
TIMING ANALYSIS
TIMING ANALYSIS
Perhaps one of the most interesting items to come out of our hourly analysis is that there are Sporadic Es receptions reported for all 24 hours of the day. It is important to remember that this data is notated in the local time to the DXer - so time zones do not come into play here. There is obviously a pretty stark drop off in the overnight hours, but even in the period from Midnight local time to 6am local time...nearly a full 0.5% of all logs are received when conventional wisdom tells us that no Es should be received at all!
We have always been told that Sporadic Es typically will occur during two peak periods - once in the morning and again later that afternoon/evening. So, we are told if we get a good opening in the morning, to be prepared that evening for another round of DX.
The data shows that, historically at least, this is the case. However, what I was surprised to see is that the evening events are more productive than the morning events.
Now, are the evening hours more productive because the morning events occur when many DXers are unavailable to DX while at work or school? That is absolutely something we should consider as a possibility.
The peak hour for Sporadic Es logs occurs at 7pm local time to the DXer, with 11.4% of all loggings occurring in the 7pm hour. This is regardless of time zone.
The next most productive hour is also in the late afternoon/evening, as 6pm local time brings in 11.2% of all loggings. So, more than a fifth of all Sporadic Es logs occur between 6 and 7pm local time to the DXer. In other words, these are prime hours that DXers should definitely be checking their radios and maps regularly, looking for Es conditions.
The morning hours finally appear on our productivity list in the third spot with 11am local time to the DXer bringing in 9.5% of all loggings. Just behind this is 10am local time with 8.7% of all loggings.
Rounding out the top five for best times for Sporadic Es, we go back to the late afternoon/evening with 5pm local time to the DXer producing 8.3% of all loggings.
How does hourly activity change over the course of the season? Is there a certain time of the season when some hours are more productive than others?
Generally speaking, the breakdown of activity by hour/month is fairly flat. As you might expect, June and July own the bulk of the action, especially between 8am and 11pm local time.
Where things get a little more, interesting, is after midnight. Now, in all fairness I do have to offer that we are talking very, very small sample sizes between midnight and 5am local time. Even with a slight bump between 6a and 7a, it is still a very small sample size. In small sample sizes, slight differences can appear very large.
Still, it is interesting when we find little spikes in the data - even amongst these smaller sample sizes.
As an example, is there something specific that causes May to nearly double its share of the activity from 6a to 7a compared to the entire rest of the day?
What causes July to have such a large portion of the 3a and 5a local time share? Are these where we see those long-lasting openings in higher frequency? From my own logbook, I can tell you most of my loggings that occurred after 9pm local time (this includes both Charleston and Mandeville logs) occurred in July. So, maybe?
If that is the case, why does June have a higher portion of the Midnight to 2am activity? If July was truly getting more late night receptions, I would expect that to show up in these hours, too. In fact, June has higher portions of the activity from 8pm all the way through 2am.
Also, the "double dip" shows up very clearly in August. It is interesting that it is less pronounced in say, July. if anything, July shows a very active period between the two peaks, right in the middle of the day between 1pm and 5pm local time.
What is it about July that drives this mid-day activity? I remember the 2021 season, it felt like that mid-day period was very active as I had openings in July from Charleston, SC up into maritime provinces of Canada and New England producing large numbers of logs in this window.
GEOGRAPHIC & DISTANCE ANALYSIS
GEOGRAPHIC & DISTANCE ANALYSIS
LOGS BY US STATE
LOGS BY US STATE
What happens if we examine the data based on received and reporting location? Do we see any hotspots of activity?
As you might imagine, the center portion of the United States seems to get the highest concentration of logs. This means that DXers from both sides of the country have a shot at reaching these locations within single hop distances (generally, below 1600 miles).
Given the sheer number of stations available to hear, it is not all that surprising that Texas is the top state for receptions, at nearly 13% of all received US receptions. Equally understandable is that Florida is not too far behind at nearly 12% of all US receptions during the analysis period. Given the density of DXers located on the East Coast, Es openings that follow a North/South path between mid-Atlantic/Northeastern US DXers down into Florida would probably be a prime cause of so many Florida receptions.
This would imply that there are a number of Sporadic Es clouds that develop in a line that starts in Northern Alabama and stretches northeastward into West Virginia/Virginia and into the Mid-Atlantic region. This would provide DXers in the Eastern half of the country with paths into Florida.
We are working on doing additional analysis specific to paths between DXers and their reported DX that will hopefully expose this and other productive paths.
Part of what gives this theory at least a little bit of credibility is the drop in receptions of stations in the Northeast US in states like NY and PA. Given the saturation of available radio stations in these states, it stands to reason that they should be producing much higher on the state list than they are. New York accounts for roughly 1.4% of all receptions.
However, given the high density of DXers on the East Coast of the US, states like NY and PA would be too short of a distance for them to receive via Sporadic Es. Therefore, receptions from this area would tend to be geared more towards the South and Southwest (assuming the common Es path discussed earlier) into states like Louisiana, Arkansas, Oklahoma, Florida and Texas. In fact, we do see that Oklahoma (4.7% of receptions), Louisiana (2.9% of receptions) and Arkansas (2.4% of receptions) all have higher reception rates than any of the big East Coast states.
Minnesota is another state that stands out for it's reception rate of 5.4% of all receptions. Being in the center of the country as well as having a large saturation of available radio stations, it makes sense that Minnesota would be this high on the list.
ALL NORTH AMERICAN RECEPTIONS (2017-2024)
ALL NORTH AMERICAN RECEPTIONS (2017-2024)
This map shows a marker for each received location in the span of this analysis (2017-2024). This includes all receptions of stations located in North America. There are additional receptions of European stations, however these were received by a small number of DXers and will be analyzed separately as their own path.
This map shows very clearly the density of stations on the Eastern half of the United States. This means that any DXer that is located within single hop range of these locations has a large number of stations available that they can receive. However, it also means that these DXers are more likely to be located themselves in an area with a large number of stations occupying the frequencies on their local band. As such, these DXers are likely to have fewer open frequencies available from which to receive DX.
What correlation do we see in the location of each unique DXer in this analysis compared to the distribution of received stations? Let's take a look.
DXER LOCATIONS
DXER LOCATIONS
As you might expect, the Eastern half of the United States/Canada has the highest concentration of DXers reporting in this analysis. This puts them largely within single-hop range of the highest concentration of stations available to log. This also places, as mentioned above, these same DXers in saturated markets with many radio stations on the dial - clogging up frequencies.
PRELIMINARY PATH ANALYSIS- US RECEIVED STATIONS
PRELIMINARY PATH ANALYSIS- US RECEIVED STATIONS
While we continue to work on our path analysis and mapping project, we can take a look at some preliminary numbers, at least.
With regards to specifically receptions of U.S. stations, there were 1,196 unique paths from a combination of DXer State/Prov, Country to Station State, Country. Presented at right are the Top 100 producing paths from that combination.
Now, there are some biases in this data set, based on certain DXers that are more active or prone to Sporadic Es events due to location, openess of their local FM band, etc.
If we remove the most active DXer from this list (more on that in a bit), our numbers change a slightly. First, we drop down to 1,160 unique paths and our "Top 100" looks ever so slightly different.
INTERNATIONAL DX - HEARD COUNTRIES (MAPS)
INTERNATIONAL DX - HEARD COUNTRIES (MAPS)
ABOVE: Countries logged by North American FM DXers from 2017-2024 through FMList.org. BELOW: A zoom in specifically of Caribbean countries.
LOGS BY COUNTRY (EXCEPT US, CANADA AND MEXICO)
LOGS BY COUNTRY (EXCEPT US, CANADA AND MEXICO)
In all, 38 different countries have been logged by North American DXers between 2017 and 2024 on FM.
Most of these are from Central America and the Caribbean. However, there are quite a few countries in Europe that also make the list thanks to some very well-placed DXers in Newfoundland and the New England coast.
Outside of Canada and Mexico, the next highest log count comes from The Azores (551 logs!). Two DXers have turned in logs for this tiny group of islands, both located in the far Northeast of North America.
Closer to the mainland, countries like Bermuda (155 logs, 20 DXers) and Dominican Republic (145, 13 DXers) are big draws as well.
CANADIAN LOGS
CANADIAN LOGS
With so many US DXers within Single-Hop Es range of Canada, it is no wonder that Canadian logs are so well represented.
Ontario, close to home for many East Coast DXers, is the top draw with 1538 total logs. Likewise, Quebec's 680 logs shows a top target for DXers in the Eastern half of the continent.
Manitoba (512 logs) and Alberta (449 logs) represent another target for US DXers, especially in the Central region of the country.
All 10 provinces are represented, and one territory (Nunavut). Only Northwest Territories and Yukon Territory are missing from the log.
MEXICAN LOGS
MEXICAN LOGS
As with Canada, Mexico represents a target that lies within largely Single-Hop range for the vast majority of DXers in North America.
Only one Mexican state did not make an appearance in the FMList data, Tlaxcala. All other Mexican states are reported, some more frequently than others.
Chihuahua, to the Southwest of Texas and South of New Mexico is the top target with 733 loggings. Neighbor Coahuila (414) and coastal Tamaulipas (382) are also big draws.
On the other end, more rare Mexican states include Estado de Mexico (6 logs), Hidalgo (4 logs), Oaxaca (2 logs), and Guerrero (1 log).
So, when should DXers look for these countries to appear in their openings? First, let's see if there are any trends in a month-over-month basis.
Certainly, it seems as if July is when many of these more Southerly openings occur. Even with countries with more than just a handful of logs submitted, such as Puerto Rico (138 logs, 120 in July) and Dominican Republic (145 logs, 107 in July).
May also seems to be relatively consistent at producing Southerly openings. There is a belief among many of the DXers we have spoken to that early openings tend to favor a Southern direction into Mexico and the Caribbean. This data may show hints of that in some cases such as Guatemala and Honduras that lean a bit more heavily towards May.
Some of the countries a bit closer to the mainland such as Bermuda, Cuba and Mexico, along with some Central American countries such as El Salvador have a more equitable distribution amongst each month.
Do these openings occur every year? Or do they happen at regular occurrences? The chart below can help guide us to find out.
An eight-year span probably isn't going to reveal too much in regards to annual trends, but we do see a few things that stick out.
2021, in particular, was a really strong year for Southerly openings, it would appear. Anecdotally, I do remember several openings in July of 2021 when I was living in Charleston, South Carolina. At the time, I was logging a number of stations in Puerto Rico while others were seeing Cuba, Dominican Republic, etc. So, perhaps much of that July volume we saw in the top chart was from those July 2021 openings?
As with the monthly breakdown, countries that are closer to the mainland such as Cuba, Cayman Island, Bahamas, Bermuda, and Jamaica seem to be reported on a regular cadence. Some of the others seems to have a reappearance from 2021 to 2023. It is far too early to be able to determine if that every other year sort of cadence is consistent. If so, DXers should be on the look out in 2025 to their South!
DISTANCE AND DXERS ANALYSIS
DISTANCE AND DXERS ANALYSIS
DISTANCE DISTRIBUTION - BY LOGS AND BY UNIQUE DXER
DISTANCE DISTRIBUTION - BY LOGS AND BY UNIQUE DXER
Another way to gauge the productivity of an opening or even a whole season is by how distant of receptions the opening produced.
To do that, we have broken distances between DXer and received station into four categories:
Short-Haul: This is DX between 300 and 700 miles from the DXer. This usually occurs when the MUF is rising very high, which shortens the distance of the DX starting with the lower FM band and working its way up. This represents about 5.2% of all loggings.
Medium-Haul: This is DX between 701-1200 miles from the DXer. This is the vast majority of Sporadic Es receptions and the norm to expect during a Sporadic Es opening. This represents 70.8% of all loggings.
Long-Haul: This is DX between 1201-1600 miles from the DXer. These are much more rare than the other two categories and on the upper end pushes the limits of what we believe single-hop Sporadic Es propagation is capable of. This represents 22.5% of all loggings.
Possible Double-Hop Es: The rarest of the rare, these are receptions that exceed 1600 miles from the DXer. The lower end of this scale could include some very long single-hop receptions.....but the vast majority of any receptions beyond 1600 miles are likely some form of double-hop reception. This represents 1.3% of all loggings.
In this analysis, we look not only at the percentage of logs that fall into each category, but at the percentage of DXers that have reported loggings that fall into each category. This tells an even bigger story!
To do this, we counted the number of unique DXers that reported receptions in each category and then divided that by the total number of unique DXers.
For example, it should come as no surprise that 96.9% of DXers that submitted Sporadic Es logs reported receptions in the Medium-Haul category. It is somewhat surprising that Long-Haul Es are reported by nearly 78% of all DXers. It seems that while they are a much smaller portion of the population of logs, they are widely experienced (just perhaps not producing a large number of logs).
Let's focus though on the ultra-rare Possible Double-Hop Es. Reported by only 12.5% of all DXers, these extended distances are not even experienced by the vast majority of DXers. To make it even more clear how rare these events are, if we examine who the DXers are that are reporting these, we find that the vast majority of these Possible Double-Hop Es logs are reported by three DXers.
If we remove those three DXers from the pool, we see the percentage of DXers reporting logs drops down to 10.9%. However, the percentage of Possible Double-Hop logs drops to a stunning 0.2%. Just 88 logs scattered amongst 21 DXers that exceed 1600 miles. It is the rarest of rare, the unicorn of FM DXers for a reason!
The bottom chart on the left shows the impact removing those top 3 DXers has on the data.
DISTANCE DISTRIBUTION - BY MONTH
DISTANCE DISTRIBUTION - BY MONTH
Is there a month that is more prone for producing Possible Double-Hop Es? When should we have our ears perked for the ulta-distant?
For the most part, the distribution of distances by month is fairly flat across the board. August is a little less likely to produce Short-Haul Es than the rest of the months, but the percentages are fairly consistent month-over-month.
That is, of course, except for Possible Double-Hop. It seems the month of July has a bit more of an advantage in creation of Possible Double-Hop Es than the rest of the months. To be fair, it is a much maller population than all of the other months, but the distribution is interesting.
Perhaps the mechanisms that create double-hop Es - where reflections between more than one Es "cloud" - are more prevalent in July?
To coincide with this, we actually see a slight increase in the proportion of Long-Haul Es in July compared to June as well. This adds further credence to the theory that possibly July openings can lead the way in distance of receptions.
LOGS BY UNIQUE DXER (TOP 25 BY VOLUME)
LOGS BY UNIQUE DXER (TOP 25 BY VOLUME)
While we are on the topic of DXers, let's take a look at who the most active DXers are in our analysis. The chart above represents the Top 25 DXers in our dataset by logging volume.
Now, I am keeping their names anonymous and using only their location to identify them. But you can still see that there are definitely DXers that are either in locations prone to better Sporadic Es conditions, or are simply more active.
Take our top spot out in Goldfield, NV for example. They ring in with more than 10.000 logs in our dataset and almost 14% of all logging volume! This is a DXer where almost the entire FM band is free of any local or even strong semi-local stations. So, it doesn't take much for openings to appear for this DXer. In addition, their noise floor is very low, which means it doesn't even take a strong opening for Sporadic Es to materlialize. Likewise, they are in a location that is more apt to be in line for Possible Double-Hop Es, when there are openings out West and again in the East. Finally, they are retired, so they have more free time to devote to DX, watching for openings and taking advantage of their fantastic location for DX!
There are also DXers such as the one in Coley's Point, Newfoundland, Canada that are in fantastic locations to take advantage of both East Coast Sporadic Es openings as well as to link up with Es "clouds" over the Atlantic and receive propagation of European stations. This has led to them submitting more than 3,200 logs (4.5%) within the 8 years of this analysis. With their mix of 100 kHz and 200 kHz spacing, there is an increased density of stations from European countries that this DXer can take advantage of. Just like with our DXer in Goldfield, this Coley's Point DXer is in a very quiet location with few strong locals and a low noise floor. As such, they are also able to get in on many of the Double-Hop Es openings that are found in our dataset.
The DXers in Hanson, MA, Rodanthe, NC and Tabernacle, NJ were early adopters of FMlist and therefore have many years of data between them. In addition, they are in locations that provide them with excellent openings such as North/South up/down the East Coast, Westward towards the center of the country, further South into the Caribbean and even Central America! They are experienced DXers with well-constructed setups, allowing them to take advantage of any openings that show up!
STATION ANALYSIS (INCLUDING RDS DECODE DATA)
STATION ANALYSIS (INCLUDING RDS DECODE DATA)
MOST FREQUENTLY LOGGED U.S. STATIONS (TOP 25)
MOST FREQUENTLY LOGGED U.S. STATIONS (TOP 25)
Do you ever feel like during a Sporadic Es opening, you keep hearing the same stations over and over? Well, if it is one of the stations on our list at right, you may be on to something.
These are the top 25 most frequently logged stations in our data set. These may represent common pathways for openings or stations that get out very well during anomalous propagation.
For instance, WSMR in Sarasota, Florida, with a grand total of 182 reported loggings leads the way as the most commonly heard station. In fact, stations in FL represent 16 of the 25 most logged stations on our list. This definitely shows a strong path into FL, perhaps the MA to FL path we saw earlier in our preliminary path analysis is showing up here?
The middle of the country shows up in our top 25 list well as well. Texas, Oklahoma, North and South Dakota, Kansas and Nebraska are all represented in the top 25 stations list. The also helps to provide validating support to the notion that the central part of the US, with crossing paths from both the Eastern and Western U.S. is a area of strong activity.
All told, these 25 stations total 2, 195 logs, or about 3% of all logging volume.
The most logged station, regardless of location, is RTP Antena 1 in Azores with 232 logs.
RDS DECODE ANALYSIS
RDS DECODE ANALYSIS
OVERALL RDS DATA - U.S. NATIONWIDE
OVERALL RDS DATA - U.S. NATIONWIDE
Before we can start a real analysis of RDS decoding data, let us first get a level set on just how many stations in the United States are transmitting an RDS PI Code. This data comes from PI Code data within the WTFDA Station Database: https://db.wtfda.org/
The overall national average is 30.7% of all U.S. stations are transmitting a PI Code. Some parts of the country are more prevalent in their usage of RDS codes than others. That can be seen in the heatmap, above, which shows a strong presence of RDS in several New England states while the Western half of the U.S. is much more sparse in their RDS usage.
How can this information be helpful for DXers? If you have an opening to an area that has higher/lower RDS usage, you can know better what to expect from the opening as far as the ability to produce RDS decodes.
It turns out there are also some frequencies that have a higher proportion of RDS usage than others. One area that might not come as a surprise to many DXers is the usage by stations in the Non-Commercial (88.1-91.9 MHz) vs. Commercial (92.1 MHz and above) portions of the band.
Non-Commercial stations broadcast a PI code at a lower rate (25.6%) than Commercial stations do (32.3%). Again, this makes logic sense that a commercial station - which relies so heavily on advertising dollars which are driven largely by ratings - would want their listeners to know which station they were tuning into. So, the higher the MUF of an opening, the better chance a DXer has at getting an RDS decode.
U.S. RDS USAGE - BY FREQUENCY
U.S. RDS USAGE - BY FREQUENCY
What frequencies are the most heavy with RDS usage? The chart at left shows the frequencies with an RDS usage percentage that exceeds that of the overall average of 30.7%.
The top 32 spots on this list are all frequencies in the commercial portion of the band. The first non-commercial frequency - 88.9 MHz - doesn't show up until the 33rd spot on the list with a 33% RDS usage. In fact, it is the only non-commercial frequency with an RDS usage that exceeds the 30.7% average.
Quite a few of the frequencies with higher usage are on the upper end of the band - in the High MUF range above 104.3 MHz. In fact, 12 of the top 58 frequencies are in this range.
That leaves 45 frequencies between 92.1 and 104.1 MHz with RDS usage between 30.9% and 46.3%. That means DXers with an opening into the commercial part of the band have between a 1/3rd and nearly a 50% chance of their received station carrying a PI code.
So.....now how does this equate to what DXers are actually experiencing?
Before we dive too deeply into that question, let's start with a disclaimer:
It is very likely that DXers are more likely to log a station when they receive an RDS decode than if they do not. During a Sporadic Es opening, when time is limited, a DXer will not want to spend a large amount of time sitting on a frequency waiting for a verbal ID from a station. A DXer that records a portion of - or all of - the band for later review can do this more leisurely and spend the time necessary to identify the station. But during a live DX session, time is of the essence. A quick RDS decode and moving on helps a DXer be able to maximize their ability to snag loggings.
Also, we cannot overlook the surge in usage of RDS autologgers in both being able to spot a Sporadic Es opening and to add stations that might be missed while DXing. I know that for my own DXing in 2024's lackluster season, there were times where the only stations I logged from an opening came as a result of my autologgers.
When we take all of this into consideration, it is a safe assumption that DXers are leaning heavily on RDS decodes to help them navigate openings. It is likely, therefore, that this can show up in our data.
Interestingly, more than half of logged stations did NOT come with an RDS decode. While the 48.4% of loggings that did is still well above the overall U.S. national average, it is interesting to note that DXers are still largely relying on what they HEAR to ID a station, not just what they see!
Knowing that we are looking at 8 years of data I wondered also if there was any general trend of RDS decoding that might point to increased usage of SDRs and other receivers that carry the RDS PI code on a display? Between that and an increase in the number of DXers utilizing RDS autologgers, would there be a trend more towards the "Yes" over time?
It isn't drastic, but yes. There was a low spot in 2020 with only 31% of loggings carrying an RDS decode, but there has been a general trend since then of increased RDS decodes in logging data.
Now, there was a slight rebound of non-decode logs in 2023, the 2024 season represented the highest proportion of RDS decodes within any year in the dataset.
If we look at stations located outside of the U.S., we actually see a little higher decode rate. There may be a few factors at play here such as language barriers (an RDS decode is a much easier way to log a station when the DXer does not speak the language of the received station) and RDS usage (stations in Europe are much more likely to carry an RDS PI code than U.S. stations do.
That last part especially pans out in the data with the countries with the highest rate of RDS decodes among DXers being those in Europe. Portugal (87.8% of logs), Spain (87.29% of logs), Iceland (57.14% of logs) and Canary islands (56.25% of logs) all carry much higher decode rates than anything we see in any of the U.S. station data.
Even when we look "closer to home" at countries like Canada (49.28%) - with a large number of French speaking stations, especially in the Eastern half of the country - and Mexico (41.25%), we see relatively high RDS decode rates. This speaks to the theory that a DXer presented with a language barrier may be more likely to log a station with an RDS PI code than one without.
CONCLUSIONS & FINAL THOUGHTS
CONCLUSIONS & FINAL THOUGHTS
This analysis is a continuing work in progress. We will be adding more logging data with each new season, we will be likely looking for new angles and slices of the data that we hadn't thought of before. That is to say, don't consider anything you see here to be "the final word" on any of the metrics we looked at.
Sporadic Es knowledge is a continually evolving practice. It seems every year, we learn a little more as technology improves and data sharing becomes more commonplace.
Some of the takeaways I have from this data is just to reinforce long-standing ideas we have had in the FM DX community for years. Things like 'the double dip' that presents a morning and afternoon/evening opening for DXers - that actually shows up in the data.
The idea that Double-Hop Es loggings and distances are super rare - now we can quantify just how rare it is! Especially if you are not one of the three DXers that get the most of it!
The idea that some seasons produce long-lasting openings that many DXers are able to enjoy while others (ahem, 2024) produce table scrap openings that are limited in their scope and limited in their production.
The idea that there are certain "hot spot" days - we found those. The idea that certain months produce more openings to the South of the U.S. - we kinda saw that too!
As we get more and better data, more and better analysis tools....I hope that we can draw even more helpful conclusions. Can we tie any of this in to scientific data from ionosondes or other atmospheric conditions? I would love to find a way to do that.
We can't predict Sporadic Es yet. If we could, we would probably even have to change the name to drop the "Sporadic"!
But we can look back, reflect on seasons past and use them to provide context for future seasons. If even for a moment, we can just revel in the glory that is one of the most magical occurrences in all of the radio hobby.
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