QRZ! Ham Radio 8/QRZ Ham Radio Callsign Database - Volume 8.iso/pc/files/p_tapr/statecd.arc/STATECD.FMT

Text File | 1988-08-17 | 23KB | 529 lines

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(C⌐ 3▒ JU╠ 88

Eriπ Gustafson
201╕ S« Avenidß Planeta
Tucson¼ A┌ 85710



          DPL╠á DeriveΣ Datß Carrie≥ Detec⌠ (DCD)
          Fo≥ Filte≥ BaseΣ anΣ Singlσ Chi≡ Modems


                        INTRODUCTION

Iµá yo⌡á havσá ß TN├ whicΦ use≤ eithe≥ thσá AMD791░á o≥á thσ ì
TCM310╡ singlσ chi≡ modem¼ o≥ ß TN├ whicΦ use≤ ß modeφ baseΣ ì
oε audi∩ filter≤ likσ thσ PK-232¼ yo⌡ caε vastl∙ improvσ thσ ì
DC─ performancσ oµ you≥ modeφ fo≥ packe⌠ radi∩ use.

Thesσá singlσ chi≡ modem≤ werσ originall∙ designeΣ fo≥á lanΣ ì
linσá use«á  Thσ designers¼á wh∩ haΣ n∩ ideß tha⌠ thσá chip≤ ì
migh⌠á onσá da∙á bσ applieΣ t∩ ßá radi∩á system¼á madσá somσ ì
assumption≤á abou⌠á thσ incominτ signa∞ tha⌠ simpl∙á d∩á no⌠ ì
appl∙á t∩á thσ radi∩ environment«á  Thσ datß carrie≥á detec⌠ ì
functioεá fo≥ theφ wa≤ no⌠ nearl∙ s∩ critica∞ ß functioεá oµ ì
thσá modeφ a≤ i⌠ i≤ fo≥ u≤ oε ß bus∙ packe⌠á radi∩á channel«  ì
Fo≥ thσ intendeΣ purposσ oµ thesσ chips¼á therσ wa≤ expecteΣ ì
t∩á bσá onl∙ ▓ station≤ involveΣ oε an∙ ▒ channe∞ a⌠ ▒á timσ ì
anΣá thesσ station≤ werσ connecteΣ b∙ ß nicσá quie⌠á twisteΣ ì
pair«á  Unde≥á thesσ circumstances¼á thσ Carrie≥ Detec⌠ (CD⌐ ì
functioεá buil⌠ int∩ thesσ chip≤ i≤ entirel∙á adequate«á  Iε ì
thσá packe⌠ radi∩ environment¼á thσ buil⌠ iε C─ functioεá i≤ ì
nex⌠ t∩ useless.

Sincσá ╔á can'⌠ makσ thσ samσ defensσ fo≥ thσá designer≤á oµ ì
filte≥á baseΣ modem≤ specificall∙ intendeΣ fo≥ packe⌠á radi∩ ì
froφá thσá beginning¼á ╔ won'⌠ tr∙ t∩ speculatσá abou⌠á wha⌠ ì
drovσ thei≥ desigε decisions.

Thσá circui⌠á presenteΣ herσ wil∞ allo≈ you≥ TN├ t∩ bσá useΣ ì
witΦá unsquelcheΣ audi∩ thu≤ avoidinτ thσ unnecessar∙á dela∙ ì
oµ thσ squelcΦ circui⌠ founΣ iε typica∞ VH╞ F═ radios«  Thi≤ ì
circui⌠á als∩á provide≤ severa∞ othe≥á importan⌠á beneficia∞ ì
characteristic≤ fo≥ thσ DC─ system.

First¼á  sincσá  thσ assumption≤ useΣ wheε thσ TN├á softwarσ ì
wa≤á writteεá depenΣá oε DC─ representinτá thσá presencσá o≥ ì
absencσá oµ ß datß carrie≥ oε thσ channel¼á i⌠ i≤á importan⌠ ì
tha⌠á thσ DC─ circui⌠ bσ ablσ t∩ distinguisΦ ß datßá carrie≥ ì
froφá noisσá o≥á othe≥ noε packe⌠ signal≤á t∩á ßá reasonablσ ì
degree«á  Thσá DC─ circuit≤ whicΦ simpl∙ detec⌠ thσ presencσ ì
oµá AN┘á typσ oµ signa∞ o≥ noisσ oε thσ channe∞á arσá simpl∙ ì
inadequatσá t∩ thi≤ task«á Sincσ thσ DC─á circui⌠á presenteΣ ìèherσá i≤á baseΣá oε thσ updatσ signal≤ iεá ßá Digita∞á Phasσ ì
LockeΣá Loo≡ (DPLL⌐ whicΦ recover≤ botΦ bauΣ clocδ anΣá datß ì
froφ aε NRZ╔ packe⌠ datß stream¼á it≤ outpu⌠ represent≤ truσ ì
detectioε oµ thσ datß carrier.

Second¼á oncσá ßá datß carrie≥ decisioε ha≤á beeεá correctl∙ ì
made¼á i⌠á i≤ importan⌠ tha⌠ thσ DC─ indicatioε remaiε valiΣ ì
througΦá shor⌠ fades¼á collisions¼á anΣ whilσ ßá signa∞á to∩ ì
margina∞ t∩ decodσ i≤ oε thσ channel«á  Thi≤ i≤ accomplisheΣ ì
b∙á providinτá ßá DC─ "hanτ timeó oµ approximatel∙á ╡á t∩á ╕ ì
characte≥á period≤á (thi≤ caε bσ optimized⌐ t∩ holΣ thσá DC─ ì
outpu⌠á truσ througΦ shor⌠ dropout≤ froφ thσá abovσá causes«  ì
Thi≤á prevent≤á ß queueΣ u≡ TN├ froφ pilinτá oεá collisions¼ ì
transmittinτ ove≥ ß statioε whicΦ ha≤ ß margina∞ signal¼ anΣ ì
beginninτáá t∩á transmi⌠á ove≥á ßá statioεá whicΦá i≤á stil∞ ì
transmittinτ bu⌠ whosσ signa∞ receiveΣ ß shor⌠ multipatΦ hi⌠ ì
durinτ thσ packet.

Third¼á i⌠ i≤ importan⌠ tha⌠ thσ DC─ systeφ NO╘ bσ sensitivσ ì
t∩ audi∩ amplitudσ variations«  I⌠ shoulΣ responΣ iε exactl∙ ì
thσá samσá wa∙ fo≥ an∙ signa∞ tha⌠ thσ modeφ i≤á capablσá oµ ì
decodinτ regardles≤ oµ absolutσ inpu⌠ amplitude«  Sincσ thi≤ ì
DC─á circui⌠ operate≤ froφ thσ datß recovereΣ b∙ thσá modem¼ ì
al∞á amplitudσá informatioεá i≤ suppresseΣá beforσá thσá DC─ ì
circui⌠ eveε see≤ thσ signal.

                           NOTE!
ááááIµá you≥ TN├ use≤ thσ EXA╥ 221▒á demodulator¼á thi≤ ì
ááááne≈ circui⌠ i≤ unnecessar∙ fo≥ you«á  You≥ existinτ ì
ááááDC─ circui⌠ caε bσ morσ easil∙ modifieΣ fo≥ correc⌠ ì
ááááoperatioεá withou⌠ thi≤ circuit«á  Thσ modificatioε ì
ááááprocedurσá fo≥á thσ 221▒ demodulato≥á i≤á presenteΣ ì
ááááelsewherσ anΣ no⌠ repeateΣ here.


                    CIRCUIT DESCRIPTION

Thσá circui⌠ diagraφ i≤ presenteΣ iε Figurσ 1«á  Thi≤ i≤á aε ì
ASCI╔á representatioε oµ thσ schematiπ diagram«á  Whilσ thi≤ ì
isn'⌠á reall∙ ß prope≥ "standardó diagram¼á ╔ believσ i⌠á i≤ ì
readablσ enougΦ t∩ bσ useΣ t∩ duplicatσ thσ circuit«  I⌠ ha≤ ì
thσá beneficia∞á characteristiπ tha⌠ i⌠ require≤ n∩á CA─á o≥ ì
specia∞á graphic≤ softwarσ t∩ bσ ablσ t∩ vie≈á thσá diagram«  ì
Thank≤á t∩á Myklσ Raymond¼á N7JZT¼á fo≥ makinτ u≡á thi≤á BB╙ ì
forwardablσ ASCI╔ schematic.

Thσá circui⌠ consist≤ oµ thσ statσ machinσ useΣ iε thσ TNC-▓ ì
anΣ somσ dela∙ element≤ useΣ t∩ makσ thσ DC─ decision«á  Thσ ì
statσá machinσá i≤á formeΣ froφ thσ 74HC37┤á anΣá thσá 27C6┤ ì
chips«á  Thσ 74HC1┤ i≤ useΣ a≤ ß pai≥ oµ retriggerablσ dela∙ ì
element≤ anΣ fo≥ signa∞ inversioε anΣ buffering.

Thσ 27C6┤ witΦ thσ statσ machinσ codσ alread∙ burneΣ int∩ i⌠ ì
caε bσ obtaineΣ directl∙ froφ TAPR«  Iµ yo⌡ wisΦ t∩ usσ thi≤ ì
sourcσ fo≥ thσ part¼ pleasσ cal∞ Chri≤ a⌠ (602)-323-171░ fo≥ ìèpricσá anΣ availabilit∙ information«á  Thi≤ samσ codσ i≤á iε ì
thσ statσ machinσ RO═ iε an∙ ful∞ TNC-▓ clonσ whicΦ use≤ thσ ì
221▒á demodulato≥ anΣ Z8░ SIO«á  Iµ sufficien⌠á interes⌠á i≤ ì
showε iε thi≤ circuit¼á maybσ wσ caε cajolσ TAP╥ int∩ makinτ ì
circui⌠á board≤á available«á  Thi≤ woulΣ vastl∙á reducσá thσ ì
wirinτ task.

Onσá oµ thσ statσ machinσ signal≤ (whicΦ wa≤ no⌠ useΣ iε thσ ì
TNC-2⌐ appear≤ oε piε 1╣ oµ thσ 27C64«á  Thi≤ signa∞ i≤á thσ ì
DPL╠ updatσ pulse«á  A≤ lonτ a≤ thσ DPL╠ i≤ correctl∙ lockeΣ ì
t∩á thσá incominτ data¼á n∩ pulse≤ wil∞ appea≥ oε thi≤á pin« ì
Wheεá thσá DPL╠ i≤ no⌠ lockeΣ t∩ aεá incominτá datßá stream¼ ì
therσ wil∞ bσ ß continuou≤ streaφ oµ pulse≤ oε thi≤ pin.

Thσá DPL╠ updatσ signa∞ i≤ useΣ iε thi≤ circui⌠ t∩ retrigge≥ ì
thσá firs⌠ dela∙ elemen⌠ s∩ tha⌠ i⌠ neve≥ time≤ ou⌠ s∩á lonτ ì
a≤ DPL╠ updatσ pulse≤ arσ present«  Iµ thσ pulse≤ disappear¼ ì
thσ dela∙ elemen⌠ time≤ ou⌠ anΣ generate≤ thσ DC─ signal.

Thσá outpu⌠á froφ thσ firs⌠ dela∙ elemen⌠ keep≤á thσá seconΣ ì
dela∙á elemen⌠ triggereΣ s∩ lonτ a≤ DC─ i≤ true«á  Wheεá DC─ ì
goe≤á false¼á thσá seconΣá dela∙ elemen⌠á begin≤á ßá timeou⌠ ì
sequencσá whicΦ keep≤ thσ DC─ outpu⌠ truσ unti∞ thσá timeou⌠ ì
perioΣ expires«  Thi≤ i≤ thσ sourcσ oµ thσ DC─ "hanτ time".

Whilσá thσ circui⌠ presenteΣ herσ i≤ primaril∙ intendeΣá fo≥ ì
120░ bauΣ VH╞ F═ operation¼á i⌠ wil∞ als∩ worδ wel∞ fo≥á 30░ ì
bauΣ H╞ packe⌠ work«á  Iµ thi≤ i≤ you≥ application¼ thσ timσ ì
constant≤ oε thσ dela∙ element≤ wil∞ havσ t∩ bσ adjusted«

Thσ timσ constan⌠ oµ thσ "hangó generato≥ (0.4╖ u╞ cap⌐ wil∞ ì
havσá t∩á bσá increaseΣ fo≥ 30░ bauΣ operatioε s∩á tha⌠á thσ ì
tota∞ capacitancσ i≤ 2.░ uF.

Thσá timσá constan⌠ whicΦ i≤ optimuφ fo≥ thσá DC─á generato≥ ì
(thσá 0.▒á u╞á ca≡ iε fig«á 1⌐ wil∞ depenΣ oεá ßá numbe≥á oµ ì
factor≤á includinτ thσ bandwidtΦ oµ thσ radi∩ useΣ aheaΣá oµ ì
thσá modem«

Yo⌡á shoulΣá picδá ßá valuσá fo≥á thσá DC─á generato≥á dela∙ ì
capacito≥ sucΦ tha⌠ thσ DC─ circui⌠ produce≤ approximatel∙ ß ì
1░ percen⌠ dut∙ cyclσ oµ falsσ DC─ "ONó time«  Thσ falsσ DC─ ì
O╬á timσ shoulΣ bσ observeΣ whilσ monitorinτ receive≥á noisσ ì
oεá ßá channe∞ whicΦ i≤ ABSOLUTEL┘ freσ oµá  AN┘á narrowbanΣ ì
signal≤ whicΦ fal∞ withiε thσ demodulator'≤ passband«á  Thi≤ ì
include≤ CW¼á RTTY¼á interna∞ receive≥ birdies¼ A═ carriers¼ ì
compute≥á spurs¼á packe⌠ datß carriers¼á etc«á ┴ gooΣ wa∙ t∩ ì
assurσá thi≤á i≤á t∩ le⌠ thσ receive≥á monito≥á thσá S-╣á o≥ ì
greate≥á outpu⌠ oµ ß noisσ bridgσ witΦ n∩ antennß connected« ì
Remembe≥á t∩á havσá thσá filte≥á oµá appropriatσáá bandwidtΦ ì
selecteΣá anΣá centereΣá ove≥ thσ modeφá passband«á  fo≥á H╞ ì
packet¼á thi≤ i≤ ß 50░ H· filte≥ a≤ i≤ normall∙ useΣ fo≥á C╫ ì
anΣ RTT┘ operation«

Thσá DC─ generato≥ dela∙ capacito≥ wil∞ probabl∙ neeΣ t∩á bσ ìèsomewherσ iε thσ rangσ oµ ▓ t∩ ┤ time≤ thσ 0.▒ u╞ valuσ useΣ ì
fo≥ 120░ baud.

BotΦá negativσá truσá anΣá positivσá truσá DC─á output≤á arσ ì
provideΣ s∩ tha⌠ yo⌡ ma∙ usσ thσ polarit∙ whicΦ i≤á requireΣ ì
b∙ you≥ TNC«á  Also¼á JMP▒ anΣ JMP▓ allo≈ thσ DC─ circui⌠ t∩ ì
bσ configureΣ t∩ operatσ correctl∙ froφ eithe≥ ß positivσ o≥  ì
negativσá truσ C─ outpu⌠ froφ whicheve≥ modeφ chi≡ i≤á founΣ ì
iε you≥ TNC.


                        TNC SIGNALS

Oncσ yo⌡ havσ constructeΣ thσ DC─ circuit¼á yo⌡ wil∞ havσ t∩ ì
obtaiε somσ signal≤ froφ you≥ TN├ fo≥ thσ ne≈ DC─ circui⌠ t∩ ì
use«á  Yo⌡ wil∞ als∩ havσ t∩ arrangσ fo≥ thσ outpu⌠ oµá thi≤ ì
circui⌠á t∩ bσ substituteΣ fo≥ thσ norma∞ DC─ signa∞ useΣ iε ì
thσ TNC.

Thσ signal≤ requireΣ fo≥ thσ DC─ circui⌠ operatioε are:

1.  ┴á samplσ oµ thσ datß recovereΣ b∙ thσá demodulato≥ ì
ááááiε thσ modeφ chip.

2.á ┴ samplσ oµ ß clocδ whicΦ ha≤ ß frequenc∙ oµ eithe≥ ì
áááá1╢á o≥á 3▓á time≤ thσ bauΣ ratσ (X1╢á o≥á X3▓á bauΣ ì
ááááclock).

3.á Thσ intercepteΣ Carrie≥ Detec⌠ (CD⌐ signa∞ froφ thσ ì
áááámodeφ chip«á  Thi≤ i≤ thσ C─ generateΣ b∙ thσ modeφ ì
ááááchi≡ baseΣ oε amplitudσ oµ thσ inpu⌠ audio.

4.á ┴ sourcσ oµ ½ ╡ volts«á  Iµ yo⌡ usσ al∞ CMO╙ parts¼ ì
ááááthσá curren⌠ requirement≤ arσ minimal«á  Thσ 74HC1┤ ì
ááááMUS╘á bσá ßá CMO╙á par⌠ fo≥á thσá circui⌠á t∩á worδ ì
ááááproperly.

5«  Ground


Therσá arσ s∩ man∙ differen⌠ TNC≤ t∩ whicΦ thi≤ circui⌠á caε ì
bσ applieΣ tha⌠ ╔ canno⌠ givσ specifiπ interfacσ informatioε ì
fo≥ al∞ oµ them«á  However¼ ╔ caε providσ signa∞ piε number≤ ì
fo≥á thσ ▓ lanΣ linσ modeφ chip≤ mos⌠ frequentl∙ encountereΣ ì
anΣá ╔ caε hel≡ witΦ signa∞ location≤ iε thσ AE┴ PK-23▓á anΣ ì
PK-87¼ thσ Kantronic≤ KAM¼ anΣ thσ Paπ Comφ TINY-▓ TNCs.



Thσ signal≤ oµ interes⌠ oε thσ AMD791░ modeφ chi≡ are:

1.  Receivσ Datß outpu⌠ (RD)-----╛ piε 24

2.  Carrie≥ Detec⌠ (CD)----------╛ piε 25
ááááThi≤ signa∞ i≤ negativσ truσ fo≥ thσ 791░ chip.è


Thσ signal≤ oµ interes⌠ oε thσ TCM310╡ modeφ chi≡ are:

1«  Receivσ Datß outpu⌠ (RXD)----╛ piε 8

2«  Carrie≥ Detec⌠ (CDT)---------╛ piε 3
ááááThi≤ signa∞ i≤ positivσ truσ fo≥ thσ 310╡ chip.

3.á Iεá TNC≤á whicΦá usσ thσ TCM310╡ chi≡á bu⌠á d∩á no⌠ ì
ááááprovidσ anothe≥ sourcσ oµ thσ bauΣ clock¼á likσ thσ ì
ááááKantronic≤ KAM¼á yo⌡ caε usσ thσ signa∞ a⌠ piε ▓ oµ ì
ááááthi≤ chip«á  Thi≤ signa∞ i≤ ver∙ closσ t∩ 1╢á time≤ ì
ááááthσá bauΣá ratσ (19.1▒ KH· insteaΣ oµ 19.▓ KH·á fo≥ ì
áááá120░ baud).


                       TNC INTERFACE

Iµ you≥ TN├ ha≤ provisioε fo≥ ß TAP╥ stylσ modeφá disconnec⌠ ì
header¼á thesσ signal≤ (includinτ thσ X1╢ o≥ X3▓ bauΣ clock⌐ ì
wil∞á bσ easil∙ locateΣ anΣ convenientl∙ interfaceΣ a⌠á thi≤ ì
header«á  Iµá i⌠ doesn'⌠ havσ thi≤ header¼á yo⌡ wil∞ havσ t∩ ì
fisΦ arounΣ iε thσ circui⌠ oµ you≥ TN├ oε you≥ owε t∩ locatσ ì
them.

ááááSHAM┼á O╬ TH┼ MANUFACTURE╥ O╞ ┴ TN├ WIT╚á N╧á MODE═ ì
                   DISCONNEC╘á HEADER!íá

ááááThσá absencσ oµ ß standarΣ modeφ disconnec⌠á heade≥ ì
áááámean≤á yo⌡á ma∙ no⌠ CONVENIENTL┘ usσá AN┘á externa∞ ì
áááámodeφá witΦá thσ deficien⌠ TNC«á  Usinτ ßá standarΣ ì
áááádisconnec⌠ system¼ thσ externa∞ modeφ caε providσ ß ì
ááááfron⌠á pane∞ switcΦ t∩ allo≈ yo⌡ t∩ selec⌠á betweeε ì
ááááthσ externa∞ anΣ thσ interna∞ modem«á

ááááModem≤á whicΦ yo⌡ migh⌠ likσ t∩á interfacσá withou⌠ ì
ááááloosinτá thσá usσ oµ thσ interna∞ AFS╦ modeφá woulΣ ì
ááááincludσá thσ BPS╦ » MANCHESTE╥ F═á modem≤á requireΣ ì
ááááfo≥ severa∞ oµ thσ satellites.

Iε an∙ case¼á thσ DC─ signa∞ currentl∙ useΣ iε you≥ TN├ wil∞ ì
havσá t∩á bσá disconnecteΣá anΣá rerouteΣá througΦá thσá ne≈ ì
circuit«


                  STANDARD HEADER SIGNALS

Thσ signa∞ location≤ oε thσ standarΣ modeφ disconnec⌠ heade≥ ì
are as follows:

Receive Data is obtained from header pin 18.

Carrier Detect is obtained from header pin 2.è
DataCarrie≥á Detec⌠á (DCD⌐á i≤ inserteΣá a⌠á heade≥á piεá 1«  ì
Jumpe≥ froφ header pin 1 to header pin 2 is removed.

Thσá X1╢á (TNC-2⌐ o≥ X3▓ (TNC-▒ anΣá possibl∙á TNC-▓á clone≤ ì
usinτá aεá 853░ HDL├ controlle≥ insteaΣ oµ thσ Z80SIO⌐á bauΣ ì
clocδ i≤ obtaineΣ froφ heade≥ piε 12.


              COMMERCIAL TNC SIGNAL LOCATIONS

Herσ i≤ thσ informatioε yo⌡ neeΣ t∩ finΣ thσ prope≥á signal≤ ì
iεá severa∞á commerciall∙á availablσá TNCs«áá  Thi≤á i≤á no⌠ ì
intendeΣá t∩á bσ ß completσ lis⌠ b∙ an∙á means«á  I⌠á merel∙ ì
represent≤á thσá unit≤ whicΦ ╔ havσ haΣ availablσá t∩á appl∙ ì
thi≤á circui⌠ t∩ herσ locally«á  Thesσ arσ thσ onl∙ TNC≤ fo≥ ì
whicΦ ╔ havσ specifiπ interfacσ informatioε a⌠ thi≤ time.


                         AEA PK-87

I⌠á i≤ relativel∙ eas∙ t∩ interfacσ thi≤ ne≈ DC─ circui⌠á t∩ ì
thσá PK-8╖á iε spitσ oµ thσ fac⌠ tha⌠ therσ i≤á n∩á standarΣ ì
modeφá disconnec⌠á header«á  Thi≤á i≤ becausσá therσá i≤á n∩ ì
requiremen⌠á t∩ switcΦ bacδ t∩ thσ interna∞ DC─ circui⌠ oncσ ì
thσá modificatioε i≤ installed«á  Iµ thi≤ werσá aεá externa∞ ì
specia∞á purposσ modem¼á yo⌡ woulΣ bσ forceΣ t∩ opeε thσ TN├ ì
casσ anΣ movσ severa∞ jumper≤ wheneve≥ yo⌡ wisheΣ t∩á changσ ì
thσá modeφ beinτ used«

However¼á fo≥ ou≥ purpose≤ iε thi≤ modification¼ thσ jumper≤ ì
providσá convenient¼á easil∙á locateΣ place≤ t∩á obtaiεá anΣ ì
injec⌠ signals.

Thσá Receivσ datß signa∞ i≤ obtaineΣ froφ thσ cente≥ piεá oµ ì
JP4.

Thσá Carrie≥á Detec⌠ signa∞ i≤ obtaineΣ froφ thσ enΣ oµá JP╡ ì
whicΦ connect≤ t∩ thσ modeφ chip.

Thσá DC─ outpu⌠ signa∞ froφ thσ ne≈ circui⌠ i≤á inserteΣá a⌠ ì
thσ cente≥ piε oµ JP5«á  Usσ thσ NEGATIV┼ TRU┼ output«á  Thσ ì
jumpe≥á originall∙á installeΣ a⌠ JP╡ i≤á removed«á  Thσá DC─ ì
indicato≥ oε thσ fron⌠ pane∞ wil∞ sho≈ thσ actioε oµ thσ ne≈ ì
DC─ circuit.

Thσá X3▓ bauΣ clocδ signa∞ i≤ obtaineΣ froφ piε 1│ oµ U2░ (ß ì
74LS39│ divider)«á  Don'⌠ bσ tempteΣ t∩ ge⌠ thi≤ signa∞ froφ ì
thσá "clockó linσ oε J4¼á thσ externa∞ modeφá connector¼á a≤ ì
thi≤ i≤ ß X▒ clock.

╔á seσ s∩ man∙ manufacturer≤ sendinτ onl∙ thσ X▒ bauΣá clocδ ì
ou⌠ t∩ aε auxiliar∙ modeφ connecto≥ tha⌠ ╔ havσ t∩ wonde≥ iµ ì
the∙á simpl∙ don'⌠ realizσ tha⌠ synchronou≤ modem≤ requirσ ß ì
clocδá whicΦ i≤ ß multiplσ oµ thσ bauΣá rate«á  Asynchronou≤ ìèmodem≤ caε cheapl∙ anΣ easil∙ dividσ thσ X1╢ clocδ t∩ ge⌠ X▒ ì
bu⌠á i⌠á i≤ harΣ fo≥ synchronou≤ modem≤ t∩ derivσá ßá faste≥ ì
clocδ froφ thσ X▒ signal.



                         AEA PK-232

Thσ PK-23▓ i≤ als∩ relativel∙ eas∙ t∩ interfacσ iε spitσá oµ ì
thσá fac⌠á tha⌠á AE┴ faileΣ t∩ implemen⌠á ßá standarΣá modeφ ì
disconnec⌠á heade≥á eveε iε thei≥ flagshi≡á TNC«á  Fo≥á somσ ì
reason¼á oεá thi≤ bo° AE┴ decideΣ rathe≥ thaε brinτ ou⌠á thσ ì
wronτ clocδ ou⌠ t∩ thσ externa∞ modeφ connector¼á the∙ woulΣ ì
brinτ ou⌠ n∩ clocδ a⌠ all.

Thσá Receivσ Datß signa∞ i≤ obtaineΣ froφ thσ cente≥ piεá oµ ì
JP4.

Thσá Carrie≥ Detec⌠ signa∞ i≤ obtaineΣ froφ thσ enΣá oµá JP╢ ì
whicΦá i≤á NO╘á connecteΣá t∩ piε │ oµá thσá externa∞á modeφ ì
connector.

Thσá X3▓á bauΣ clocδ signa∞ i≤ obtaineΣ froφ piεá 1│á oµá U╕ ì
(als∩ ß 74LS39│ divider).

Thσá DC─á outpu⌠á froφ thσ ne≈ circui⌠ i≤á inserteΣá a⌠á thσ ì
cente≥á piεá oµ JP6«á Usσ thσ NEGATIV┼á TRU┼á output«á   Thσ ì
jumpe≥ originall∙ installeΣ a⌠ JP╢ i≤ removed.


T∩á usσá thσ ne≈ DC─ circui⌠ witΦ ß PK-23▓ oεá VH╞á F═á 120░ ì
baud:

1.á Se⌠á thσá audi∩ leve∞ froφ thσ radi∩á s∩á tha⌠á thσ ì
áááátuninτáá indicato≥á "spreadsóá full∙á eveεá oεá thσ ì
áááástatioε witΦ thσ lowes⌠ transmitteΣ audi∩ leve∞á oε ì
ááááthσ channel.

2.á Thσ existinτ DC─ thresholΣ contro∞ shoulΣ bσ se⌠ s∩ ì
áááátha⌠á thσá existinτ DC─ indicato≥ LE─ oε thσá fron⌠ ì
áááápane∞á light≤á u≡ wheneve≥ therσ i≤ AN┘á signa∞á o≥ ì
áááánoisσ inpu⌠ t∩ thσ TN├ froφ thσ radio« Bσ surσ tha⌠ ì
ááááeveε thσ statioε witΦ thσ lowes⌠ amoun⌠ oµ audi∩ oε ì
ááááthσá channe∞á light≤ thi≤ LED«á   Thi≤á LE─á shoulΣ ì
ááááextinguisΦá wheε therσ i≤ n∩ audi∩ inpu⌠á froφá thσ ì
ááááradi∩ (deaΣ carrie≥ froφ repeate≥ etc.).

Iµá yo⌡á wisΦá t∩á observσá thσ actioεá oµá thσá DC─á signa∞ ì
generateΣá b∙á thσ ne≈ circuit¼á attacΦ ß ▒á ╦á resisto≥á iε ì
serie≤á witΦ ß LE─ t∩ thσ LE─ outpu⌠ oµ thσ ne≈ DC─ circuit« ì
Thσ anodσ oµ thσ LE─ shoulΣ bσ connecteΣ viß thσ resisto≥ t∩ ì
+╡ volts«  Thσ cathodσ oµ thσ LE─ shoulΣ bσ connecteΣ t∩ thσ ì
LE─ outpu⌠ oµ thσ ne≈ DC─ circuit«á  Iµ yo⌡ wish¼á thi≤á LE─ ì
caε bσ mounteΣ oε thσ fron⌠ pane∞ wherσ i⌠ i≤ visible«á  Usσ ì
ß higΦ effecienc∙ LED.è

                      Pac-Comm TINY-2

Thσá Pac-Comφ TINY-▓ doe≤ includσ ß modeφ disconnec⌠ header«  ì
I⌠ i≤ labeleΣ J╡ oε thei≥ schematiπ diagram«á  Fo≥ thi≤ the∙ ì
ge⌠ +▒ attaboy.

Unfortunately¼á Pac-Comφá attacheΣ J╡ pin≤ 1▒ anΣ 1▓ t∩á thσ ì
wronτá par⌠ oµ thσ bauΣ clocδ divide≥á chain«á Thesσá heade≥ ì
pin≤á shoulΣ havσ beeε iε serie≤ witΦ piε ▒ oµá U10«á   Thi≤ ì
erro≥ result≤ iε therσ beinτ ß X▒ bauΣ clocδ signa∞ oε thesσ ì
pin≤á insteaΣá oµ thσ X1╢ bauΣ clocδ tha⌠ shoulΣá bσá there«  ì
So¼á eveεá thougΦá the∙á diΣ implemen⌠á ßá modeφá disconnec⌠ ì
header¼á yo⌡á wil∞á havσ t∩ obtaiε thσ X1╢ bauΣá clocδá froφ ì
elsewherσá oεá thσá circui⌠ board«á  Fo≥ thi≤á the∙á ge⌠á -▒ ì
attabo∙ (a⌠ leas⌠ the∙ arσ breakinτ even).

Thσ X1╢ bauΣ clocδ signa∞ i≤ obtaineΣ froφ U1░ piε 1«

Receivσ Datß i≤ obtaineΣ froφ J╡ piε 17.

Negativσá truσ Carrie≥ Detec⌠ (CDT⌐ i≤ obtaineΣ froφ J╡á piε ì
2.

                           NOTE!
áááááThi≤ i≤ aε inverteΣ versioε oµ thσ C─ outpu⌠á froφ ì
áááááthσ TCM310╡ chi≡ itself«  Sincσ thi≤ i≤ ß negativσ ì
ááááátruσá logiπá signal¼á JMP▒ oε thσ ne≈ DC─á circui⌠ ì
áááááwil∞ bσ useΣ insteaΣ oµ JMP2 whicΦ woulΣá normall∙ ì
ááááábσ useΣ fo≥ ß TCM3105.


NEGATIV┼ TRU┼ DC─ froφ thσ ne≈ circui⌠ i≤ applieΣ t∩ thσ TN├ ì
a⌠ J╡ piε 1«  Removσ thσ connectioε betweeε J╡ pin≤ ▓ anΣ 1«  ì
Thσá existinτ DC─ indicato≥ LE─ wil∞ NO╘ sho≈ thσ actioεá oµ ì
thσ ne≈ circuit.

Iµá yo⌡á wisΦá t∩á observσá thσ actioεá oµá thσá DC─á signa∞ ì
generateΣá b∙á thσ ne≈ circuit¼á attacΦ ß ▒á ╦á resisto≥á iε ì
serie≤á witΦ ß LE─ t∩ thσ LE─ outpu⌠ oµ thσ ne≈ DC─ circuit« ì
Thσ anodσ oµ thσ LE─ shoulΣ bσ connecteΣ viß thσ resisto≥ t∩ ì
+╡ volts«  Thσ cathodσ oµ thσ LE─ shoulΣ bσ connecteΣ t∩ thσ ì
LE─ outpu⌠ oµ thσ ne≈ DC─ circuit«á  Iµ yo⌡ wish¼á thi≤á LE─ ì
caε bσ mounteΣ oε thσ fron⌠ pane∞ wherσ i⌠ i≤ visible«á  Usσ ì
ßá higΦ effecienc∙ LE─ anΣ increasσ thσ valuσ oµ thσá serie≤ ì
resisto≥á t∩á matcΦ brightnes≤ witΦ thσá othe≥á fron⌠á pane∞ ì
indicators..

Iµá yo⌡á wisΦá t∩á observσá thσ actioεá oµá thσá DC─á signa∞ ì
generateΣá b∙á thσ ne≈ circui⌠ oε thσ buil⌠ iεá fron⌠á pane∞ ì
LED¼á yo⌡á wil∞ havσ t∩ d∩ thσ interfacσ ß bi⌠á differently«  ì
First¼á yo⌡ wil∞ ge⌠ thσ negativσ truσ CD╘ signa∞ froφ piε ▒ ì
oµá JPD«á   Theε inser⌠ thσ LE─ outpu⌠ signa∞ froφá thσá ne≈ ì
circui⌠á a⌠ eithe≥ piε ▓ oµ JP─ o≥ piε ▓ oµ J5«á  Removσ thσ ìèjumpe≥á currentl∙á installeΣ a⌠ JP─ oεá thσá TINY-▓á circui⌠ ì
board«  Iµ thσ ne≈ circui⌠ i≤ interfaceΣ iε thi≤ manner¼ thσ ì
"RFDCDóá signa∞á caε n∩ longe≥ bσ used«á  Thi≤ i≤á n∩á grea⌠ ì
loss, however, as it will also no longer be necessary.




                       Kantronics KAM



Interfacinτá anythinτ t∩ ß Kantronic≤ bo° isn'⌠ ß job¼á it'≤ ì
aεá adventureíáá  Kantronic≤á ha≤á aεá officia∞á polic∙áá oµ ì
discouraginτá anyonσ froφ hookinτ an∙ thirΣ part∙ devicσá t∩ ì
thei≥á TNCs«á  Thi≤á include≤á externa∞ modem≤ oµá an∙á kinΣ ì
(Neve≥á minΣá tha⌠ thei≥ crysta∞ bal∞ ha≤ proveεá cloud∙á a⌠ ì
bes⌠ iε thσ pas⌠ wheε tryinτ t∩ predic⌠ wha⌠ modem≤ migh⌠ bσ ì
popula≥ or necessary iε thσ future).

Thi≤á polic∙á wa≤á enunciateΣá t∩ mσá b∙á person≤á iεá thei≥ ì
technica∞á suppor⌠á departmen⌠á iεá tw∩á separatσá telephonσ ì
conversations«á  S∩ i⌠ wa≤ no⌠ surprisinτ t∩ finΣ tha⌠á the∙ ì
didn'⌠ providσ ß modeφ disconnec⌠ heade≥ iε thσ KAM.

Wha⌠ ╔ diΣ finΣ ß littlσ surprising¼á however¼á wa≤ thσ fac⌠ ì
tha⌠á the∙á als∩ refusσ t∩ providσ aε individua∞á owne≥á an∙ ì
assistancσ witΦ signa∞ locations«  The∙ don'⌠ sa∙ the∙ don'⌠ ì
know¼á the∙á sa∙á the∙á WON'╘ hel≡ youíá Iµá yo⌡á want¼á fo≥ ì
instance¼á t∩ interfacσ ß JAS-▒ (FO-12⌐ stylσ BPS╦ modeφá t∩ ì
you≥á Kantronic≤á TNC¼á yo⌡á arσá oεá you≥á owεá a≤á fa≥á a≤ ì
Kantronic≤á i≤ concerned«á  Potentia∞ Kantronic≤ buyer≤á wh∩ ì
arσ interesteΣ iε workinτ digita∞ mode≤ througΦ thi≤ anΣ thσ ì
upcominτ MICROSA╘ packe⌠ storσ anΣ forwarΣ satellite≤ shoulΣ ì
takσ note.

Iµá Kantronic≤ though⌠ tha⌠ onσ da∙ the∙ migh⌠ possibl∙ makσ ì
ßá radio¼á yo⌡á woulΣ havσ t∩ usσá thσá optiona∞á Kantronic≤ ì
built-iεá radi∩á iε al∞ thei≥ TNCs«á    Thanδ goodnes≤á the∙ ì
don'⌠ als∩ makσ computers...

I⌠á turn≤ ou⌠ tha⌠ thσ necessar∙ signal≤ AR┼ availablσá (fo≥ ì
120░á bauΣ a⌠ least⌐ iε thσ KAM«á  I⌠ i≤ indeeΣ possiblσá t∩ ì
interfacσá eithe≥ thσ 120░ bauΣ BPS╦ » MANCHESTE╥á F═á modeφ ì
requireΣ fo≥ thσ JAS-▒ birΣ o≥ thi≤ DC─ circui⌠ (o≥ both⌐ t∩ ì
thσ KAM.

A⌠ thi≤ timσ i⌠ i≤ unclea≥ whethe≥ thσ requireΣ clocδ signa∞ ì
i≤á availablσ fo≥ thσ DC─ circui⌠ t∩ operatσ a⌠ 30░ bauΣá oε ì
thi≤ TNC«á  Eveε iµ i⌠ is¼á i⌠ woulΣ bσ morσ troublσ thaε i⌠ ì
i≤á wortΦá t∩á interfacσá a≤ i⌠á woulΣá eithe≥á requirσá tw∩ ì
separatσá DC─ circuit≤ o≥ ß switchinτ arrangemen⌠á t∩á allo≈ ì
thσ usσ oµ onσ fo≥ botΦ modems.

Sincσá i⌠ i≤ unlikel∙ tha⌠ thσ filte≥ » slice≥ modeφ useΣ iε ìèthi≤á bo°á i≤ ß stella≥ performe≥ wheεá workinτá witΦá smal∞ ì
shif⌠á t∩á bauΣ ratσ rati∩ signal≤ oµ thσ typσ useΣá fo≥á H╞ ì
packet¼á maybσá wσ shoulΣ onl∙ reall∙ concerε ourselve≤ witΦ ì
120░ bauΣ operatioε anyhow«

I⌠á i≤ wortΦ notinτ tha⌠ fo≥ wide≥ shif⌠ t∩ bauΣ ratσá rati∩ ì
signal≤ likσ RTTY¼ ASCII¼ anΣ AMTO╥ thσ filte≥ » slice≥ typσ ì
demodulato≥á performancσ i≤ perfectl∙á adequate«á  Wheεá thσ ì
shif⌠á t∩ bauΣ ratσ rati∩ i≤ greate≥ thaε 1¼á a≤ witΦá thesσ ì
modes¼ mos⌠ oµ thσ transmitteΣ signa∞ energ∙ i≤ concentrateΣ ì
arounΣá anΣá ver∙ closσ t∩ thσ tw∩ tonσá frequencies«á  Wheε ì
thi≤á i≤á thσ case¼á thσ filte≥ » slice≥á i≤á thσá preferreΣ ì
methoΣá oµ demodulation«á A≤ thesσ mode≤ d∩ no⌠ operatσ iε ß ì
Carrie≥ Sensσ Multiplσ Acces≤ (CSMA⌐ environmen⌠ likσ packe⌠ ì
requires¼á thσá buil⌠ iε C─ functioε i≤ adequatσá fo≥á thesσ ì
mode≤ a≤ well.

Fo≥ 120░ bauΣ operatioε then¼á thσ signa∞ locatioε point≤ oµ ì
interest in the KAM are as follows:

Thσ Receivσ Datß (RXD⌐ signa∞ i≤ obtaineΣ froφ piε ╕ oµá thσ ì
TCM310╡á modeφá chip«á  Thσ Kantronic≤ schematiπ show≤á wha⌠ ì
appea≥ t∩ bσ somσ numbereΣ pad≤ (1╖ anΣ 18⌐ oε thi≤ leaΣá t∩ ì
thσá processor«á  Iµá yo⌡á caε locatσ thesσá point≤á oεá thσ ì
circui⌠á board¼á i⌠ ma∙ bσ easie≥ t∩ obtaiε thσ signa∞á froφ ì
onσ oµ thesσ points.

Thσá X1╢á bauΣá clocδ signa∞ i≤ obtaineΣ froφ piε ▓á oµá thσ ì
TCM3105.

Thσ POSITIV┼ TRU┼ Carrie≥ Detec⌠ (CDT⌐ signa∞ froφ thσ modeφ ì
i≤á obtaineΣ froφ piε │ oµ thσ TCM3105«á  Thi≤ linσ froφ thσ ì
modeφ t∩ thσ CP╒ i≤ labeleΣ witΦ ▓ numbereΣ pad≤ (╖ anΣá 8)«  ì
Thσá connectioε betweeε thesσ ▓ location≤ shoulΣ bσá broken«  ì
JMP▓ oε thσ ne≈ DC─ circui⌠ wil∞ bσ used.

Thσ DC─ outpu⌠ froφ thσ ne≈ circui⌠ i≤ injecteΣ a⌠ piε 2▒ oµ ì
the 63B03 CPU.

Thσá fron⌠ pane∞ LE─ whicΦ normall∙ indicate≤ thσ CD╘ signa∞ ì
activit∙ wil∞ sho≈ thσ actioε oµ thσ ne≈ DC─ circuit.