Advance Information
MT88E45
Parameter
North America: Bellcorea
Europe: ETSIb
UK: BTc
Mark (Logical 1) Frequency
Space (Logical 0) Frequency
Received Signal Level
1200 Hz +/- 1%
2200 Hz +/- 1%
1300 Hz +/- 1.5%
2100 Hz +/- 1.5%
-4.23 to -36.20 dBm
(476 to 12 mVrms)d
-5.78 to -33.78 dBme
-5.78 to -37.78 dBm
(-8 to -40 dBV)
(-8 to -36 dBV)f,g
Signal Reject Level
-48.24 dBm (3mVrms) for
On-hook No Ring Signalling
such as VMWI
On-hook: -47.78 dBm
(-50dBV)
Transmission Rate
1200 baud +/- 1%
-6 to +10 dB
1200 baud +/- 1%
-6 to +6 dB
Twist (VMARK/VSPACE
)
Signal to Noise Ratio
Single Tone (f):
-18 dB (f<=60Hz)
>= 25 dB
(300 to 3400 Hz)
>= 20 dB
(300 to 3400 Hz)
-12 dB (60<f<=120Hz)
-6 dB (120<f<=200Hz)
+25 dB (200<f<3200Hz)
+6 dB (f>=3200Hz)
Tip/Ring Op-Amp (GS1) Gain
Vdd = 5V +/- 10%
0 dB
-2 dBh
0 dB
TBD
Tip/Ring Op-Amp (GS1) Gain
Vdd = 3V +/- 10%
-3.5 dB
-5.5 dBi
a. ANSI/TIA/EIA-716 and draft TIA/EIA-777. Bellcore has agreed to the values and will synchronize its requirements.
b. ETS 300 778-1 (On-hook) Sep 97, ETS 300 778-2 (Off-hook) Jan 98.
c. SIN 227 Issue 3 Nov 97, SIN242 Issue 2 Nov 96.
d. North American on-hook signalling range. The off-hook range is inside the on-hook range: 190mVrms to 12mVrms.
e. dBm - Decibels above or below a reference power of 1 mW into 600 ohms. 0 dBm = 0.7746 Vrms
f. dBV - Decibels above or below a reference voltage of 1 Vrms. 0 dBV = 1 Vrms.
g. ETSI on-hook signalling range. The off-Hook signalling levels are inside this range: -8.78 to -30.78 dBm (-11 to -33 dBV).
h. The 5V ETSI Tip/Ring op-amp gain can be 0 dB if there is no FSK reject level requirement.
i. 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
goes low again the tGA duration must start over. To
set tGA=0, set R2 to 0.
The TIA Type 1 standard includes an FSK reject
level:
In Figure 5, tDP is the delay from the start of CAS to
EST responding, tDA is the delay from the end of CAS
to EST responding. The total delay from the start of
CAS to STD responding is tREC=tDP+tGP. The total
delay from the end of CAS to STD responding is
•
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
t
ABS=tDA+tGA.
FSK Demodulation
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).
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.
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
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