Table 36 show modem operational-status Field Descriptions for MICA Modems
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Modem (slot/port) Operational Status:
|
This parameter identifies the modem.
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Parameter #0 Disconnect Reason Info:
|
This parameter displays reasons for call disconnect.
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Parameter #1 Connect Protocol:
|
This parameter displays the connect protocol for the current session, which can be synchronous (SYNC) mode, asynchronous (ASYNC) mode, AppleTalk Remote Access (ARA) 1.0, ARA 2.0, Link Access Procedure for Modems (LAP-M), Microcom Network Protocol (MNP), FAX mode, Signaling System 7/Continuity Test (SS7/COT), or ISDN Mode.
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Parameter #2 Compression:
|
This parameter displays the compression protocol used for the current connection, which can be None, V.42
bis
TX (transmit), V.42
bis
RX (receive), V.42
bis
both, or MNP5 data compression.
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Parameter #3 EC Retransmission Count:
|
This parameter displays the error correction (EC) retransmission count, or the number of times the MICA technologies modem has gone into error recovery in the TX direction for a particular connection.
The higher the number, the worse the connection. However, compare this parameter against the count produced by Parameter #36 (EC packets transmitted, received) to determine if there really is a problem.
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Parameter #4 Self Test Error Count:
|
This parameter displays the total errors generated during a self-test run.
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Parameter #5 Call Timer:
|
This parameter displays the length of the call in seconds. The timer starts when the CONNECT modem state is reached.
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Parameter #6 Total Retrains:
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This parameter displays the count of total retrains and speed shifts.
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Parameter #7 Sq Value:
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This parameter displays the measure of the receive signal quality (SQ) bit error rate for the chosen modulation, as estimated by the Digital Signal Processor (DSP), where 0 is the highest BER value and 7 the lowest. Depending on the setting of the SQ Threshold (S32), the DSP seeks an SQ value somewhere between the highest and lowest levels. For example, if S32 = 2 (the default), an SQ value of 3 is sought. If the SQ value drops below the threshold for longer than the duration of S35, the DSP attempts a downward speed shift or retrain. Similarly, if the SQ value goes above the threshold for longer than S34, an upward speed shift or retrain is attempted.
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Parameter #8 Connected Standard:
|
This parameter displays the modulation, which can be V.21, Bell03, V.22, V.22
bis
, Bell212, V.23, V.32, V.32
bis
, V.32terbo, V.34, V.34+, K56Flex, V.90, V.110, or ISDN.
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Parameter #9 TX, RX Bit Rate:
|
This parameter displays the TX bit rate from the local data communication equipment (DCE) to the remote DCE and the RX bit rate from the remote DCE to the local DCE.
The following data carrier connect standards support the rates indicated in bits per second (bps):
-
V.21 TX, RX—300 bps
-
V.22 TX, RX—1200 bps
-
V.22
bis
TX, RX—2400 bps
-
V.23 TX (originate)—1200 bps
-
V.23 RX (originate)—75 bps
-
V.32 TX, RX—4800 and 9600 bps
-
V.32
bis
TX, RX—4800, 7200, 9600, 12000, and 14400 bps
-
V.34 TX, RX—2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400, and 28800 bps
-
V.34+ TX, RX—2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400, 28800, 31200, and 33600 bps
-
K56Flex TX—32000, 34000, 36000, 38000, 40000, 42000, 44000, 46000, 48000, 50000, 52000, 54000, 56000, 58000, and 60000 bps
-
K56Flex RX—2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400, 28800, and 31200 bps
-
V.90 TX—28000, 29333, 30666, 32000, 33333, 34666, 36000, 37333, 38666, 40000, 41333, 42666, 44000, 45333, 46666, 48000, 49333, 50666, 52000, 53333, 54666, and 56000 bps
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V.90 RX—2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400, 28800, 31200, and 33600 bps
-
Bell103 TX, RX—Up to 300 bps
-
Bell212 TX, RX—0 to 300 and 1200 bps
The following fax connect standards support the rates indicated in bps:
-
V.17 TX, RX—7200, 9600, 12000, and 14400 bps
-
V.27ter TX, RX—2400 and 4800 bps
-
V.29 TX, RX—7200 and 9600 bps
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Parameter #11 TX, RX Symbol Rate:
|
This parameter displays the TX symbol rate used to transmit samples to the line and the RX symbol rate used to receive samples from the line. The rates are synchronous with each other.
The following data carrier connect standards support the indicated bit rates:
-
V.21 TX, RX—300 bps
-
V.22 TX, RX—600 bps
-
V.22
bis
TX, RX—600 bps
-
V.23 TX (originate)—1200 bps
-
V.23 RX (originate)—75 bps
-
V.23 TX (answer)—75 bps
-
V.23 RX (answer)—1200 bps
-
V.32 TX, RX—2400 bps
-
V.32
bis
TX, RX—2400 bps
-
V.34 TX, RX—2400, 2743, 2800, 3000, 3200, and 3429 bps
-
V.34+ TX,RX—2400, 2743, 2800, 3000, 3200, and 3429 bps
-
K56Flex TX—8000 bps
-
K56Flex RX—3200 bps
-
V.90 TX—8000 bps
-
V.90 RX—3000, 3200, and 3429 bps
-
Bell103 TX, RX—300 bps
-
Bell212 TX, RX—600 bps
The following fax connect standards support the indicated bit rates:
-
V.17 TX, RX—2400 bps
-
V.27ter TX, RX—1800 bps
-
V.29 TX, RX—2400 bps
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Parameter #13 TX, RX Carrier Frequency:
|
This parameter displays the TX carrier frequency used by the local DCE and the RX carrier frequency used by the remote DCE.
Data carrier frequencies are as follows:
-
V.21 TX RX—1080 Hz (originate) and 1750 Hz (answer)
-
V.22 TX, RX—1200 Hz (originate) and 2400 Hz (answer)
-
V.22
bis
TX, RX—1200 Hz (originate) and 2400 Hz (answer)
-
V.23 TX (originate)—1700 Hz
-
V.23 RX (originate)—420 Hz
-
V.23 TX (answer)—420 Hz
-
V.23 RX (answer)—1700 Hz
-
V.32 TX, RX—1800 Hz
-
V.32
bis
TX, RX—1800 Hz
-
V.34 TX, RX—1600, 1800, 1646, 1680, 1829, 1829, 1867, 1900, 1920, 1959 Hz
-
V.34+ TX, RX—1600, 1800, 1646, 1680, 1829, 1829, 1867, 1900, 1920, 1959 Hz
-
K56Flex TX—Does not apply.
-
K56Flex RX—1600, 1800, 1646, 1680, 1829, 1829, 1867, 1900, 1920, 1959 Hz
-
V90 TX—Does not apply.
-
V90 RX—1600, 1800, 1646, 1680, 1829, 1829, 1867, 1900, 1920, 1959 Hz
-
Bell103 TX, RX—1080 Hz (originate) and 1750 Hz (answer)
-
Bell212 TX, RX—1200 Hz (originate) and 2400 Hz (answer)
Fax carrier frequencies are as follows:
-
V.17 TX, RX—1800 Hz
-
V.27ter TX, RX—1200 (originate) and 1600 (answer)
-
V.29 TX, RX—1700 Hz
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Parameter #15 TX, RX Trellis Coding:
|
Trellis coding adds dependency between symbols to make the detection in noise more robust (Forward Error Correction). Trellis coding is displayed in values of 0, 8, 16, 32, or 64. Use the following key to correlate the trellis code values with the connection standard:
-
0—V.22, V.22
bis
, V.21, Bell212, Bell103, V.29, or V.27
-
8—V.32, V.32
bis
, or V.17
-
16, 32, 64—V.34, V.34+, V.90, K56Flex
Note MICA technologies modems do not support values of 32 or 64 in the RX direction, but do support values of 16, 32, and 64 in the TX direction.
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Parameter #16 TX, RX Preemphasis Index:
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The preemphasis index involves shaping the raw transmit spectrum to deal with spectrum roll-offs. The preemphasis index can take on the values from 0 to 10. A zero denotes no reshaping. Typical values usually fall in the range from 0 to 2, or 6 to 7. This index is used with V.34 and V.34+ connection standards.
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Parameter #17 TX, RX Constellation Shaping:
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Constellation shaping is a technique for improving noise immunity by using a probability distribution for transmitted signal points. The signal states are used to predict the sensitivity to certain transmission impairments. Constellation shaping is used with the V.34 and V.34+ connection standards.
Values displayed by this parameter are either none or active (Off or On).
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Parameter #18 TX, RX Nonlinear Encoding:
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Nonlinear encoding occurs during the training phase and moves the outer points of the constellation away to deal with nonlinear distortion. Nonlinear distortion (in the range from 0 to 200 Hz) tends to affect the higher-powered signals. Moving the outer constellation points out reduces the chance of error. Nonlinear encoding is used with the V.34 and V.34+ connection standards.
Values displayed by this parameter are either none or active (Off or On).
Note MICA technologies modems support nonlinear coding in both directions.
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Parameter #19 TX, RX Precoding:
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Precoding serves the same purpose as the preemphasis index, but instead manages the bits and not the raw transmit signals. This management is done only when asked for and therefore will occur only in the RX mode. Precoding is used with the V.34 and V.34+ connection standards.
Values displayed by this parameter are either none or active (Off or On).
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Parameter #20 TX, RX Xmit Level Reduction:
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The Xmit (transmit) level affects the transmit signal with 0 to 15 in dBm of reduction. If nonlinear distortion is detected, the MICA technologies modem will request a lower-powered TX signal. If the remote end detects nonlinear distortion, it will also request a lower-powered TX signal. Xmit level reduction is used with the V.34 and V.34+ connection standards.
Values displayed by this parameter are the transmit signal and reduction, in dBm.
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Parameter #21 Signal Noise Ratio:
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A signal to noise ratio (SNR) is the ratio between the expected signal and the error signal.
For example, consider a four-point constellation at (
x
,
y
) = (–1,1), (1,1), (1,–1), and (–1,–1). The receive signal comes in at (
x
^,
y
^) = (0.5,1.5). The expected value, although not guaranteed, is (1,1). The error vector is then calculated as follows:
e
= (
x
–
x
^,
y
–
y
^) = ([1–0.5], [1–1.5]) = (0.5,–0.5)
and the SNR is calculated as follows:
SNR = 20*log10 [magnitude(expected value
x
,
y
of constellation) /
magnitude(error)]
SNR = 20 log10 [magnitude(1,1) / magnitude(0.5,–0.5)] = 6.02 dB
This parameter displays the ratio measurement of the desired signal to noise. MICA technologies modems measure the SNR in only the signal band that has a rate equal to the baud rate (that is, 3200 Hz, 2400 Hz, and so on).
Note that a 28.8-kbps connection demands an SNR of about 37 dB. If the rate is lower than this value, the quality of the connection diminishes. A 33.6-kbps connection demands an SNR of 38 to 39 dB. A clean line has an SNR of about 41 dB.
The values displayed by this parameter range from 0 to 70 decibels (dB) and change in 1-dB steps.
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Parameter #22 Receive Level:
|
The receive level is the power of the received signal and ranges from 0 to –128 dBm in 1-dBm incremental steps. The ideal range is about –22 dBm in the United States and –12 dBm in Europe.
In theory, MICA technologies modems can handle a receive level up to –4 dBm. However, the receive level they can handle is a function of the echo level. If there is absolutely no echo, the MICA modem should be able to handle a –4 dBm level. As the echo level goes up, the receive level that the MICA modem can handle moves from –4 dBm to –5 dBm, and so on.
The optimum range for the receive level displayed by this parameter is from –12 dBm to –24 dBm.
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Parameter #23 Frequency Offset:
|
Frequency offset is a difference between the modulation carriers—that is, the frequency shift in the receive spectrum between the expected RX carrier frequency and the actual RX carrier frequency.
The values displayed by this parameter range from +/–32 in 0.125-Hz steps. The typical value is 0 Hz.
Note Values of up to +/–7 Hz can be found on analog trunk circuits and will be compensated for by the MICA technologies modems.
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Parameter #24 Phase Jitter Frequency:
|
Phase jitter frequency is the peak-to-peak differential between two signal points.
The following calculation models a typical RX carrier:
e
^
j
(
wt
+
a
)
but when phase jitter is detected, the RX carrier is modeled as follows:
e
^
j
[
wt
+
a
+
K
sin(
bt
+
c)
]
where:
w
= carrier frequency
a
= carrier phase
K
= magnitude of sinusoidal phase jitter
b
= frequency of sinusoidal phase jitter
c
= phase of sinusoidal phase jitter
Uncanceled phase jitter looks like “rocking” of the baseband QAM constellation. The points look like arcs with the outer points having longer arcs.
The phase jitter measurements displayed by this parameter range from +/–32 in 0.125-Hz steps. The typical value is 0 degrees (that is, phase jitter is not normally present).
Note This phase jitter value is found only on analog trunk circuits. Typical frequencies are power generation frequencies and their harmonics (that is, 60, 120 Hz within the United States; 50, 100 Hz international). MICA technologies modems cancel all known frequencies.
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Parameter #25 Phase Jitter Level:
|
Phase jitter level is the amount of phase jitter measured and indicates how large the “rocking” is, in degrees. On an oscilloscope, the constellation points would look like crescent moons. The jitter level corresponds to magnitude
K
as described in Parameter #24.
Values displayed by this parameter can range up to 15 degrees. The typical value is 0 degrees (that is, phase jitter is not normally present).
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Parameter #26 Far End Echo Level:
|
Over long connections, an echo is produced by impedance mismatches at 2-wire-to-4-wire and at 4-wire-to-2-wire hybrid circuitry.
This parameter displays the far-end echo level (that portion of the transmitted analog signal that has bounced off of the analog front end of the remote modem), which can range from 0 to –90 dBm.
A MICA modem cannot handle near-end echo if far-end echo is present and the round-trip delay is greater than 10 microseconds. This constraint comes from the number of taps in the echo canceler of MICA modems.
Assuming that there is no near-end echo, the performance of the receiver varies as the ratio of the receive level divided by the far-end echo (RECEIVE LEVEL/FAR END ECHO). As the echo level rises, the receiver performance degrades. (This is why the MICA modem can handle “hotter” receive levels with less echo.)
The technical reason for this degradation has to do with
dynamic range
. Every echo canceler has some residual echo (error) left in the signal. This residual echo adds to the power of the receive signal going through the rest of the MICA modem receiver. With little residual echo, there is more dynamic range for the actual receive signal.
For a call to go from the MICA modem to the local switch and back into MICA, the reported far-end echo level must be less than –55 dBm. A greater echo level indicates a digital-to-analog conversion in the path between the MICA modem and the switch. MICA modems are not supported in this topology.
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Parameter #27 Phase Roll:
|
This parameter displays the phase roll, which affects the echo signal coming back to the MICA modem.
A certain constellation pattern is transmitted from a MICA modem when the echo signal reaches the central office (CO). Some echoed form of this signal/constellation pattern is sent back to the MICA modem; however, the constellation shape may be rotated from 0 to 359 degrees. This rotation is called the
phase roll
.
The echoed signal consists of a frequency component and a phase component. If the frequency component changes at all, a correction is needed for echo cancellation to work correctly. A slight variance (an unknown amount that would have to be determined through experimentation) in the phase may not affect how the echo canceler performs. Too much change in phase also needs correcting for proper echo cancellation to occur.
The phase roll value ranges from +/–32 in 0.125-Hz steps. The typical value is 0 or close to 0.
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Parameter #28 Round Trip Delay:
|
Round-trip delay is the total round-trip propagation delay of the link in microseconds. This delay is important for proper echo cancellation.
This parameter displays the round-trip delay; the amount of delay varies with each network.
Note The buffer speed for MICA modems is 4096 bps; therefore, at 2400 bps the delay is 1.7 seconds, and at 3429 bps, 1.19 seconds. Because round-trip delay is measured before the bps rate is chosen, round-trip delay is used to disable those bit rates for which the round-trip delay cannot be supported. For example, if the round trip-delay is 1.25 seconds, 3429 is disabled for that train attempt.
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Parameter #30 Characters transmitted, received:
|
This parameter displays the total count of characters (before modem compression of any type) received and transmitted.
|
Parameter #32 General Portware Information:
|
Not used.
|
Parameter #33 PPP/SLIP packets transmitted, received:
|
This parameter displays the total count of Point-to-Point Protocol (PPP) and Serial Line Internet Protocol (SLIP) packets transmitted and received. This total could include all PPP/SLIP packets, including BAD/ABORTED packets.
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Parameter #35 PPP/SLIP packets received (BAD/ABORTED):
|
This parameter displays the total count of the bad or aborted PPP/SLIP packets, and is a subset of the counter shown in Parameter #33 (PPP/SLIP packets received). A counted PPP packet has a bad FCS, or the SLIP packet has a transparency error. Errored PPP frames should be displayed only when asynchronous framing (no EC protocol) is being used.
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Parameter #36 EC packets transmitted, received OK:
|
This parameter displays the number of EC packets transmitted (the number of TX frames that the client modem has accepted) and the number of EC packets received (the number of RX frames that the MICA modem has accepted).
|
Parameter #38 EC packets (Received BAD/ABORTED):
|
Parameter #38 is identical to Parameter #3 (EC Retransmission Count). It may read differently from Parameter #3, depending on how the software requests the parameter information.
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Parameter #39 Robbed Bit Signalling (RBS) pattern:
|
This parameter displays the number of robbed bits detected in the connection. The robbed bits are used for in-band signaling. This information is reported only for K56Flex by the analog modem. The six least significant bits of the returned value indicate the periodic RBS pattern, where a 1 denotes a pulse code modulation sample with a robbed bit.
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Parameter #40 Digital Pad, Digital Pad Compensation:
|
A digital pad can be implemented by the CO to attenuate a “hot” signal. Compensation boosts the signal by the amount of the pad.
This parameter displays values that usually range from 0 to 10 dB, with typical values being 0, 3, and 6 dB.
Note A digital pad is mandatory for K56Flex, but configurable for V.90 using S52. K56Flex supports only 0, 3, and 6 dB. V.90 supports steps of 1/8192 dB, but it is reported to the host in steps of 0.125-dB granularity.
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Line Shape:
|
The display at the end of the report shows line shaping as a frequency-response graph of the channel. The
Y
(vertical) axis represents frequencies from 150 Hz (top of chart) to 3750 Hz (bottom of chart) in 150-Hz steps. The
X
(horizontal) axis represents a normalized amplitude. The graph can help identify nulls, bandwidth, and distortion (irregular shape). A flat spectrum plot is best.
This display is available only for V.34, V.90, and K56Flex connection standards.
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Parameter #9 TX, RX Bit Rate:
|
This parameter displays the TX bit rate from the local data communication equipment (DCE) to the remote DCE and the RX bit rate from the remote DCE to the local DCE.
The following data carrier connect standards support the rates indicated in bits per second (bps):
-
V.21 TX, RX—300 bps
-
V.22 TX, RX—1200 bps
-
V.22
bis
TX, RX—2400 bps
-
V.23 TX (originate)—1200 bps
-
V.23 RX (originate)—75 bps
-
V.32 TX, RX—4800 and 9600 bps
-
V.32
bis
TX, RX—4800, 7200, 9600, 12000, and 14400 bps
-
V.34 TX, RX—2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400, and 28800 bps
-
V.34+ TX, RX—2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400, 28800, 31200, and 33600 bps
-
K56Flex TX—32000, 34000, 36000, 38000, 40000, 42000, 44000, 46000, 48000, 50000, 52000, 54000, 56000, 58000, and 60000 bps
-
K56Flex RX—2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400, 28800, and 31200 bps
-
V.90 TX—28000, 29333, 30666, 32000, 33333, 34666, 36000, 37333, 38666, 40000, 41333, 42666, 44000, 45333, 46666, 48000, 49333, 50666, 52000, 53333, 54666, and 56000 bps
-
V.90 RX—2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400, 28800, 31200, and 33600 bps
-
Bell103 TX, RX—Up to 300 bps
-
Bell212 TX, RX—0 to 300 and 1200 bps
The following fax connect standards support the rates indicated in bits per second (bps):
-
V.17 TX, RX—7200, 9600, 12000, and 14400 bps
-
V.27ter TX, RX—2400 and 4800 bps
-
V.29 TX, RX—7200 and 9600 bps
|
Parameter #11 TX, RX Symbol Rate:
|
This parameter displays the TX symbol rate used to transmit samples to the line and the RX symbol rate used to receive samples from the line. The rates are synchronous with each other.
The following data carrier connect standards support the indicated bit rates:
-
V.21 TX, RX—300 bps
-
V.22 TX, RX—600 bps
-
V.22
bis
TX, RX—600 bps
-
V.23 TX (originate)—1200 bps
-
V.23 RX (originate)—75 bps
-
V.23 TX (answer)—75 bps
-
V.23 RX (answer)—1200 bps
-
V.32 TX, RX—2400 bps
-
V.32
bis
TX, RX—2400 bps
-
V.34 TX, RX—2400, 2743, 2800, 3000, 3200, and 3429 bps
-
V.34+ TX,RX—2400, 2743, 2800, 3000, 3200, and 3429 bps
-
K56Flex TX—8000 bps
-
K56Flex RX—3200 bps
-
V.90 TX—8000 bps
-
V.90 RX—3000, 3200, and 3429 bps
-
Bell103 TX, RX—300 bps
-
Bell212 TX, RX—600 bps
The following fax connect standards support the indicated bit rates:
-
V.17 TX, RX—2400 bps
-
V.27ter TX, RX—1800 bps
-
V.29 TX, RX—2400 bps
|