Chirping for Large-Scale Maritime Archaeological Survey: A Strategy Developed from a Practical Experience-Based Approach
Figure 1
Examples of a NW–SE oriented profile through the “Æ Lei” barrage in Haderslev Fjord, recorded using different subbottom profilers and a conventional echo-sounder in order to compare the various systems. In the profiles, the barrage can be seen to the left and the feature to the right is a narrow sailing channel. (a) ELAC sediment echo-sounder (Laz 4700, 30 kHz). (b) Knudsen sediment echo-sounder (320 M, 33 khz). (c) Ordinary Furuno echo-sounder (FE-881 MK, 28 kHz). (d) Analogue Datasonics Chirp II (sweeping the interval 2–22 kHz) equivalent to today’s digital Teledyne Chirp III. To the right is a map of the local area and the barrage; the latter dates from the late 4th century AD [4]. The red line represents the sailing line. Graphics based on Grøn [1].
