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AO-16开放语音中继模式 [复制链接]

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离线BD6AHP
 
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3601
只看楼主 正序阅读 0楼 发表于: 2008-01-31
老卫星ao-16经过地面开发团队的努力,成功完成修复,现在开放奇怪的语音中继模式,上行使用145.920mhz fm,下行使用437.026mhz dsb。
离线BD6AHP
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3601
只看该作者 7楼 发表于: 2008-02-10
keep on working
离线BG8DMY
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29247
只看该作者 6楼 发表于: 2008-02-10
现在如何了?
离线BG4XOV
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只看该作者 5楼 发表于: 2008-01-31
呵呵呵   有能力就关注下。
离线bd4rs
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5111
只看该作者 4楼 发表于: 2008-01-31
一颗起死回生的卫星,值得关注。
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只看该作者 3楼 发表于: 2008-01-31
顺便发几张图,大家可以看到副载荷是如何搭载的。一颗主卫星下面搭载了一批的小卫星。






离线BD6AHP
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只看该作者 2楼 发表于: 2008-01-31
原文如下:

ao-16 recovered for voice operation
amsat vice president of operations drew glasbrenner, ko4ma, said this week the ao-16 satellite was successfully reconfigured as a voice repeater. in orbit since 1990, ao-16 had a serious on-board computer failure. the satellite was partially recovered approximately 6 months ago with its beacon and boot loader operational. however, ao-16 could not support any user traffic because of this failure.

a team which included bruce rahn, wb9anq and jim white, wd0e, advising mark hammond, n8mh as the primary groundstation performed a series of memory tests points toward a hardware failure which prevents restarting the spacecraft's original mission software successfully. mark put in many early hours during the multiple reloads and test sessions, with bruce, jim, and others advising.

after the conclusion that the spacecraft computer system was damaged and as discussions about decommissioning were taking place, jim recalled a series of low level commands included in the spacecraft design by tom clark, k3io during construction. one of these commands allows an uplink receiver to be directly tied to a downlink transmitter. the twist is that the uplink is regular fm but the downlink via the bpsk transmitter is dsb (double sideband).

mark placed the satellite in this mode and some testing was undertaken. the satellite hears very well, and the reduced bandwidth by using either usb or lsb on the groundstation receiver allows for a very robust downlink. tuning the downlink is just like on a linear transponder, meaning it is tight and with fast doppler. uplink tuning is not required, just as with the fm mode v/u satellites.

with testing complete the operations team announced the satellite is now open to general use on voice for a test period. the uplink is 145.920 mhz fm, and the downlink is 437.026 mhz ssb +/- doppler shift. please restrict your uplink power to a reasonable level, and do not transmit without being able to hear the downlink. all the general single-channel guidelines apply.

ao-16's receiver has a 15 khz wide crystal filter with sharp skirts. so if your nbfm transmitter is set with a ±5 khz deviation, you may well find your signal hitting the filter "walls". you may get better performance if you crank the deviation back a bit. the 70cm transmitter antenna configuration is left hand circular polarity (lhcp). the 2m receiving antenna is a 1/4 wave whip.

operators report the fading is quite dramatic, which means the bird is spinning and tumbling. we could never hear this before on ao-16 when it was transmitting its normal psk signal, since we didn't hear the effect of fading on the uplink in this mode. with voice operation the fading effect is quite apparent.

reports of successful contacts via ao-16 have been received from around the world. the downlink has even been copied indoors with a temporary antenna. enjoy ao-16's new life! thank you to all involved for your hard work.
离线BD6AHP
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只看该作者 1楼 发表于: 2008-01-31
下面是我自己翻译的ao-16公告,英语水平不行,大家将就着看吧。



  amsat操作副总裁drew glasbrenner(ko4ma)本周宣布,ao-16被成功地重新配置成了语音中继模式。自1990年以来,ao-16存在一个严重的计算机故障。大约6个月前这颗卫星部分恢复了信标和引导装载程序操作。但是,因为这个故障,ao-16仍然不能为任何用户提供服务。

  一个主要由bruce rahn(wb9anq)、jim white(wd0e)、mark hammond,(n0mh)组成的地面站团队进行了一系列的内存测试,去寻找阻止卫星原有任务软件正常执行的硬件故障。他们在早期的多次重新加载和测试阶段花费了很多时间。

  在做出卫星计算机系统已经损坏,卫星实际已经不能正常运行的结论后,jim回忆了在卫星建造阶段由tom clark(k3io)编写的低层指令。指令中的一部分允许一部上行收信机直接连通一部下行发信机,上行信号为fm,而下行是通过bpsk发信机的dsb(双边带)信号。

  mark将卫星置于这种模式下,然后进行了一些测试。卫星的信号非常好,地面电台接收机上使用usb或者lsb模式以减少带宽允许一个非常强的下行信号。按照线性转发器一样调整下行接收频率,这因为信号存在快速的多普勒频移,而上行发射频率和普通的fm模式v/u卫星一样是不需要调整的。

  在测试结束团队宣布这颗卫星用语音模式开放一段时间以供测试。上行频率是145.920mhz fm,下行频率是437.026mhz +/- 多普勒频移 ssb模式。请在上行频率上使用合理的功率,并且如果听不到下行信号请不要尝试发射。

  ao-16的接收机有一个滤波边缘陡峭的15 khz带宽晶体滤波器。所以如果你的窄带fm发信机设置±5 khz的偏移,那么你可以发现你的信号命中了滤波器的壁垒。如果你调整回一点偏移,你可以获得更好的效果。卫星0.7米段的发信机天线是左旋圆极化,2米段收信机是1/4波长鞭状天线。

  操作者们报告说信号衰落非常有戏剧化,因为卫星在旋转和翻滚。在ao-16以前正常传输psk信号时我们可能永远听不到像这样的情况,因为我们听不到在psk模式下上行信号的衰落影响。但在语音模式下这种衰落影响是显而易见的。

  通过ao-16通联成功的报告来自世界各地。甚至在市内使用一个临时天线也能信号受到下行信号。享受ao-16所带来的新生活吧!感谢你们的辛勤工作。