Advertisement Channels (37, 38 and 39) are not operable in Direct test Mode.https://devzone.nordicsemi.com/f/nordic-q-a/77905/advertisement-channels-37-38-and-39-are-not-operable-in-direct-test-modeHi All, I am using a 3rd Party (Japan) nRF51822 module in a device and it is running a modified Direct test mode firmware without Soft device. Upon testing, it is found that advertisement channels (37, 38 and 39) are not operable when constant carrieren-USTelligent Community 13Tue, 27 Jul 2021 12:20:31 GMTRE: Advertisement Channels (37, 38 and 39) are not operable in Direct test Mode.https://devzone.nordicsemi.com/thread/322047?ContentTypeID=1Tue, 27 Jul 2021 12:20:31 GMT137ad170-7792-4731-bb38-c0d22fbe4515:679d61dc-8dd8-41be-a489-978742809b2fSimonr<p>Hi</p> <p>The DTM application (in SDK v12.3.0 which is the latest version supporting nRF51 series devices) enables the DTM test functions described in <a href="https://www.bluetooth.com/specifications/">Bluetooth Specification</a> version 4.0, Vol. 6, Part F. The purpose of DTM is to test the operation of the radio at the physical level. You can check out this <a href="https://infocenter.nordicsemi.com/topic/struct_appnotes/struct/appnotes_nan34.html">application note</a> on how to set up a production test using DTM.</p> <p>Best regards,</p> <p>Simon</p><div style="clear:both;"></div>