How to test one channel Advertising?

Dear Nordic

how i test one channel advertising?

I change inside advertising_init() 

   ble_gap_adv_params_t m_adv_params;

   m_adv_params.channel_mask[4] =0x60;       // advertising only in channel 39

Is it right way  or anything additional settings needed?

Tested in nrf52832 DK using SDK 15 its advertising but i don't know is this work properly how i know its advertising only in channel 39

can you help me to achieve this?