Silicon Laboratories SI2493/57/34/15/04 - Manual (Page 252)

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10.4. Compliance Testing
Regulatory compliance testing requires the modem to be configured in specific ways and controlled to perform
specific operations necessary to make required measurements. Compliance testing commands and configuration
information are provided.
Some helpful commands for conducting compliance testing on the ISOmodem are listed in Table 152. The modem
register defaults configure the modem for FCC operation.
Homologation testing requires that the ISOmodem signal output be measured for each modulation and data rate.
The AT&T3 command establishes an analog loopback connection to the phone line and places the modem in data
mode. The modulation is controlled by the &H command. This command is insufficient for homologation for several
reasons:
 It is not possible to configure the output tone to be as if from the answering or originating modem.
 It is not possible to configure the data rate used in an analoop connection within a given modulation.
 Three data patterns need to be sent during output testing: all marks, all spaces, and random data.
Once transmission with automatic data generation is initiated, the modem goes off-hook and begins to transmit the
data in the modulation selected by the existing &H command. Transmission continues until the ATH command is
sent after escape.
Table 152. AT Commands for Compliance Testing
AT Command/Test Method Desired Response
ATH1 Continuous off-hook
ATH0 Return on-hook
AT&Hn (see command description for n) Set modulation
AT&T3 (requires load and loop current) Turn on carrier (originate)
Set S10 = 255 to keep the modem under test from hanging up after the
remote modem is unplugged. Connect with another modem (Si24xx in
answer mode); then, unplug the other modem.
Turn on carrier (answer)
AT&T4
Initiate transmit as originating modem
with automatic data generation
AT&T5
Initiate transmit as answering modem
with automatic data generation
ATX0 Blind dial (no dial tone)
AT*Y1D (example: AT*Y1D1 for DTMF1) Send continuous DTMF digit
ATM2 Speaker on continuously
ATM0 Turn off speaker
AT:Uhh,xxxx (hh is U register and xxxx is the hex value to be written) Write a U register
AT:Rhh (hh is U register) Read a U register
AT:R Read all U registers
ATA Send Answer Tone for 3 seconds
AT:U4D,0008 ATX0 ATDT Send Calling Tone
Connect test modem and remote modem through a telephone line sim-
ulator. Configure test modem without protocol. Set test modem
S10 = 255. Connect phone in parallel to remote modem. Set remote
modem to desired modulation. Dial remote modem and connect. Take
parallel phone off-hook. Remove power from remote modem. Test
modem transmits indefinitely.
Transmit a specific modulation