Advance Information
MT88E45
North America: Bellcore
a
1200 Hz +/- 1%
2200 Hz +/- 1%
-4.23 to -36.20 dBm
(476 to 12 mVrms)
d
-48.24 dBm (3mVrms) for
On-hook No Ring Signalling
such as VMWI
1200 baud +/- 1%
-6 to +10 dB
Single Tone (f):
-18 dB (f<=60Hz)
-12 dB (60<f<=120Hz)
-6 dB (120<f<=200Hz)
+25 dB (200<f<3200Hz)
+6 dB (f>=3200Hz)
0 dB
-3.5 dB
Europe: ETSI
b
UK: BT
c
Parameter
Mark (Logical 1) Frequency
Space (Logical 0) Frequency
Received Signal Level
Signal Reject Level
1300 Hz +/- 1.5%
2100 Hz +/- 1.5%
-5.78 to -33.78 dBm
e
(-8 to -36 dBV)
f,g
On-hook: -47.78 dBm
(-50dBV)
1200 baud +/- 1%
-6 to +6 dB
>= 25 dB
(300 to 3400 Hz)
>= 20 dB
(300 to 3400 Hz)
-5.78 to -37.78 dBm
(-8 to -40 dBV)
Transmission Rate
Twist (V
MARK
/V
SPACE
)
Signal to Noise Ratio
Tip/Ring Op-Amp (GS1) Gain
Vdd = 5V +/- 10%
Tip/Ring Op-Amp (GS1) Gain
Vdd = 3V +/- 10%
a.
b.
c.
d.
e.
f.
g.
h.
i.
-2 dB
h
-5.5 dB
i
0 dB
TBD
ANSI/TIA/EIA-716 and draft TIA/EIA-777. Bellcore has agreed to the values and will synchronize its requirements.
ETS 300 778-1 (On-hook) Sep 97, ETS 300 778-2 (Off-hook) Jan 98.
SIN 227 Issue 3 Nov 97, SIN242 Issue 2 Nov 96.
North American on-hook signalling range. The off-hook range is inside the on-hook range: 190mVrms to 12mVrms.
dBm - Decibels above or below a reference power of 1 mW into 600 ohms. 0 dBm = 0.7746 Vrms
dBV - Decibels above or below a reference voltage of 1 Vrms. 0 dBV = 1 Vrms.
ETSI on-hook signalling range. The off-Hook signalling levels are inside this range: -8.78 to -30.78 dBm (-11 to -33 dBV).
The 5V ETSI Tip/Ring op-amp gain can be 0 dB if there is no FSK reject level requirement.
The 3V ETSI Tip/Ring op-amp gain can be -3.5dB if there is no FSK reject level requirement.
Table 4 - FSK Signal Characteristics
FSK Demodulation
The FSK characteristics are shown in Table 4. In
North America, TIA (Telecommunications Industry
Association) also defines standards. The Type 1
Caller ID CPE standard is ANSI/TIA/EIA-716. The
Type 2 standard is being drafted to become TIA/EIA-
777. The North American FSK characteristics in
Table 4 are from ANSI/TIA/EIA-716. They differ from
those Bellcore published in SR-TSV-002476 and SR-
3004. Bellcore is represented in TR41.3.1 and will
synchronize to the TIA requirements in its future
documents.
The TIA Type 1 standard includes an FSK reject
level:
•
if data is not preceded by ringing (e.g. VMWI),
FSK signals below 3mVrms (-48.24 dBm) shall
be rejected
•
if data is preceded by ringing, FSK detection
may be extended below 3mVrms
The MT88E45 is compliant with the Bellcore/TIA,
ETSI and BT requirements with the Tip/Ring op-amp
gains in Table 4. In Europe if the country specific
FSK requirements do not incorporate ETSI’s FSK
reject level then the Tip/Ring op-amp gain can also
be 0dB at 5V and -3.5dB at 3V to meet the ETSI
minimum CAS level for on-hook signalling (-40 dBV).
For 3V operation, the FSK receiver becomes more
sensitive and lower level signals will be accepted
than at 5V. To maintain the FSK reject level, the Tip/
Ring input op-amp gain should be reduced. Note that
since the Tip/Ring op-amp is also used for Tip/Ring
CAS detection, the CAS level will also be reduced for
on-hook detection.
9
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