Spectrogram Analysis
Archivist's Note: The following spectrograms were generated from recovered audio files. Several contain visual anomalies that were not identified until digital enhancement in 2024. Interpretations vary.
TRANSMISSION 74-012
Date: 07/22/1974 | Duration: 11.7s | Frequency range: 1400-1427 MHz
Analysis: First transmission to show repeating structure. Pattern interval: 2.3 seconds. Early project documentation classified this as "probable natural origin." This assessment was revised in 1976.
TRANSMISSION 75-034
Date: 02/08/1975 | Duration: 8.9s | Frequency range: 1400-1427 MHz
Analysis: Repeating pattern with 7.4-second interval. Notably, this interval appears in multiple subsequent transmissions. Dr. Elmore's notebook references this pattern frequently. Significance unknown.
TRANSMISSION 76-089
Date: 11/03/1976 | Duration: 23.4s | Frequency range: 1400-1427 MHz
Analysis: When contrast is enhanced, a pattern emerges in the 1400-1420 MHz range. Some researchers have noted it resembles geographic coordinates. The coordinates, if accurate, point to a location in the Pacific Ocean. Nothing is there.
TRANSMISSION 77-031
Date: 04/12/1977 | Duration: 31.2s | Frequency range: 1400-1427 MHz
Analysis: Signal intensity significantly higher than previous transmissions. The frequency modulation follows patterns consistent with Dr. Elmore's linguistic framework. This was the first transmission where message intent was considered unambiguous: a warning.
TRANSMISSION 77-A [FINAL]
Date: 08/15/1977 | Duration: 72.1s | Frequency range: 1400-1427 MHz
Analysis: The most complex signal received. Full linguistic structure identified. Successfully translated: "We hear you. We have always heard you. Stop sending. They can hear you now."
Additional note (2024): The final 4 seconds of this transmission contain a secondary signal embedded beneath the primary. It has not been decoded. Some analysts believe it is not meant for us.
Additional note (2024): The final 4 seconds of this transmission contain a secondary signal embedded beneath the primary. It has not been decoded. Some analysts believe it is not meant for us.
Spectrogram analysis conducted using modern digital signal processing tools. Original analog spectrograms from ECHO-1 were not recovered.