Hey everyone do you know about Communications Receivers:

A communications receiver is a type of radio receiver used as a component of a radio communication link. Now you might be asking is if a communication receiver is the same as a Broadcast receiver. And the answer is to that is that they are not the same but they are similar in a way. The best way to know the difference between the two is that broadcast receivers only receive broadcast bands, such as the medium wave and/or longwave AM broadcast bands and the VHF FM broadcast band, while a communication receiver receives a wider part of the radio spectrum not used for broadcasting that includes the shortwave bands. For example the radios in your cars is a broadcast receiver, while the pictures shown below is an example of a communication receiver.
The Radio receivers are as old as radio itself. After all, radio signals had to be intercepted and converted into an intelligible form to be useful. At first the signals transmitted and received were by Morse code (radio telegraphy). Fittings these types telegraphy aboard ships were mandatory in the first decade of the 20th century (1900's). The Titanic disaster (1912) changed that. A ship was an hour away but did not hear the Titanic's distress call. A ship that did hear the distress call was more then three hours away, but rushed to the scene. By then, the titanic had sunk with great loss of life.
Voice transmissions (radio telephony) came into use in the 1920's. A frequency was set apart for calling and distress. Quiet times were prescribed to enable listening for distress calls.