Rainbow Electronics DS3150 User Manual
Page 7
DS3150
7 of 22
TRANSMITTER
Through the ZCSE* input, the device is configured to accept either bipolar data or NRZ data to be input
to the transmitter. When the ZCSE* input is tied high, bipolar data must be applied at the TPOS and
TNEG inputs. In this mode, the device will not perform B3ZS/HDB3-encoding on the outgoing data
stream. When the ZCSE* input is tied low, an NRZ data stream must be applied at the TPOS input
(TNEG is ignored). In this mode, the device will perform B3ZS/HDB3-encoding on the outgoing data
stream.
The clock applied at the TCLK input is used to transmit data onto the T3/E3/STS-1 line. Hence, TCLK
must be of transmission quality (i.e., accurate to
±
20ppm). The duty cycle of TCLK is not a key
parameter as long as the clock high and low times listed in Section 3 are met.
The DS3150 also has the ability to generate a number of different patterns, including an unframed all
ones pattern, which is also the E3 AIS signal; a 101010… pattern; or a T3 Alarm Indication Signal (AIS).
See Figure 1E for a description of the T3 AIS. The TDS0 and TDS1 inputs are used to select these
onboard patterns (Tables 2A and 2B).
The DS3150 interfaces to the transmit T3/E3/STS-1 coax cable through a 1:2 step up transformer (Figure
1B). It will drive the 75Ω cable and create the proper waveforms required for interfacing to T3/E3/STS-1
lines. In T3 and STS-1 modes, the LBO (line build out) pin controls waveform shape. For cable lengths
fewer than 225ft, LBO should be pulled high. For 225ft or more of cable, LBO should be pulled low.
Tables 1C through 1G and Figure 1D detail the waveform template specifications and testing parameters.
The transmitter can be disabled and the Tx+ and Tx- outputs three-stated through the TTS* input (Table
2A).
The transmit driver monitor constantly checks the analog signal output at Tx+ and Tx-. If the output fails,
then the DM* output will be pulled low. When the transmitter is disabled (TTS* = 0), the driver monitor
is also disabled.
Table 1C. T3 TRANSMIT WAVEFORM TEMPLATE
TIME AXIS RANGE
NORMALIZED AMPLITUDE EQUATIONS
-0.85
≤
T
≤
-0.68
0.03
-0.68
≤
T
≤
0.36
0.5 {1 + sin[(
π
/ 2)(1 + T / 0.34)]} + 0.03
Upper
Curve
0.36
≤
T
≤
1.4
0.08 + 0.407e
-1.84(T - 0.36)
-0.85
≤
T
≤
-0.36
-0.03
-0.36
≤
T
≤
0.36
0.5 {1 + sin[(
π
/2)(1 + T/0.18)]} - 0.03
Lower
Curve
0.36
≤
T
≤
1.4
-0.03
Governing Specifications: ANSI T1.102-1993 and Bellcore GR-499