Today is Cosmonautics Day in Russia, a holiday that celebrates the first manned space flight made on April 12, 1961 by the 27-year-old Soviet cosmonaut Yuri Gagarin. Gagarin circled the Earth for 1 hour and 48 minutes aboard the Vostok 1 spacecraft. Coincidentally, it is also the anniversary of the first Space Shuttle launch that occurred 20 years after the historic Vostok flight.
Tonight on what is known as Yuri’s Night cosmonauts on board the International Space Station made contact with St Petersburg in Russia.
The pass of the ISS over the UK starting aat 20:28 UTC was extremely bright and visible despite the cloudy sky and as it passed into Eastern Europe the contact began on 145.800MHz. I managed to capture some very scratchy audio with my FUNCube Dongle and the loft antenna.
In my quest to get better reception of the Russian navigation satellites I have installed the Satellite AR application on my Orange San Francisco Android phone. Up to now I have used a simple compass and a pass prediction to work out where the satellite will appear and how I think it will travel across the sky. Then after having acquired the signal fettling the antenna to get the best signal. While it has given me good results I wasn’t convinced I was getting the best signal I could.
The serious method of doing satellite tracking is to use a motorised azimuth antenna rotor connected to a PC running some prediction software. The commercial solutions are hideous expensive and while there are plenty of home-brew solutions available it would still mean a lot of expense in terms of time and money, so I looked for an alternative method.
Then I discovered this brilliant Android app! I used it for the first time late last Sunday evening when it was dark and was suitably impressed, so had a proper attempt in the fading daylight today and was able to take a few photos.
The AR stands for augmented reality and what you get is a view of the sky through the phones camera and overlaid are the positions of any satellites in view. The application uses the phones GPS, compass and accelerometers to work out where the camera is pointing, so you get to see the satellite as if it were visible in the sky. It is really quite spooky!.
I selected the Russian LEO Satellites option for a pass this afternoon and using a couple of elastic bands to lash the phone on to the antenna post I could then point the antenna directly at where the satellite was supposed to be. The satellite today being COSMOS 2429 on 150.030MHz. The main thing I seem to have been doing wrong was while I had the antenna point in the correct bearing I had the elevation far too low. I needed to be pointing it much higher up in the sky.
I was able to got some excellent audio, with the signal still booming in when it had disappeared off the display. I have enclosed a small extract below, note some of the signal fading is because I was trying to take the photos while holding the antenna in my other arm… it gets quite heavy!
I brought my phone back in January for the pricey sum of £80. While not the most powerful Android around, only having version 2.1 of the operating system and is prone to crashes and resets it is probably one of the best purchases I have ever made, it is even better now I can use it to chase down signals!
This weekend I was supposed to be off to North Yorkshire for a weekend dog agility event. Unfortunately due to a family emergency we were forced to change plans. So yesterday I found my self at home and in between doing some much needed odd jobs I had the chance to get out the 2 meter YAGI and capture a couple of passes of those Russian navigation satellites I blogged about last week.
Each pass lasted the best part of 15 minutes from the first faint signal acquisition to finally losing it as it sped out of range. Below is an except from the first pass at around 10:00 UTC. The signal is clear and the different tones used can be clearly distinguished. These captures should prove useful for testing any decoder.
Russian Parus Satellite 27-11-2011 by nerdsville It is quite fun standing with the antenna and pointing in the direction where I expecting the satellite to appear and then once the signal is acquired then fettling it during the pass to maintain the best signal strength.
Not sure what my neighbours are making of all these antics, perhaps I should try to find that extension cable so I can use headphones to monitor the pass rather than letting it blast out the laptop speaker! It must look odd me standing there waving an huge antenna about and receiving strange foreign voices (from the ARISSat-1 satellite) and now this weird ‘morse code’
At the weekend I attended a dog agility show in the depths of Cambridgeshire, there is always a lot of waiting around in between runs and so I was sat in the foggy car park. To pass the time I had taken along my PRO-26 scanner. I monitored amateurs on GB3PY and GB3OV chatting about the tropospheric ‘lift’ they were experiencing, found a few taxi firms complaining about the fog, some hospital paging but it was pretty boring.
I was idly scanning around when I happened across a strange signal on 149.9375Mhz. I could hear a definite doppler shift in the tones so it was a satellite. Checking my pretty useless 9th Edition UK Scanning Directory the frequency was identified as being in the Russian radio navigation and satellite beacon band.
Over the last couple of days I have done some research and discovered it is the Russian Parus Navigation System which dates back to the 1970s. The transmission was in fact on 149.940Mhz but I had the scanner set on 12.5kHz stepping. I have been trying to track and capture more of the signals but had been hampered by a persistent source of interference at home, but did get some audio
These satellites are very easy to receive on a handheld scanner though obviously you’ll get better results on an external antenna. The tx power is about 10 watts (+40 dBm) so with a 140dB path loss on an overhead pass (alt = 1000 km) you’ll get about a microvolt in a zero-gain antenna, which is enough to hear.
The VHF frequency carries the time data and orbital parameters for the current and other satellites. There is a second transmission on around 400MHz- its in an 3:8 ratio with the VHF carrier frequency. This is unmodulated- i.e cw. It is used to measure the Doppler shift, to determine when the satellite is dead abeam the observer. The transmitted time, and the orbital data, tell you where the satellite was in the sky when that happened- or, put another way, if you know where the satellite is relative to you, then you know where you are- well, you’re somewhere on a line at right angles to the satellite’s track. You then wait for another satellite, and obtain another poition line- and where they cross, then bingo- that’s where you are. Hope that makes sense!
Parus could give you a fix in 1-2 hours; and had an accuracy of 100m anywhere on the earth’s surface. Okay that’s poor compared to GPS, but in the 1970’s it was revolutionary.
It isn’t just Doppler that determines the receiver bandwidth, although you do take it into account. Most satellites have a much higher FM deviation than a normal narrowband FM transmission- the NOAA met sats are about 19kHz deviation I think- and these nav sats are higher too, but not that much. But for decoding, you do need to resolve the 7kHz second markers which a narrow filter won’t easily do.
There is also a lot of information about the Soviet space program on the Zarya website
I would like to decode these signals at some point, providing I can sort out reception. I have found a number of historical guides and projects in addition to the articles linked to in the thread above.