Hi Mark,

Trying to upload a 19kB image today, after checking well all the settings per your mail below, last pass was a few minutes ago and 19.4% uploaded. Leaving the station on automatic and see how it goes through.

Actually to note that I was putting too much power out previously and this morning (after reducing it) I got your message (20/03/2021) through the bird, also from others (thank you guys), text is working fine, great. Wish to experiment with the images as it is a great way for motivating students to satellites, space and engineering. 

Send also a text message today which was uploaded successfully.

Thanks and I will continue to experiment on the images.

73


Jean Marc (3B8DU0


On Mar 26, 2021, at 10:59 PM, Mark L. Hammond <marklhammond@gmail.com> wrote:

Chris lays it out well!  My first thoughts:

1-transmitter desensing receiver Turn down the power, use filters to clean up, separate antennas
2-software issue.  If using PSGS, get the latest version!
3-here's a little trick.  I find uplinking better at 145.841 MHz

73,

Mark L. Hammond [N8MH]
AMSAT Director and Command Station



On Fri, Mar 26, 2021 at 2:52 PM Chris Thompson <chrisethompson@gmail.com> wrote:
Stephen,

For an upload the spacecraft remembers how far you got through the upload process.  It stores the file offset for the last byte that it received.  When you login and request to upload of the same file on the next pass it tells you the offset number to start from.  The ground station software should then begin uploading from that point.  So in theory it should complete over several passes as needed.

One common issue is having too much uplink power so that you can't receive while uplinking.  The full duplex nature of the channel means that you need to be able to receive responses from the spacecraft when your receiver might be desensitized.  So make sure either your antennae are isolated enough or you are not using too much power.  10 -25 watts should be sufficient into a yagi.

But tell us a bit more about the setup you are using,  Which software, tnc, radio, antenna and we can try to help.

73
Chris

73
Chris

On Fri, Mar 26, 2021 at 2:35 PM <sjdevience@gmail.com> wrote:
I've successfully been working the Falconsat-3 PBBS, downloading files and uploading text messages. However, when I try to upload a bigger file, like an image, I can't get it to complete even across a number of passes. I've been trying to upload a 20 kB jpeg, but the most I can get uploaded is around 18%. Some passes it doesn't start to upload anything, even though I'm capturing other data coming down and it acknowledges my callsign on the system. After a few unsuccessful passes, it starts to upload again from 0%.

I'm trying to figure out which part of the link is the problem. I switch from my TH-D72 to my TM-V710 so that the uplink is 50W, so maybe my downlink is not consistent enough to hold the connection? My UHF side is only 5 elements, so maybe not as much gain as others are using.

Does it restart the upload from scratch because of how the satellite software is written or is it something with the ground station software?

Any advice would be appreciated.

-Stephen
N8URE

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