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56K V.92 Data, Fax, and Voice Chipset
56 Intel Confidential Programmer’s Guide
+MS=m see “m”
Modulation Selection: This command sets the type of modulation used and the
send and receive speeds. Settings for Bn, +MS=m, Nn and S37 determine the al-
lowable modem connections. Nn performs the same function as the +MS=m <auto-
mode> parameter. S37 performs the same function as the +MS=m <max rate> pa-
rameter.
Modems using MD566X chipsets can be configured by the +MS=m command to
support only asymmetrical or symmetrical connections. The transmit and receive
speeds are the same in symmetrical connections and different in asymmetrical con-
nections. The type of connection is set by the <carrier> parameter. The chipsets
default to the ITU-T V.90 or V.92 mode depending on firmware version. If the con-
nection is non-V.90/V.92 the chipsets fall back to V.34 mode. Note that the transmit-
ter speed and receiver speeds typically are different for most V.34 connections over
the PSTN.
The +MS command sets the modulation speeds in the V.34 chipsets; however, B0
also must be sent to set the modulation to V.22. Sending B1 sets the modulation to
Bell 212. These commands can be typed before or after the +MS command. For ex-
ample, to set the modulation to ITU-T V.22:
+MS = V22, 1, 1200, 1200; B0
To check the settings for the +MS command, type AT+MS?
m = <carrier>, <automode>, <min rate>, <max rate>
Defaults: m = V90, 1, 0, 0
<carrier > This eight-digit string parameter specifies the type of modulation used.
Approved codes are shown in the following table. The modem can switch automati-
cally between some types.
<carrier> Description
V21 V.21 300 bps
V22 V.22 1200 bps
V22B V.22 bis 1200 and 2400 bps
V23C V.23, with constant carrier; 1200 bps forward and 75 bps reverse
V32 V.32 4800 and 9600 bps
V32B V.32 bis 7200, 9600, 12,000, and 14,400 bps
V34 V.34 asymmetrical connections: 2400, 4800, 7200, 9600, 12,000,
14,400, 16,800, 19,200, 21,600, 24,000, 26,400, and 28,800 bps
V34S V.34 symmetrical-only connections: 2400, 4800, 7200, 9600,
12,000, 14,400, 16,800, 19,200, 21,600, 24,000, 26,400, 28,800
bps
V34B V.34 extended asymmetrical connections: 2400, 4800, 7200, 9600,
12,000, 14,400, 16,800, 19,200, 21,600, 24,000, 26,400, 28,800,
31,200, and 33,600 bps
V34BS V.34 extended symmetrical connections: 2400, 4800, 7200, 9600,
12,000, 14,400, 16,800, 19,200, 21,600, 24,000, 26,400, 28,800,
31,200, and 33,600 bps
Table 3-4. Data Mode Command Descriptions (Continued)