-- o ICOM

•
Designation
MicroSal-A
MiCroSat·B
MicroSat.c
MiCroSal-O
Designation
MiCro$at-A
MiCroSat-B
MicroSat.c
MiCroSat·D
Name
PACSAT
DOVE
NUSAT
LUSAT
Downlink
437.050
145.973
437.1 00
437.150
"Owner"
AMSAT-NA
BRAMSAT (Brazil)
Weber State Univ
AMSAT·LU
have a !>eparate AF output socket on the rear
panel that bypasses the volu me control. To
transmit on the uplinks , you need a 2 meter
F M transmitter.
FO-1 2 is very strong, so you can use a
vertical coll inear antenna at close range .
Many o pe rators fa vor beam a nte nnas.
though , and they will have more than enough
gain for practical purposes. Steering in azimuth
is then essential, and elevation highly
desirable, if you want to be able to observe all
passes .
An AX .25 Terminal Node Controller
(TNC) is essential for use with a suitable
VO U or computer terminal just as for terrestrial
packet. You can process telemetry data
by hand or by a simple program on the co m­
puter. It is not possible to display the raw data
direct ly from the modem on a VOU or 1200
baud terminal, as it is in AX .25 packet
formal.
Reading: The FO-JZ Handbook. contains
full descriptions of the satellite and its systems,
as well as essential details of telemetry
decodi ng .
Fuji-OSCA R-!2 Technical Handbook ,
AMSAT·UK, London, EI2 SEQ , England,
64 page s (obtain from AM SAT· UK , 4
pounds airmail, AMSAT-VK. or Project
OSCA R).
Miller J .R . , G3RUH, " A Packet Radio
PSK Modem for JAS-I /FO-12 ," Ham Radio
. February 1987. pp . 8- 22.
Mlcrcsats
General: Four small Microsats. conceived
by AMSAT North America, are presently
under co nstruction and testing. Launch is
scheduled for the second half of 1989, along
with UoSAT-O (and. of cou rse, the primary
commercial mission SPOT·2). See Table I
for a summary of their main features . Their
orbits will be circular, much like UoSAT·
2 ' s, and pola r with a 99-minute period and
appearances around 10:30 a.m. and 10:30
p.m. local time. They will be stabilized,
Earth-pointing , with strong signals, hopefu l­
ly requi ring only omnidirectional antennas.
At the time of writing this article (February
1989). details of the telemetry da ta and packet
BBS access have not been finalized , but we
expect them to be quite straightforward.
Associated Equipment: Since communication
with Microsats A/C/O will be identical
to communication with FO-12 , simply refer
to the FO-12 section of this article for details
ofthe equipment you need.
Reading: The Mic rosats are new, and the
60 73Amateur Radio · June, 1989
Uplinks MHz
145.900192019401960
145.8401860/8801900
Tablt' !.
8J 1JAS >BF.ACX~
Mission
Packel Radio BBS (PACSAT)
voce synthesis experiment
CCO TV Camera Experiment
Packet Radio BBS (PACSAT)
Signallng Format
AX.251200bpsasFG-12
BFM Voice
AX.25 1200 bps as FG-12
AX.251200 bps as FG-12
co ncept is evolving fast. The paper by Tom
Clark sketches the program from its conception
to today. and explains the designs in a
very readable and entertaining style.
Clark T. , W3IWI . " AMSAT's Mic rosat /
PACSAT Program," Proceedings ofthe 7th
ARRL Computer Networking Conference,
October 1988, pp. 41-47 .
JohnsonL.V . , WA7GXO, "Microsat Pro­
[ect-e-Flight CPU Hardware," Proceedings
of the 7th ARRL Computer Networking Conference,
October 1988 , pp. 104-106.
Price H ., NK6K , a nd MeGwie r R .,
N4HY. " PACSAT Software," Proceedings
ofthe 7th ARRL Compiaer Networking Conference
, October 1988, pp. 145-149.
UoSAT-O
General: UoSAT-O is scheduled fo r
launch on Ariane in the second half of 1989,
with 4 AMSAT Microsats and the primary
commercial mission, SPOT-2.
T he orbit will be circular. much like
UoSAT-2' s, polar with a 99-minute period
and appeara nces around 10:30 a. m. and
10:30 p.m. , local time, with strong signals.
Hopefully, it will require only omnidirectional
antennas .
The downlink frequency will be around
437 MH z FM, and user uplink around 145
MHz FM. UoSAT- O will use a 9600 bits/s
data rate in both directions with AX.25 packet
radio formal.
As above, details of the telemetry and
packet BBS access have not been finalized
yet , but we expect them to be straightforwa
rd . As the number ofe xperienced users
:
JAS- 1 RA 88/03/ 19 07, 11,58
275 546 684 690 743 876 887 861 002 349
644 001 519 532 538 546 548 538 686 00 1
710 7 12 690 746 738 674 921 144 000 000
010 101 100 000 100 000 001 101 111 000
8Jl~JAS )BEAC(lN ( lJI C> :
aAS ~ 1 NO 88/03/19 07: 12 :00
Mailbox availabl ~ .
Soft.ca re loaded at 88/03/17 05:25:00
Mode ,JD 'l'ransmit.ter- wi ll be tcggIed ON/OFF
e ve ry t.co hours using this e pcch .
Figure ! . FO-!2 telemetry in "unconnected " Ax'25 packet frames
as theyappear on your terminal. The telemetrycontains 4Onumbt'rs
which you can decode into voltages, currt'nts, temperatures, status
points. etc.
grow. we foresee more automated co mmunication.
Telemetry Forman Uplink and downlink
will use 9600 bits/s direct FSK. That is, " I"
will ca use an increase in carrier frequency.
and " 0 " a decrease.
Precisely controlled shap ing of the bit transitions
will be essential to constrain the data's
audio spectrum to under 7 kHz, and to ensure
rel ia bl e communication th rough conventional
FM radios with a 20-25 kHz radio
channel.
The data will also need to be ra ndomized
(scrambled) before transmission, and unscrambled
again after reception. This is to
ensure that no long runs of all " Is" or all
" Os " are transmitted , which would be
especially erro r-prone in this modulation
arrangement.
Because the audio bandwidth is somewhat
wider than the normal voice. signals must go
directly from the receiver's FM discriminator
to the transmitter's varactor frequency
modulator.
Telemetry Demodulation: The G3R UH
9600 Baud Packet Radio Modem was introduced
in mid-1988. and by February 1989
some 500 modems were in worldwide circulation
for high speed terrestrial packet radio
links.
UoSAT· O has an identical modem des ign
onboard. The modem provides all the mod u­
lation and demodulation circuits required for
UoS AT-O. It 's designed for use with a Terminal
Node Controller (TNC). typified by
the TNC-2, TNC-2oo, TNC-220. Tiny-2.
PK·80, PK·87, PK· 88. etc. It's a high performance
, full-duplex modem that works with
most voiceband NBFM radios. assuming only
minor mod ifications.
A key feature is digital generation of the
transmit audio waveform. Precise shaping
compensates for the amplitude and phase response
of the receiver. This results in a
"matched filter" system. which means that
the received audio offered to the data detector
has the optimum characte ristic (eye) for minimum
errors. It also allows very tight control
of the transmit audio bandwidth.
Decoder Specifications:
Modulation-FM. Audio applied direct to
TX varactor . ± 3
kHz deviation gives
RF spectrum 20 kHz
wide ( -60 dB). Fits
st a nd a rd chan nel
easily.
TX Modulator- Eightbit
l o n g di g ital
F.I.R. transversal
filter in EPROM for
transmit waveform
genera tion (l 2·bit
o p t io n a l) . Gives
"brick-wall "
audio
spectrum. Typically
- 6 dB at 4800 Hz,
- 50 dB at 7500 Hz.
Allows com pe nsation
for distant reo.
cetver (the channel)
to ac hieve perfect