selective calling การใช้

• A more commonly used system is called Selective Calling or Selcall.
• Selective calling prevents the user from hearing others on a shared channel.
• Selective calling is akin to the use of a lock on a door.
• Trunked radio systems have built-in unit ID and selective calling features.
• One segment turns the selective calling off.
• Modat is used for unit ID and emergency buttons, rather than for selective calling.
• Some selective calling systems experience falsing.
• Tone squelch, or other forms of selective calling, is sometimes used to solve interference problems.
• Use of selective calling and tone squelch systems such as DTMF, CTCSS and DCS are allowed.
• These systems send tone sequences to identify a unit ( unit ID ) rather than for selective calling.
• Selective calling systems can overlap; a radio may have ( group call ) and DTMF individual calling.
• After confirming the channel is indeed idle, it then sends a brief selective calling signal identifying the intended recipient.
• Selective calling locks out all signals except ones with the correct key to the lock ( the correct code ).
• In "'DTMF "'selective calling, the radio is alerted by a string of digits.
• MDC signaling includes a number of features : unit ID, status buttons, emergency button, and selective calling.
• Some aircraft radios used SELCAL ( selective calling ), which muted the receiver unless an assigned tone was received.
• Selective calling features fit into two major categories : " individual calling " and " group calling ".
• Selective calling locks out all signals except ones with the correct'key', in this case a specific digital code.
• In uses where missed calls are allowable, selective calling can also hide the presence of interfering signals such as receiver-produced intermodulation.
• Generally only voice transmission is allowed under personal radio service regulations, although tone and digital selective calling features are allowed in some countries.