Silicon Laboratories SI2493/57/34/15/04, SI2494/39 manual AT Commands for Compliance Testing

AN93

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.

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	Turn on carrier (answer)
answer mode); then, unplug the other modem.
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<digit> (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	Transmit a specific modulation
modem to desired modulation. Dial remote modem and connect. Take
parallel phone off-hook. Remove power from remote modem. Test
modem transmits indefinitely.

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.

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