Specifications

AN93
122 Rev. 0.8
Homologation testing requires that the Si2493/57/34/15/
04 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.
The data sent during &T4 and &T5 transmission tests is
controlled by the S40 register.
The data rate for &T4 and &T5 commands is controlled
by the existing &G command. In V.34 cases, where a
data rate may use multiple symbol rates, the symbol
rate is controlled by the S41 register. If an invalid
combination of data/symbol rate is selected, the modem
chooses a valid symbol rate. It is the responsibility of
the operator to select valid combinations for testing.
After the &T4 or &T5 command is issued and the
modulation output has begun, a result code stating
“CONNECT” followed by the data rate (as if the output
were an actual connection) is sent. The 300bps rate
does not give the speed after “CONNECT.” The &G4
command allows V.34/2400bps operation, and &G3
allows V.22bis/1200 bps operation.
The answer tone output must also be measured during
homologation testing. A bit in memory allows a
continuous answer tone to be output in the same way
as a continuous DTMF tone through the AT*Y1
command. After issuing the commands AT&H10 and
AT*Y2A (separate line required for each), a constant
answer tone is produced, and the modem is returned to
command mode. The tone continues until a character is
received or the S7 timer expires. After the command
has been terminated, the modem returns on-hook and
sends the “NO CARRIER” message.
For homologation testing, it may be necessary to output
the V.29 modulation with transmit data. The +FTM
command includes additional codes given in Table 90 to
initiate output with the transmit data specified in S40.
AT:Uaa,xxxx (aa is U-Register and xxxx is the hex value to be written) Write a U-Register
AT:Raa (aa 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
simulator. 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
Table 88. AT Commands for Compliance Testing (Continued)
Table 89. Symbol/Data Rate
S41 V.34 Symbol Rate Allowable Data
Rates
0 (default) 2400 symbols/second 2400—21600
1 2743 symbols/second 4800—26400
2 2800 symbols/second 4800—26400
3 3000 symbols/second 4800—28800
4 3200 symbols/second 4800—31200
5 3429 symbols/second 7200—33600