Packetizer

Character Error Rate Calculator for Text Telephony

Parameters
ms per packet1
ms per character2 or choose
% packet loss
redundant encodings3
Results5
Audio coding
Packet rate6: pps = 1000 / packet time
Packet requirement7: ppc = (character time / packet time) + 1
Effective packet loss: % = packet loss(1 + redundancy)
Character error rate8: % = 1 - (1 - effective loss)packet req 9
Text coding (RFC 4103 or Recommendation ITU-T V.151)
Character error rate8: % = packet loss(1 + redundancy)

Notes:

  1. Number of milliseconds represented by each packet.
  2. Approximate number of milliseconds required to transmit a single character. For example, Baudot takes approximately 160ms to transmit a character.
  3. Number of redundant encodings, such as packets, according to RFC 2198.
  4. To update results, move to another parameter field, e.g., by tabbing, or simply press the Update results button.
  5. Packet requirement is dislayed at full precision. However, the other results are displayed with no more than two non-zero digits in the fractional part since this is a gross measurement.
  6. Number of packets transmitted per second.
  7. Number of packets required to form a complete character.
  8. Character error rates above 1% are considered unacceptable.
  9. When character time is less than packet time, this equation is superceded by the effective loss, thus quantizing the character error rate.