xe0092 Xecom, Inc, xe0092 Datasheet - Page 8

• Manufacturer Part Number: xe0092
• Description: Surface-mount Daa Modules For Audio Or Data Transfer
• Manufacturer: Xecom, Inc

XE0092 Applications Notes
Dialing:
The public switched telephone network permits tone and
rotary (pulse) dialing. The XE0092 supports both types.
Tone dialing requires an external signal source to generate the
dialing tones. The /OH line on the XE0092 may be pulsed to
create pulse dialing.
Pulse Dialing: The XE0092 generates dialing pulses
through momentary closures of the switch-hook. Each digit
is represented as a series of pulses, one pulse for a one to ten
pulses for a zero. The pulse rate in North America is ten
pulses per second. The dialing pulses are asymmetrical. The
correct duty cycle in North America is 31 milliseconds on and
69 milliseconds off. An inter-digit delay of at least one
hundred milliseconds separates the digits.
Tone Dialing: To permit tone dialing the XE0092 seizes the
line, /OH active. For each digit a unique DTMF, Dual Tone
Multiple Frequency, tone pair is applied to TX+ and TX-.
The higher frequency tone is always larger than the lower
frequency one.
milliseconds, and leave a minimum of 70 milliseconds be-
tween digits.
The following chart shows the correct DTMF signal frequen-
cies for each digit.
XECOM
Digit
1
2
3
4
5
6
7
8
9
0
*
#
Lower Tone
Transmit the tones for a minimum of 70
697
697
697
770
770
770
852
852
852
941
941
941
Upper Tone
1209
1336
1477
1209
1336
1477
1209
1336
1477
1336
1209
1477
(8)
Signal Levels:
FCC Part 68 Rules set the allowable signal level in the US for
all signals placed on the telephone line other than live voice.
Other countries have similar regulations. Signal levels are
measured in dBm. Zero dBm is 1 milliwatt through a 600 ohm
load.
Distortion:
Distortion is the most common measure of the quality of the
signal path provided by the DAA. The primary sources of
this distortion is the line current holding circuit, although board
layout and other factors can introduce distortion.
Distortion varies with frequency. The voice band of the
telephone line is limited to less than 4000 Hz. High speed
modems such as 33.6K bps and 56K bps require virtually all of
this bandwidth for signal transmission. Even if the distortion
through a device is good in the center portion of the spectrum,
signal quality is compromised if distortion greatly increases at
the outer limits of the voice band. The XE0092 provides a low
distortion signal path across the entire voice band.
Caller ID Reporting:
The telephone network normally sends the Caller ID signal
between the first and second ring signals. If the user activates
the /CID input while the XE0092 is off-hook, the Caller ID
signal is passed through to the host through the RX pins on the
XE0092. If the XE0092 is off-hook, /OH low, Caller ID pass-
through cannot be enabled regardless of the state of /CID.
XE0092