Maritime communications band
The frequency range between the mediumwave broadcast band and shortwaves between 1605 - 3800 kHz is called maritime communications band; in German, this band is called „Grenzwelle“ (Border wave), in the English language areas, there is no special name for this portion of the electromagnetic wave spectrum, usually it is referred to as mediumwaves or shortwaves.
On some multiband receivers, you find band range switches with designations like MB (maritime communications band).
At the time of short-wave maritime radio, most short distance maritime communications took place here; radio traffic near coasts or ports has been moved to the VHF range.
The maritime distress frequency of 2182 kHz (working in amplitude modulation or USB) has replaced the former CW telegraphy distress frequency of 500 kHz. Digital Selective Calling (DSC) is used on 2187.5 kHz. The remaining coastal radio station turned away from monitoring the maritime distress frequencies; with the digital Global Maritime Distress and Safety System (GMDSS), the obligation for ships to continuously listen to the distress frequency of 2182 kHz also came to an end.
The 2173.5–2190.5 kHz range has still an ITU allocation for „mobile service, distress and calling“.
In coastal areas and ports, the VHF frequency 156.8 MHz (VHF channel 16) serves as calling frequency.
In some areas of the world, this shortwave range is used for broadcasting; because it is useable because of the special propagation situation in tropical areas, the same frequency is referred to as tropical bands.