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Model 474DM 40 MHz Advanced Digital Bit Synchronizer Mezzanine

Product Support

  • Range quality noise and filtering performance in a mezzanine module


  • Tunable data rates from 8Hz to 40MHz ALL Codes


  • Processes all IRIG standard and randomized codes


  • Two independent encoders, with TTL & Bipolar outputs


  • Options include Viterbi and Frame Sync Verify  / Bit Error Rate Test


Technical Manual

Program\User's Manual


Technical Specs

Software & Drivers


Supplemental System Products


1611P Bit Synchronizer

1602P PCI Data System

1626P VME Data System



40MHz PCM Bit Synchronizer Mezzanine mounts on Acroamatics 1611P Bit Synchronizer and Acroamatics 1602P Single Board TM Processor to provide additional bit synchronizer capabilities.




The 474M PCM Bit Synchronizer is a new, state-of-the-art compact size Digital Bit Synchronizer mezzanine daughter module intended for use with a variety of compatible Acroamatics full-size PCI Telemetry Processing and Bit Sync modules. The 474DM features a range of advanced  functional and performance features. Rates a tunable from 8 Hz to 40 MHz for ALL codes, with excellent lock/stability/noise performance characteristics.  The card contains selectable input sources, AGC and DC restoration circuitry, and programmable Digital pass filtering for optimum data recovery. Sophisticated PLL (phase-locked loop) circuitry synchronizes a clock to the incoming signal to extract digital data from the PCM input. This circuitry produces NRZ-L data and clock outputs for use by a PCM format decommutator or similar equipment. It also provides encoded PCM outputs suited to use with data recording, best source select, encrypt/decrypt equipment, and a range of other instruments / applications. The unit accepts all IRIG standard PCM input codes and has a bit error performance better than 1 dB of theoretical, in all modes and data rates of operation. The Model 474DM can be attached to either the Model 1602P, 1626P or 1611P cards. All Acroamatics documentation is supplied on CD-ROM.


System Software


GUI Setup and Operation Status of the Model 1611P's and 474DM's are controlled via a single interface with drop down menus for individual cards. The software automatically recognizes all of the bit synchronizers as well as their features. Setup configurations can be stored and retrieved for all previous missions as a group or individually. A page lock command accessible via the GUI reminds users before executing new instructions in order to avoid mistakes during a live mission. Remote users can control the units via an Ethernet port. If two users are viewing the system simultaneously, both see the changes made in real time by either user.

Technical Specs



Program select, 1 of 2 inputs


Greater than 60dB at 20MHz


Program selectable: Hi-Z/Lo-Z. Single Ended: 4kΩ/75Ω, with Differential RS-422 support on request

Signal Level

0.2 to 24V p-p

DC Offset

20V max  Hi-Z

Baseline Variation

 Tracks sinusoidal offsets to 100% p-p signal amplitude at 0.1% bit rate

PCM Codes

 Program selectable: NRZ-L/M/S, Biø-L/M/S, DBiø-M/S, DM-M/S, MDM-M/S, RZ


 Program selectable: RNRZ 9/11/15/17/23, forward/reverse


Bit Rate Range

8bps-40Mbps ALL codes

Tuning Resolution

0.1% of bit rate

Capture Range

3 times the programmed loopwidth, typical

Tracking Range

±12% typical, with programmable limiter

Loop Bandwidth

0.1% to 3.2%, program selectable in 0.1% increments

Sync Threshold

0dB for NRZ-L and Biø-L codes

Sync Maintenance

(LW=0.1%) –2dB NRZ-L and Biø-L codes

Sync Acquisition

(LW=1.6%, SNR > 12dB) Typically less than 32 bit periods

Sync Retention

(LW=0.1%, SNR > 3dB) Retains sync through > 128 consecutive dropouts

Bit Error Rate

(LW=0.1%) to within 0.5 dB of ideal bit error rate performance curves, in all modes and at all rates


NRZ-L Data

Jumper Select: three TTL, one RS422/TTL

Data Clock

One each: 0º, 90º, 180º, 270º; RS422/TTL at 0º & 90º

Data Polarity

Program selectable: normal/inverted


Data Source

Program selectable: Recovered Data or External data/clock


±2 Volts balanced output, 50mA drive current


Program selectable: RNRZ 9/11/15/17/23

PCM Codes

Program selectable: NRZ-L/M/S, Biø-L/M/S, DBiø-M/S, DM-M/S, MDM-M/S, RZ


Signal Type

Jumper selectable: RS422 or TTL


120Ω RS422, 75Ω TTL

Data Code


Data Clock

Program selectable: Normal/Inverted, 1x or 2x


Hosts Supported

Plugs onto Model 1611P, 1602P or 1626P

Cooling Requirements

30 Linear FPM

Power Requirements

+5VDC at 1.1A, +12VDC at 100mA, -12VDC at 100mA. Power supplied by host board


6.59” (16.51cm) H x 4.0” (10.16cm) W x .50” (1.27cm) D Host and module fits in standard slot


Operating 0 to +40°C, non-operating –40 to +86°C

Relative Humidity

Up to 90% non-condensing


Operating 6G, Non-operating 25G


Operating 0.5G, 5 to 2000Hz, Non-Operating 1.2G, 5 to 500Hz

specifications subject to change without notice

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