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Chaos Computer Club 1997 February
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1997-02-28
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Appendlx B - Am7911 versus Am7910 FSK Modems
Tho Am7g11 Modem has Ihe same basic sl.üc4ure and tunclion
a5 the Am7910. The devices dit~cr only in the speCifications tor
carrter detect and handshake limin9 necossary to support their
intended applitalions
Am7910
S«ilchod-ne Iwork applications
Am791 1
Leasea-line. Telex and Video lext app,ications
Hardware Ditterence
Ttie on~y hardware or hook-up di~crence between Ihe Am7910
ar:d ~6m7911 is Ihe resistor requ~rOd between CAP' and CAP2'
100 ohms fo, the Am7910
910 ohms for Ihe Am7911
MC4 I MC3MC2 j MCl I MCo |
O, O O O ' O
1 o . 0 0 0 1
. O ' O O j 1 1 0
1 o ! o ~ O ! 1 , 1
o ~o 1 ~ o o
0 1 0 j 1 0 1
! 0 1 0 1 1 1 1 0
O O 1 ' 1 ' 1
1 o 1 1 O O O
1 0 i ~O I O I 1
~O ' 1 O ' ~O
I 0 1 1 o I ~I ~
j O ~1 j 1 1 0 1 o
0 1 ~1 0 1
C . 1 1 i 1 0
0 1 1 , 1 i 1
' 1 , O i O ~O O
.
1 1 0 1 0 0 1
j 1 ; 0 1 0 , 1 i O
1 0 0 ' 1 . 1
i 1 1 0 j 1 1 0 0
1 t 1 0 1 1 1 o , 1
i 1 ; 0 1 1 1 1 j O
, 1 1 0 . 1 1 1
! 1 1 1, o o ~ o
j 1 ~ 1 1 ~' O . 1
1, j 1 ~ 'O i 1 O
t 1 0 1 1 .
1 ~, 1 ~ ' O i O .
I 1 ~ 1 1 ! O ' 1 Reserved
! 1 ~ 1 1 ~ 1 o .
~ 1 ~ 1 ' 1 i
. . .
~U~ lo 150 baud backvrard channel is ava~la~le
A summary o! the charac~erislics o, the Am7911 that are ditter-
ent than ihe Am r 910 are as follo~vs;
· Reduced Ca. rier Detect response time
· Red-uced R rs to CTS response iime
· ReduCed Squelch lime for 1200bps modems
· Two new moaeS for Bell 202 with 150bps back channel
· Three new modes for V 23 Y'hh sch turn-oR tone
· The V.23 modes include 1 50bps back channel
· The Am7s11 supports the CCI~ R.20 recommendations for
Telex ctpplicat~ons
Ihe lollöwing tables and ligurc-s tor the Am7911 represent Ihe
dala sheet variations Irom the Am7910 shown in Appendr' A.
TA8LE 1. Am7911 MODE SELECTIABLE
Ben 103 Orig~nate 300bps {ull dup!ex
Bcll 103 Answer 300bps full duplex
3ell 2021200bps ha!t duplex wi~h 5bps back cha:,nel
Bell 202 120Übps \'ith amplitude equalizer and SbpS back channel
CCITT V.21 Orig 300bps loll d'~p~ex
CCITT V.21 Ans 300bps tull doplex
CCITT V.23 Mode 2 1200bp$ hait duplex
CCITT V 23 Nlode 2 wi~h amplitude eq~alizer 120Übps halt duplex.
CCITT V 23 Mode 1 600bps halt duplex
ResOrved
9eli 202 1200bps with 150bps back channel
Bell 202 1200bps `~'ith amptitude ecDalize! and 150bps back channel
CCITT V 2q Mode 1 600bps wi~h soN lurn-off
Rese~`cd
CC'TT V 231~,odc 2 1200bps with Sott iarn~cH.
CCI1~T ~r 23 Mcde 2 ,200bps wilh ampl~tude e~ual~zer and sott turn-at1'
:
Bell 103 Orig loopback
Bel' lu3 Ans loopback
Bell 202 Main !oopback
Be!l 202 wi~h amplitude equatizer loopback
CCITT V 21 Orig icopback
~CiTT V 21 Ans loarback
CCITT V 23 Mode 2 main loopback
CCITT V.23 Mode 2 with ampillude equalizer loopback
CCITT V.23 Mode 1 main loopback
CCtTT V 23 Back loopback
Bell 202 150bps Back loopback
Am791 1
FSK MODEM
woRLD.cHIprM
Advanced Micro Devices
DISTINCTIYE CHARACTERISTICS
· Compiete rSK MODEM in a 28-pin package - just add
line interface
· Compatible with Beil 103/113/108, Bell 202, CCITT V.21,
CCITT V 23 sp~cifications
· Mode seler table 5 or 150 baud backward channel
/or Bell 202
· Up to 150 baud on V.23 backward channel
· CCITT V.23 modes ~yith optional sott carner turn ~ ot' leature
· Fast response times tor ieased-line networks
· No external tiltering required
· All diglal signal pro~essing, digital fillers and ADC/DAC
Included on-chip
· Includes essential RS 232/CCITT V.24 handshake signals
1
-
GENERAL DEscRlpnoN
The Am7911 is a single-chip asynchronous Frequency Shitt
Keying (FSK) voiceband modem inlended for use in leasod
line applications. It is pin selectable for baud rates oi 300.
600 or 1200 bits per second and is compatible with thc
applicable Bell and CCITT recommended slandards for
103/113!106, 202, V.21 and V.23 type modems. Flve mode
controi lines select a deslred modem configuration, tor Bell
202 applicabons, the Am7911 provides a 1sobps back
channel in audition to the standard 5bps channel, and for
V.23 up to 1sobps back channel operation is possible
Digital signal processsing techniques are empioyed in the
Am7911 {o perform all major functions such as modulalion
demodulation and tiltering. The Am7911 contains on-chip
analog-to-digital and digital-to-anatog converter circuits to
minimize Ihe external components in a syslem This device
includes the essential RS-232iCCITT V 24 terminal control
siguals with TTL lovels.
Clocking can be generated by attaching a cnystal to the
internal crystal oscillator amplilier or by applying an ex-
ternal cioch signal.
A data access arrangement (DM) or acoustic coupler musl
provide the phone line interface externally.
The Am7911 is labricated using N-channel MOS technol-
ogy in a 28-pin pachage All the digital input and outpsut
signals (except the external cioch sigual) are TTL compati-
ble Power supply requirements are ~ 5 volts.
F gure 2. Block Diagram
cAP
~C&P, C~
R!CEIVED 0
CA~IER
t0,~4,~
J~LTRANSVITTED,C ,p~5~:TTLR
FAC5
, : ~
_ ~~
1
~cOc~ _
LiC, C - llAfACF COATROL =
jJAl~4,bAL c ~
arADY _
~- _ _
~.~ m
_ 5I F V O ~L
LACM