Which means that it won't be all that successful at intercepting convoys. Furthermore, still need to be telling your minesweepers to clear a path for the U-boat to leave port. One of our fun ways of finding and killing them.
Radio intercepts were still being made even with the German burst transmissions and didn't we establish in the last thread that that convoy range detection was a load of BS? It's longer than post-war boats were getting against diesel snorklers a decade later, and snorkling puts a heck of a lot more noise into the water than any merchant ship's engines do.
The noise from a single ship or Sub doesn't compare at all to the noise generated by a convoy , its an order of magnitude higher and thus apples and oranges. Burst transmitions were not even ready before the end of the war so I doubt any one was interecting them either, especially since no XXI got into patrols before the war ended either
There are document cases of the Hipper detecting convoy 50km away and thats a surface ship which are much less effective using hydrophones.
Radio Intercepts were of little tactical value in helping kill the sub.A type XXI was much faster underwater than the Type VII and much longer endurance. In tactical terms they were an order of magnitude harder to kill with ballistic ASW weaponary, which was every thing except the accoustic torpedos.
HF/DF was of emence value in vectoring in enemy aircraft and Sub hunting patrols to attack them before they reached the Convoy. In effect it trippled or quadrulped the effective search sweep range against Uboats. Which on average was about 10 nm on the surface.
In historical plane attacks , only 8% of the detected targets were attacked and sunk, the rest got away. If they were attacking type XX-I uboats, the figure would probably be more like 1-2% kills.
Further more 3/4 of the Uboats sunk by aircraft alone, did so either on subs in port or in transit. Operational results indicate that only 1% of schnorkeling subs were detected intransit. In 1943 only 2 subs were sunk in port while 47 were sunk in port in 1944/45. To get that level of kill in 1943 , you have to have destroyed the LW by then. Meanwhile historically few of the Uboats had schnorkels in 1944 , infact only 1/4 of the operational boats had them by the end of 1944. The XX-I had scknorkel as did the XX-III , so most of these air kills & surface kills, would not have occured either.