INTRODUCTION ECHO CANCELLER TIMING RECOVERY CARRIER RECOVERY EQUALIZER

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INTRODUCTION ECHO CANCELLER TIMING RECOVERY CARRIER RECOVERY EQUALIZER

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MAPPING ST75C50
INTRODUCTION ECHO CANCELLER TIMING RECOVERY CARRIER RECOVERY EQUALIZER, HANDSHAKE,RETRAIN,RATE NEGOTIATION CARRIER DETECT TRANSMIT FILTER COEFICIENTS TONE DETECTOR PROGRAMMING GENERAL PURPOSE TONE GENERATOR APPENDIX
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INTRODUCTION purpose this application note explain what "interesting internal variables" that Read, Written Modified using commands. Some these variables have dedicated commands modify them, like SETGN _TXGAIN tone detector. However whole (even external when using ST18933) also DUAL internal peripherals accessed using three above mentioned commands.
AN536/0694
address, characteristic read, write, read write), function data pump variables listed below basic modem functional blocks. Caution Mapping variables, given appendix only valid Revision ST75C50. There guarantee that will remain exactely same further revisions.
MAPPING ST75C50 ECHO CANCELLER _RTDELAY _EC_STA Round trip delay number bauds (R/W) Echo canceller execution status word. echo canceller frozen data mode reading _EC_STA performing logical with value $0002 before writing _EC_STA. (i.e. other bits must changed) Residual echo power estimator determining loss connection. ABS() value this variable will greater than indicate connection loss, otherwise near Far-end echo frequency offset. offset FRQOFF*.0366 typically, FRQOFF $1b(27) 1Hz. Initial far-end echo power after near echo canceller convergance. This variable read data mode following typical values.
VALUE $FFF6 $FFF7 $0000 $000A (-10) (+10) POWER 9dBm -12dBm -39dBm -69dBm
(PWREST+1)
(FREQOFF+3) DELTA
FEECENBL
echo canceller enabled. $FFFF Enabled $0000 Disabled (when initial far-end power less -69dBm.
TIMING RECOVERY (FRQOFF+1) PSITHRSH Receive clock frequency offset. timing phase adjustement threshold timing signal dpll.
Comments local-to-remote modem timing offset calculated using following formula FRQOFF TIMING OFFSET PSITHRSH normal timing offset within 1.0e-4 most connections CARRIER RECOVERY (FRQOFF+1) Receive carrier frequency offset. OFFSET FRQOFF*.0366 Typically, FRQOFF $1B(27) 1Hz.
EQUALIZER, _RX_STA (R/W) Equalizer frozen independently simultaneously. freeze equalizer freeze change _RX_STA must modified data mode other bits must unchanged. Read value change only corresponding bits _RX_STA word.
(_AGCSCA+1) (R/W) Automatic gain control level receive signal varies from $80(0dBm) $7fff (48dBm).
MAPPING ST75C50 RDQUA Equalizer error energy gives idea signal noise ratio seen receiver. RDQUA following typical values.
VALUE $00C0 $0180 $0300 $0600 $0C00 $1800 $3000 POWER
_RDCPT EQFRK0E EQFRK1E
Output Demodulator. Complex number, used display received eye.
(R/W) Complex even equalizer coefficients. (R/W) Complex equalizer coefficients.
HANDSHAKE,RETRAIN,RATE NEGOTIATION _SHSK Handshake progression counter contains information about progress handshake v.32 v.22b modes. read examine progression handshake contains normal values error values below: V.32 ORIG MODE
EVENT AC_DET AC/CA CA/AC S_DET SB_DET R1_DET S_DET SB_DET R3_DET E_DET DATA MODE SHSK Normal Value SHSK Error Value RTRN, after
V.32 ANSW MODE
EVENT AA_DET AA/CC S_DET S_DET2 SB_DET R2_DET E_DET DATA MODE SHSK Normal Value SHSK Error Value RTRN, after
V.22B MODE
EVENT DATA SHSK Normal Value ORIG,$80 ANSW ORIG,$90 ANSW
_RE_HSK
Stored word values which were sent received their chronological order during handshake, retrain, rate negotiation. Positions _RE_HSK (_RE_HSK+4) contain history during handshake retrain while (_RE_HSK+5) (_RE_HSK+8) contain history during rate negotiation request.
MAPPING ST75C50 _TSPEED (R/W) Target speed initialized CONF RTRA commands changed data mode case remote RTRA requests. %0000000000000010 1200 %0000000000000011 2400 %0000000000000100 4800 %0000000000000101 7200 %0000000000000110 9600 %0000000000000111 12000 %0000000000001000 14400 (R/W) Target RWORD initialized CONF RTRA commands changed (both them) data mode case remote RTRA requests. reference CCITT recommendation bits programmed following order
(CCITT RECOMMENDATION) B00, B01, B02, B03, B04, B05, B06, B07, B08, B09, B10, B11, B12, B13, B14, D15, D14, D13, D12, D11, D10, D09, D08, D07, D06, D05, D04, D03, D02, D01, (_TRWORD)
_TRWORD _RWORD
RNTHRSH
(R/W) Threshold rate negotiation during handshake retrain. quality receive signal observed (can disabled command MODC) corresponding word proposed handshake retrain rate negotiation. default value $300. This gives typical word authorization characteristics shown below:
SPEED authorized 14400 12000 9600 7200 24DB 24DB 21DB 18DB
Doubling threshold will decrease corresponding approximately. CARRIER DETECT DETH1 DETH LOSSTH1 LOSSTH (R/W) (R/W) (R/W) (R/W) Fast detection threshold Slow detection threshold Slow loss threshold Fast loss threshold
carrier detect contains signal level integrators, fast integrator quick detection with limited precision slow integrator enhanced precision. There four thresholds programmed with default values each modes V.22B, V.33, V.17, FSK, V.29, V.27 which modified user after conf command. Typical values shown below doubling value will increase threshold approximately (-40DBM) (-44DBM) (-47DBM) (-51DBM) DETH1 (fast detection threshold) DETH (slow detectiion threshold) LOSSTH1 (slow loss threshold) LOSSTH (fast loss threshold)
MAPPING ST75C50 TRANSMIT FILTER COEFICIENTS TXCOEF GAIN SHIFTVAL (R/W) Address first pulse shaping/compromise equalizer complex coefficient (16-bit real,16-bit imag). (R/W) Attenuation factor transmit filter. (R/W) Gain (Left shift value) from conjonction with GAIN fine adjustment transmit signal. down scaling.
pass-band pulse shaping transmit compromise equalizer functions combined transmit filter coeficients. pulse shaping also performs multi-phase interpolation from different baud rates fixed sample rate 7200Hz (14400Hz V.27 4800) thus requiring multiple coeficient sub-tables containing complex (16-bit real,16-bit imag) coeficients. number coeficients depends shape, baud rate,and sampling rate. default table depending compromise equalizer selected conf command loaded from coeficient memory external memory, after which, desired, they modified user. table below summarizes location number coeficients loaded. DEFAULT VALUES)
MODE V.32/33/17 BAUD RATE 2400 PHASE COEF/PHS STRT TXCOEF (TXCOEF+64) (TXCOEF+128) TXCOEF (TXCOEF+48) (TXCOEF+96) TXCOEF (TXCOEF+16) (TXCOEF+32) (TXCOEF+48) (TXCOEF+64) (TXCOEF+80) TXCOEF (TXCOEF+14) (TXCOEF+28) (TXCOEF+42) (TXCOEF+56) (TXCOEF+70) (TXCOEF+84) (TXCOEF+98) (TXCOEF+112) TXCOEF (TXCOEF+10) (TXCOEF+20) (TXCOEF+30) (TXCOEF+40) (TXCOEF+50) (TXCOEF+60) (TXCOEF+70) (TXCOEF+80) (TXCOEF+90) (TXCOEF+100) (TXCOEF+110) ROLL-OFF* 0.125 COMPEQ*
V.29
2400
0.20
V.27(2400)
1200
0.50
1(FLAT)
V.27(4800)
1600
0.50
1(FLAT)
V.22 ORIG/ANS
0.50
1(FLAT)
MAPPING ST75C50 TONE DETECTOR PROGRAMMING LEVOUT BIQCOEF (R/W) Programmable static levels. (R/W) 16*2*6 Biquad coeficients. Coef. order each order cells Where each order cell following xfer function
POWCOEF
(R/W) Power coeficients Power estimator using absolute value input signal
BPWIRE CPWIRE
(R/W) Biquad estimator input wiring addresses FORMAT [4TH ORDER BIQ(MSB),PWR(LSB)] (R/W) Comparator input wiring addresses FORMAT wiring addresses furnished bpwire,cpwire from following possible sources SIGNAL SIGNAL*2 SIGNAL*4 ORDER BLOCK OUTPUT POWER OUTPUT STATIC LEVELS PROGRAMMED LEVOUT (R/W) Number tone detector cells active (0-15) Outputs tone detectors. byte _TONEDET contains outputs tone detector cells byte _TONEDET+1 contains outputs cells When corresponding signal positive input comparator higher than that negative input. Only _NTDCELL bits valid time, other
_NTDCELL _TONEDET
GENERAL PURPOSE _TXGAIN (R/W) Transmit gain. signal transmit multiplied this number. This value modified SETGN command.
TONE GENERATOR _TGNFLG (R/W) Tone generator flag. Each four bits this variable define corresponding tone generator enabled. This value modified TGEN command. (R/W) Tone generator phase reversal threshold. different from phase reversal will executed tone genarator after _TG0PHC bauds. This used V.32 answer tone generation (default value 1080 450ms). (R/W) each four tone generators contains: _TGNBLK+(3*i): Frequence tone (i.e. $4000 1800Hz). _TGNBLK+1+(3*i): Instantanous phase. _TGNBLK+2+(3*i): Amplitude ($7FFF refers maximum signal).
_TG0PHC
_TGNBLK
MAPPING ST75C50 APPENDIX Address Equivalences Version
Variable ECHO CANCELLER _RTDELAY _EC_STA PWREST FREQOFF DELTA FEECENBL TIMING RECOVERY FRQOFF PSITHRSH CARRIER RECOVERY FRQOFF EQUALIZER,AGC _RX_STA _AGCSCA RDQUA _RDCPT EQFRK0E EQFRK1E $017 $192 $2A7 $048 $CBC $CFC $EA2 $E8A $E95 $016 $019 $BAC $BAE $BBD $BCE Address Variable CARRIER DETECT DETH1 DETH LOSSTH1 LOSSTH TRANSMIT FILTER COEFICIENTS TXCOEF GAIN SHIFTVAL TONE DETECTOR PROGRAMMING LEVOUT BIQCOEF POWCOEF BPWIRE CPWIRE _NTDCELL _TONEDET GENERAL PURPOSE _TXGAIN TONE GENERATOR _TGNFLG _TG0PHC _TGNBLK $002 $003 $3A8 $001 $3E6 $476 $536 $456 $466 $006 $007 $2E4 $2E2 $2E1 $F9A $F99 $F9C $F9B Address
HANDSHAKE,RETRAIN, RATE NEGOTIATION _SHSK _RE_HSK _TSPEED _TRWORD _RWORD RNTHRSH $1BB $1BD $1AF $1B0 $014 $2AA
Caution $1000 Addresses when using ST75C50 single chip ST75C50CIA part. $9000 Addresses when using Emulation Module.
Information furnished believed accurate reliable. However, SGS-THOMSON Microelectronics assumes responsibility consequences such information infringement patents other rights third parties which result from use. licence granted implication otherwise under patent patent rights SGS-THOMSON Microelectronics. Specifications mentioned this publication subject change without notice. This publication supersedes replaces information previously supplied. SGS-THOMSON Microelectronics products authorized critical components life support devices systems without express written approval SGS-THOMSON Microelectronics. 1994 SGS-THOMSON Microelectronics Rights Reserved Purchase Components SGS-THOMSON Microelectronics, conveys license under Philips Patent. Rights these components system, granted provided that system conforms Standard Specifications defined Philips. SGS-THOMSON Microelectronics GROUP COMPANIES Australia Brazil China France Germany Hong Kong Italy Japan Korea Malaysia Malta Morocco Netherlands Singapore Spain Sweden Switzerland Taiwan Thailand United Kingdom U.S.A.

INTRODUCTION ECHO CANCELLER TIMING RECOVERY CARRIER RECOVERY EQUALIZER

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