background image

21

Theory of Operation

The Adder 882i circuit block diagram is shown in Figure 15. The unit has two
basic  functions:  multiplexing  signals  onto  an  optical  fiber,  and  demultiplexing
signals from an optical fiber. The Adder 882i accepts up to ten intercom inputs,
eight digital inputs and four remote relay closures and time division multiplexes
them onto a single optical fiber.

          

       

Figure 14: Electronics Block Diagram

All signals on the optical fiber are digital and, therefore, relatively insensitive to
transmission  level  variations.  As  a  demultiplexer,  the  unit  separates  the
multiplexed  signals  it  receives  from  the  optical  fiber  and  converts  the  audio
information  back  into  analog  signals.  There  is  a  one-to-one  correspondence
between inputs and outputs at opposite ends of the system. Intercom inputs and
outputs  are  on  their  respective  Intercom  Modules  located  on  the  front  panel.
Refer to Figure 1 on page 7.

Summary of Contents for Adder 882i

Page 1: ...Adder 882i Intercom Data Multiplexer Instruction Manual Telecast Fiber Systems Inc 102 Grove Street Worcester MA 01605 Tel 508 754 4858 Fax 508 752 1520 www telecast fiber com...

Page 2: ...2...

Page 3: ...l Connections 13 Intercom Modules 13 4 Wire 14 Clear Com 14 RTS Telex 15 Intercom Replacement 16 Digital Data 17 Power Connections 18 Input Power Fuse 19 Operating Details 19 Battery Charging 19 Indic...

Page 4: ...4...

Page 5: ...16 Figure 11 Data D Connectors on Front panel 18 Figure 12 Power Connector and Fuse Locations 18 Figure 13 Front Panel Indicators 19 Figure 14 Electronics Block Diagram 21 Figure 15 Digital I O Conne...

Page 6: ...6...

Page 7: ...r Com 2 Wire POWER PORTS TERM ON OFF d w GAIN IN OUT NULL A B 8dBm MAX LEVEL 600 Ohm AUXILIARY 4 WIRE AUDIO I O Figure 1 Front Panel of the Adder 882i Within the Adder 882i unit the intercom audio sig...

Page 8: ...sion multiplexed WDM One unit transmits from the Tx ST connector at a wavelength of 1300 nm and also receives at 1550 nm on the same connector The other unit transmits from the Tx ST connector at 1550...

Page 9: ...ier and to Telecast Fiber Systems Inc Leave the protective plastic caps on the optical connectors until it is time to attach the fiber s to the units Place the caps back on the connectors whenever the...

Page 10: ...r end WARNING Do NOT use the Adder 882i optical output for this purpose Never look directly into the end of the optical fiber while either end of the system is operating Eye damage is possible Inspect...

Page 11: ...Figure 5 A refers to the first numbered channel and B refers to the second numbered channel of the pair UNIT A SWITCH SETTING 1 2 3 4 5 6 7 8 8 10 MIC IN 0 or 40db gain LINE IN 0 or 10db gain Input Im...

Page 12: ...12 These are printed On the PC Board Figure 6 Main PCB Optical Connections Refer to Figure 7 before beginning the optical connections Figure 7 Optical Connectors on the Rear Panel...

Page 13: ...not be installed on one fiber units In the same way the system can be operated on two coaxial cables at distances up to 300m By connecting a coax from the TX on one side to the RX on the other a link...

Page 14: ...d See Audio Setup on page 4 PIN FUNCTION Impedance Signals 1 Ground 2 Input 3 Input 600 Ohm Input MIC 8 dBm LINE 32 dBm 4 Output 5 Output 600 Ohm Load 8 dBm Table 3 4 Wire Intercom Connections Figure...

Page 15: ...y power 5 to10 belt packs with each intercom module from theViper s internal power supply Many more belt packs can be added if powered externally Refer to your intercom manufacturer s documentation fo...

Page 16: ...trols Re adjust these controls to optimize performance as required Pin Function 1 Ground 2 VDC Power Ch 1 Audio 3 Ch 2 Audio Table 5 RTS Intercom Pin out Intercom Module Replacement Intercom modules w...

Page 17: ...lustrated in Figure 11 A 110 W terminating resistor placed across the balanced inputs may be needed if cable lengths using 110 W twisted pairs are in excess of 6 feet The serial communications protoco...

Page 18: ...N OUT NULL A B 8dBm MAX LEVEL 600 Ohm AUXILIARY 4 WIRE AUDIO I O Figure 11 Data D Connectors Power Connection When using the standard Telecast power supply connect the 4 pin XLR connector to the Adder...

Page 19: ...2 Wire POWER PORTS TERM ON OFF d w GAIN IN OUT NULL A B 8dBm MAX LEVEL 600 Ohm AUXILIARY 4 WIRE AUDIO I O Figure 13 Front Panel LED Indications External Power When this green LED is illuminated an ex...

Page 20: ...tors To operate the power switch 1 Pull the lever away from the panel 2 Move it up for power ON or down for power OFF The power switches at both units must be on for the system to achieve normal funct...

Page 21: ...single optical fiber Figure 14 Electronics Block Diagram All signals on the optical fiber are digital and therefore relatively insensitive to transmission level variations As a demultiplexer the unit...

Page 22: ...s 5 8 Refer to Table 6 Digital Cable Connections on page 17 for instructions on selecting the CCU capability When this option is selected the RS 422 and RS 232 serial communications for that connector...

Page 23: ...trated in Figure 2 on page 8 A D High speed analog to digital converters located in each intercom Multiplexer Sequentially presents 8 RS 422 digital inputs and 8 digitized audio signals from the A D c...

Page 24: ...Corrective Action No operation All indicators off No power Make sure power switches on both ends are on and that the external power supplies are delivering 13 8 24VDC No operation INTERNAL RESERVE LED...

Page 25: ...to 8 dBm 90 dB Digital Characteristics Serial Communications Data Interface Signal Level Data Rate RS 422 Balanced TTL levels 0 150 kBits sec RS 423 TTL levels 0 150 kBits sec RS 232 8 Vp p 0 38 4 kBi...

Page 26: ...3 dBm 15 13 dBm RX Sensitivity 28 30 dBm 28 30 dBm Power Requirements Voltage 12 to 24 VDC Current 1 5 amperes maximum 13 8 VDC NOTE Although the units will operate at 12 VDC 13 8 VDC is required to c...

Page 27: ...e maintenance and care Nor shall this warranty apply to any damage caused in whole or in part by attempts by personnel other than Telecast s personnel as approved in advance in accordance with the for...

Reviews: