Conference 7.286::space

on 25-oct-1991  I copied the following from SARA
300 baud ascii bell 202 normal

SPACE
BP 99
93162 NOISY LE GRAND CEDEX FRANCE
SATELLITE AMATEUR DE RADIOASTRONOMIE
ECOUTE DE L'ACTIVITE DECAMETRIQUE DE JUPITER
FX0SAT FX0SAT FX0SAT
^@<ESC>CYCLE nxh
;1^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H
^A^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H
^B^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H
^C^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H
^D^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H
^E^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H
^F^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H
etc


NOTE: the data was in one long string, I cut it up as show
above base on what I think the tlm format might be,

binary_line_number        16 bytes of data
binary_line_number + 1    16 bytes of data

I guess for 256 lines of data, as the binary_line_number
is a 8 bit field.


Does anyone know the tlm format or where I might 
find the data on the fomat,

I have called AMSAT and they have not info on the TLM



thanks john
    

    
The following appeared arrived on the W3IWI PBBS today. Headers have been
stripped for brevity -- Tom
 
SB  SARA@AMSAT < F6BVP  $5814_F6BVP  
SARA DATA FORMAT
R:911127/1120z [email protected] [Balto/Wash MD/DC]
R:911125/2053Z @:F6BVP.FRPA.FRA.EU #:5814 [Paris - FBB5.13]
Joe G3ZCZ has initiated a series of information bulletins on SARA satellite. It
seems that a  lot of interest  has emerged from  this Radio Astronomy Satellite
but there was a lack of  informations concerning the data format. Here are some
informations I  found in  the November  issue of Belamsat Satellites Newsletter
edited by ON1KHP. 
 SARA transmitting characteristics
- frequency : 145.955 MHz
- frequency modulation +/- 5 Khz
- data rate 300 bauds
- level 0 (start bit): 2200 Hz, level 1: 1200 Hz
- measurement window 171 secondes separated by a one second blank
- Start of measure message in ASCII code:
SARA
ESIEESPACE
BP 99
93162 NOISY LE GRAND CEDEX FRANCE
SATELLITE AMATEUR DE RADIOASTRONOMIE
ECOUTE DE L'ACTIVITE DECAMETRIQUE DE JUPITER
FX0SAT FX0SAT FX0SAT
 
- each line is terminated by ASCII character 13 (CR) and (10) LF
- the number of the measure is then transmitted using a 3 bytes format:
CYCLE NxXXX
- where XXX is the binary coded cycle number with LSB transmitted last.
- the measurements are then transmitted in 256 messages (frames with couples of
elementary measures) such as:
T C0 C1 C2 C3 C4 C5 C6 C7 C0 C1 C2 C3 C4 C5 C6 C7
- T representing the frame number (0 to 255)
- CX represnting  the amplitude of  the X channel  (0 to 7),  the MSB beeing an
even parity bit
- at the end are transmitted 48 redondant bytes for error correction.
 
The format for the error correction is given in the next message.
73's de Bernard, F6BVP.
/EX
 
SB  SARA@AMSAT < F6BVP  $5815_F6BVP  
SARA ERROR CORRECTION SCHEME
R:911127/1118z [email protected] [Balto/Wash MD/DC]
R:911125/2118Z @:F6BVP.FRPA.FRA.EU #:5815 [Paris - FBB5.13]
The data transmitted  by the SARA  satellite are protected  by a redondant code
which  provides  error  correction  capability.  Only the 4096 bytes of usefull
information are protected. They are separated  into 4 pages of 1024 bytes  with
page number from 1  to 4. In each  page bytes are numbered  from 1 to 1024  (11
bits format). A twelth bit is added  in the LSB position in order to  obtain an
even number of 1 in the byte number.
The 48 redondancy bytes are initialized at 0 value. The first 12 are associated
with the  page number  1 and  so on.  The code  for the  4 pages are completely
independant.
Each bit of  the byte number  is associated with  a redondancy byte. The LSB is
associated  with  with  the  redondancy byte  number  one,  the  MSB  with  the
redondancy byte number 12.
The data byte is added with  all redondancy bytes which have an  associated bit
value of one. This addition is actually an exclusive OR operation bit per bit.
 
Here is an example of the data format for page 1 byte 17
 
Page 1                                        Redondancy 1
 
byte 17 ---> 00000010001               
                 + parity -------
                                 >
                     000000100010
                               !-------------------------- red. byte 2
 
                           !------------------------------ red. byte 6
 
Hope these informations will help thos  who are interested in decoding the data
received from SARA.
73's from Bernard, F6BVP.
/EX
    

I have been told that Belmastat journal number 10. 
has infomation on the SARA TLM and that the full tlm 
format is supposed to be in number 11. 


So does anyone have a copy that they can post?

73 John

or as the tlm say  88's SARA


    

    I have just receive a project report (in French) from esieespace
    on SARA, SATELLITE AMATEUR DE RADIO-ASTRONOMIE  
       Compte-rendu du projet   avril 1992
    
    it is about 110 pages long,
    would someone be interested in translating it,
    at least the technical sections, (there is a Financement chapter)
    
    chapter title are:
    1.	Avant-Propos
    2.	Esieespace
    3.	La mission scientifique
    4.	La conception de SARA
    5.	La realisation de SARA
    6.	Les essais
    7.	Le financement
    8.	Kourou
    9.	L'explotation
    10.	Conclusion
    11.	Annexes
    
    Bigliographie
    Index
    Table des figures....  
    
    thanks john
    

    one intersting line
    
    La transmission descendante se ferait a 145.955 MHz
    ok under stand that one, but then it goes on to say
    
    et la transmission montate a 437.5 MHz
    
    is this (437 Mhz freq) a up or down link or can you tell
    from this 
    
    one thing that I know know is that the battery voltage
    on VCO1 sub channel is the raw voltage before regulation
    
    jb
    

    That's the up link.
    
    (Sorry, I don't have time to try to translate something anywhere near
    that long... I'm not a real good translator anyhow.  I hope someone
    else volunteers.)
    
    /Charlotte

    thanks, found another line at lunch time that also points to
    it being the uplink ... 
    et lat frequence de telecommander que nos convenait a linterieur de la
    bande radio-amateures 432-438 MHz...
    
    so I would think telecommander is the command up link
    
    and when they talk about the 145 freq they cal it the 
    frequence de telemesure   or I would assume the TLM freq.
    
    
    thanks  john
    

re .5
    
>    et la transmission montate a 437.5 MHz
    
    I expect that's a typo. Replace "montate" with "montante", meaning
    (more or less) "going up".
    
    Sorry, no time for the whole doco and in any case my French is almost
    all rusted away.

    re .4
    
    I can always start... 
    
    
    PROJECT REPORT
    --------------
    1. Foreword
    2. Esieespace  (sp ?)
    3. The Science Mission
    4. SARA design
    5. SARA realisation.
    6. Trials
    7. Founding
    8. Kourou
    9. Exploitation
    10. Conclusion
    12. Appendices
    
    Suggested readings
    Index
    Figures
    
    Now if you want more (110 pages !) you can mail me some sections.
    ( but be patient as I will be out the 3 first weeks of july)
    
    
    	Raymond.

    Ok thank you for the translation, I will mail you a copy today,
    'esieespaace' is the name of the club that built the SARA satellite
    
    thanks john
    

    Having received the previously mentionned booklet from John, I finally
    started the translation.
    
    Of course some time has passed since the last reply, but I dare to hope
    that all the interested individuals are still with us.
    ( I went on holydays %^} then I had some customer courses to teach %*{
    
    Anyway I have translated the foreword (next reply) and the Chapter 3
    (The science mission) If you are interested I will continue with
    chapters 4,5 and 9.
    
    			 Enjoy.
    
    
    

				SARA LAUNCH 
				ARIANE V44
		    on the 17th of july 1991 at 1.46 GMT


	Foreword

SARA was launched on the 17th of july 1991 from Kourou (French Guyana)
Since then it orbitates above us and transmit signals.

SARA is the first satellite that has been build in France by amators.
Accessing space is an extraordinary adventure, much remains to be done.
If this adventure is more and more commercial, it still contains a large
part of dreams and emotions. If technology evolves, if the space environ-
ment is now well known, errors are still outlawed in the quest to orbit. 

In this report, we wanted to tell the SARA story. We have been honest, 
mistakes and their generally minor consequences have been described.

ESIEESPACE is one of the space clubs from ANSTJ (*), who build and launch
experimental rockets since 30 years. In a few years probably,a club will
wish to endeavor in a similar adventure. It is not the purpose of ANTSJ to
provide youths will space rockets building kits; imagination and initiative 
must prevail. We didn't want to give here an integral description of
SARA, but simply to show it as an example.

The SARA adventure wouldn't have been achieved without help from unnumerous 
partners. Let's hope they will feel in this pages the results of their help
and our thanks.

(*) ANSTJ: Association Nationale Sciences Techniques Jeunesse
    
        

			3. The Science Mission.
			-----------------------

3.1 In quest of an experiment
-----------------------------
	The  SARA adventure started by the quest for a scientific experiment
to be done in orbit. After an exploratory phase of consulting different
science laboratories, the need for simplicity led us to choose the 
proposal from the Meudon Observatory astronoms: the sudy of Jupiter's
electro-magnetic radiations.

	Radio-electric storms occur in the atmospheres of planets with a
strong magnetic field. Earth, Saturn and especially Jupiter are good examples.
In all those planets, violent radio-electric emissions occur with a frequency
in direct relation with the strength of the magnetic field. The Sun however
is certainly the most important source of such phenomenons. The highest
activity is recorded on Jupiter when the Sun is at his maximum activity.
Hence it is interesting to observe Jupiter during a complete solar cycle, i.e.
11 years approximately.

	Discovery of these radiations occured in the fifties, with the advent
of astronomical researchs in the radio-electric domain, thanks to the RADAR
and radio-telescope inventions.

	Jupiter's ionosphere is quite complex. Its radio-emissions offer
useful information on its structure and on the interaction between its main
satellites (Io) and the plasma core wich surronds the planet.

	Jupiter's radio-electric emissions were well explored from Earth
at least for frequencies higher than the cut-off frequency caused by
Earth ionosphere (*). The plasma wich constitute this ionosphere acts as
a real shield to electromagnetic radiations up to a certain frequency wich
depends essentially on the electronic density of ionosphere, wich itself 
varies a lot depending on the solar flux. Also, at night, this cutoff frequency
sags easily one octave (30 to 15 Mhz). Jovian radiations being maximum at those
frequencies, reception was easy.

	With the beginning of astronautics in the sixties, orbiting probes have 
been used to measure low frequency radio noise (<20MHz) and also to listen
more systematically to transiant radiations from Jupiter.

	Scientific satellites Alouette, IMP6 and especially RAE I and II (this
one on lunar orbit) have harvested informations wich allowed on one side to 
map the radio-electric noise and to demonstrate its galactical not thermical
origine, and on the other side, to examine with more precision the low
frequencies spectrum (<10 MHz).

	Hence, to summarize, jovian radiations in the 2-15 MHz range wich
relate to important transitional phenomenons in the jovian athmosphere are not
easily traced for three reasons:

		- High attenuation due to terrestrial ionosphere wich
		  allow transmission of those frequencies only sporadically.

		- Satellite based measures are not easy to use due to lack
		  of homogeneity, calibration and accessibility)

		- Some measurements were parisited by other instruments on
		  probes wich should have done those measurements. (Voyager)

	Nowadays, long term tracking of those radiations is still uneasy
and doesn't justify realisation or even boarding of large research mission.
This is why, a small satellite like SARA, dedicated to the reception
of Jupiter'signals in the 10 meters range looked attractive.

	The strength of Jupiter' radiations allows for the use of an omni-
directionnal receiver, simple and thus reliable. On another hand, a low
temporal resolution as well as a long term follow up allows to achieve a
scientific mission wich complements the work done by french radio-astronomers.

	The exploitation of those data easily decoded using limited equipment
allows a cross-examination of those data collected above the ionosphere and
those data collected on the ground. This procedure allows for noise extraction
(especially solar originated noise), the remaining pulses coming from Jupiter.

	It is worth to note that exploitable data collection can only occur
during flight over illuminated areas, because the ionosphere better shields
noise that originates from earth, natural (polar dawn) or man made (radar,
transmitters etc...)



		Follows a picture of an electrical signal from Jupiter
		recorded on 26.6 MHz (ground station)




(*) Ionosphere: high atmosphere layer, heavily ionised, wich shields 
                the planet against incoming radiations.

    
    
    (Translator note: this is the complete chapter, there is no 3.2)

    Thank you very much for the translation, I have made
    a hard copy and will be looking forward to reading it
    tonight
    
    
    thanks john
    

    re -1 
    
    John,
    
    Nice to see that you are still on board. I tried to VAXmail you
    but up to now I'm not lucky.
    
    Tucker::Biro 	no such user on Tucker  (Unix node ?)
    Declb1::Biro	node unknown from several important network nodes.
    			(hidden area ?)
    
    Anyway, I'll try to continue as soon as I get some spare time.