[sarex] Re: ariss, PCSAT2
ka1rrw at yahoo.com
Mon Aug 17 08:36:08 PDT 2009
Bob Bruninga and I are similar that we both love Amateur Radio satellite operations and we are both a bit if a loose cannon. Actually I prefer the tile of “Pirate” that was given to me by Roy Neal (SK).
However Bob is modest in his connections with the Military.
The PCSAT2 project was military funded project with an Amateur Radio project as a Piggy-Pack project.
The PCSAT2 project did not take the normal route required for ARISS Amateur radio projects. Bob was able to use his Military back door without prior ARISS approvals. The ARISS team was basically required to accept the PCSAT2 project at face value. The backdoor bypassed what few ARISS check/balances that were in place. The ARISS Hardware team was not fully aware of all of the different modes of operation that PCSAT2 supported.
The PCSAT2 project went live from ISS on August 5, 2005. A few weeks later we discovered that was a problem with PCSAT2 causing interference during a Soyuz and Progress docking operations.
During an ARISS teleconference in November 2005, I specifically ask Mr. Bruninga “Did you inform the ARISS Hardware team of all of the operating modes and frequencies used by PCSAT2?”
Mr. Bruninga responded “No I did not”.
Then Frank Bauer responded “Thanks Miles”.
The PCSAT2 fallout:
This project may have long ramifications for installing Future amateur radio transmitters on ISS. If we are required to reduce harmonic radiation by 80 db on future transmitters we will need to modify our transmitter with additional external filters.
Amateur radio projects on ISS were often touted as low power systems that could not interference with ISS systems. Now NASA knows that our project do have the potential for causing potentially serious interference.
Another project that was accepted at face value from Bob Bruninga, was the Kenwood TM-D700 transceiver project. The Kenwood TM-D700 radio is a Very good radio and supports many great features. Unfortunately the users have the ability to change the setup parameters on the TM-D700 in such a way, that the radio can become unwieldy.
I do no have time to go into all of the problems with the Modified TM-D700 in the memo. So of the basic issues are:
Note these issues are only with the Modified TM-D700 and not with a common factory version of the Terrestrial TM-D700.
Only 6 Channels are easily accessible. The rest of the channels require knowledge of how configure separate Transmit and Receive channels on two different radios at the same time.
Packet Mail Data throughput (at 1200 baud) has been reduced from approximately 300 bits per second to less than 50 bits per second. For all practical purposes the Packet Mail Box is unusable.
Note: If you turn off the TM-D700 internal modem and connect the radio to an external modem (KPC-3 or KPC-9612) the Packet Mail data throughput increased to approximately 500+ bits per second.
Digital Repeater modes such as Unproto and APRS are much slower than terrestrial versions of the TM-D700.
The User interface is too complicated and some ISS crew members have been blamed for screwing up the settings when they tried to dial up their favorite channels. Others such as Bill MacArthur just forced the radio into VFO mode to disable the excessive features.
Additional information can be found in the ARISS meeting minutes.
4. PCSAT2, Presenter: F. Bauer
Frank asked Bob Bruninga to give a status of PCSAT2 operations.
[There ] have been safety issues with PCSAT2 that have impacted the rest of ARISS hardware currently on orbit, and these could have implications for future amateur radio payloads.
Frank asked Bob to describe PCSAT2 safety concerns. JSC required 4 inhibits on his 2W transmitter during EVA and operating the robotic arm. PCSAT2 was designed with a load across the battery to prevent overcharging, which limits how long the payload can be turned off. PCSAT2 used astronauts as a backup command-off path, but coordination of that effort is difficult as well as coordinating the ground commands.
Frank noted that PCSAT2 has spurs that are interfering with the Soyuz and Progress docking and undocking TV operations. Bob noted that there is a ~450 MHz spur that is more than 60dB down (per commercial specs), but NASA wants it to be 80 dB down. Frank noted that there was a time when there were high-priority discussions with the crew regarding PCSAT2 ops, including using ARISS internal hardware by the crew to command PCSAT2 off, but the main ARISS team was not totally informed or brought in to help.
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