Good evening to all, Academy of Ham Radio, welcoming all those to this channel who are having interested in Ham Radio and we would like to announce through our channel that we are planning to conduct Ham Radio demonstrations and awareness programmes to the college students, those institutes, educational institutes who are willing to have these type of sensitising awareness programmes in their institute are requested to contact us. We are ready to conduct these programmes and coming to today's our topic, distress signal. In fact, we are having different types of signals like distress signal, urgency signal, safety or security signal, time signal, testing signal, like this we are having wide variety of signals in Ham Radio.
Among them, top signal is distress signal. Every ham should know about this distress signal and it is very very important in examination point of view also. Distress signal, what is distress signal and what does it indicate and what action if you intercepts distress message.
Distress signal, it indicates a ship, aircraft or any other mobile vehicle threatened by grave imminent danger and requesting for immediate actionIn radio telegraphy, distress signal symbolised herein by SOS bar, bar sent like a single signal in which the dashes are emphasised so as to be distinguished clearly from the dots. The distress signal, it will be like this d d d, da da da, d d d. In this, when compared with these dits, shorter intervals, the dashes longer intervals having clearly distinguished, we have to emphasise on this dashes.
It is having absolute priority over all other calls. Immediately, they have to stop their normal communication. Even though they are not in a position to help the distress station which is seeking the assistance, we should continue to listen on that particular frequency.
Only we can leave the frequency until unless the help is being provided by the concerned administration. This distress signal shall be addressed to all stations, not to a particular station. Distress call and message, the distress call and message like this s o s bar three times.
s o s bar means gap should not be given between this s o and s. Normally, the gap is between any letters is equivalent to three dits. Letter to letter gap is three dits normally. Specifically, if he mentions the bar that indicates there is no gap between these letters, it will it shall be sent like a single signal s o s bar three times and then d e call sign of the mobile station which is in distress like a titanic or something like that.
Whichever station seeking for immediate assistance due to its emergency and particulars of his position, kind of disaster, distress and particulars of his position means they should give their position according to the latitude and longitude and type of disaster and the kind of assistance they desired. Any other information which might facilitate the rescue operation. In the similar manner, distress message shall be followed in radio telephony like this.
Instead of s o s bar, we have to pronounce mayday as in French expression maider three times. In place of d e in telegraphy, here in this case radio telephony, this is and followed by our call sign whichever station is in distress like a titanic or any other mobile vehicle which is in grave danger. And the similar manner as like in Morse code message, particulars of his position, kind of assistance they desired, particulars of position as per latitude and longitude and any other information which might facilitate the rescue.
Distress frequency and silent periods. The distress frequency in radio telegraphy is 500 kilo hedges. In this frequency, 15 minutes to 18 minutes and 45 minutes to 48 minutes of every half an hour every hour.
That means, if the time is now 4 pm in the evening, 4 15 to 4 18 minutes and again after 30 minutes that is 4 45 to 4 48 minutes are silent periods. These periods we have to deliberately maintain the silence. That means, those people who are using maritime mobile services, they should maintain, they should follow this rule strictly.
Whereas, in telephony international distress frequency is 2182 kilo hedges and the silent periods are 00 to 03 minutes and again after half an hour 30 to 33 minutes of every hour. That means, if the time is now 4 pm, 4 to 4 minutes, 4 hour 3 minutes, 4 to 4 3 and again after 30 minutes that is 4 30 to 4 33 minutes. Silence should be maintained.
Those who are having some emergency situation, they can occupy these frequencies and utilise for any emergency communication. In VHF, the frequency 156.800 kilo hedges. That means, 156 mega cycles 800 kilo hedges is the international distress frequency for VHF services.
These are the things I wanted to share with all of you. Thanks very much and again I would like to meet all of you with a different topic with regard to amateur radio examination. 73 is a code word.
Best wishes to all of you. Bye for now.
17 сен 2024
