Archive for the ‘satellites’ Category

FUNcube Dongle – sold out in 49 seconds

The latest batch of 135 of Howard Long G6LVB’s FUNcube Dongle Pros sold out a few hours ago in less than a minute!

The FUNcube Dongle Pro is a tiny SDR receiver for the frequency range 64 to 1,700MHz. It’s the “ground segment” of the AMSAT-UK FUNcube satellite project.

FUNcube Dongle Pro

FUNcube Dongle Pro

The best source of information about what to do with the FUNcube dongle and how to get hold of one is the Yahoogroup. Howard is active on the list and the main website and is quick to join the discussion and respond to all manner of queries.

The FUNcube Yahoogroup page explains the background and aim to the project:

AMSAT-UK’s FUNcube is an educational single cubesat project with the goal of enthusing and educating young people about radio, space, physics and electronics.

It will support the educational Science, Technology, Engineering and Maths (STEM) initiatives and provide an additional resource for the GB4FUN Mobile Communications Centre.

The target audience consists of primary and secondary school pupils and FUNcube will feature a 145 MHz telemetry beacon that will provide a strong signal for the pupils to receive.

… FUNcube will carry a UHF to VHF linear transponder that will have up to 1 watt and which can be used by Radio Amateurs worldwide for SSB and CW communications.
Measuring just 10 x 10 x 10 cm, and with a mass of less than 1kg, it will be the smallest ever satellite to carry a linear transponder and the choice of frequencies will enable Radio Amateurs to use their existing VO-52, DO-64, HO68 and similar stations.

Howard seems to be producing and selling the Dongles at an amazing rate. But on the basis of this recent post “What do 500 dongles look like?“ there are at least another 360-odd on the production line.

NASA seeks help tracking satellite

NASA has asked amateur radio operators for help to determine if a recently launched satellite is operating. The NanoSail-D satellite was ejected automatically from the Fast Affordable Scientific and Technology Satellite, FASTSAT on Wednesday, January 19. NASA needs reports of the beacon telemetry to determine if it is operating correctly. The beacon signal is on 437.270MHz using standard AX.25 packet so APRS and packet radio operators with 70cm capability should be able to receive it.

Predictions for the satellite can be found here. Reception reports can be submitted here. Full text of the NASA press release here.

Work FM Satellites

I came across this website while reading a thread about the new Kenwood TH-D72. It claims to be the best website for current information about working FM satellites. It looks pretty good, but I really need to find the time to look through all the information. There’s a blog, too.

The trouble with this hobby is that there is so little time and so many interesting, challenging things you can do!

ISS success

Over the last few days Lynn, KJ4ERJ has been adding some very cool features to APRSISCE/32 which I’ve been helping to test. The ISS packet digipeater is still operating so as there were several good passes during the daytime I’ve been playing on it as well.

Today I managed to hear my own beacon repeated back by the space station, and this time it was also gated to the internet by TF8TTY so my call showed up on the map of stations heard through the ISS at ariss.net. I also managed to send a couple of messages through the bird. Tim, G4VXE was impressed to receive a greeting relayed via the space station. I also managed a two-way exchange with Marc, PD4U, which I think counts as an actual satellite contact.

Of course, whilst it’s fun to bounce radio waves off a satellite it isn’t a very practical method of communication. The ISS is the best QTH ever and it can hear all the activity on a frequency at the same time, so communication is only possible if not too many people use it. Lots of messages never get anywhere because they are sent at the same time as messages from other people which you can’t avoid transmitting over because you can’t hear them. The space station decodes only the strongest, so turning the power up improves your chances of success quite a bit. You can get through the ISS using a hand-held VX-8, but only at 4 o’clock in the morning when most sane people are asleep, unless you are incredibly lucky.

The new feature in APRSISCE that I mentioned is the ability to open separate windows so you can track individual stations at a more detailed mapping level. Lynn has called this Multi-Track(TM) and he thinks it will be very popular with emergency communications teams who will be able to see the entire area of the event in the main window and see exactly where individual team members are at the same time. It’s only available in the development (beta test) versions at the moment, though.

SatGates needed

The International Space Station has had its packet BBS / digipeater active for the last few days on 145.825MHz. Noel G4PEW asked me in a short APRS chat last night if I had tried listening to it. It had been a long time since I tried bouncing anything off the ISS as I got fed up with checking if the station was operational and finding that it wasn’t, so I decided to give it a go to break the monotony of nothing much happening terrestrially.

There was a good pass this afternoon and I received ten stations. I even received my own digipeated beacon and a copy of my reply to GM0ICF’s message to ALL. Unfortunately my own transmissions didn’t show up on the map and list of stations that worked through the ISS at ariss.net as it appears that I was the only station gating the signals from the space station to the internet, as the list above shows (you’ll need to click on it to enlarge it enough to be readable.)

I was using APRSIS32 to send the beacons and messages and I guess that it didn’t gate my digipeated packets as having been received via the ISS because it had already sent them to the internet direct at the time I sent them.

I’m surprised that none of the other stations sending signals up to the space station were gating them during the receive periods. We aren’t talking about important communications here, just seeing if it can be done, but it would be nice to have the proof of it afterwards. Come on, chaps, play the game and get your gateways working!

Bouncing off the ISS

There was recently a change of crew at the International Space Station and one result of that has been the reappearance after a long absence of the packet radio digipeater on 145.825MHz. When the Space Station passes over you can receive some very strong signals from it. I have decoded APRS beacons on a VX-8 handheld standing on a window sill inside the shack. But it is even better to use the main station, then you can see the positions of the stations you received on a map.

When using the ISS you need to use different settings to what you would use for terrestrial APRS. Digipeating, if enabled, must be turned off. You want to be connected to APRS-IS so you can gate received packets to the internet, but you don’t want to send anything received from the internet out to the ISS. You probably don’t want to display data from the internet on the map, to leave it clear to show those stations received by the radio. If you want to transmit through the ISS yourself you must also change the APRS path to “ARISS”.

After thinking that we really need an ISS option in APRSISCE/32 for this it occurred to me that all I needed to do was make a copy of the program in a new folder, then I could change the settings however I wanted without affecting the copy I use for terrestrial APRS. It worked fine. It was fun to see the stations heard via the satellite show up on the map, although when the map is zoomed out to cover such a large area the icons are hard to see. It was also amusing to see that the icon for the ISS’s own beacon was a bicycle. Perhaps someone should tell NASA!

After several abortive attempts to get my own beacon digipeated by the Space Station I set the transceiver to Narrow FM and got through on the first attempt using just 10W to my 300ohm ribbon cable Slim Jim in the attic. The proof is in the map of stations heard through the ISS at ariss.net.

Not a very useful activity perhaps, but fun to try.

A couple of setbacks

Computers and radio really don’t mix. I was trying to connect the FT-817 to the shack computer. I plugged the USB cables into the back of the PC, then as I lifted the cables vertical to feed them behind the shelf unit I heard the noise level on 2 metres come up quite clearly. I could probably reduce the noise using clip-on ferrites but any more noise than I already have is unwelcome. I think I might give up the computer altogether and go back to paper logging!

I also proved today that it isn’t possible to work satellites with indoor antennas. Yesterday I tried receiving AO-51 with the 3/4 wave vertical I made, but I got a readable signal for only a few seconds. Today I tried the 6 element Yagi I made a few weeks ago which received signals off the Moon when used outdoors. Pointing it at the satellite from inside the shack I again heard only a few seconds of signal from the satellite. I think there is just too much attenuation at 70cm to use indoor antennas, so satellite operation is out of the question.

I could probably combine the 6-element 70cm and the Moxon 2m antenna to make a portable hand held antenna for satellite use. But whilst it would be an interesting challenge to make a satellite contact using the FT-817 and a hand held antenna out of doors I had really hoped to be able to do it from inside the shack.


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