To compare two stations on the basis of unique spot count, SRN, distance, power, drift, kilometres per watt and spot quality (quality = kpw * snr).
NOTE: Click the 'calls are beacons' checkbox to compare two transmitting stations.
Search times are UTC and time zone differences between the stations should be kept in mind when comparing the data sets.
A 24 hour search means both stations get two grey lines so the comparison is valid across two different time zones.
Shorter search times are good for comparing two of your own antennas or hardware or your local wspr competitor.
Balloon telemetry is excluded because the distance and power reported are not valid wspr values.
• Chart elements
Spots show up as small data points on the vertical going chart lines. All reported spots within the query timespan are displayed.
Mouse over the dots to diplay unique spot count and relative time of day.
Relative time of day for a callsign is calculated from it's locator and is therefore approximate.
Missing spot line segments are deliberately omitted to show there were no spots in that time slot. Single dots or short segments are valid,
they are separated from other lines only where there are no spots in adjacent time slots.
The two trend lines are 4 degree polynomials: Google Chart trend lines Where there is no data at the trend line ends they simply follow their trend and can look bad but that's the way they work.
The horizontal axis spans the time interval of your search results, eg. it would span 2.3 hours for a 6 hour search that returned only 2.3 hours of spots.
The numbers on the h-axis are decimal hours because HH:MM doesn't provide the continuous numeric value that's needed for the calculations.
The left end of the h-axis is set to the datetime of the earliest spot in the found set and the right end is set to the most recent.
All search times are UTC.
Except for custom day searches, zero on the horizontal axis shows "now".
For custom days, zero on the horizontal axis is UTC zero at the end of the custom day.
Open the browser console to see the actual SQL time expression in the query sent to ClickHouse.
time > subtractMinutes(now(), 1440) means "all spots from 24 hours ago up to now"
time between toStartOfDay (yesterday()) and toStartOfDay (today()) means "between the last two UTC zeros"
• Spot Quality
SpotQ is a way of ranking spots that takes into account the three spot values Distance Power and SNR.
Kilometers per Watt is intuitively obvious as a reasonable measure of the performance of a reporter's antenna and receiver.
If two reporters hearing the same transmitter have identical kpw figures then it's logical that the reporter with the best SNR wins.
Hence the use of SpotQ which is kpw x SNR.
SNR is mostly a negative number so it is converted to a positive value using the formula: positive_snr = (snr + 35.5) ÷ 35.5
The value 35.5 is used in the source code of WSJT-X version 3 to set the minimum threshold for WSPR SNR type 2 spots.
• Advanced search
Access the Advanced search panel from the Compare menu.
Enter one or more SQL 'and' clauses into the SQL query text area, queries may be combined.
Look at the demo examples, it's easy to mod them and save them to the dialog.
Note: some examples work only when searching for beacons or reporters as per the sub-headings in the dialog.
- errors are shown in the browser console though the error data returned by ClickHouse can be hard to follow.
- pratice and brush up in a more helpful environment using this example query wspr.rocks/livequeries
Note: the key/column names and values to use in advanced search are in the [more...] section of the linked site above.