Saorsat

Key takeaways

Saorsat belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Saorsat to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Saorsat from memory before moving on to harder problems.

Reference excerpt

Saorsat ( SAIR-sat; a portmanteau of the Irish word Saor, meaning “free”, and a shortening of the word “satellite”) is a free-to-air satellite service in Ireland. The service launched on 3 May 2012. It was designed to provide TV service to a final 1-2% of the Irish population unable to receive other signals.

Overview The RTÉ Network Limited (RTÉNL) analogue terrestrial television (ATT) network was never capable of providing 100% population coverage in Ireland. Prior to the digital switchover, ATT population coverage amounted to 98% for RTÉ One and RTÉ Two, 95% for TG4 and 85% for TV3. Saorview DTT faces a similar difficulty. Broadcasting the channels unencrypted from the Astra 2 satellites at 28° East was not considered an option due to its large footprint covering the UK, France and many other countries. Irish broadcasters acquire rights on the basis that programming is broadcast solely to Irish audiences (i.e. some 4.5 million people) and not to approximately 100 million people within the Astra footprint. The Board of RTÉ approved the Saorsat approach developed by RTÉNL from early 2010 to enable the 1-2% of Irish households not covered by Saorview to access free-to-air digital television services. RTÉ submitted a revised DTT plan including the FTA satellite option to the Department of Communications in mid-June 2010 for approval. RTÉ publicly announced at an Oireachtas Joint Committee on Communications discussion in mid July 2010 that a free-to-air satellite service, called Saorsat, would be offered to complement the terrestrial DTT service. The satellite option is a narrow-band satellite operating in the Ka band as opposed to the normal DTH Ku band (which Sky and Freesat use), with a spot beam being dedicated exclusively to Ireland which will also provide coverage throughout Northern Ireland. The spot beam with frequency reuse means reception in most of Britain and continental Europe is not possible. RTÉ states that the chosen satellite option will cost approximately €1.5 million per year. RTÉ said that the combined offering was designed to be the most cost-effective solution for viewers and broadcasters, to offer for the first time 100% coverage of free-to-air public service television services in the Republic of Ireland and to provide full national back-up coverage on satellite in the event of an emergency or catastrophic failure of the DTT system. Approval for the revised National DTT plan and Saorsat satellite service was announced by the Minister for Communications at the end of July 2010. RTÉ did not confirm that Saorsat would broadcast from KA-SAT until February 2012. There is no other current satellite solution with a spot covering only Ireland. Strictly speaking the spot covers a large part of Wales, South West England and the Hebrides of Scotland, but the frequency and polarisation reuse scheme means that no matter how big a dish is used, interference from a similar spot over northern France would prevent reception much beyond terrestrial overspill into Wales. Reception over all of Northern Ireland may be possible. At least a Ka band LNB, dish and DVB-S2 receiver will be required to receive Saorsat. Reception of Sky or Freesat from the Astra 2 satellites at 28° East will require a separate feed and a DiSEqC or Multiswitch with a Diseqc compatible receiver. 2rn state that a dish of 1 metre (39 in) diameter is required for reception of Saorsat on the island of Ireland. Saorview is really the RTÉ NL name for the public service broadcaster multiplexes. According to the RTÉ submission to Oireachtas committee the proposed RTÉ NL operated Saorsat is expected to be a copy of Saorview. As of 28 May 2011 the test loop used the same total bitrate as the terrestrial DTT mux. A dual feed dish (with Ku and Ka LNBFs) or a separate second boxed Cassegrain "dish" is required with a Diseqc switch and HD DVB-S2 tuner to have Freesat and Saorsat on the same set-box or IDTV receiver. RTÉ has made it clear that Saorview/Saorsat will not carry television services from outside the Republic of Ireland and that people in Ireland should seek other digital services to view additional channels other than what is offered. In contrast, the Irish government has already signed an agreement to permit retransmission of BBC channels. Testing started in May 2011 on KA-SAT 9E, 20.185 GHz DVB-S2 SR25000 FEC 1/2 with pre-recorded material.

Technical The parameters are:

Ka-Sat 9A @ 9°E 20192 MHz, Left Circular Polarisation DVB-S2 QPSK 12500 Symbol rate 5/6 FEC Irish spot (there are 83 spots on Ka-Sat) It is likely a second carrier will be used to carry material on the second Terrestrial PSB mux. The second DTT mux is running with no services on many sites and there is a second DVB-S2 carrier in the same part of the Ku band for Internet Services using SR 50000 with adaptive modulation and FEC. Any DVB-S2 HD satellite receiver can in theory be used to receive Saorsat as the Ka band LNBF converts to a regular IF in the 950 MHz to 2,100 MHz band. If the receiver does not have a setting for the Ka band LNBF Lo, then a "fake" frequency 10.765 vertical rather than the real 20.185 may be entered when using the Inverto LNB with local oscillator of 21.2. To receive Freesat/Sky or other services alongside Saorsat, a dual- or multi-feed type dish or two dishes are needed with either one or more DiSEqC switches or a multi-switch. On a multi-switch the Saorsat LNB needs to be connected to vertical 0 kHz port only. The other 3 input ports are left unused. Even with the narrow beam, reception is available in the western parts of Scotland, England and Wales with an LNBF on an 80 cm (31 in) dish pointed at Eutelsat 9E.

Channels

Television Saorsat only broadcasts channels from public broadcasters (7 TV and all radio services from RTÉ + Oireachtas TV and TG4). Virgin Media One, Virgin Media Two, Virgin Media Three, Virgin Media Four, Challenge TV, Sky News, UCB Ireland and Radio Maria Ireland which are available on Saorview are not broadcast on Saorsat. Saorsat channels may be sorted in various ways depending on device as it does not use LCNs. Therefore, the service IDs are listed instead.

SIDs 5106, 5119 and 5120 are test services which may not be visible on some receivers.

Radio

See also Television in the Republic of Ireland RTÉ Network Limited Saorview

References

External links List of channels on Saorsat (Ireland)

Worked examples

Example 1 — a first encounter with Saorsat

Start with the simplest possible case. Write down what Saorsat claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Saorsat before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Saorsat ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Saorsat

In research: Saorsat appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Saorsat in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Saorsat is common in secondary-school and first-year university syllabi. It links to neighbouring topics Satellite television, so understanding it makes those chapters shorter.
In everyday life: Look for Saorsat outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Saorsat in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Saorsat means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Saorsat out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Saorsat in simple terms?

Saorsat ( SAIR-sat; a portmanteau of the Irish word Saor, meaning “free”, and a shortening of the word “satellite”) is a free-to-air satellite service in Ireland. The service launched on 3 May 2012.

Why does Saorsat matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Saorsat?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Saorsat.