Satellite Transmission Characteristics in Finland. By Luke Kindelin

1.What have you learned about telecommunications in Finland? Which wireless technologies do they use to connect the whole country? 

To answer this prompt, I was planning on writing about wireless telephony and Finland’s high coverage area per capita versus the United States. Upon further investigation and asking the natives in casual conversation, it soon became clear that this was an unfair comparison because of how far behind Europe the United States are because of land mass and regulatory style.

My cursory look at Finnish antenna systems in real life led me to an accidental discovery that I hadn’t thought about; Satellite television. This came about when I traveled to Vaasa in the middle of Finland and happened to stumble across a satellite tv antenna that was pointed very near horizontal with the ground. This peaked my interest, and led me to look further into satellite tv coverage in far northern Europe.

Three main providers of satellite television are present in the Finnish market, Sky TV (which also covers the rest of Europe), Canal Digital and ViaSat. The latter two of which are Finnish programming only via leased space on existing Europe-only satellites. Because of the extreme northern-ness of Finland, especially Finnish Lapland, this makes it an attractive environment for studying path loss because of the additional distance required for transmission. The low angle off the horizon that these satellites are parked at in equatorial orbit are yet another factor that comes into play during power measurements as the signal must propagate through a larger “slice” of the atmosphere (think of slicing an orange in half, vs cutting the just the skin off the top; you’ll get a lot more skin to bite through the second way).

Like most satellite tv broadcasters, the transmitting antennas are parked 35000km high in geosynchronous equatorial orbit, directly above the equator in a fixed position. This is so customers can point their dish once, and stay in contact without any further effort. A key downside to these satellite downlinks are their restricted power characteristics based on their power supplies – solar panels that have relatively long on-off time.

Based on the satellite system Astra 3A, currently in use by both Canal Digital and ViaSat and designed for European usage, the mean distance to ground is 44644km in Helsinki, Finland, 34.6° above the horizon and 45455km in Kaamanen, in the Finnish Lapland, 26.8° above the horizon. The satellite transmission characteristics are as follows: 11.75GHz transmission frequency, 36MHz of bandwidth, a 30-watt transmitter Pt, and EIRP of 52dBw.

Three locations for free space path loss are laid out below. With a nominal receiver gain of 37.50 dB(typical for this market), calculations were made for three locations, the Equator, Helsinki, and Kaamanen:

Pr(distance) =PtGtGrλ^2/(4π)d^2

Pr(Equator) = (52dBw)+(37.5dB)+20Log₁₀(0.025531m/((4π)(35000000m)))

Pr(Equator) = -115.22dBw

Pr(Helsinki) = (52dBw)+(37.5dB)+20Log₁₀(0.025531m/((4π)(44644000m)))

Pr(Helsinki) = -117.34dBw

Pr(Lapland) = (52dBw)+(37.5dB)+20Log₁₀(0.025531m/((4π)(45455000m))) 

Pr(Lapland) = -117.49dBw

As we can easily see from these results, the power is nearly half that which is present at the equator, and unless this is considered when choosing an appropriate ground based satellite dish, low power values will be seen. Conversely, the difference from the edges of the south to north of Finland are actually quite near, and so a standardized dish will give nearly the same result no matter where in the country it is placed. This is the case for both Finnish providers, Canal Digital and ViaSat. Sky TV, which is present in the rest of Europe, has a larger diameter dish specifically tuned for countries this far north.