posted 01-23-2016 08:51 PM               

Most of the time, the station is receiving/transmitting APRS packet communications. Occasionally, the astronauts on board will have scheduled contacts with schools or other organizations, and even less occasionally, they will make contact with amateur operators on the ground.

I was lucky enough to make a very brief contact with Doug Wheelock when he was on board the ISS in September of 2010.

The frequencies used are in the VHF range, so your scanner should be able to pick them up.

posted 01-24-2016 04:32 PM               

Just as an aside, the 145.800 frequency generally is for voice contacts, which are pretty rare.

You'll hear packet on 145.825 (a brief screeching sound, if you're not familiar with the transmssions), and will need some sort of decoding program to read them. Look up UISS and AGW packet engine for a pair of applications that will let you do this. You'll need to feed the sound from your scanner to the computer to get it to read. Also, the frequencies will change slightly due to doppler shift during the pass. Start at about 145.830 at the beginning of the pass, 145.825 during the middle and 145.820 toward the end of the pass.

As for the QSL cards, I believe you can submit a reception report as a SWL to obtain a card. If you're able to successfully decode the packet transmissions, then you can send a printout of what you received. For other transmissions, such as school contacts, you would just need to supply the usual date/time, frequency, who the contacts were between, brief description of what you heard, etc.

posted 01-25-2016 01:03 PM               

Or, you can listen to the "quality" of the signal. If you notice it's starting to be weaker or having more static, switch to the next lower frequency on your scanner.

It will be good to begin noticing the changes in the static, as you noted in your message about the last pass. During passes of other ham-radio related satellites that are in use with voice communications, one will notice a "quieting" that's occurring as the satellite comes into range.

Generally, for the ISS, you'll want to stay within the 145.820 to 145.830 frequency range. If you get a good pass, you can go down as low as 145.815 to continue hearing the signal, but anything lower than this usually won't produce any signal. With this said, however, be sure to monitor the 145.800 frequency (again, you can adjust it for doppler — 145.805 at the beginning, 145.800 at mid-pass, and 145.795 toward the end of the pass), especially if you don't hear any packet transmissions around 145.825 — there may be an astronaut voice communication in progress. Remember, these are pretty rare. Unless it's a schedule school contact, the only time that astronauts would have to use the radio is generally right before their sleep period or just after their waking up. Their workday is based on GMT/UTC time.