20m Beacon Summary
I intend to edit this page in the near future to add some more supporting information and my thoughts regarding this data, so you might want to return to this page at a later date.
I imported the CSV export of my 20m DXPlorer beacon data into a MySQL table.
While previewing the data table, I observed that although my beacon can only register the first 4 characters of my Maidenhead Gridsquare, most of the beacon data was registering 6 characters of the receiving station’s Maidenhead Gridsquare. I decided to re-calculate the reported receiver’s distance and azimuth based on 6 characters of my Maidenhead Gridsquare (DM12ou).
Luckily, I discovered DistBear – by KK6MK which greatly eased the burden of my having to write some algorithms for the recalculation (thank you KK6MK).
Then came the fun part… trying to get the DistBear results into a MySQL table! Sheeesh… I had to regex the Excel csv file to escape the text fields (callsigns and gridsquares) with quotes, then nullify my added ‘re-calculated’ fields for all records where the receiver’s Maidenhead Gridsquare was only 4 characters long. The reason for nullifying these values is that DistBear expects all gridsquares to be 6 characters long and therefore generated bogus data for the 4 character gridsquares. Also, DistBear needs the gridsquares to be all lower case during its calculations so I had to do a bit of fanagaling to avoid overwriting my properly cased raw data gridsquares with DistBear’s gridsquares.
I finally convinced MySQL to accept the CSV for import into a new data table.
I then created a MySQL view to only show the unique receiving stations as many stations had numerous ‘spots’ over the period that my 20m beacon was transmitting. Each spot occurence by these duplicated receiving stations was detecting a different transmit frequency which, in turn, caused the reported SNR and frequency drift to differ from the spotting station’s other records. I therefore wrote the view to use the average of the received SNR value and frequency drift, and the maximum received frequency for these duplicated spotting stations. I guess I could have used the average received frequency as well but decided to opt for the maximum frequency instead.
As the null values from DistBear were appearing in the resultant data view, I decided to update the ‘re-calculated’ distance and azimuth values with the original reported values where the ‘re-calculated’ distance value was null. I left my ‘re-calculated’ received latitude and received longitude as null so that I would have a secondary means of identifying which records were not truly recalculated (the primary means of identifying the records would be the 4 characted Maidenhead GridSquare).
Table 1 is the resultant summary data, sorted in descending distance, of the 42 data-points from the original 273 raw data-points. In all cases, the Power was reported to be 23.00 (dbm).
|Avg SNR||Max Freq||Avg Drift||Azimuth||Distance|
I’m using an End-fed 40m Half Wavelength antenna which lays flat on my roof. The antenna orientation is nearly exactly North to South, with the ‘free’ antenna end at the North.
As you can see from the following Antenna Analyzer information, the antenna is in dire need of some tuning!
AA-54 Antenna Analyzer
Single Point Measurement
- SWR: 2.50
- Center Freq: 14.060MHz
- Return Loss: 7.37db
- Z: 73.9 – j52.4 Ohm
- |Z|: 90.6 Ohm
- C: 215 pF
Besides my obvious antenna issues, I also have to deal with some topographic issues!
What you don’t see in this map is the large ‘earth-wall’, about 1/2 mile to my south, at an elevation of a little more than 2000 ft.
I’m effectively boxed in by large hills in all directions!