RCVDL56DPFL/SP, RCV56DPFL/SP, and RCV336DPFL/SP Designer’s Guide
1119
4-23
Function 34:
V.32 PN Length
Acc. Method: 2
Addr.: 289h, 288h
The V.32 bis/V.32 handshake and retrain sequence may be shortened or lengthened to meet special applications by
adjusting the length of the PN (TRN) sequence. The answering modem sends two TRN sequences during the handshake
while the originating modem sends only one.
The TRN time T (in ms) is calculated as follows:
Equation:
N = (2.4 x T) - 256
Where: N is the decimal equivalent of the hex number written to RAM and T is the time in ms.
Note: Values of N should be kept within 400h to 1F00h. A power-on reset will clear this location.
Changing the TRN lengths should be reserved for special applications only and is not recommended. Short TRN sequences
may jeopardize the success of the handshake or retrain. Consult the ITU-T V.32/V.32 bis specifications for TRN length
limitations. Only the originate TRN and the first answer TRN lengths are affected.
Function 36:
AGC Gain Word
Acc. Method: 4
Addr.: A00h
Function 36 is useful for determining the receive level (RL) at the Receive Analog (RXA) input. The number in RAM is related
to the receive level as follows:
Configuration
Equation
V.34, V.33, V.17, V.29, V.27
RL = N/682.7 - 52 dB
V.32 bis, V.32
RL = N/682.7 - 53 dB
V.22 bis, V.22, Bell 212, V.23/1200
RL = N/682.7 - 48 dB
V.21, V.23/75
RL = N/682.7 - 54 dB
Bell 103
RL = N/682.7 - 51 dB
Where: N is the decimal value of the hex number read from RAM.
This formula is valid only if the receive level is above the RLSD off-to-on threshold.
Function 37:
Round Trip Far Echo Delay
Acc. Method: 4
Addr.: 239h
Function 37 provides the value of the round trip delay measured during the handshake.
Equation:
RTD = (N/X) - 3.5 (for V.34)
RTD = (N/2.4) - 29 (for V.32 bis)
Where: RTD = Round Trip Delay in ms
N = Decimal equivalent of value read from RAM
X = symbol rate/1000, i.e., 2.4, 2.8, 3.0, 3.2, or 3.429 (see Function 60).
Function 45:
Equalizer Frequency Correction
Acc. Method: 4
Addr.: 811h
Function 45 provides the value of the Equalizer Frequency Correction (V.32 bis only).
Equation:
F = N/27.3 (for V.32 bis)
Where: F = Carrier frequency offset in Hz
N is the decimal value of the hexadecimal number read from RAM
Summary of Contents for RC336DPFL
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