What i have read/heard from first hand experiences, is that the sonar is very poor, compared to more modern subs. And i know for a fact that it is loud, first hand accounts have told me that.
- attack sonar - (German) Atlas Elektronik CSU 83; medium frequency active/passive
- flank sonar - (French) Thompson Sintra; low frequency passive; piezoelectric polymer antennas
The CSU 83 is
the standard sonar suite for German diesel submarines exported throughout the world; in particular it's used in the Type 209 derivatives and other subs used by: Argentina, Brazil, Chile, Denmark (the upgraded Type 207 and A14), Ecuador, India, Greece, Peru, South Korea and Sweden (Vastergotland).
It is superior (the successor) to the outdated CSU-3 used in older Argentinian, Chilean, Colombian, Indonesian, Turkish and Venuzuelan Type 209 derivatives as well as Egyptian modified Romeos.
Noticeably, Brazil still ordered the CSU 83 for the Tikuna class, with Tikuna commissioned in 2005.
The direct successor to CSU 83 is CSU 90, which has so far been installed in: German and Italian Type 212A, the latest Israeli subs, the upgraded four Greek Type 209/1100, the new South-African Type 209/1200 and the Swedish Gotlands.
According to Jane's Fighting Ships 2004/2005, the French flank sonar due to its design "reduces flow-noise" btw. I've yet to find a statement anywhere which DUUX version this flank sonar is btw.
On an international scale, the Ulas still compete pretty well as far as sonar outfit goes. Sure, not in the same class as a Type 212A, but you can't really expect that from a 20-year-old design. It has the sonar outfit available and common at its time.
Oh, and yes, they're about to be upgraded (full MLU).