Mar 14 2012

How to work the SSB amateur radio satellites such as VO-52

The SSB/CW linear transponder amateur radio satellites such as VO-52 are great fun to work but the technique required is different to that used for the FM satellites.

Simon 2E0HTS has produced a video showing how to make contacts through VO-52.

Using a home-made 10 element 435 and IO Loop for 145MHz, with a Yaesu FT-847. Simon – 2E0HTS, adjusts his (uplink) transmitted signal to correct the Doppler of the received (downlink) frequency whilst talking to fellow Ham operators around Europe. Thanks to the stations worked via the VO-52 satellite which were SP9FPP, PD0HF & SP6DCO.

Watch How To Make A VO-52 SAT QSO

Most linear satellites use what are known as ‘Inverting Transponders’ to reduce the Doppler shift. You transmit lower sideband (LSB) on the uplink and it appears as upper sideband (USB) on the downlink.

When working through linear transponders use as little power as possible, this will help extend the lifetime of the transponder and satellite batteries. As a guide ensure your downlink signal is no stronger than the satellite beacon. Low duty cycle modes such as SSB and CW are recommended.

The band plan for linear satellite downlinks is similar to what you’d expect on the HF bands with CW operation in the lower part of the downlink and SSB in the rest. Current satellite status can be seen at http://oscar.dcarr.org/

Since this video was made VO-52 has changed over to its Dutch SSB/CW transponder and now uses these frequencies:
Uplink:         435.2250 – 435.2750 MHz SSB/CW
Downlink:     145.9250 – 145.8750 MHz SSB/CW
Beacon:       145.8600 MHz CW

John Heath G7HIA wrote about operating through VO-52 in his article ‘Getting started on amateur radio satellites’ that was published by the Radio Society of Great Britain in the March 2007 edition of RadCom. Download the article at https://ukamsat.files.wordpress.com/2011/05/satellites_radcom_mar07.pdf
Copyright 2007 Radio Society of Great Britain. For personal use only – no copying, reprinting or distribution without written permission from the RSGB.

David A Palmer, KB5WIA, has written an article “Twins! A Backpack-Portable Full Duplex Satellite Station with Dual FT-817ND’s” that can be seen at http://kb5wia.blogspot.com/2010/10/satellite-portable-station.html

SimpleSatLookDown satellite tracking software http://www.uk.amsat.org/?p=8217

Jan 30 2012

Working the FM-Sat SO-50

Saudisat SO-50

Simon 2E0HTS has released a video that shows him making contacts via the amateur radio satellite SO-50.

This satellite carries an FM transponder that receives signals on 145.850 MHz and retransmits them on 436.795 MHz (+/- 10 kHz Doppler shift). Operation is a little more complex that some other satellites since the transponder needs to initially be activated by a CTCSS (PL) tone of 74.4 Hz which starts a 10 minute timer and then a 67 Hz tone is used for the contact.

The order of operation is: (allow for Doppler as necessary):
1) Transmit on 145.850 MHz with a tone of 74.4 Hz to arm the 10 minute timer on board the spacecraft.
2) Now transmit on 145.850 MHz (FM Voice) using 67.0 Hz within the 10 minute window.
3) Sending the 74.4 Hz tone again within the 10 minute window will reset the 10 minute timer.

You can set the memory channels in your handheld as follows:
Ch     TX            RX            CTCSS
1   145.850   Timer Reset 74.4 Hz
2   145.850    436.805       67 Hz
3    145.850    436.800     67 Hz
4    145.850    436.795       67 Hz
5     145.850    436.790       67 Hz
6   145.850    436.785       67 Hz
At the start of the pass tune to 436.805 and then decrease the frequency during the 10+ minute pass.

Watch Simon 2E0HTS working CT2GOY, F0FVK, SP5XSD & EA6SW/portable 6, via SAUDISAT 1C SO-50