Carrier Access SNMP manual TP Busy/Idle Switch, Setting Transmit and Receive Gain

TP Busy/Idle Switch

Table 11-5: 4-Position DIP Switch Settings

Switch Number	ON	OFF
1	N/A	Normal E&M
2	N/A	N/A
3	N/A	N/A
4	TP Idle	TP Busy

11.9 TP Busy/Idle Switch

Use switch 4 to select whether the tip-ground relays are closed (busy) or open (idle) during trunk pro- cessing. (Trunk processing occurs when the T1 line is in an alarm or reset state.) The Busy position (OFF) causes the tip-ground relays to be closed during a T1 alarm or reset period. The Idle position (ON) causes the tip-ground relays to be open during a T1 alarm or reset period.

11.10 Setting Transmit and Receive Gain

The transmit (analog-to-digital) and the receive (digital-to-analog) gain for each voice channel can be set independently using twelve 10-position DIP switches on top of the 4-wire E&M card circuit board. Each analog channel uses a bank of ten DIP switches, with five for transmit and five for receive. The gain from each switch is additive, with switches 1-5 providing transmit (analog-to-digi- tal) gain of 1, 2, 4, 8 and 16 dB, respectively. Switches 6-10 set receive (digital-to-analog) gains of 1, 2, 4, 8, and 16 dB, respectively. With all five switches off, the gain is -21dB. Because the gain from the switches is additive, any gain level between -21dB and 10dB is possible.

The digital transmission level is limited by the codec to a maximum of 3.17dBm0. The gain stages may be set to apply up to 10dB of gain; however, the maximum level of the codec must not be exceeded or distortion will result.

The analog transmission level may be set to a maximum 9.5dBm before distortion begins to occur.

11.11 Transmit (Analog-to-Digital) Gain

A transformer provides the analog input (T, R) from the 4-wire voice connections to the Access Bank

II- SNMP. The gain from each switch on the 10-position DIP switch is additive, with switches 1-5 providing gain of 1, 2, 4, 8 and 16 dB, respectively. To calculate the T1 transmit level, use the follow- ing formula:

T1 level = Analog Input level + åGain Switches - 21

The following is an example of setting transmit gain:

Suppose the analog input level is at +3dBm. With all switches off, the level at the T1 line is +3dBm - 21db = -18dBm0. To set a 0dBm0 level at the T1 line, switches 2 and 5 (gains 2dB, and 16dB) must be turned on. The level at the T1 line is then:

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