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• 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
RX eye. Up to 16 TX waveforms (32 optional). j umper selectable. Output ad justable 0-8 V. pk-pk. Scramblcr-ctgandomizerj: 17-bit max imal length LFSR scrambler. Jumper selectable Data or BERT (bit error rate test) mode. RX Demodulator-Audio from receiver discriminator. 50 mY-JOY. pk-pk. 3rd orde r Butterworth filter. 6 kHz. Data Detect ci r cuit for use on simplex (CSMA) links . Independent unscrambler. New digital PLL clock recovery ci rcuit with 11256th bit resolution. Average lock-in time. 50 bits (depends on SNR). Connects-to AX.2S TNC "" Modem Disconnect" jack. Suitable for T NC-2 (and any other. prov ided the internal modem can be bypassed). Standard TNC digital connections needed: TXOata. TXClock (l6x bit rate). RXData. Data Detect (,"OCO"). GND. TTL levels. RADIO: TX Audio. RX Audio. G ND. Power/PCB-Io-I5 V DC at 40 rnA (C MOS ROM s). 170 rnA (NMOS ROMs). Total 19 ICs (13 C MOS , two OACs . two EPROMs). 5 volt regulator and heat sink. 16 0 x 100mm double - sided. plated through. solder resist. full ground plane. No hard-to-get parts . Instru ction book let. 16 pages. Availability-The PCB is available from G3RUH (19 pounds airmail plus 6 pounds for the pair of EPROMs . which you may Photo B. FO~J2 PSK Modem in cabinet showing controls. copy). Assembled/tested boards can be obtained from Pac-Comm . RadioKit plans to stock complete kits of parts-check. Project OSCAR will take PC B orders . Canadian outlets are being arranged . Associated Equipment: You can use a 70 em FM radio to receive UoSAT-O. Tuning rate can be quite coarse ; I kHz steps will be adequate. You must take audio direct from the receiver's FM discriminator. implying a minor internal modification. To transmit on the uplink . you need a 2 meter FM transmitter. Apply modulation directly to the varactor to provide true FM . UoSAT-O should be strong. A vertical collinear antenna may be adequate at d ose range. An AX .25 Terminal Node Controller (TNC) is esscntialto use with a suitable VDU or computer terminal. just as for terrestrial packet. II is nol possible to display the raw data direct from the modem on a VOU or 9600 baud terminal device as it is in AX .25 packet formal. Reading : Ward 1. . GO/K8KA. " T he UoSAT-O Packet Communications Experiment." Proceedings ofthe 7th ARRL Computer Networking Conference , October 1988. pp.186-193. Miller J.R.• G3RUH. " 9600 baud Packet Radio Modem Design." Proceedings of the 7th ARRL Computer Netl'.'Orking Conference, October 1988. pp. 135-140. 1JJ C,RCU,TS Number 19 0 n your Feed back card OU TPUT I ' "A OUTPU T 2 '"A OU T PUT 2 ' "A Great Ideas From Our Readers Volta ge Doubler Circuit I've used this circuit for the past two years to drive relays of24 and 28 volts DC from a f2-volt power supply. It is a DC-DC converter which powers a 28-voIt DC antenna relay. You can use this circuit with almost anyPNPor NPN power transmission. It will work the first time every time. At hamfests, 28-voIt relays often cost 1655, but because of th6 voltage rating. most hams don't bUy them. Parts: For ut, you'll need a NE 555 timer. C1 & C2 require 50 11Ft 25 vofts DC. NPN, 01: TlP29; TlPI20; 2N4922; TlP61; TlPll0; and 2N4921. PNP. 02: TlP30; TlP125; 2N4919; TlP62; TlP62; TIPtt5; and2N4918. Chuck Steer WA31AC Philadelphia PA MILL E D B RASS H O U S ING-;g~;== I=='= L 0 I NPUT CUT P C BOARD AN D SOLDER SAGEe WIRE L IN E TO THE BRA SS HOUSING PROPER OR L E AD CONFI GU R ATION t R{ [] "111 COUPL ED t o 85"-;.(1 MA IN "" ;-,. • , '" ,k "' '" , l''' " , ok f' oo ok 1 1 0 0 1 1 :l- 00 " ~~. --{t;i" 2-W8'f 230412 160 MHz Power Divider MAIN 1j COU PLED adapter, one of only severa! coonectors that should be used at 2 GHz and above. Check also Sealecrro, Inc.• 225 Hoyt St., Mamaroneck NY 10543, for microwave-band connectors. Parts: L 1 = Sage~ 3 dB wireline; Rl = 500 microstri{Hype termination; R2 _ 50{} termination . Here's a handy little device for 130m enthusiasts. This allows a user to split the powerofthe precision La input into two 500 equal power 2160 MHz non-interacting signalsources. Both outputs go to theirrespective receWe andtransmit mixers. which are independent ofeach other. D. Masc8ro WA3JUF SMA stands for small miniature Ottsville PA 18942 73 Amateur Radio • June, 1989 61
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