T3 E3 Testing

T3 (DS3) Subrate and Scrambling


GL's T3 (DS3) E3 Analyzer is now enhanced with scrambling and subrate features. Sub rate allows DSU manufacturers to control bandwidth from service provider end and sell user specific bandwidth. Data Service Unit (DSU) Subrate feature in T3 (DS3) E3 Analyzer allows to configure the DS3 network for the following DSU vendors' algorithms for T3 interface: Digital Link, Larscom, Verilink, and Adtran.

The analyzer allows to choose scrambling in each DSU mode. Scrambling was implemented to address various 0s-density when used in WAN interface. User can monitor such communications using GL's USB T3 E3 Analyzer.

The following block diagram illustrates subrate implementation in the analyzer.

Alarm and Error windows for the T3 (DS3) and E3 Analyzers

Data descrambler

  • After the data is descrambled, the data descrambler block is used to descramble incoming data using a configured polynomial. 
  • The scrambler can be turned off for data not using descrambling.
  • This block uses a normal descrambling serial polynomial which can be configured for multiple polynomials

Data Filter

  • The Data filter uses a multi-framed aligned block ram which is used to enable or disable the incoming data.
  • By enabling or disabling the incoming data, software can configure the incoming data to support the different DS3 DSU vendor subrates

Filter Descrambler

  • Some Vendors only support scrambled data of the subrate. The unused payload is left unscrambled.
  • This block descrambles the data using a similar polynomial descrambler as the first descrambler block but only on the incoming filtered bandwidth data.

GL's USB T3E3 Analyzer unit supports the following DSU algorithms for T3 interface:

Digital Link




Related Link:

 Back to Laptop T3 E3 T1 E1 Ethernet Analyzer Page