[amsat-bb] AO-7 CW Telemetry

EMike McCardel mccardelm at gmail.com
Thu Jul 31 21:03:20 UTC 2014


The December 1974 issue of the AMSAT Newsletter covered AO-7 telemetry fairly in depth. Included was a description on reading the telemetry followed by a telemetry conversion table.
You can find the issue in Phil Karn's archive
The article begins at about page 100 of the PDF


EMike McCardel, KC8YLD
VP for Educational Relations AMSAT-NA

Sent from my iPhone

> On Jul 31, 2014, at 2:26 PM, John Papay <john at papays.com> wrote:
> It is very rare to hear clear CW from the AO-7B
> telemetry beacon around 145.972.  Most of the time
> there is no beacon at all.  Sometimes there is
> jibberish.  Usually the signal is very weak.
> With AO-7 going through eclipse on every orbit, the
> satellite can come out of eclipse in different modes/
> options.  Recently there have been times where the
> beacon has transmitted clear CW over North America,
> something I have not heard over the years.
> According to the DK3WN website, there was some cw
> telemetry back in 2002 when the satellite was discovered
> to be working again.  And there was some discussion about
> what is valid data based on the last 3 digits sent in the
> 24 group block of data.  If the value is 649, 650, or 651,
> the data is likely valid.
> I first heard the image of the cw signal around 958.  It was
> so loud I thought it was a valid user at first.  But since
> the cw was all numbers I tuned up to the beacon frequency and
> there the signal was louder than anything I have ever heard
> on AO-7.  It took a while for me to get the recorder running
> but I managed to capture some data.  After playing it back I
> found that there was only one block of data where the last
> group was valid, a 649.  Other later transmissions were loud
> but the data was much different and the last group was not
> correct.
> I couldn't locate a telemetry calculator at first so I decided to
> build one on Excel using the formulae provided by DK3WN.  The
> data follows:
> AO-7B Telemetry 24July2014   2318UTC
> POS  Parameter                Range     Raw  Real
> 1A Total Solar Array Current  0-3000ma  171 2094.5ma
> 1B +X Solar Panel Current     0-2000ma  193  110ma
> 1C -X Solar Panel Current     0-2000ma  157  830ma
> 1D +Y Solar Panel Current     0-2000ma  108  1810ma
> 2A -Y Solar Panel Current     0-2000ma  286  250ma
> 2B RF Power Out 70/2          0-8watts  204 7.3728W
> 2C 24 Hour Clock Time         0-1440min 201 15.16min
> 2D Batt Ch/Discharge Current-2000/+2000 207  -1720ma
> 3A Batt Voltage               6.5-16.4  361  12.7V
> 3B Half Batt Voltage          0-10v     397   9.7V
> 3C Batt Charge Reg #1         0-15v     340   6V
> 3D Batt Temperature         -30 to +50C 300   95.8C
> 4A Baseplate Temperature    -30 to +50C 446   27.72C
> 4B PA Temperature 2/10      -30 to +50C 401   94.32C
> 4C +X Face Temperature      -30 to +50C 430   51.4C
> 4D +Z Face Temperature      -30 to +50C 498  -49.24C
> 5A PA Temp 70/2             -30 to +50C 545   29.2C
> 5B PA Emitter Current 2/10    0-1167ma  502   92.84MA
> 5C Module Temp 70/2         -30 to +50C 543   32.16C
> 5D Inst. SW Regulator         0-93ma    527   33.14MA
> 6A RF Power Out 2/10         0-10,000mw 606   23.076MW
> 6B RF Power Out 435           0-1000mw  643   219.9MW
> 6C RF Power Out 2304          0-100mw   679   255.881MW
> 6D Midrange Telemetry Cal     0-.5v     649   0.49
> There are some values which are obviously not correct.
> Some sensors might not be working properly since some
> values are out of range.  However, the solar panel numbers
> might be somewhat correct.  I wouldn't doubt it if the
> transmitter was putting out 7 watts at the time.
> Perhaps there are those who are familiar with the AO-7
> telemetry that can make some sense out of the data.
> Unfortunately we don't have multiple blocks of good data
> to compare readings.  Maybe some have recorded recent CW
> data and can find some good blocks that can be shared here.
> The data was copied on my Arizona remote and Skype was being
> used to listen.  But I am fairly confident that the cw copied
> is correct.
> 73,
> John K8YSE
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