Features of the VERSITRON Model CDS-20
Clock Distribution System
 

THEORY OF OPERATION

The simplified block diagram to the right illustrates the basic circuits contained in the CDS-20. Three master reference frequencies provide inputs to separate reference modules (RMs) at 1.0, 1.544, and 5.0 MHz. RM output signals are applied to all three master divider (MD) cards. The input circuitry on each MD card combines all three separate inputs, forming one composite master reference signal for each board. Each MD card generates a total of 21 different base frequencies, distributed via a bus system to the individual line driver cards (LDs). Each MD continuously compares its operations with the other two cards.

A 4 KHz vote signal compares its operations with the other two cards. A 4 KHz vote signal insures that the three master reference inputs are at the same frequency. A 5 Hz sync vote signal establishes phase coherence amoung the 21 base frequencies. The line driver cards provide clock outputs to the user interface.

View Minimum System Requirements.

REFERENCE MODULES

The CDS-20 Clock Distribution System utilizes reference modules (RMs) to accept external standard reference inputs. The RMs then apply output signals to all three master divider cards (MDs) in the CDS-20 chassis.

The following table shows the RM models available

Model

Inputs

Input
Impedance

Connectors

IN

OUT

RM1-1

1.0 or 1.544 MHz

600

BNC

BNC

RM1-2

1.0 or 1.544 MHz

50

BNC

BNC

RM101-1

1.0 or 1.544 MHz

600

BNC

Fiber

RM101-2

1.0 or 1.544 MHz

50

BNC

Fiber

RM102

1.0 or 1.544 MHz

—

Fiber

BNC

RM3-1

5.0 MHz

600

BNC

BNC

RM3-2

5.0 MHz

50

BNC

BNC

View Minimum System Requirements.

VERSITRON reference module

 

MASTER DIVIDER CARD

The CDS-20 Clock Distribution System utilizes the master divider card (Model MD2-20) to accept reference frequencies and then generate 21 base frequencies. A CDS-20 system will operate with one MD2-20 but a full triplicated system requires three MD2-20 cards. Jumper settings on the MD2-20 card permit compatibility with the appropriate input reference signal or to correctly establish a master/slave configuration.

Slots 1-3 in the CDS-20 chassis are reserved for the MD2-20 cards.

Dimensions of MD2-20: 5.75" wide x 16.5" length x 0.75" high.

View Minimum System Requirements.

 

LINE DRIVER CARDS

The CDS-20 operates with 1 to 14 of the Model LD3 line driver cards, each of which can select any one of 21 base frequencies. Further dividing the selected frequency produces 8 sub-frequencies, each of which is selectable for the 6 different output driver circuits. Each of the 6 LD outputs may be wired to provide a single balanced output or two unbalanced outputs. The lowest frequency generated by each LD card is continuously monitored for symmetry.

The table below shows the available frequencies from the Model LD3 Line Driver Card:

Bus Channel Number

Standard Frequencies (Hz)

f

f/2

f/4

f/8

f/16

f/32

f/64

f/128

1

3.072 M

1.536 M

768K

384 K

192 K

96 K

48 K

24 K

2

2.048 M

1.024 M

512 K

256 K

128 K

64 K

32 K

16 K

3

1.544 M

772 K

386 K

193 K

96.5 K

48.25 K

—

—

4

307.2 K

153.6 K

76.8 K

38.4 K

19.2 K

9.6 K

4.8 K

2.4 K

5

200 K

100 K

50 K

25 K

12.5 K

6.25 K

3.125 K

—

6

120 K

60 K

30 K

15 K

7.5 K

3.75 K

1.875 K

—

7

112 K

56 K

28 K

14 K

7 K

3.5 K

1.75 K

875

8

104 K

52 K

26 K

13 K

6.5 K

3.25 K

1.625 K

—

9

88 K

44 K

22 K

11 K

5.5 K

2.75 K

1.375 K

—

10

80 K

40 K

20 K

10 K

5 K

2.5 K

1.25 K

625

11

72 K

36 K

18 K

9 K

4.5 K

2.25 K

1.125 K

—

12

67.2 K

33.6 K

16.8 K

8.4 K

4.2 K

2.1 K

1.05 K

525

13

64 K

32 K

16 K

8 K

4 K

2 K

1 K

500

14

62.4 K

31.2 K

15.6 K

7.8 K

3.9 K

1.95 K

975

—

15

57.6 K

28.8 K

14.4 K

7.2 K

3.6 K

1.8 K

900

450

16

52.8 K

26.4 K

13.2 K

6.6 K

3.3 K

1.65 K

825

—

17

43.2 K

21.6 K

10.8 K

5.4 K

2.7 K

1.35 K

675

—

18

24 K

12 K

6 K

3 K

1.5 K

750

375

—

19

8 K

4 K

2 K

1 K

500

250

125

—

20

6.4 K

3.2 K

1.6 K

800

400

200

100

50

21

4.8 K

2.4 K

1.2 K

600

300

150

75

—

The CDS-20 Clock Distribution System can also generate additional frequencies by utilizing Line Driver/ Synthesizer Cards. Model numbers and available frequencies are shown in the table below:

Bus Channel Number

Standard Frequencies (Hz)

Base

f1

f2

f3

f4

f5

f6

Outputs

LD/S-1

8 K

6.176 M

4.632 M

3.088 M

1.544 M

—

—

6 Bal

LD/S-2

8 K

6.312 M

3.156 M

1.578 M

789 K

—

—

6 Bal

LD/S-3

8 K

5.0 M

2.5 M

1.0 M

500 K

—

—

6 Bal

LD/S-4

8 K

921.6 K

460.8 K

230.4 K

115.2 K

—

—

6 Bal or 12 Unbal

LD/S-5

8 K

12.928 M

9.696 M

6.464 M

3.232 M

—

—

6 Bal

LD/S-T1

1.544 M

—

—

—

—

—

—

6 Bipolar

LD/S-E1

2.048 M

—

—

—

—

—

—

6 Bipolar

View Minimum System Requirements.

MASTER/SLAVE CONFIGURATION

When the CDS-20 is operated as a slave unit, the 4 KHz signal from the "master" CDS-20 unit is brought through the slave reference modules (RMs) to the slave master divider cards (MDs). Each of the cards compares its own sync signal with the 4 KHz vote signal from the other two cards. If a discrepancy is detected, the alarm is activated and the MD card in error removes its output from the frequency bus. Thus the slave CDS-20 unit maintains the same frequency stability as the master CDS-20 unit. The MDs and line driver cards (LDs) in the slave unit operate in the same manner as in the master unit.

The slave unit can be linked to the master unit with either copper or fiber optic cable. The fiber link provides security, greater distance, and immunity to EMI/RFI, ground loops, transients and lightning strikes.

View Minimum System Requirements.

POWER SYSTEM

The CDS-20 Clock Distribution System is designed to operate with a fully duplicated power system. The two primary supplies, Model PSAC01, convert 115/230 VAC to 16 VAC that is distributed to separately fused dual regulators on each card that provide DC operating voltages. A loss of one of the primary supplies and/or regulators has no effect on the operation of the CDS-20. However, if such a loss occurs, the audible alarm will activate and remain on until the problem is corrected. A DB-9 connector on each power supply provides an interface for remote status or control.

View Minimum System Requirements.

The PSAC01 is comprised of
1 input and 1 output module.

STATUS INDICATORS

The CDS-20 Clock Distribution System utilizes status indicators or audible alarms on the following system components:

 

LED

Description

Audible
Alarm

Master
Divider Card

Status lamp ON indicates that all four fuses are continuous and both power circuits are operational; confirms functionality in a triplicated system

Reference Module

Status lamp ON indicates external reference signal is present and that the signal is being sent to the master divider card.

Line Driver Card and Line Driver/Synthesizer CArd

Status lamp ON indicates that all four fuses are continuous and both power supplies are operational. Confirms a base frequency is present and all stages of the main divider are operating correctly.

Power Supply

Status lamp ON indicates power is present at remote interface connector, MD card, and LD or LD/S card.

View Minimum System Requirements.

PHYSICAL CHARACTERISTICS

The Model CDS-20 Clock Distribution System is designed to be installed in a standard 19 " rack and requires 7" of vertical height. The CDC-20 chassis measures 7" H x 17.25" wide x 18.5" deep.

The chassis has 17 card slots. Slots 1-3 are used for MD cards and slots 4-17 are used for LD or LD/S cards. The left side of the chassis holds the power supplies. All power and signal connections are made on the rear of the chassis. The front panel is hinged to provide access to the MD cards, LD and LD/S cards, and power supplies. Status indicator lights and alarm lights can be viewed thru the plexiglass front panel.

View Minimum System Requirements.

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VERSITRON INC.
83 Albe Drive - Suite C - Newark, DE 19702
Need Help? Call 1-800-537-2296, or 302-894-0699 Fax. 302-894-0624
www.versitron.com
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