Adder™ 161 Audio 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

Adder™ 161

ii

Telecast Fiber Systems

Telecast Adder™ 161 Table of Contents Introduction Installation Unpacking Installation of Rack Mount Units Line Power Fiber and Coaxial Cable Runs Transmitter Setup Procedure Audio Signal Setup Optimizing S/N Ratios Receiver Setup Procedure Optical Connections Electrical Connections Audio Connections Digital Connections 48 VDC Phantom Power Line Power Connection Input Power Fuse Battery Charging Panel Indicators Powering Up Theory of Operation Digital I/O Circuits, Data Connectors 1 and 2 Digital I/O Circuits, Data Connectors 3 and 4 Audio I/O Circuits, Audio Inputs Audio I/O Circuits, Audio Outputs Optical Outputs Main Curcuits Explained Accessory List Troubleshooting Specifications Repair Warranty

1 1 1 2 2 2 3 3 4 4 6 7 7 8 9 9 9 10 10 11 11 12 12 12 15 15 16 16 17 18 19 20

iii

Adder™ 161

List of Figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16.

Installing the Rack Mount Adapters TX Audio Setup Controls: Input Gain RX Audio Setup Controls Transmitter Main Circuit Board Receiver Main Circuit Board ST Optical Connectors, Rear Panel XLR Connectors, Rear Panel DB-9 Connectors, TX and RX, Rear Panel Power Connector and Fuse Locations TX and RX, Front Panel Electronic Block Diagram TX Digital Input Circuit (Connectors 1 & 2 only) RX Digital Output Circuit (Connectors 1 & 2 only) TX Audio Input Stage Audio Output Circuit Battery Charger Block Diagram

2 4 4 5 6 7 7 8 9 10 11 12 13 14 15 16

List of Tables Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7.

iv

Maximum Fiber Lengths Input Signal Levels XLR Audio I/O Cable Connections Digital Cable Connections Power Connections Output Signal Levels Adder 161 Main Circuits

2 3 7 8 9 15 16

Telecast Fiber Systems

Introduction The Telecast Adder™ 161 System consists of an Adder 161 TX fiber optic transmitter/ multiplexer and an Adder 161 RX receiver/demultiplexer. The TX unit multiplexes and sends up to 16 audio signals, two digital data signals, and four remote relay closures. The RX unit receives the transmission and restores the analog signals. Audio inputs are set up by internal DIP switches that set amplifier gain to accept either mic or line level. Audio outputs are always at line level. Two of the four digital connectors provide RS-422 and RS-232 compatible signals in one direction. The four digital connectors also provide remote contact closures transmitted in one direction. An internal Ni-Cad battery provides backup power in the event of line power loss. The Adder 161 is available in a compact, lightweight 19 inch rack mount. The electrical connections connections are discussed later in this manual. Within an Adder 161 TX transmitter unit, the audio signals are first digitized and then multiplexed with the digital control signals. The combined electrical signal is converted to an optical signal and launched into the fiber optic cable. All signals are restored at the receiver. The Adder 161 TX has a port to allow clock synchronization with additional Telecast products. * The Adder 161 also has a coaxial cable link that may be used as an alternate to the fiber.

Installation Unpacking The Adder 161 System consists of: • One Adder 161 TX Transmitter • One Adder 161 RX Receiver • Two external power supplies (AC/DC adapters) • Plastic or metal covers for optical connectors • Hardware kits for rack mount units After unpacking, inspect the units for mechanical damage. Inspect all electrical connectors for bent or damaged pins and latches. Report any damage to the carrier and to Telecast Fiber Systems, Inc. Leave the protective plastic caps on the optical connectors until it is time to attach the fiber to the units. Store the caps for later use. Replace the caps on to the connectors whenever the fiber is left disconnected.

1

Adder™ 161 Installation of Rack Mount Units Units are shipped ready for bench use. All connections are made to the rear panel. To mount a unit, rack ears must be attached. Each rack ear is held in place by two #10 flat head screws (see Figure 1).

Figure 1: Installing the Rack Mount Adapters Place each unit in its intended location before attaching any cables or wires. This will prevent accidental damage to the cables or their connectors.

Line Power The external power supplies require 120 VAC. Be sure that AC outlets are within reach of their 6-foot power cords.

Fiber and Coaxial Cable Runs The installer is responsible for providing the fiber optic cable runs, which are available from Telecast Fiber Systems, Inc. The “Accessory List”, at the end of this manual, contains part numbers for the cable and other items required for the system. Be sure that the fiber core diameters are compatible with the intended installation distances as shown in Table 1. Fiber core diameter

Maximum fiber length 850 nm

50 microns 62.5 microns 8 microns (single mode)

1310/1550 nm

2 km 3 km 20 km

Table 1. Maximum Fiber Lengths

2

10 km 8 km 20 km

Telecast Fiber Systems The system units are factory configured for the fiber type to be used. Inspect the fiber ends and clean them with clean, dry compressed air or with KimWipes that have been wet with isopropyl alcohol. Fingerprints or other dirt on the optical connector end surfaces will reduce the received optical signal level. If the system is to be used with a coaxial cable instead of an optical fiber, use Belden type 8281, 75 coax, or equivalent. The maximum length for coax cable is 500 meters (1640 feet).

Transmitter Setup Procedure Audio Signal Setup Note: Setting up the internal switches on the rack mount unit requires removal of its top cover. The DIP switches should be set before installing the units in their racks. The setup DIP switches for line or mic input levels are inside the Adder 161 TX on the main circuit board. There are 16 switches, one for each channel. A representative DIP switch is shown in Figure 2. Setup steps are not required if all inputs are at the factory default of 600, 0 dB gain (line level). Setup steps are required if mic level inputs will be used, if 10 K input impedance is required, or if an optional 10 dB boost is desired at the TX. The RX output default setting is 0 dB, unity gain. In the figures throughout this manual, each switch is shown in its default position.

600 balanced (low Zin)

10 K balanced (high Zin)

Unity +10 dB +20 dB +30 dB +40 dB +50 dB

Unity +10 dB +20 dB +30 dB +40 dB +50 dB

+18 dBm peak +8 dBm peak -2 dBm peak -12 dBm peak -22 dBm peak -32 dBm peak

+16 dBV peak +6 dBV peak -4 dBV peak -14 dBV peak -24 dBV peak -34 dBV peak

Table 2: Input Signal Levels

3

Adder™ 161 1. Determine the appropriate TX input gain for each channel.

600 Ω

20 10

Z in

40

30 Gain

dB

50

Figure 2. TX Audio Setup Controls: Input Gain 2. With the power switch off, remove the top cover by removing the six #4 flat head screws. 3. With the connector panel of the TX unit facing you, set the DIP switches as needed. 4. Replace the TX top cover and reinstall the screws.

Optimizing S/N Ratios To obtain an improved noise floor in cases of low input signal levels (+ 8 dBm), the input gain can be set to + 10 dB and the RX attenuation set to - 10 dB. Thus, the signal levels remain at the same reference level throughout.

Receiver Setup Procedure The setup switches for the output levels are inside the Adder 161 RX on the main circuit board. The factory default is 0 dB. 1. With the power switch off, remove the top cover of the RX by removing the six #4 flat head screws. In Figure 3, A refers to the odd numbered channel and B refers to the even numbered channel of the audio pair. 2. Determine for which line outputs the 10 dB cut is to be used. Receiver Output Gain A

B

ƒ

ƒ Fine Level

A

B

−10 −10

Figure 3. RX Audio Setup Controls: Trimpots and Gains 4

Telecast Fiber Systems 3. With the connector panel of the RX unit facing you, move the DIP switches as needed. 4. Adjust the output signal levels to normalize the outputs using the Fine Level trim pot in each output circuit of the Adder 161 RX. The range of adjustment is ± 2 dB. 5. If the system is to be used with coaxial cable rather than fiber, move the small switch near the alarm switch on the PCB to the COAX position. See figure 5 for the exact location. 6. Replace the RX top cover and reinstall the screws.

Figure 4. Transmitter Main Circuit Board

5

Adder™ 161

Figure 5. Receiver Main Circuit Board

Optical Connections WARNING! Never look directly into the end of the optical fiber while either end of the system is operating. Eye damage is possible. Refer to Figure 6 before beginning the optical connections. The fiber optic connections to the TX and RX units are identical. The Adder 161 is compatible with industry standard ST type connectors. It may be used with installed backbone cables or with dedicated cables. Assembled cables and connectors are available from Telecast Fiber Systems, Inc. For custom cable fabrication, use type ST connectors such as Telecast part number CONN-ST-QC. Always follow the connector manufacturer’s directions when fastening a connector to the cable. A Quick-crimp kit, part number CKIT-ST-QC, is available from Telecast. Connect the fiber to the Adder 161 at each end. If a coaxial cable is used instead of a fiber, cap the optical connectors on the panels to protect them.

6

Telecast Fiber Systems

1

3

5

7

9

11

13

15

1

2

COAX OPTICAL DATA I/O DC INPUT 12-24 VDC

3

SLO

4 2

4

6

8

10

AUDIO

12

14

16

DATA

CLOCK

Figure 6. ST Type Optical Connectors, Rear Panel

Electrical Connections Audio Connections Audio I/O is via 3-pin XLR connectors with industry standard wire locations. See Table 3 and Figure 7. Pin

Signal

1 2 3

Ground Balanced I/O (-) Balanced I/O (+)

Table 3. XLR Audio I/O Cable Connections The XLR connectors are on the rear panel as shown in Figure 7. Transmitter XLR connectors are female Switchcraft type E3FST-AU. Receiver XLR connectors are male Switchcraft type E3MST-AU. TX (Female)

RX (Male)

1

2 3

or

3

2

1

1

3

5

7

9

11

13

15

1

2

COAX OPTICAL DATA I/O DC INPUT 12-24 VDC

3

SLO

4 2

4

6

8

AUDIO

10

12

14

16

DATA

CLOCK

Figure 7. XLR Connectors, Rear Pane 7

Adder™ 161 Digital Connections Digital signal connections are made via the DB-9 connectors as shown in Figure 8. The connection specifications are listed in Table 4. A 110 terminating resistor placed across the balanced inputs may be needed if cable lengths are in excess of 6 feet (if using 110 twisted pair). Serial communications can be RS-232 at one end and RS-422 at the other, if desired. Contact closure input to the TX is activated by connecting it to ground or to a TTL logic 0 signal level. Contact closure output from the RX is established by an isolated, normally open, dry contact.

1

3

5

7

9

11

13

15

5

1

9

6

1

2

COAX OPTICAL DATA I/O DC INPUT 12-24 VDC

3

SLO

4 2

4

6

8

AUDIO

10

12

14

16

DATA

CLOCK

Figure 8. Rack Mount, DB-9 Connectors, TX and RX, Rear Panel

Pin Number 1 2 3 4 5 6 7 8 9

Connectors 1, 2

Connectors 3, 4

RS-422 in (-) contact out gnd RS-232 out RS-422 out (-) RS-422 in (+) RS-232 in contact out contact in RS-422 out (+)

no connection contact out gnd no connection no connection no connection contact out contact in no connection

Table 4. Digital Cable Connections The digital I/O connector on both the rack mount and portable units, TX and RX, is an AMP 747905-2, DB-9 sub miniature female.

8

Telecast Fiber Systems 48 VDC Phantom Power A 48 VDC microphone bias supply is available to the TX units. The voltage is supplied from a DC/DC converter that is connected through 10 K to pins 2 and 3 of the XLR connector. The XLR connector circuit board has 16 switches for enabling this power to the microphones. These switches are accessible by removing the top cover of the rack. The switches are numbered on the XLR circuit board.

Line Power Connection Insert the 4-pin XLR connector from the standard Telecast power supply into the Adder 161 DC INPUT 12-24 VDC receptacle, and plug the supply into a 120 VAC line. See Figure 9 for locations followed by Table 5 for connections.

1

3

5

7

9

11

13

15

1

4

2

3

1

2

COAX OPTICAL DATA I/O DC INPUT 12-24 VDC

3

SLO

4 2

4

6

8

AUDIO

10

12

14

16

DATA

CLOCK

Figure 9. Rack Mount Power Connector and Fuse Locations Any power supply used with the Adder 161 must provide 1.5 amps continuous. Use the wiring connections in Table 5. The power connector is Switchcraft D4M. Pin 1 2 3 4

Signal ground no connection no connection +12 to 24 VDC

Table 5. Power Connections Note: Although the units will operate at 12 VDC, 13.8 VDC is required to charge the internal reserve battery.

Input Power Fuse The 2-amp time delay power fuse is accessible from the rear panel on the rack mount units (Figure 9). Be sure to use the same fuse type if replacement is required. 9

Adder™ 161 Battery Charging Charge the internal UPS batteries for 16 hours by attaching each unit to its external power supply. This will permit battery operation for up to 20 minutes during line power losses.

Panel Indicators The LEDs on the front panels of the rack mount units are shown in Figure 10. •External Power This LED is green when an external supply of 12 to 24 VDC is connected. •Internal Reserve

This LED is green when power is on and the battery is adequately charged. It turns red when the battery is discharg ing, and turns green after one half hour of charging. There may be a few minutes of reserve power after the indicators turn off.

•Rx Status

This red LED on the receiver is on when the fiber optic link is not properly attached or when the system units are not commu nicating properly. This indicator is meaningful only if the external power or the internal reserve LED is lit.

•Coax Tx

This green LED on the receiver is on when the incoming signal is selected on the coax and not on the fiber optic input.

•Optical Tx

This green LED on the receiver is on when the incoming signal is selected on the fiber optic input and not on the coax input.

•Audible Alarm

An audible alarm has been incorporated into the Adder 161 in addition to the LED indicators on the front panel. This alarm will alert the user that the external input power to the system has either failed completely or has dropped below the operating level necessary to charge the internal batteries. An alarm on/off switch for the audible alarm is located inside each unit on the main circuit boards (see Figures 4 and 5 on pages 6 and 7).

ADDER  161

ON

AUDIO MULTIPLEX ER — TRANSMITTER

EXTERNAL POWER MASTER

OFF

SLAVE MODE

Telecast Fiber Systems, Inc. Made in U .S.A.

INTERNAL RESERVE

ADDER  161 ON

AUDIO MULTIPLEXER — RECEIVER

EXTERNAL POWER COAX

OFF

OPTICAL

RX STATUS

TRANSMISSION INTERNAL RESERVE

Figure 10. Tx and Rx Front Panels 10

Telecast Fiber Systems, Inc. Made in U.S.A.

Telecast Fiber Systems

Powering Up Note: Never try to move the power switch on any front panel without first pulling on the switch lever to disengage its lock. With power off at both units, check all electrical and optical connections as described under “Installation” on page 1. Firmly seat and latch all connectors. Power Switch Operation: 1. Pull the lever away from the panel. 2. Move it up for power on, or down for power off. 3. Switch on the power to both Adder 161 units. The power switches at both units must be on for the system to function. Verify that the green external power LEDs are illuminated, and that the red rx status LED is not lit. If you do not get this result, refer to Troubleshooting on page 17.

Theory of Operation The Adder 161 circuit block diagram is shown in Figure 11. The Adder 161 TX accepts up to sixteen audio inputs and up to four digital inputs, and time division multiplexes them onto a single optical fiber or coaxial cable. The system has two basic functions: multiplexing signals onto an optical fiber or coaxial cable and demultiplexing these signals. ADDER 161 RX

ADDER 161 TX Analog Inputs

Analog Outputs

+ − Typ. 1 of 16 Digital Inputs

+ − Typ . 1 of 2

Multiplexer

Transmitter

Typ. 1 of 16

Optical Fiber or Coaxial Cable

Digital Outputs

Typ. 1 of 2

Contact Closure Input

Contact Closure Output Receiver

Typ. 1 of 4

Demultiplexer Typ. 1 of 4

Figure 11. Electronic Block Diagram All signals on the fiber* are digital and, therefore, relatively insensitive to transmission level variations. As a demultiplexer, the Adder 161 RX separates the multiplexed signals it receives from the fiber and converts the audio information back into analog signals. Coaxial cable may be optionally used instead of fiber optic cable. There is a one-to-one correspondence between inputs and outputs at opposite ends of the system. *All references to transmissions on fiber also apply to the coaxial cable output.

11

Adder™ 161 Digital I/O Circuits, Data Connectors 1 and 2 The TX digital input buffer circuit shown in Figure 12 accepts both data signals (RS-232, RS-422 and RS-423) and contact closures and delivers this information to the multiplexer. The data handling portion of the circuit is connected only to DB-9 subminiature data connectors 1 and 2. It also accepts a contact closure indicated by the switching of pin 8 to ground level, pin 3. This can also be accomplished by a TTL connection closure with pin 3 as the ground reference. The RX digital output buffer circuit shown in Figure 13 accepts the demultiplexed data and contact closure signals and provides them at appropriate levels to the DB-9 subminiature data connector. The output closure output is via an SPST-NO relay; this closure is not ground referenced.

Digital I/O Circuits, Data Connectors 3 and 4 These connectors have contact and relay closure capability only. Digital data can only be accepted and sent on connectors 1 and 2. The contact input and relay output circuits are as described above. The pin wiring for connector 3 and 4 closure circuits is the same as on connectors 1 and 2.

Audio I/O Circuits, Audio Inputs Audio inputs and outputs are on sixteen separate XLR connectors, each of which is connected to a circuit as shown in Figure 14. Inputs can be set to have a balanced input impedance 600 or 10 K. The audio input circuit shown in Figure 14 can accept a wide range of signal levels. Refer to “Specifications” for details. +5

100k 10k

Data to Multiplexer

.1 74HC14A

+5

+5 BAT54S 39k

22pf

39k

10k

2

1

+

8 MAX909 7 36 4 5

Data to Multiplexer

10k 10k 594837261

OUT +

Data I/O

10k

22pf

-5

IN +

Figure 12. Digital Input Circuit (Connectors 1 and 2 only) 12

Telecast Fiber Systems

1 of 4 MC33179

+5 51

10k

10/16 +

10k 5v FMMD6100

C

FMMT2222A 51

1k

Data from De-Multiplexer

D Data from De-Multiplexer

180pf

A

B 6 of 74HC14

E F

51

180pf

594837261

OUT +

Data I/O

IN +

Figure: 13. RX Digital Output Circuit (Connectors 1 and 2 only)

13

Figure 14. TX Audio Input Stage

Adder™ 161

14

Telecast Fiber Systems Audio I/O Circuits, Audio Outputs The audio output circuit is shown in Figure 15. The output impedance is 30 , balanced.

100pF

100pF

Figure 15. Audio Output Circuit

30 Balanced output into 600

Frequency response @ +8 dBm

Unity gain

+18 dBm peak

From 20 Hz to 25 KHz

±0.2 dB

-10 dB

+8 dBm peak

From 20 Hz to 25 KHz

±0.2 dB

Table 6. Output Signal levels

Optical Outputs The optical output is generated from a high power LED or Laser coupled to the fiber. User connections are made at a bulkhead type ST connector on the rear panel of the rack mount unit. Transmission cable must be matched to the fiber pigtail type specified at the time of manufacture. The input uses a pin diode and amplifier to convert the optical signal back into an electrical signal.

15

Adder™ 161 Main Circuits Explained A/D, TX

High speed analog to digital converters located in each audio channel.

Multiplexer, TX

Sequentially presents two RS-422 digital inputs, four contact closures and sixteen digitized audio signals from the A/D converters to the optical output driver.

Demultiplexer, RX Takes sequential digital signals from the pin diode and separates them: sixteen to the D/A converters, two to the RS-422 transmitters and four to the contact closure relays. D/A, RX

High speed digital to analog converters located in each audio channel convert the digitized signal back to analog audio.

Battery charger (all units)

The battery charger (shown in Figure 16) is active whenever an Adder 161 unit is receiving DC power between 13.8 and 24 VDC. Charging current is limited to a trickle level at any voltage input. Full charge takes 16 hours. Table 7. Adder 161 Main Circuits

Front Panel Power Switch +12 VDC to +24 VDC

4

Charge Control Circuit

Internal Battery

Switch Mode Power

Power to Electronics

1

External Power LED Internal Reserve LED Front Panel

Figure 16. Battery Charger Block Diagram

Accessory List The following accessories are available from Telecast: • Optical power meter kit (includes wavelength filter) • Cable repair kit • Loop-back cable to localize signals during installation test • Replacement Ni-Cad battery pack • Quick-crimp kit to attach ST connectors to fiber optic cable • Prefabricated cables built to custom lengths 16

Telecast Fiber Systems

Troubleshooting Symptoms

Possible Cause

Corrective Action

No operation, all indicators are off

No power

Make sure both units have their power switches on, and that their external supplies are delivering between13.8 and 24 VDC.

internal reserve LED off

Battery depleted power switch off

Make sure both units have their power switches on. Recharge the battery.

internal reserve LED red

External power loss or internal battery depleted.

The light becomes green after a 1/2 hour of use with the AC power adapter. If the light does not turn green, replace the battery.

No operation rx status LED on

Fiber or coax communications failure

Check for broken or disconnected fibers and faulty wires, or that the Adder 161 unit on the other end is powered on and operational.

Very low output on one audio chan.

Microphone on input with 0 dB selected

Move internal DIP switches to a higher gain setting.

Signal distorted on one channel

Line input with gain setting too high

Move internal DIP switches to a lower gain setting.

Internal reserve battery fails quickly

Reserve battery is not charged, or has failed

Connect to power source of 13.8 to 24 VDC for 16 hrs. Replace battery if charging is not successful.

System goes dead as soon as external power is removed

reserve battery dead or disconnected

Check battery connection. If okay, replace the battery.*

Noisy signal with a A/D input level too low low level input source

Increase input gain on preamplifiers.

*Replace the internal Ni-Cad battery every two years as part of routine maintenance. Whenever there seem to be problems, first verify the adequacy of optical power at the Rx end of the fiber. Use an optical power meter such as the one in the Accessory List. 17

Adder™ 161

Specifications Audio Characteristics

18

Input Signal Levels 600 balanced (low Zin) Unity gain +10 dB +20 dB +30 dB +40 dB +50 dB

+18 dBm peak +8 dBm peak -2 dBm peak -12 dBm peak -22 dBm peak -32 dBm peak

10 K balanced (high Zin) Unity gain +16 dBV peak +10 dB +20 dB +30 dB +40 dB +50 dB

+6 dBV peak -4 dBV peak -14 dBV peak -24 dBV peak -34 dBV peak

Output Signal Levels 30 balanced output into 600 W Unity gain -10 dB

+18 dBm peak +8 dBm peak

Frequency response @ +8 dBm From 20 Hz to 25 KHz

±0.2 dB

Total Harmonic Distortion From 20 Hz to 20 KHz (@ +8 dBm) 1 KHz (@ +18 dBm)