Practice with oscill - Telecommunication

FSK signals used by wired communication equipment for Caller ID, SMS and others purposes.

On-hook FSK-packet Caller ID (wav, 85kB):

From ETS 300 659-1:

  • first 250 ms. Channel Seizure Signal: shall consist of a block of 300 continuous bits of alternating "0"s and "1"s. The first bit to be transmitted shall be a "0". The last bit to be transmitted shall be a "1". It shall start the data transmission only in "on hook" data transmission.
  • next 150мс. Mark Signal: shall either consist of a block of 180 ± 25 mark bits or, as a network operator option, Mark Signal may consist of 80 ± 25 mark bits.
  • Other - data: Message type, Message length, presentation layer message, Checksym

Channel Seizure (10ms delay from packet start):


Mark Signal (300ms delay from packet start):



Data  (700ms delay from packet start):