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Home Introduction Abbreviations Q Codes Alotted Spectrum Frequency Band Frequency Control and Contact
Signal Types and Time Zones QSL Card , Log Book And Equipment Book

FREQUENCY CONTROL


FREQUENCY CONTROL AND MEASUREMENT
The transmitter must be tuned accurately so that no energy is radiated outside the authorised bands.

following are some means to fulfil such needs:


REPEATER
An Amateur station that simultaneously retransmits the transmission of another station.
It extents the distance of communication..
It is mostly used in VHF band. The standard shift between transmitting and receiving frequency for Amateur Radio VHF band is 600 kHz.
Repeaters can be of two types as follows:
1:simplex

2:duplex

in simplex repeaters, we use a single frequency for the transmission and receiving purposes.ie:
145MHz
in duplex repeaters, two seperate frequencies are used for transmission and receiving purpose.ie:
145 and 145.6 MHz(a difference of -.6MHz).

AMATEUR SATELLITE SERVICE
A radio communication service using stations on earth satellites for the same purpose as those of Amateur service is called Amateur satellite service. An Amateur satellite is a repeater in space with a large coverage on the earth. Except for geo-stationary orbits, satellites don’t stay in one spot. Orbiting Satellites Carrying Amateur Radio is called OSCAR. It is intended for multiple access by Amateur stations in all countries.


CONTACT ESTABLISMENT:
The antenna used sould not disturb the power lines or telephone lines.Also, the heigth of the antenna sould not affect the aircraft motion.
The antenna sould be erected,desined and constructed properly.The antenna type should be selected as per the freq band used.


PRECAUTIONS TO BE TAKEN BEFORE ESTABLISHING CONTACT WITH AN AMATEUR STATION
Before transmitting, the station shall take precautions to ensure that its signals will not interfere with transmissions already in progress. If such interference is likely, the transmission shall commence only when there is an appropriate break in communications.



PROCEDURE BY WHICH AN AMATEUR STATION ESTABLISHES CONTACT WITH ANOTHER STATION: The General call shall Consist of the word CQ three times followed by the word DE in Morse Code and THIS IS in voice, followed by the stations callsign three times and the ending signals AR K.

Eg. Morse: CQ CQ CQ DE VU2JOS VU2JOS VU2JOS AR K

The call may be sent three times at intervals of two minutes and then it shall not be repeated for another ten minutes. The reply to a call shall consist the callsign of the calling station not more than three times, the words DE in Morse Code and the words THIS IS in voice and the callsign of the station called, not more than three times. Transmission of a message shall be terminated by the signal AR in Morse Code and by the word OVER in voice.


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