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Re: IDEFEIX Thanks




>Hello John,
>
>thank you for the geetings, but I verily was not alone and IDEFIX is the result of a real teamwork as you
might dream of every day where each one took its place seamlessly.
>You may pay them tribute by looking at the website and keeping on sending tlm reports.
>
>The pass of last midnight was a real pleasure for eyes and ears as the sky was clear and elevation almost
at zenith and a lot of people were able to see IDEFIX passing overhead
and hear the signals that were very
strong. The visual magnitude was around 0 and even in the lights of the
center of Paris it was as plain as a
bright star.
>I heard it with a 4 el handheld yagi from my balcony while visually tracking it.
>
>Last news:
>The internal temperature is around 32 deg celsius, decreasing now. Last monday, it was around -20 deg
celsius after having been in total obscurity for more than 24 hours not
even seeing the earth reflection as
indicated by the telemetry. The third stage slowly revolves around
itself and spins too. Both effect combine
to affect illumination. In fact, we expected even worse conditions and
the temperature range is within the
limits.
>The batteries are in good health.
>
>Starting from wednesday-thursday night, the telemetry channels of CU1 are all zero while the processor
still keeps on transmitting frames and timing the payload. There are
three possible causes in the order of
highest to lowest probability :
>- thermal crackdown in the pcb affecting the ADC SPI bus or power supply.
>- thermal crackdown in the ADC chip
>- chip destruction by high energy particule.
>- uP port destruction.
>
>When the payload cools down and the pcb shrinks, we'll have a chance to recover the telemetry if the first
hypothesis is the right one.
>
>As for the translation of the terms:
>OPTRO :each payload is fitted with two light sensors which are basically a BPW21 photodiode behind a  2mm
thick PTFE windows giving a cosine response of incident light flux. The
photodiode is wired as a photocell
loaded by a 5k resistor. Under full sun at AM0, the max voltage is
around 150 mV depending on temperature.
One the two light sensor is fitted with a LM335Z temperature sensor to
allow for correction (TEMP OPTRO
channel).
>On the pictures, the light sensors are the two brass bolt like extrusions ontop the payload housing (Z+
side). One is besides the X+ side (coax connectors), the other at X-
side (arming plug connector). The
description of the light sensors is given at http://www.satedu.net 
>
>TEMP BOITIER : case temperature taken at the bottom of the X+ side of the payload. You can see the exact
place in the pictures at http://www.idefix-france.net. LM335Z sensor.
>
>T ISD : a temp sensor glued on the ISD25120 voice recorder chip. One of the voice message is a 1800 Hz tone
recorded at 20 deg celsius. As the internal free running clock of the
ISD is temperature dependent, the
measure of the received tone frequency gives a very rough estimate of
the internal temperature of the
payload. < 1800 Hz => < 20 deg, > 1800 Hz => >20 deg .
>
>MOY ORBITE : on CU2, three channels are monitored for mean, max and min values.
>OPTRO1
>OPTRO2
>TEMP OPTRO
>There are two mean values : a 10 minutes one, which integrates the values of the last ten minutes and an 90
minutes one. The last one is reset every 90 minutes while the first one
is a sliding mean.
>That was devised to get some tlm values around the orbit as it was impossible to have amateur stations
continuously monitoring the sat.
>In the decoded tlm channels, you read :
>OPTRO1 mean value, 10 and 90 minutes (orbit)
>OPTRO1 min value since mean reset and time stamp
>OPTRO1 max value since mean reset and time stamp
> and the same applies to OPTRO2 and OPTRO TEMP.
>
>So we need only a full super frame ( 5 frames, each with subframes) every 90 minutes.
>The instantaneous light sensor value (E subframe on CU2, A and B subframe on CU1) is transmitted during
each frame i.e. every 12 seconds on CU1 and every 22 seconds on CU2 to
adequately sample the spin rotation.
>
>The place of the other temp sensors is visible in the pictures on the web site.
>
>The voltage of the Li Thyonile batteries is measured after the schottky coupling diodes (400 mV drop).
>On CU1, it is measured during standby, on CU2, it is measured during transmit.
>On CU2, the RF power indication is taken from a diode rectifier located near the PA output coil and the
spacing has been adjusted to get roughly 600 mV at 1.25W ouptut. The
indication is temperature dependent and
the TX temp sensor is located just besides the PA which is a BLT50.
>
>The processor is a 80c32X2 on the two payloads.
>On CU1, it comes with a 32k ROM and its internal RAM. On CU2, 32kRAM are added to store the values for the
mean, max, min calculations.
>On both CU, the processor generates directly the 1200 Hz bpsk Manchester modulated subcarrier which  feeds
the FM TX BF input. It also drives the SPI bus (1 MAX186 on CU1, 2
MAX186 on CU2), the ISD25120 voice
recorder and TX on/off control. The clock frequency is 6.144 MHz.
>The processor also generates an internal time stamp which slightly drifts with time, that's the reason why
the telemetry decoding software adds the PC date to appreciate the time
stamp drift quite exactly. The drift
is regular and has almost a fixed value slightly depending on
temperature. The time stamp is generated with
the internal timer.
>The processor is placed in sleep mode when not in use to reduce the current drain.
>The processor program architecture is a basically a state machine whose all states are defined and looped
allowing for the processor to reset and recover even in the case the
stack is corrupted by a SEU.
>
>Two switching mode power supplies are used, one for 5V processor and sensors, one for 7.5V Tx generation.
The 5V TX for vco/buffer and synth (a few mA) is derived from the 7.5V
via a linear regulator. The on/off
control of the switcher is used for TX control.
>
>Mechanically, the PCB are located on an H like structure 'floating' in the case along with two batteries.
>The 10 other ones are fitted on the bottom of the case with thermal insulation.
>The cases have been mirror polished while the internal faces have been left rough. That was the compromise
we choosed to cope with the totally unknown illumination or dark periods
along with internal dissipation. It
seems to be right altough we have to carefully study it with a post
analysis of the telemetry.
>
>There are 12 Li Thyonile, 13 A.h, 3.6 V batteries (LSH20 SAFT, space qualified model) arranged in 4 series
3 parallel giving 14.4 V no load. A better arrangement would have been
to get higher voltage and lower
current as the capacity is inversely related to current draw. The
switchers allowed for that but there was a
technical issue that we hadn't the time to care for leading to that
suboptimal stacking.
>
>Hope it gives you some insight of IDEFIX and answers your questions.
>
>Best 73.
>Ghislain F1HDD/ON1RG
>
>
>Hi Guys,
>
>Thanks to Amsat-F and F1HDD
>Having a lot of fun with IDEFIX
>and the WDECPSK  telemetry decode software.
>
>Works fine with my soundcard.
>Plenty of valid telemetry frames collected.
>
>Could someone post a translation on this bb for
>some of the main terms seen in the telem. please.
>
>Optro
>Moy Orbite
>Temp Boiter
>T ISD
>Moy IO
>
>Thanks
>
>and 73 all
>
>John G7HIA
>
-- 
--------------
Ghislain RUY
F1HDD/ON1RG
--------------
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