Saorview reception test using TV3 teletext

lawhec

I tried searching to see if this had been brought up before, but I can't seem to find any mention of it in the forum, so this might be useful...

*** THIS ONLY WORKS IF YOU ARE RECEIVING TV3 FROM AN ANALOGUE TERRESTRIAL TRANSMITTER - ALSO THIS WILL NOT WORK FOR VIEWERS FROM THE MT. LEINSTER TRANSMITTER DUE TO A DIFFERENT AERIAL GROUP BEING REQUIRED FOR DIGITAL TRANSMISSIONS. ALSO SEE DOWN AT THE BOTTOM FOR OTHER POSSIBLE SCENARIOS CONCERNING OTHER TRANSMITTERS ***

This is based on the Freeview reception test checker, designed in mind for those whom at present cannot get DTT reception either because current Freeview broadcasts are too weak to be received reliably, or that their relay does not currently carry them. In the case of Saorview, all transmitters currently broadcasting analogue TV3 are now broadcasting Saorview, although some may be broadcasting at reduced power and/or directional restrictions compared to when analogue transmissions are finally switched off. This test is intended for reception prediction when Saorview broadcasts at full power.

1. Go to TV3 on your television.

2. Press the 'Teletext' button on your remote control.

3. Go to page 284. You will see either rows of white blocks or a description page explaining the test.

If you see the page with white blocks, check to see if there are any individual blocks missing. You can ignore any rows that are missing. If there are any blocks missing, then Saorview reception, now or in the future, may be not be possible or not be reliable and your aerial for reception may require replacement.

The description page then says to try the same test on page 284 on Tecas TG4 - ignore this as it is currently unavailable.

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Some things to bear in mind for this reception test - In my case, the reception test is a big failure however Saorview reception is fine albeit with slightly less signal quality compared to Freeview reception 99.9% of the time. Passing the test should be an almost as good guarantee that you can get Saorview.

There are also some discrepancies in using the reception test from some transmitters aside from Mt. Leinster...

Three Rock - Analogue TV3 is on channel E35 while the current single Saorview multiplex is on E54 with the second multiplex planned for E58. Using the test from Three Rock may not give reliable results. However if you also receive TG4 on channel E55 and your reception is about the same as TV3, then the test may be more reliable.

Spur Hill - Analogue TV3 is on channel E60 while the current single Saorview multiplex is on E45 with the second multiplex planned for E49. Current aerials aligned for analogue TV reception at Spur Hill are likely to be UHF Group C/D designed for the reception of frequencies from E48 to E68; the second multiplex falls within this band, but not the current multiplex. Therefore reception may not be reliable especially in fringe areas. If the aerial requires replacing, a Group E aerial is recommended.

Maghera & Clermont Carn - Analogue TV3 is on channel E66 from both of these sites. Maghera currently broadcasts Saorview on E48 with a second multiplex planned for E55, while Clermont Carn currently broadcasts Saorview on E53 with a second multiplex planned for E57. While both digital and analogue transmission lie within UHF Group C/D aerials, the large frequency gap between TV3's analogue transmission and Saorview transmissions, the test may be slightly less reliable. It should also be worth remembering that currently there are heavy directional transmitting restrictions at Clermont Carn to the north of the site. In this case, the test should be used to predict future reception rather than current.

shinobi

Should they not have started this 'aerial check' prior to official launch?
If people were made aware of it prior to now it would have cut out a lot of the ambiguity around the aerials & requirements. TV3 displays analogue text test fine, but TG4 analogue text doesn't even scan to page 284 (Receiving Kippure).

Gerry Wicklow

lawhec wrote: »

......

The description page then says to try the same test on page 284 on Tecas TG4 - ignore this as it is currently unavailable.

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read again

rlogue

Nice idea in theory.

How is it going to work at transposer sites like Moville that do not carry analogue TV3 but do carry Saorview?

Antenna

This teletext test was workable in the UK, where pre-ASO DTT was usually a known proportion of analogue ERP.

that is not the case here, current DTT versus analogue coverage also differs greatly depending on transmitter

Spur Hill DTT is for example much greater power that the 'equivalent' analogue power (to eliminate need for relays in some places). The much greater power incidentally more than compensates for Ch45 being a bit 'out of group' for existing C/D (48-69) aerials.

for SOME transmitters it might be a valid test. Others, such as Spur Hill and 3 Rock, DTT seems to be fine with very poor analogue (with very jumbled teletext)

lawhec

rlogue wrote: »

Nice idea in theory.

How is it going to work at transposer sites like Moville that do not carry analogue TV3 but do carry Saorview?

Safer to carry it on TV3 where all such sites broadcasting carry Saorview, whereas this is not the case with TG4.

Antenna wrote: »

This teletext test was workable in the UK, where pre-ASO DTT was usually a known proportion of analogue ERP.

that is not the case here, current DTT versus analogue coverage also differs greatly depending on transmitter

Spur Hill DTT is for example much greater power that the 'equivalent' analogue power (to eliminate need for relays in some places). The much greater power incidentally more than compensates for Ch45 being a bit 'out of group' for existing C/D (48-69) aerials.

for SOME transmitters it might be a valid test. Others, such as Spur Hill and 3 Rock, DTT seems to be fine with very poor analogue (with very jumbled teletext)

Indeed the test doesn't scale as well for the Irish transmitter network, whereas the test in the UK is in most cases using frequencies that will be used for PSB multiplexes post-DSO. The test itself assumes that the equivalent DVB-T ERP is 7db below the peak ERP for analogue broadcasts on the same channel, so where the analogue transmitter is 500kW, the equivalent for DVB-T is 100kW. The only main transmitter where the DVB-T final ERP is to be worse than -7db compared to analogue is Kippure.