Comtrol AT Commands - Manual (Page 87)

AT Commands for CX81801/CX06833/CX81300/CX06827 Modems Reference Manual
102184B Conexant 3-61
+MRR: Report Syntax
Response: +MRR: <tx_rate>,<rx_rate>
<tx_rate> Decimal transmit rate in bits/s.
<rx_rate> Decimal receive rate in bits/s.
Example: +MRR: 28800, 48000
%E - Enable/Disable Line Quality Monitor and Auto-Retrain or Fallback/Fall
Forward
Controls whether or not the modem will automatically monitor the line quality and
request a retrain (%E1) or fall back when line quality is insufficient or fall forward when
line quality is sufficient (%E2). The parameter value, if valid, is written to S41 bits 2 and
6.
If enabled, the modem attempts to retrain for a maximum of 30 seconds.
Syntax
%E<value>
Defined Values
<value> Decimal number corresponding to the selected option.
0 Disable line quality monitor and auto-retrain.
1 Enable line quality monitor and auto-retrain.
2 Enable line quality monitor and fallback/fall
forward. (Default.)
Result Codes
OK <value> = 0, 1, or 2.
ERROR Otherwise.
Fallback/Fall Forward. When %E2 is active, the modem monitors the line quality
(EQM). When line quality is insufficient, the modem will initiate a rate renegotiation to a
lower speed within the V.34/V.32 bis/V.32 (RC336) modulation speeds. The modem will
keep falling back within the current modulation if necessary until the speed reaches 2400
bps (V.34) or 4800 bps (V.32). Below this rate, the modem will only do retrains if EQM
thresholds are exceeded. If the EQM is sufficient for at least one minute, the modem will
initiate a rate renegotiation to a higher speed within the current modulation speeds. The
rate renegotiations will be done without a retrain if a V.32 bis connection is established.
Speeds attempted during fallback/fall forward are those shown to be available in the rate
sequences exchanged during the initial connection. Fallback/fall forward is available in
error correction and normal modes, but not in direct mode or synchronous mode with
external clocks.