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Speg's 2015 Broadcast FM DX Log
- Capitalized items are what were heard on the air to identify the station. Distances are in miles.
- Red call letters indicate new stations. Tan call letters indicate new stations this year.
- Explanation about estimation of critical frequency and electron density is at bottom of page.
- Unidentified or unconfirmed list
Es Contacts: 7
Different Stations: 6
New Stations: 1
States: 4 (ID MD MT WY)
Canadian Provinces: 0
Mexican States: 0
Countries: 1 (US)
The critical frequency and electron density of the sporadic-E layer are estimated by
calculating the minimum values to allow the reflection of the radio waves from the station
requiring the highest critical frequency of the broadcast frequencies and distances
observed. The following assumptions are used: (1) The height of the Es layer is 105 km,
and (2) constant (no tilt), and that (3) the signal is affected only by the Es layer and
not the temperature profile or weather in the elevations below the Es layer. Given
otherwise similar parameters, the signal needing the highest critical frequency and
electron density of the Es layer are those of shorter reflection distances or higher
broadcast frequencies. The values listed were derived mathematically, but the 105 km
height was used to compare values to the PROPLAB-PRO radio propagation computer program
(which agreed reasonably well).