Character Error Rate Calculator for Text Telephony

This calculator is used to compute the character error rate when using RFC 4103 or similar text-based communication protocols to send text over the Internet character-at-a-time. The calculator will show the character error rate when sending audio via the audio channel or using RFC 4103 for text transmission.

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:

Number of milliseconds represented by each packet.
Approximate number of milliseconds required to transmit a single character. For example, Baudot takes approximately 160ms to transmit a character.
Number of redundant encodings, such as packets, according to RFC 2198.
To update results, move to another parameter field, e.g., by tabbing, or simply press the Update results button.
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.
Number of packets transmitted per second.
Number of packets required to form a complete character.
Character error rates above 1% are considered unacceptable.
When character time is less than packet time, this equation is superceded by the effective loss, thus quantizing the character error rate.