6.0 DSL/G.fast Measurements
The DSL synchronization process for the MTTplus-523 is outlined as follows:
1.
Activation, Discovery or Handshaking:
Powering on the unit takes the DSL modem into activation and
acknowledgement phase, also known as handshaking. The goals of this are to determine which tones can be used and
how many bits can be assigned to each tone. Initialization typically uses two pilot tones to begin activation. Normally the
modem initiates the process when it is turned on and connected to the DSL line. Messages are sent using the pilot tones
to ensure that both ends are ready for transceiver training process.
2.
Training:
DSLAM measures and adjusts the power output to equalize the circuit. Unless configured otherwise, it
negotiates the fastest possible speed based on local loop conditions.
3.
Channel Analysis:
DSLAM tells the modem which options are configured and sends a predefined medley of tones so the
modem can report its signal-to-noise ratio.
4.
Exchange:
DSLAM sends the minimum signal-to-noise ratio and decides on the power output per tone.
5.
Showtime:
Initialization concludes in which the line is active and higher layer protocols, such as ATM, can begin
negotiation to transfer data over the connection. Showtime indicates that the port is working properly and synchronized.
The following measurements and parameters are displayed in the various tabs:
Line Status:
Displays all measurements related to the DSL layer
Errors:
Displays line signal alarms/errors that have occurred
Tones:
Displays graphs and tables of carrier tone measurements: bits per tone, SNR per tone, HLOG per tone, and QLN
per tone
Events:
Displays a log of all events that have occurred on the link since the test was started or measurement was cleared
or reset
6.1 Setup
Setup tab
Modem Type:
XTU-R Mode
The test set will try to synchronize with the far end DSLAM in either ADSLx or VDSL2 mode.
G.Fast FTU-R Mode
The test set will try to synchronize with the far end G.fast DPU.
Select the desired mode and press
Retrain
to initiate testing.
MTTplus-523_e-manual, D07-00-117P RevA00
