Silent APRS ISS Pass 7-16-2011

The ISS made its scheduled pass yesterday afternoon around approx 3:30 here, and I and KD8BXP had arranged our schedules in hopes of making contact again via APRS on the ISS. As seen in our previous videos and blog posts I had received his message but I was just attempted to get a position digi through the ISS, so this time we were hoping to see if we could make a two contact during the pass. But this pass was silent, neither I nor KD8BXP heard any APRS traffic. At first I was wondering if the bldg I was parked next to at my part time job was blocking the ISS but from the path of the pass I knew it should be passing in open skyies and I was in the clear for most of the entire pass. But once I learned via Twitter that KD8BXP did not hear anything either then I knew it was not my location. I got on the computer and checked on site and saw that earlier passes had also been silent so it was determined that the APRS station was shut off. Guess I should have checked the site before attempting this QSO. But this is still all very new (and exciting) to me and still learning and experimenting but then that is one of many purposes and enjoyments of the Amateur Radio hobby.
Also the “mystery” behind the Visible and Invisible passes has been solved. Upon doing reading, KD8BXP determined that these tracking sites are more geared for people wanting to “SEE” the ISS and not “HEAR” like we are wanting to do. Thus the magnitude value also given in the tracking information. So now we know that when it says “Invisble” pass this does not mean invisible to RF. And now I understand why my previous casual attempts to hear the ISS failed because I was going strictly by the tracking info saying that the ISS was Visible or not and not looking at the actual Elevation (Azimuth) of the pass. But I have been now! In my searching I found another site that is strictly an ISS Tracking site at and KD8BXP shared this site with me as well which send you alerts based on your Twitter profile location.
I have set up alerts for several good passes for the next couple of days on the site. These are the following passes that I hope to make additional attempts:

July 18 – Pass Beginning at 15:09, Max at 15:14 – 62 degree pass
July 19 – Pass Beginning at 7:43, Max at 7:48 – 61 degree pass
July 19 – Pass Beginning at 14:11, Max at 14:16 – 52 degree pass
July 21 – Pass Beginning at 13:52, Max at 13:57 – 74 degree pass
July 22 – Pass Beginning at 6:26, Max at 6:31 – 71 degree pass (yes a little early but a good pass to try)

So hopefully during some of these passes the APRS station on the ISS will be active again. I will post more updates later on the results of these passes. Until then and hope everyone is having a good weekend – 73s!


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