AMSAT-NAAMSAT News Service

July 7, 2002

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AO-40 Schedule Change

Effective on orbit 765, on all days except Wednesday, the S2/K-Tx beacon only and passband segments are active again for testing. Note that the beacon only session (no passband) for S2 and K Tx's is MA 116-120, and the beacon + passband session is MA 120-128. As before, on Wednesday, the V-Rx along with L-band Rx's are connected to the passband from MA 120-128.

N  QST AO-40  S2 Downlink     #=Wed, @=non-Wed    2002-06-30
MA      036   120#  116@  120@  128   160   200   240   036
---------1-----4-----2-----6-----3-----5-----7-----0-----1
MB       |  *  |  *  | S/K | S/K |     |  *  |  *  |  *  |
RUDAK    |     |     |     |     |  *  |     |     |     |
V-Rx     |     |  *  |  *  |     |  *  |     |     |  *  |
U-Rx     |  *  |     |     |  *  |     |  *  |  *  |     |
Passband | UL  | VL  |     | UL  |     | UL2 |     |     |

--W4SM for the AO-40 command group.

[ANS thanks Stacey W4SM for the above information.]

Yoshihiro JF6BCC/KH2GR provided the same data in a revised format:

MA         36           116   120   128        160    200      36
------------+------------+-----+-----+----------+------+--------+
Daily       =====S-MB===============><==RUDAK==><=====S-MB=======
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Wed. Only   <===UL============><=VL=>           <=UL2=>
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Exc. Wed.   <===UL=======>     <=UL=>           <=UL2=>
                        <===K-MB===>
-----------------------------------------------------------------

PCsat Test Results

On Thursday, 27 June a user load test was conducted on PCsat before it goes back into maximum eclipses. PCsat is still usable in the afternoon sun, but not in the morning or at night due to not being charged up. PCsat is running out of battery power and resetting itself every eclipse.

RESULTS: A qualified success. With a user load of 56 simultaneous users, the success rate was over 97%, thus validating the viability of the PCsat and other space digipeaters (ISS) as a means of letting a large number of users share a satellite during a pass.

DISCUSSION: But it was still not a full load test, since the digipeater was still only lightly loaded (maybe 10% of design load). The design goal of PCsat was to be able to support on average about 300 to 500 users per day in the USA. PCsat was not available during Field Day due to run down batteries. Maybe then we could have seen how the design would have worked with a full load of several hundred users. The following are the details of the test.

SUCCESS: 30 out of 31 with the correct settings were successful (97%).

LOAD: 16 others were trying (QRM) but had the wrong digipeater callsign because PCsat reset in eclipse and was not properly configured. Of these, one station reported transmitting every 12 seconds throughout the pass in frustration. Compared to the requested nominal 2 minute rate, he counts for an added channel load of 10 more users... for a total of 56.

The desired transmit duty cycle per user was to be one packet every 1 or 2 minutes. Most users appear to have adhered to that objective and still were able to achieve success.

If we make it to the next full sun period in September, maybe we can try again to get a full user load to validate the design.

Thanks for all your participation.
Bob Bruninga
WB4APR

These calls were successful:

AA3VO,AA9LC,AB7QN
K5OE,K9ORP,KA0AZS,KB0VBZ,KB1GUE,KB5HPL,KC0JHQ,KC4ZGQ,KD7MJC
N3SOK,N4QWF,N6CO,N6JLH,N7VMR,N9ORP,N8ORJ,NP3ZY
W3SMK,W4JBB,W8AAS,WA4SAS,WA4SSP,WB4APR,WB4JBB,WB8NW
VE3DOH,XE2ARF

[ANS thanks Bob WB4APR for the above information.]

The 7 Billion Mile Uplink

How's your uplink today?

When controllers made contact with Pioneer 10 at a distance greater than 7.4 billion miles they used the 70 meter dish at Goldstone, California with an uplink transmit power of 200 kW. The Pioneer 10 spacecraft received the signal at -131.7 dBm after a transit time of about 11 hours.

The reply from Pioneer 10 was received back on Earth an additional 11 hours later. The received downlink signal strength from the spacecraft was about -183 dBm. Signal processing algorithms peaked the received signal at -178.5 dBm. Telemetry decoding of the 16 bps data stream was able to be processed at a signal-to-noise ratio of -0.5 dB. It was also detected by SETI.

So the next time you're thinking of putting off tweaking your antenna system remember you've got lots of work to do! One old timer told ANS, "If your antenna stayed up all winter then it wasn't big enough!"

ANS in Brief

With the change in Editors, ANS has made some changes in format. ANS has split the news section from the Satellite Report, for a trial period. Please send your thoughts on this to VE3FRH@amsat.org. Both sections will be available to all subscribers of ANS. Mike Seguin N1JEZ the Principal Satellite Investigator, will continue to supply the satellite information section and all information should be sent directly to N1JEZ@amsat.org.

ANS is looking for two more co-editors to take turns in the development of ANS, If you are interested please send an e-mail to VE3FRH@amsat.org

[ANS thanks Robin Haighton VE3FRH for the above information]

Weekly Satellite Report

Link to the weekly report on satellite ...

All Satellites
ISS . RS-12 . RS-13 . RS-15 . AO-7 . AO-10 . UO-11 . UO-14 . AO-16 . DO-17 . WO-18 . LO-19 . FO-20 . UO-22 . KO-23 . KO-25 . IO-26 . AO-27 . FO-29 . TO-31 . GO-32 . SO-33 . PO-34 . SO-35 . UO-36 . AO-40 . SO-41 . SO-42 . NO-44 . NO-45 . MO-46


Please send any amateur satellite news or reports to the ANS Editors at ans-editor@amsat.org

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This week's AMSAT News Service bulletins were edited by AMSAT  News Service Editor JoAnne Maenpaa WB9JEJ, wb9jej@amsat.org.

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