Satgen277 Satellite Profile No6 Dove by GM4IHJ 16th July 94 BID of this msg is SGEN277 Please use this BID if you retransmit this msg For anyone wanting to listen to a satellite for the first time, Dove is the perfect target. It is a simple tranmitter of voice and digital packet telemetry coming down on 145.825 MHz FM approx. It can be acquired on a dipole antenna and FM receiver roughly every 100 minutes between 0930 local sun time ( add 1 hour for summer time) and 0130 the next day, thereby providing roughly ten orbit passes in succession for stations above latitude 52. Stations nearer the Equator miss 3 or 4 orbits around 1800 local because the satellite passes through their hemisphere too near the pole to be heard by them. A typical telemetry frame is received using an FM receiver on 145.825 MHz feeding its audio to an AFSK 1200 bps modem (eg Tiny 2 ) , which passes ascii text to a computer running any of the standard packet protocols ( Eg PACKCOM ). DOVE-1>TLM : 00:59 01:56 02:88 03:34 04:58 05:58 06:70 07:51 08:70 09:6C 0A:A1 0B:FF 0C:E7 0D:DA 0E:FF 0F:26 10:E2 11:AC 12:00 13:E0 14:A3 15:B6 16:72 17:68 18:6B 19:6A 1A:70 1B:01 1C:71 1D:6C 1E:D6 1F:64 20:D3 DOVE-1>TLM : 21:D2 22:7C 23:13 24:12 25:2B 26:02 27:01 28:00 29:15 2A:04 2B:65 2C:00 2D:5A 2E:4F 2F:AA 30:D7 31:A8 32:00 33:00 34:AD 35:A3 36:AA 37:AA 38:90 Telemetry blocks 26 to 2B are the solar panel currents which vary as the satellite spins. Block 26 is reading 02 and block 2B is reading 65. These are hexadecimal numbers . To get decimals we multiply the first number by 16 and add the second number to it. So 02 stays as 2 and 65 becomes 101. We next take this number and apply it to the decode formula of the form :- A x N x N + B x N + C . for box 26 A=0 B=.00215 and C =-.01075. Applying this formula to box 26 we get a very small negative value indicating that -X panel is not seeing the sun so there is no current production . By contrast when box 2B value of decimal 101 is decoded we get a figure of .21891 amps. for the +Z solar panel which is seeing nearly maximum sunshine. Please note these 26 to 2B box figures change rapidly as the satellite spins in the sunlight. Using Dove telemetry you can do hundreds of useful experiments, working out its spin rate , its orientation, its solar current ( particularly when it goes into earth shadow ), its doppler shift and lots of other interesting features of satellite management and environment reporting. Indeed Dove is an excellent educational tool. Less effective is Dove's voice broadcast. It was hoped that at one time it would eventually be able to " TALK" its telemetry. But this has proved much more difficult than anticipated. At present Dove says something that sounds like " Ti This is Dough is Vee " , when it is trying to say - Hi this is Dove. The problem lies in the method of phonemes used to produce the speech which relies on the collection of suitable syllabels to make up the English words. Programming a satellite to talk in syllables when it is already up in space is very difficult, and this problem is increased by the fact that Dove has to be shut down on 2m before ground control can talk to it . Dove can reply on S band but very severe doppler shift and a simple circuit failure in Dove have made this nearly impossible. 73 de John GM4IHJ @ GB7SAN