Data Link Test Sets

Model 650 Single Channel Data Transmission Test Set
Model 650 Data Transmission Test Set

The GDP Model 650 Data Transmission Test Set fills the need for high performance data-link verification and qualification at an affordable price. The user is provided with totally independent transmit and receive functions to allow rapid fault isolation and data link characterization. Simulated signal perturbations are created in the test lab by adding noise, baseline offset and varying signal levels. Features such as an internal 6-digit frequency synthesizer and IRIG Code generator and converter make the Model 650 especially suited to the test and evaluation of PCM Telemetry data link systems and components.

The Model 650 provides measurement capability for: Accumulated Bit Errors, Measured Bit Error Rate, Elapsed Test Time, Accumulated Errored Seconds, Errors per Second, Measured error Symmetry, 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

A modular architecture gives the Model 650 superior flexibility. A fully programmable frequency synthesizer allows transmit clock generation from 1 bps to 50 Mbps with 6-digit resolution. A flexible interface structure, which provides IRIG code converters for both input and output data, allows the Model 650 to fully support test and evaluation of telemetry receive, and 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 data accumulation and formatting for the front panel and remote monitoring ports, are provided by the embedded microprocessors.

  1. 1 bps to 36 Mbps Operation (Standard)
  2.      • 1 bps to 50 Mbps Operation (Optional)
  3. Independent Transmitter and Receiver
  4. Measures: Bits, Seconds, Bits in Error, Seconds in Error, Bit Error Rate (instantaneous
  5.      and average)
  6. Data Symmetry & Bit Slip Tests
  7. TX & RX Frequency Measurement
  8. 16 PRN Sequence Codes Forward & Reverse 2n-1, n= 5,7, 9, 11, 15, 20, 23, 31 (Forward or
  9.      Reverse) and User Defined Taps on 31-bit Register.
  10. Fixed Programmable Data Patterns 8, 16, 32, 64, 128, 256-bit or Dotting
  11. Internal DDS Frequency Synthesizer
  12. IRIG Code Generation and Conversion
  13. Randomizer / Derandomizer (Fwd & Rev)
  14.      • IRIG (215-1), 29-1, 211-1, 217-1, 223-1, V.35, V.36
  15. Convolution Encode / Decode (Optional)
  16. TTL, Bipolar, RS-422 Signal Interfaces
  17. Remote Control / Monitor: RS232 (Standard)
  18.      • EtherNet, IEEE-488 (Optional)
  19. Internal Noise Source (Optional)
  20.      • Programmable Eb/No and Signal Level
         • Automatic Eb/No Test (Optional)
  21. Analog Signal Output Interface (Optional)
  22. Acquisition Time Test (Optional)
  23. Jitter Test (Optional)
  24. Link Delay Test (Optional)
  25. 3½" Rack Mount Chassis

Independent Transmitter and Receiver
1 bps to 36 Mbps NRZ codes (17.5 Mbps for 2X codes) Standard
1 bps to 50 Mbps NRZ codes (30 Mbps for 2X codes) Optional
TTL-50 Mbps, Bipolar-40 Mbps, RS-422-40 Mbps
Frequency Display:
Receive and Transmit Bit Rate, Measured

Input Termination:
High Z / Low-Z on TTL & Bipolar

Data Pattern Selectable:
Forward & Reverse PRN codes:
25-1, 27-1, 29-1, 211-1, 215-1, 217-1, 219-1, 220-1, 223-1, 225-1, 231-1,
User selectable Taps
Recycle data patterns, programmable:

8, 16, 24, 32, 64, 128, 256 bits
or Dotting pattern
IRIG Bit-Codes:

Data Randomizer / Derandomizer:
V.35, V.36 or FWD/REV RNRZ-L 2N-1(N=15 [IRIG-STD 106], 9, 11, 17, 23)

Convolutional Encoder (Viterbi Decoder):
Rate ½ ; K 7
Selectable convolution order and polarity

Data/Clock Outputs:
Transmit I-and Q (Option)-Data
Transmit Clock

Clock Input:
External Transmit Clock

Transmit Timing:
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-rates
From 1.0E-06 to 0.5
Insert Gap
Selectable data slip
Up to 9999 bit times
Selectable data gap
Up to 9999 bit times
Bit Rate Jitter
AC Base-line Variation
With Analog Option
Signal Amplitude Modulation
With Analog Option

Receive Data and Clock, Synchronization:
Auto Polarity Correction
Auto-correlation BER up to 3 x 10-1
ReSynch Threshold, Selectable
Error Allowance Threshold

Test length from 102 thru 1012 bits
Total Count since test start:

Bit-Error Rate
Average Bit-Error Rate
Sync Acquisition (Option)
Data Link Delay (Option)
BER vs Eb/No Performance
Jitter Performance

Transmit Data with level and offset adjust:
Signal level:
100 mVp-p to 4 Vp-p (50 ΩLoad)
DC offset:
Up to +5V or - 5V (Peak signal + Offset + Noise)
AC Offset
Bit Rate Jitter

Internal programmable Eb/No generator
External Noise Input

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

AC Input:
90 to 264 VAC Auto-set
Single Phase, 47-63 Hz
3.5 (H) x 20 (D) x 17 (W), inches
20 lbs.
19 inch EIA rack mount

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

RS-232 Serial Interface
IEEE488 Interface
10/100 Base T