DA 122, DA 142, and DA 152. The information of DA 122, DA 142, and DA 152 units is conflicting. The two sources of information are OB. Stab. Ing. Rommel and Fl. Stab. Ing. Speiler of the Luftwaffe E-Stelle. Spieler was a specialist in pressure units, and his information may be more authentic than Rommel's, since the latter was in charge of all Luftwaffe mine material development. The contrasting opinions are as follwos:

DA 122 (Spieler) – Same as DA 102 with a coarse acoustic component as an anti-mine-sweeper circuit.

DA 122 (Rommel) – Similar to DA 102 with a six- to seven second time constant for pressure actuation. Anti-swell protection renders the unit passive for 1/2 hour after pressure actuations subisde, if two or three pressure actuation are recorded without actustic actuation.

DA 142 (Spieler) – Same as DA 102, but requires an 18-second pressure pulse for use against large ships and to increase sweeping difficulty.

DA 142 (Rommel) – Same as DA 122, but with low-frequency (20 cps.) acoustic com-ponent.

DA 152 (Spieler) – Same as DA 102, but with rate-of-change acoustic similar to A 105.

DA 152 (Rommel) – Has four-contact pressure component requiring rate of change pressure signature.