Satellite update

  Thanks go out to N0AGI (Nagi) for forwarding information about the new PSAT APRS/PSK31 satellite. For a while this weekend, KD0KZE had a gateway set up in Circle Pines to receive signals from the five APRS satellites on 145.825 simplex. KE0NA (Dave) is also experimenting with using 145.825 as the priority channel on his RX-only 145.390 gateway (KE0NA-11) in NE Mpls, but so far has gated no packets from the satellites. Nagi is the only person that has had any luck with this effort, to my knowledge. 

  Here is the text of the announcement from Bob Bruninga (WB4APR), who is the guy that pretty much invented APRS: 

I forgot to post here on APRSSIG the exciting success of the new APRS satellite, PSAT including its PSK31 Transponder allowing both APRS digipeating and PSK-31 multi-user communications.  Launched on 20 May.  See http://aprs.org/psat.html

What we need is more IGates bringing the downlink into the APRS-IS.  So, if you have a spare radio and can run another IGate instance, we invite you to tune it to 145.825.  The satellite signal is weak with only 350 mW, but when it is over your station, it is 10 dB stronger than on the horizon.  A good OSCAR class station has no problems…

I don’t expect anyone to wear out their rotators tracking PSAT, no, just a simple vertical over a ground plane will do.  Either a 19” vertical whip over a large 6 foot square ground plane or even better, a 58” vertical monopole over the ground plane.  This ¾ wavelength vertical has almost 7 dBi gain and will pick up signals during the few minutes overhead.  If we have enough of these simple omni monitoring stations/igates then the fact that they only receive near overhead is made up for by the larger number of such simple stations.

The larger ground plane (as large as possible) gets closer to the theoretical 3 dB gain of a reflector.

   As Bob mentioned, the PSAT satellite also has a transponder for the PSK31 digital mode -- and it operates on ten metres! 

  You can listen to the PSAT on 435.350 using FM and transmit on 28.120 SSB. There's more information on this uplink/downlink scheme here. Using ten metres will minimise the Doppler shift. Per the site, "The Doppler on the 10m band is about 15 times less than on 70 cm and changes at a rate between about 1 to 5 Hz per second". Also, it's claimed that a vertical monopole will work well enough to reach the satellite, so you don't need to wrangle big 10M beams. This might be an excellent use for 1/4-wave ground-plane antennae, as the higher radiation angle (take-off) works in your favour.

  The problem is that this arrangement only works well with full duplex. I'm thinking that I can use a UHF HT to receive the signal and use my Android phone's "Droid PSK" app to decode it. Meanwhile, my FT-897 would transmit using a SignaLink TNC. 

  PSK31 signals are only slightly wider in bandwidth than CW, and up to thirty simultaneous QSOs can be carried by the transponder. So, it's not like an FM satellite where only one person at a time can use it. This might be an opportune time to finally set your rig up for digital modes.

  You can check out the predicted passes for the PSAT here. Select "PSAT" from the drop-down menu. Remember to subtract five hours for Central Dayight Time, and realise that this may change the day. There are, of course, apps that can run on your phone and even alert you to upcoming passes. 

  In general terms, it looks as if there's regularly a pass around midday (here in Minneapolis) that's reasonably high and at least ten minutes long. There are also some very nice passes around 9 AM. Nothing in the evening. 

  Aside from the PSAT, a new FM satellite will be launched in late August of this year. This is the Fox 1, and some basic info on it can be found here. It's expected to have a larger "footprint" than the SO-50 satellite that most are familiar with, and the uplink/downlink frequencies are reversed from the SO-50. For the SO-50, you transmit on 2M and listen on UHF. For the Fox 1, you transmit on UHF (435.180 67.0 PL) and listen on two metres (145.980 center). 

  More Fox satellites are expected to be put into orbit, with at least one being digital. 

  Don't forget the FUNCube-1 (AO-73), if you have a dual-band radio that can handle SSB. The transponder is only working at night, and we have regular passes here sometime between 10 and midnight that are decently high and about twelve minutes long. For this satellite, you transmit on UHF LSB (lower sideband) around 435.140 and listen on 2M USB around 145.960 -- adjusting for Doppler shift. 

  The FUNCube might be interesting to try on Field Day, when other bands close for the evening. 

  This summer, the EO-79 will turn on its transponder and we will have yet another SSB satellite available. 

  Just listening to satellites can be fun, and gives you valuable practice in spotting and tracking them so that you'll be ready when you get a chance to transmit. And using packet FM (APRS) to reach an APRS satellite is pretty easy, without worrying about reception, offsets, and mode.