DX Reminder Alert Anatomy: Frequency, Mode, Spotter and Source
The phone rings, the screen lights up and a callsign appears that you have waited for. What you do in the next ten seconds decides whether you work it. A DX Reminder alert carries more than the callsign, and the extra fields are not decoration. The frequency tells you where to tune, the mode tells you what to switch on, the spotter tells you who heard the station and the source tells you how the report reached you. An operator who reads these four items in a glance knows whether to run to the radio, to tune quietly or to wait for a second report. This article explains each field, what to make of it and how to combine them into a quick decision, using what the app and its list of changes say about the alert and the list of spots.
What an Alert Contains
When a callsign you watch is reported on a band and in a mode that you ticked, the app raises an alarm for that combination. It rings once for the callsign, band and mode, however many spotters report the same station, and it shows the newest spot of them. The notification carries the frequency and mode of the spot, and, since Android 4.2, the spotter and the source travel with the notification itself. That change was made because a paired watch skips the buttons that the notification draws on its own and shows only the frequency and mode, so the extra details were moved into the notification proper. On the phone, the alarm has Stop and Snooze buttons visible without expanding the notification, so the first look is also the place where you silence it.
The home page of ly4a.com shows the same idea in its demonstration: each entry has a callsign, a frequency in kilohertz, the band, the mode and the spotter, and for automatic reports a signal figure in decibels. That is the structure to keep in mind when you read your own alerts.
The Callsign: Check It Twice
The callsign is the one you entered, so the surprise is rarely in the call itself. Still, read it. A watched call may appear with a suffix or a prefix, for example as a portable station, and a short call such as a two-letter special event call may be sent by a station other than the one you expect. In a DXpedition, the same team may use several callsigns on different bands and modes, so a spot with a call you did not add may be the same operation. Compare the alert with your notes, and when you are not sure, a look at the cluster page for the new call is a ten-second check.
The Frequency: Where to Tune
The frequency in the alert is the frequency in the spot, which is the frequency at which the spotter heard the station, written in kilohertz. On CW and SSB it is the place to tune, with a small correction for the spotter’s own calibration. A spotter whose receiver is off by a few hundred hertz gives a frequency that is slightly wrong, so tune around it. In a pileup the frequency in the spot is the DX station’s transmit frequency, and the station may be listening on a different one, a situation called split operation. The article on split operation explains how to find the listening frequency, and a listen on the DX frequency for a few cycles usually reveals it, because the station announces “up 2” or “listening 5 to 10 up”.
For FT8 and FT4, the frequency is an audio offset inside the standard sub-band, and the DX station sits at some point between 200 and 3,000 hertz of the dial frequency. The report gives the dial frequency plus the offset as a total. If you use WSJT-X, set your radio to the dial frequency of the band, and look for the call in the decoded list and the waterfall. The band and mode are in the alert so that you can switch quickly: do not forget to change the radio to the right mode before you call.
The Mode: What to Switch On
The mode in the alert is the mode of the spot, and it matches the cell that you ticked. The app keeps band and mode apart, so a CW alert means real CW, an SSB alert means SSB, and FT8 and FT4 are not mixed. That helps: if the alert says 17 metres CW, the station is on CW there, and a SSB call will not be answered. If you ticked several modes for the same call, each can ring on its own, so you may receive an alarm for the same station in CW and a second alarm in FT8. That is useful for a new mode slot and for a new band slot, since each is a separate chance. Read the mode before you press anything.
The Spotter: Who Heard the Station
The spotter is the station or the receiver that reported the DX. The callsign of the spotter is a source of information. First, it tells you where the signal was heard. A prefix near yours means that the propagation reaches your area, since the spotter’s location is probably similar to yours. A spotter on another continent, for example one in the Pacific, reports a path that may not reach you at all. The same DX station can be strong in Japan and absent in Lithuania, and the alert will ring for both. Look at the prefix of the spotter and ask whether the propagation is likely to be similar for you.
Second, the spotter can be a person or a machine. A person types a spot after working or hearing a station, and it can contain a typing mistake in the callsign or a frequency error. A machine, such as a skimmer or a receiver that decodes digital modes, reports the call that its software decoded. Both kinds are useful, and the next field helps you tell them apart.
The Source: How the Report Reached You
The app watches five sources: DXScape, DXSummit, DXHeat, PSK Reporter and the Reverse Beacon Network. The source named in the alert tells you the type of report. DXSummit, DXScape and DXHeat are DX cluster services, where reports are mostly typed by people, though some are automatic. PSK Reporter collects reception reports of digital modes sent by listening stations, and the Reverse Beacon Network collects the decoded calls of CW skimmers. The article on the five sources compares them in detail. For reading an alert, the idea is simple: an automatic report is fast and reliable for the fact that the signal was decoded at that place, and a human spot is more likely to describe a station that was worked or is calling CQ, with a note.
Some reports include a signal figure in decibels. For FT8 the value is the signal-to-noise ratio of the decoded signal, as described in the article on the FT8 signal report, measured in a reference bandwidth of 2,500 hertz. A report of minus 8 dB is decodable and decent, and plus 10 dB is strong. For CW skimmers, the figure is the signal-to-noise ratio at the skimmer. A strong value from a spotter near you is a good sign. The same number from a spotter far away tells you only about the distant path.
A Quick Decision Table
| What the alert shows | What it probably means | What to do |
|---|---|---|
| Spotter prefix near your region, strong report | The path to you is open | Go to the radio now and call |
| Spotter on another continent | The signal exists, the path to you is unknown | Listen first; check other spots |
| Automatic source, weak report | A decodable signal under difficult conditions | Try digital or CW; expect a hard pileup |
| Human spot, no signal figure | Reported by a person; may include errors | Verify the call and frequency by ear |
| Same call, different band or mode | A second chance for a new slot | Move to that band or mode if you need it |
| Alert repeats after the interval | The station is still, or again, on the air | Check whether you already worked it |
From the Alert to the List of Spots
The alarm shows the newest spot, but the app also keeps a list of the spots, with the newest at the top. It is worth opening it after an alarm. The list shows how many spotters have reported the call, on which frequencies and in what order, and it lets you see a pattern. If three reports in the last minute agree on one frequency, the station is probably there. If the reports are spread over several kilohertz, someone has a calibration problem, or the station is moving, or there are two stations with similar calls. On Android, the status line reads “PSKR live” while the live feed from PSK Reporter is connected, so you know that digital-mode reports are arriving within seconds and not in batches. The article on the live feed explains that behaviour.
Fresh Spots and Stale Spots
Every spot has an age, and the age matters more for some stations than for others. A DXpedition that runs for two weeks is on the air for hours, so a spot ten minutes old is probably still valid. A portable station that makes a handful of contacts and goes silent may be gone in five minutes. An operator who is working a pileup moves along the band, usually upwards, so the frequency of an older spot may be wrong by a kilohertz or two. Read the alert as a statement about the recent past, and use the list of spots to see how recent. When the newest spot is old and there are no others, tune to the frequency and listen before you call, because the station may have left or may be quiet between calls.
Common Mistakes When Reading Alerts
- Calling on the spot frequency in a split pileup. You will be calling on the transmit frequency of the DX and will not be heard. Listen for the working instruction first.
- Ignoring the mode. The alert may be for FT8 while your radio is on SSB, and the first few seconds go to switching.
- Trusting a single human spot. A typing error in a callsign can send you after the wrong station. Confirm by ear.
- Forgetting the time. A spot that was true a few minutes ago may be over. The newest spot is the one shown, but the station may have left, and a quick look at the list tells you how fresh it is.
- Dismissing the alarm and then forgetting it. Use Snooze if you need a minute, so that the alert comes back.
Setting Up the App So That Alerts Are Useful
The quality of the alert depends on the table. If you tick only the bands and modes that you can work, every alert is a real chance, and you can spend your attention on reading it. If you tick everything, the alerts are many and mostly useless. The repeat interval also matters: for a rare station, a short interval refreshes the picture, while for a common station a longer one keeps the phone calm. The settings are described in the article on alarm settings.
The Bottom Line
A DX Reminder alert is a compact report with four fields beyond the callsign. The frequency tells you where to tune, with a warning that in a pileup the DX may listen elsewhere. The mode tells you what to switch on, and it matches the cell you ticked. The spotter tells you where the signal was heard, so its prefix helps you judge whether the path reaches you. The source tells you how the report was made, from a human typing in a cluster to a machine decoding CW or digital modes, sometimes with a signal figure in decibels. Read the four fields in a glance, check the list of spots for agreement and then go to the radio.
Frequently Asked Questions
What information does a DX Reminder alert show?
The callsign, the frequency and mode of the newest spot and, in current versions, the spotter and the source. Stop and Snooze are on the notification.
Why does the alert show a frequency if the DX works split?
The spot gives the frequency where the DX was heard transmitting. For a split pileup, listen to find where the station is listening, then set your transmit frequency to that.
What does the spotter tell me?
Who heard the station and where. A spotter close to you suggests that the path reaches your area, while a distant spotter may describe a path that does not.
Is a human spot less reliable than an automatic report?
Human spots can contain typing errors in the callsign or frequency. Automatic reports reflect what software decoded, which is reliable for the fact that the call was heard, though not for who is calling whom.
Where can I see the previous spots?
In the list of spots in the app, where the newest spot is at the top. It helps to confirm the frequency and the timing.
Why did I get two alerts for the same station?
The app rings once for each callsign, band and mode. If you ticked more than one band or mode, each combination can ring on its own.