January 2008 - AMSAT-BB - mailman.amsat.org

Satellite tracking programming ideas
by Phil 18 Jan '08

18 Jan '08

Thank you for reading this. I'm currently marooned because of flood water, and likely to be so for at least another week, so to pass some time I decided to upgrade my satellite tracking program. Disappointingly, playing with the current satellites in this country is pointless so the programming exercise is purely academic. Originally, my tracking program displayed the link frequencies but I decided that was unnecessary since the radio has a perfectly good display itself. So to make frequency corrections, due to hardware errors, or to listen to another part of the downlink I simply used the radio's tuning knob. The program detected that the receiver's frequency had changed and calculated a new uplink frequency. This requires some manual intervention in that I have to stop the automatic tracking, turn the knob and then restart the tracking. This could take a few seconds which would mean that the tracking could be a few seconds behind. The alternative is to click on an up / down tuning arrow which will stop the tracking and adjust the received frequency. Clicking on a restart button would restart the tracking. I think that's the way satpc32 works. I've probably got too much time on my hands and both methods seem to work equally well. Does one method have an advantage over the other? The update interval has to be fairly short so that a manual frequency change can be quickly detected. I'm currently updating the radio based on time. The alternative is to update based on frequency, say every time the higher frequency changes by 20Hz. This would lessen the number of radio updates during periods where the Doppler effect is at a minimum but does it matter if the radio is undated unnecessary? The rotator bearing is updated every ten degrees but that's to lessen mechanical fatigue. Regards, Phil.

6 5

Re: Satellite tracking programming ideas
by Wayne Estes 18 Jan '08

18 Jan '08

Phil, you correctly point out that full Doppler tuning can sometimes have errors due to either the earth station or the satellite frequency drifting slightly. The best solution to compensate for the drifting depends on WHAT is drifting. In my case, I know my FT-847 435 MHz transmit frequency drifts a few hundred Hz during a long transmission. Consequently, as my transmitter slowly drifts, I turn my FT-847's Sub Tune knob to keep my uplink signal sounding good on the Doppler-tuned downlink. The Sub Tune knob adjusts SatPC32's TX offset. Alternatively, I can click the + and - keys on my keyboard's number pad as required to adjust TX offset in 100 Hz increments. Or I could press the - and = keys to tune TX offset in 10 Hz increments. If your receiver or the satellite's transmitter is drifting, I suppose you should click the CAT menu and use the Downlink Calibration adjustments. Then, in theory, you can tune across the transponder and enjoy perfect automatic Doppler correction. In practice, I frequently have to tweak my TX offset to keep my signal sounding good on the Doppler-tuned downlink, and I often tune manually to chase the downlink from stations that don't use automatic Doppler tuning. Wayne Estes W9AE Oakland, Oregon, USA, CN83ik

1 0

Re: Lunar Short Wave echo experiment looking for Listen er reports
by Keith N4ZQ 18 Jan '08

18 Jan '08

If I'm reading the chart correctly at http://aa.usno.navy.mil/data/docs/RS_OneDay.php it looks like this event doesn't start till after Moon Set on the east coast of the states.. Oh well, looks like I won't have to give up any sleep.. ;-) Keith -- Ernie Howard <w8eh.Ernie(a)gmail.com> wrote: They have a web page that confirms the 19/20th UTC. http://www.haarp.alaska.edu/haarp/mbann.html HAARP-LWA Experiment Schedule Date From To Transmitted Frequency (UTC) UTC Hr:Min) (MHz) 19 January 2008 05:00 06:00 6.7925 06:00 07:00 7.4075 20 January 2008 06:30 07:30 6.7925 07:30 08:30 7.4075 Ernie W8EH Trevor wrote: > Some real DX signals to listen out for on 6.7925 MHz and 7.4075 MHz. > Note one part of the text says Jan 18/19th but when times are specified the > 19th and 20th are given. Could there be a typo here ? anyone know ? > > ARR report > http://www.arrl.org/?artid=7958 > > 73 Trevor M5AKA > --------------- _____________________________________________________________ Click here for a free directory of employee development and training solutions. http://thirdpartyoffers.netzero.net/TGL2221/fc/Ioyw6i4s28jsSbqvMqji812cnCmZ…

2 1

Tnx for Echolink nodes
by Bob Cutter 18 Jan '08

18 Jan '08

Thanks to all the other stations who linked to the overloaded main node, KG4YZY. It made it possible for a lot more of us to listen. 73, Bob KI0G 617 ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

1 0

AO7B
by k3szh＠netzero.net 18 Jan '08

18 Jan '08

It may not be a great feat,but for me working Fabio PY4AJ grid GH70un on AO7B on Jan.17,2008 at 23:35 utc was.Since he was outside my foot print and no schedule.Like they say if you can hear them, you can work them. My next goal and it's a long shot working Mak SV1BSX maybe a bigger antenna again? 73 Joe AMSAT 3788 since 1976 _____________________________________________________________ Click for free information on accounting careers, $150/hour potential. http://thirdpartyoffers.netzero.net/TGL2221/fc/Ioyw6i4s2cOefO1TNoOYZk1pstjz…

1 0

Re: Lunar Short Wave echo experiment looking for Listener reports
by Trevor 18 Jan '08

18 Jan '08

Thanks Ernie and Ed, I couldn't find that Moonbounce page when I first looked on the HAARP site. 73 Trevor M5AKA ___________________________________________________________ Support the World Aids Awareness campaign this month with Yahoo! For Good http://uk.promotions.yahoo.com/forgood/

1 0

Lunar Short Wave echo experiment looking for Listener reports
by Trevor 18 Jan '08

18 Jan '08

Some real DX signals to listen out for on 6.7925 MHz and 7.4075 MHz. Note one part of the text says Jan 18/19th but when times are specified the 19th and 20th are given. Could there be a typo here ? anyone know ? ARR report http://www.arrl.org/?artid=7958 73 Trevor M5AKA --------------- Daily Amateur Radio RSS News: http://www.southgatearc.org/ Email your news items to: editor at southgatearc.org News On Your Website: http://www.southgatearc.org/rss/index.htm News On Your PC: http://www.southgatearc.org/rss/newsreader.htm Upload Your News: http://www.southgatearc.org/news/your_news.htm --------------- __________________________________________________________ Sent from Yahoo! Mail - a smarter inbox http://uk.mail.yahoo.com

2 1

FL amsat net alternative echolink node
by Andrew Glasbrenner 17 Jan '08

17 Jan '08

If KG4YZY echolink is busy, try N4HHA 44310 or the live stream on www.ni4ce.org. back to net control duties... 73, Drew KO4MA

1 0

QUAKESAT
by Andrew Rich 17 Jan '08

17 Jan '08

Anyone working quakesat ? Seems to have a high power out ? 7 watts ? ---------------------------------------------------------------------------- Andrew Rich VK4TEC vk4tec(a)people.net.au http://www.tech-software.net

1 0

sequencer switching
by w7lrd＠comcast.net 17 Jan '08

17 Jan '08

G'morning My 1.2Ghz system is progressing nicely. I am currently working on a sequencer for "switching around" my amp. I have several good quality coax relays. Are some preferred over others? A couple I have require reversing polarity to switch them back. This is requiring more circuitry and complexity. Are these latching relays necessary? I'm seeing several relays available on ebay. The time spent in transmit is miniscule compared to receive. 73 Bob W7LRD Seattle "if this were easy, everyone would be doing it"

2 1