Data Link Test Sets

Model 652 / 652A Dual Channel Data Transmission Test Set (BERT)
Model 652 Data Transmission Test Set

The GDP Model 652 Data Transmission Test Set fills the need for high performance data-link verification and qualification at an affordable price. The user is provided with two totally independent channels, and each channel provides independent transmit and receive functions. This allows for rapid fault isolation and data link characterization. Features such as an internal 6-digit frequency synthesizer and IRIG-106 Bit-Code generator and converter make the Model 652 especially suited to the test and evaluation of data link systems and components.

The Model 652 provides measurement of:
Accumulated Bit Errors, Measured Bit Error Rate, Elapsed Test Time, Accumulated Errored Seconds, Errors per Second, Accumulated Bit Count Integrity loss (Bit Slips), Measured Transmit and Receive clock rate.

Operating ease and test flexibility is the result of using microprocessor control to augment high-speed hardware functions. A high contrast vacuum fluorescent display provides setup and test result information in easy-to-use formats.

Functional Description

The unique architecture of the Model 652 provides superior flexibility. A fully programmable frequency synthesizer allows transmit clock generation from 1 bps to 52 Mbps with 6-digit resolution. A flexible interface structure, which provides IRIG-106 code converters for both input and output data, allows the Model 652 to fully support test and evaluation of telemetry processing systems.

The BER (Bit Error Rate) Module, is the major functional element in the Model 650. A microprocessor resident on the BER module controls the BERT transmit and receive circuits through user commands issued from the local front panel or remote control port. Communication between the microprocessor module and the BER module is accomplished using semaphores passed into a dual-port RAM architecture. All high-speed functions are provided by hardware

Functions such as data generation, PRN correlation, error detection and accumulation are performed by hardware. Low speed functions, such as test result accumulation and formatting for the front panel and remote monitoring ports, are provided by the embedded microprocessors.

Expansion slots are provided for addition of options. The Model 652A is available which is the standard Model 652 with additional TTL Inputs and Outputs.

  1. 2 Independent Data Link Testing Channels
  2.      • Each channel can select between two RS-449 channels & one HSSI channel
         • TTL I/O Optional (MD652A)
         • Bit rates up to 52 Mbps per channel
         • Independent Transmitter and Receiver on each channel
  3. Measures: Bits, Seconds, Bits in Error, Seconds in Error, Bit Error Rate (instantaneous
  4.      and average)
  5. Bit Slip Tests
  6. TX & RX Frequency Measurement
  7. 16 PRN Sequence Codes Forward & Reverse
  8.      • 2n-1, n= 5, 7, 9, 11, 15, 20, 23, 31 (Forward or Reverse)
         • User Defined Taps on 31-bit Register.
  9. Fixed Programmable Data Patterns 8, 16, 32, 64, 128, 256-bit or Dotting
  10. Internal DDS Frequency Synthesizer or External clock inputs
  11. IRIG-106 Code Generation and Conversion
  12. Randomizer / Derandomizer
  13.      • IRIG-106, V.35, V.36
  14. Remote Control / Monitor: RS232
  15. 3½" Rack Mount Chassis

Two Independent Channels
Each channel provides Independent Transmitter and Receiver
1 bps to 52 Mbps NRZ codes
(26 Mbps for 2X codes)
I/O Data Types:
HSSI [Micro-D 50F], RS-449 [DB37F]
Frequency Display:
Measured Receive and Transmit frequency
Data Pattern Selectable:
Forward and Reverse PRN codes:
2N-1 [N= 7, 9, 11, 15, 20, 23, 31]
User selectable Taps
Recycle data patterns, programmable 8, 16, 24, 32, 64, 128, 256 bits or Dotting
IRIG-106 Bit-Codes:
Data Randomizer / Derandomizer:

V.35, V.36 or IRIG-106 RNRZ-L (215-1)

Independently Selectable Data/Clock Outputs, each channel contains:
52 Mbps
35 Mbps (2 output connections per ch)
40 Mbps (Optional)

Clock Source:
External Terminal Timing Input
Internal Frequency Synthesizer Six (6) digit-plus-exponent

Data Perturbations:
Force output ALL 1s or ALL 0s
Insert a single error
Insert a single slip
Insert bit-error-rate
From 1.00 x 10-06 to 5.00 x 10-01
Insert Gap
Data forced to zero
Programmable Data Gap
From 1 to 9999 bit times forced to zero and a programmable period of 1 to 9,999,999 bits between gaps.
Selectable Data Slip
After a programmable period of 1 to 9999 bit times

Data Delay (NRZ):
Tunable from 0 to 650 nsec (in 5 nsec steps)

External 10MHz Reference Clock:
0 to +10 dBm, ¼ watt max power
Accuracy 10 ppm

Input Termination:
HSSI- 50 Balanced 110 Ohms Line-to-Line
RS-449– Balanced 120 Ohms Line-to-Line
TTL –75 Ohms or 50 Ohms (Optional)

Receive Data and Clock, Synchronization:
Auto Polarity Correction
BER up to 3 x 10-1
Selectable Resynchronization Threshold
Errors/Second Allowance Threshold:

Selectable 0 to 15

Test length from 102 thru 1012 bits
Total Count since test start:
Bits, Bits-in-Error, Seconds, Errored-Seconds, Slips
Bit-Error Rate
Average Bit-Error Rate

Power ON/OFF
Display and Keypad
Soft Control Keys
LED Status

AC Input:
90 to 264 VAC Auto-set
Single Phase, 47-63 Hz

3.5" (H) x 20" (D) x 17" (W)
20 lbs.
19 inch EIA rack mount

0° C to 40° C Operating; 28° C to 60° C Non-Operating
Relative Humidity:
5 to 95%, no condensation
0 to 10,000 ft
Forced-air Cooling

RS-232 Serial Interface
Ethernet 10/100