Introduction of Marine VHF Radio Frequency
Some novice crew members have some doubts about the frequency of marine VHF radio. This article gives a brief explanation of the frequency of marine VHF radio.
Maritime Radio, also known as ship radio, is a kind of VHF radio. According to the unified regulations of ITU, the working frequency range of ship radio station is: TX: 156.025-157.425MHz, RX: 156.025-163.275MHz. The work channel is divided into international channel, American channel, Canadian channel and European inland channel, and 10 meteorological channels (including 8 American Meteorological channels and 2 Canadian meteorological channels) are used to listen to the meteorological information of American and Canadian coasts. The figure below shows the frequency table of Retevis maritime VHF radio, which is helpful for our understanding.
The early ship radio station had only 28 channels, and the difference between each two channels was 50KHz, which is shown in the figure, that is
, channel 01,02 ~ 28. Because it can not meet the communication requirements between ships and shore, ITU has added 29 channels, which are shown in the figure
, namely 60,61 ~ 88 channels. Specifically, a new channel is inserted between each two channels, and the difference between each two channels is 25kHz, so there are a total of 57 channels. The identified channels 
are half duplex channels, that is 06, 08 ~ 17, 67 ~ 77, and the rest are duplex channels.
At that time, the maritime industry of the United States and Canada developed rapidly, and 57 channels still could not meet the demand of port communication. Therefore, the receiving frequency of 22 double attack channels was changed to the transmitting frequency, and 22 half duplex channels were added, which were represented by * A, that is
. In addition, two AIS dedicated half duplex channels, A1 and A2, with frequencies of 161.975mhz and 162.025mhz are added, 
as shown in the figure.
There are also 10 weather channels, i.e. channels in WX channel, of which 8 and 9 are Canadian weather channels, and the rest are American weather channels.
