Multi-Tech Systems MT2834MR6 manual Line Probe Commands

Chapter 3 - AT Commands

3.15 Line Probe Commands

Before V.34 negotiation, the local and remote modems use modulated calling and answering tones to exchange capability information . If V.34 mode communication is successful, probing signals are exchanged to identify impairments in the telephone channel. Using the results of these line probes, communication parameters are set, including carrier frequencies and data rates used for transmission. The following commands apply to modems only in V.34 mode.

%DPn	Read Line Probe Data
	n = 0 or 1
	Default: %DP0
	The modem does not normally store data acquired during line probe. To examine the line
	probe data using the L9, L10, or L11 commands, set the %DP1 command to read and store
	line probe data.
	%DP0 disables reading of line probe information during the handshake.
	%DP1 enables reading of line probe information during the handshake.
%DFn	Format Line Probe Data
	n = 0 or 1
	Default: %DF0
	Use this command to selects line probe data displayed as a graph with the Y axis showing
	signal strength in dBm, or as a table with dBm values shown numerically. The graph format
	shows data in 150 Hz increments from 150 Hz to 3750 Hz. The table format shows data in
	75 Hz increments from 150 Hz to 3750 Hz.
	%DF0 displays line probe data in graph format.
	%DF1 displays line probe data in table format.
&RP	Immediate Line Probe
	Default: none
	This command initiates a retrain that makes the processor read line probe information for
	display using the L9, L10, and L11 commands. Before issuing this command, escape to
	command mode while remaining online. To combine both actions, use the following
	command string: +++AT&RP<CR>.
	The modem will not read and store the line probe information from this retrain unless a
	%DP1 command is first issued.
Ln	Display Line Probe Data
	n = 9–11
	Default: none
	These immediate action commands cause the modem to display line probe information
	when it is in V.34 mode. The line probe information must first be read and stored by the
	modem (see “Read Line Probe Data”). Data format is controlled by the Format Line Probe
	Data command, %DF.
	The display commands are valid only in online mode. To use them online, you must first
	escape to command mode with +++AT<CR>. To return online, enter ATO.
	ATL9 displays signal strength information.
	ATL10 displays the signal to noise ratio (SNR).
	ATL11 displays noise information.

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