Bit Synchronizers

Model 2266 Multi-Channel PCM Bit Synchronizer (cPCI)
Model 2266 Multi-Channel PCM Bit Synchronizer

The GDP Model 2266 Multi-Channel PCM Bit Synchronizer houses up to eight high-performance bit synchronizer modules. The optimized digital design of this unit affords the highest performance characteristics currently available.

The Model 2266 is capable of maintaining synchronization with the signal of interest down to –3 dBEb/No. When searching for the signal, acquisition is attainable in less than 50 bits. The unit is very robust and can maintain synchronization for a period of at least 256 bit periods without a transition.

The standard IRIG randomizer/derandomizer for both forward and reverse sequences is provided. CCITT V.35 and V.36 scrambling/descrambling is also provided. A variety of Viterbi decoders are available including R1/2 K7 (Std), R3/4K7 and R1/3 k7 (please inquire for other FEC options). The MD2265 includes several unique features to determine the quality of the data. The first is an Eb/No (Signal Quality)measurement. From this measurement, the error rate of the data can be determined. The BSM201B also measured errors in the frame synchronizer pattern as well as errors in the viterbi stream when these modes are enabled. A bit-error-rate(BERT) function is also provided. This allows link test in a short loop-back to verify proper operation of the module, or long loop-back to measure performance of the link. An advanced lock detector ensures a solid lock indication for the module.

To assure synchronization to the intended data stream,the Frame Pattern Detector may be invoked. Up to a 64-bit long pattern is detected. Maintaining synchronization with this pattern at the programmed repetition rate and synchronization strategy produces a lock signal. An Automatic Polarity Correction (APC) mode is also provided for inverted data.

The optional Auto Scan feature is available to scan the input for up to 8 combinations of bit rates, input codes and frame patterns (per Bit Sync channel). When one of the signals is present, the Bit Sync automatically locks onto it and recovers the data and clock.

  1. Up to 8 Channels
  2. Bit Rates
  3.      • 5 bps to 20 Mbps
         • 5 bps to 40 Mbps (Opt)
  4. Hot Swap Redundant Power Supply
  5. Performance within 1 dB of theory
  6. Loop Bandwidth Settings from 0.01% to 1.6%
  7. Accepts NRZ-L/M/S, BiØ-L/ M/S, DM-M/S; MDM-M/S
  8. Status Indicators
  9.      • Sync and Loss
  10. Bit Rate Deviation Display
  11. Randomizer/Derandomizer
  12. Scrambler/Descrambler CCITT V.35/36:
  13. Viterbi Decoder
  14. Frame Pattern Detector
  15. Signal Quality Status
  16.      • Eb/No Measurement
         • Frame Sync Pattern Error Count (BER Status)
         • Viterbi Error Count
         • BERT/ PRN BER Measurement
  17. Advanced Lock Detection
  18. Auto Bit-Rate Scan (Opt)
  19. QPSK/OQPSK/SOQPSK Resequencer (opt)
  20. Remote Control via.
  21.      • RS-232 (Std)
         • IEEE-488, Enet (Opt)
  22. 7-inch High Chassis
Inputs, each Bit Sync
Analog Inputs
Up to 4 Inputs per Bit Sync- 50 ohms (optional 75) or High Z (Transition Module Dependent)
Digital Inputs
Differential RS-422 and TTL (Optional)

Bit Rate Range
5bps to 20 Mbps (40 Mbps Optional)
Tuning Resolution
Input Levels
0.2 Vpp Min., ± 12 V Max.. (others available)
DC Offsets
100% of the input peak-to-peak signal level.
AC Offset
No degradation up to 100% of input signal amplitude at 0.1% of the bit rate.
Loop Bandwidths
0.01% to 1.6%
Acquisition Range
2x LBW
Sync Acquisition Threshold
SNR 0 dB
Sync Maintenance
SNR –3dB
Sync Acquisition
< 50 bits
Sync Retention
256 bits without transitions
Bit Error Rate
1 dB to 40 Mbps

Input/Output PCM Codes
IRIG 106-96 forward and reverse
CCITT V.35/V.36
Viterbi Decoder
R 1/2, K 7 with G1/G2 Swap and G2 Invert, (others available)
Frame Pattern Detector
Up to 64 bits with programmable strategy and APC
Auto Scan (Optional)
Searches up to 8 Bit Rate, Code, Frame pattern combos per Bit Sync
Output Data Polarity
Input polarity normal / inverted.
Output Clock Phase
0, 90, 180, 270 degrees

Outputs, each Bit Sync Channel
TTL (Each Channel):
Four Coded PCM and Three Clocks (Programmable 0, 90° 180, 270 degrees)
RS422 (Each Channel):
Two Coded PCM and Two Clock (Programmable 0, 90, 180, 270 degrees)
Bipolar Tape Output:
(Each Channel)- One +/-1V - Coded PCM
Front Panel Monitor (Each Channel):

One Selected Input Monitor, one PCM Data Out, one Clock Out
Bit Synchronization, Frame Pattern and Viterbi
Signal Quality Status:
Eb/No, Deviation, Frame Sync Pattern Error Count, Viterbi Error Count and BERT / PRN BER Measurements on Front Panel Display and Remote Port