Cisco Systems ATA 188 manual How to Calculate Scaling Factors, Recommended Values

Chapter 5 Parameters and Defaults

Optional Feature Parameters

•off-timecontrols the length of time between audible tones in milliseconds (ms) expressed as an integer from 0 to 0xffff sample at 8000 samples/second.

•total-tone-timecontrols the length of time the tone is audible (0 to 0xffff). If this value is set to 0, the tone will play until another call event stops the tone. For DialTone, BusyTone, ReorderTone, and RingBackTone, the configurable value is the number of 10 ms (100 = 1 second) units.

For the other tones, the value is the number of samples at 8000 samples/second, where the following information applies:

–Frequency ranges from 0 to 4000 (Hz)

–Transformed Frequency = 32767 · cos (2pi·Frequency/8000)

–Amplitude ranges from 0 to 32767

–Transformed Amplitude = A · 32767 · sin (2pi·Frequency/8000)

The scaling factor A determines the volume level of the tone. To calculate scaling factors, see the “How to Calculate Scaling Factors” section on page 5-42.

Note All tones are persistent (until the Cisco ATA changes state) except for the call-waiting tone and the confirm tone. The call-waiting tone, however, repeats automatically once every 10 seconds while the call-waiting condition exists.

How to Calculate Scaling Factors

Use the following formula to calculate the scaling factor A:

A=0.5 * 10^((k+10-(n-1)*3)/20)

In this formula, k is the desirable volume in dBm; n is the number of frequency components. The ^ symbol means to the order of.

Example

If a one-frequency component of -20 dBm volume level is desirable, then:

A=0.5 * 10^((-20+10)/20)= 0.16

Recommended Values

The following settings are recommended for the US:

•DialTone = "2,31538,30831,3100,3885,1,0,0,1000" (approximately -10 dBm)

•BusyTone = "2,30467,28959,1191,1513,0,4000,4000,0" (approximately -21 dBm)

•ReorderTone = "2,30467,28959,1191,1513,0,2000,2000,0" (approximately -21 dBm)

•RingBackTone = "2,30831,30467,1943,2111,0,16000,32000,0" (approximately -16 dBm)

•CallWaitTone = "1,30831,0,5493,0,0,2400,2400,4800" (approximately -10 dBm)

•AlertTone = "1,30467,0,5970,0,0,480,480,1920" (approximately -10 dBm)

Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide (H.323)

5-42 OL-4008-01