Saturday, October 25, 2014

Ultimate QRP DX: 4M Moon Mission!

China's recent effort to send a spacecraft to the moon has had a nice benefit for VHF ham radio.  Attached to the last stage rocket is a radio transponder developed by LX0OHB, that outputs a 1-watt signal in JT65B mode on 145.980 MHz USB.  The transponder sends repeated callsigns, messages, voltages, temperatures, and has an on-board experiment monitoring space radiation levels.  More information is at the 4M website.  The spacecraft was launched 10/23/2014, will briefly orbit the moon on 10/27, and then will return back to earth on 10/28.

I was very surprised to find out that my small EME station (two 7-element VHF yagis and a preamp at the mast) was more than capable of reliably decoding the telemetry from this spacecraft!  Capturing a QRP (one watt) signal from over 300,000 km away is pretty remarkable.  I use exactly the same setup as I do for EME, and also run the 4M Data Delivery Client to automatically send the received packets from the 4M back to their central data warehouse.  Seems at this point in time there are around 30 stations providing the warehouse with live feeds of packets coming down from 4M as it heads towards the moon!

The keplerian elements for tracking 4M seem are near the bottom of this post: and the current position of the spacecraft is shown on their webpage at (for doublechecking your own tracking software).

Monday, June 30, 2014

ISS Contact - Field Day 2014

In the days prior to the ARRL 2014 Field Day, there were postings on the internet indicating that crew on board the International Space Station (ISS) might be making voice contacts for the event.  How exciting!

To get ready, I set my home satellite station to run on emergency (battery and inverter) power, and waited for the first pass of the ISS at 11:11am local time here.  Sure enough, just after AOS, at around 11:12am I could hear FM signals coming through the noise on the 145.800 FM downlink.  A minute or two later and the ISS (using call NA1SS) was full quieting!  I tried to make a QSO, and they came right back, woohoo!  I had a voice recorder running at the time, here's the audio from the quick contact:

In the first pass at 1811z, I heard NA1SS copy NU6S, K6LCS, KB5WIA, W6TO, WD9EWK, KO6TS, and a few more.  An hour and a half later (1949z), the ISS came by on a second pass (this time to the north), and I heard them copy quite a few more stations:  K6GHA, KJ6ZL, KE1B, K6XX, W6CKL, V7?LGY, WB6NOA, W6HQ, W6HTY, N7OY, VA7VW, N7OY a second time, WA2TND, VE7N, W6NN, KE6IWM, KJ6PFW, VE6EGN, VA7GAB, and AC0RA.  At that point (1957z) the ISS went LOS, but were still making contacts.  Links to the the full audio recordings from both passes are here:

ISS Field Day 2014 - Saturday 1811z
ISS Field Day 2014 - Saturday 1949z

All in all, a pretty exciting experience!  It's not often I get a chance to make contact with someone in orbit!