Odd goings on with Channel 5HD on Astra 28.2E since the demise of the old frequency

[smipx]

I have recently done a full retune (updated satellites.xml and then full automatic scan) on 28.8E following the frequency change of Channel 5HD the other week. The new transponder seems somewhat weaker than the old. I recently fitted a larger Zone2 dish and a new quad LNB and new cabling and spent a lot of time aligning the disk nice and carefully and was pretty pleased with my hour of tweaking. I get an SNR of 96% on BBC transponder (with AGC of 72%) and on ITV it is 86%/71% and on channel4 it is 87%/71%. I don't get any picture breakup any longer (as I did a bit in bad weather previosuly with my old LNB and rusty old Zone1 dish).

until..... I was watching a channel 5 program that I recorded a few days back and there was some breakup. I decided to look closer and noticed that the new transponder was SNR of 73% AGC of 73%. No picture breakup on the live broadcast (at the time I looked) but I investigated further. Here is where it gets very odd......

the new transponder for Channel 5 is meant to be:
11307H 5/6 according to rxtvinfo.com
and according to Lyngsat is is 11306H 2/3
and according to satandpcguy is 11307H 2/3

The tune I did tuned it in as 11306H 2/3

I then (for a laugh) did a manual scan of both 11307H and 11306H 5/6 and 2/3 and all the scans gave the same channels and all with 73%/73% !!

All a bit academic (and a bit confusing for my little brain) but my question is whether, if I have a marginal signal for Channel 5HD 73% then will it make any differerence if I stick with one or the other (11306 / 11307) when I the heavy rain/snow comes down and make the signal even more marginal?

One to ponder.

Paul

[Joe_90]

SNR of 73% is not marginal. You're well inside the capability of the tuner to lock the signal with an acceptable bit error rate. My own zone 2 dish (east coast of Ireland) is only managing just under 60% on this transponder, but I don't get any signal breakup - may be a different story in heavy rain, though!

The frequency is supposed to be 11306H or 11307H depending on which listing you check (as you have found), but the tuner in the receiver uses AFC and AGC to lock onto the signal, so a matter of a couple of Mhz in the setting doesn't make much difference. That transponder is on Astra 2F and it's a move from the old Astra transponder, so it may well be weaker.

[smipx]

SNR of 73% is not marginal. You're well inside the capability of the tuner to lock the signal with an acceptable bit error rate. My own zone 2 dish (east coast of Ireland) is only managing just under 60% on this transponder, but I don't get any signal breakup - may be a different story in heavy rain, though!

The frequency is supposed to be 11306H or 11307H depending on which listing you check (as you have found), but the tuner in the receiver uses AFC and AGC to lock onto the signal, so a matter of a couple of Mhz in the setting doesn't make much difference. That transponder is on Astra 2F and it's a move from the old Astra transponder, so it may well be weaker.

Many thanks for clarifying that. I thought I was going a bit mad!!

[Huevos]

and according to satandpcguy is 11307H 2/3l

Are you really getting your satellite info from a website in Gandia, Spain?

It is 11307 H 27500 QPSK 2/3.

1 MHz is going to make no difference.

[smipx]

No, I just looked at many sources and there seemed to be no one "standout" correct frequency or FEC value :-)

[BrianG61UK]

<snip>
All a bit academic (and a bit confusing for my little brain) but my question is whether, if I have a marginal signal for Channel 5HD 73% then will it make any differerence if I stick with one or the other (11306 / 11307) when I the heavy rain/snow comes down and make the signal even more marginal? ...

There is only one transponder and your receiver must be working out what the actual FEC is (be it 2/3 or 5/6) and locking on to the frequency correctly.
I can't imagine it would make any difference whether you specified 11306 or 11307.

Maybe if you kept trying say 11305, 11304, 11303 until you found one that didn't work and then came back to the last one that worked you'd find it was less reliable; but only being about 1MHz out should make no difference.

[abu baniaz]

Alternatively:
Do not use details the satellites.xml file, i.e do not perform a scan using the scan functions in Enigma2.
Instead, use ABM or AB 28.2 which will read the SI tables and get the details. If necessary, update the websites that the image teams use to scrape details from.

[smipx]

I think I will leave alone as it is working okay and like everyone says 1Mhz is not going to make any massive difference. I did update the satellites.xml before doing it and it is asking for 11306 but as the next nearest are 11264 and 11344 I guess the tuner looked at 11306 and found the juice broadcasting at 11307

The oddest thing though. If I look at etc\enigma2 there is no user defined satellites.xlm and if I look in etc/tuxbox then there is a file dated 14/12/2022 (so presumably updated) and it shows:

<sat name="28.2E Astra 2E/2F/2G" flags="1" position="282">
.......
<transponder frequency="11264000" symbol_rate="27500000" polarization="0" fec_inner="2" system="0" modulation="1" />
<transponder frequency="11264000" symbol_rate="27500000" polarization="1" fec_inner="2" system="0" modulation="1" />
<transponder frequency="11306000" symbol_rate="27500000" polarization="0" fec_inner="2" system="0" modulation="1" />
<transponder frequency="11306000" symbol_rate="27500000" polarization="1" fec_inner="4" system="0" modulation="1" />
<transponder frequency="11344000" symbol_rate="27500000" polarization="0" fec_inner="4" system="0" modulation="1" />
<transponder frequency="11344000" symbol_rate="27500000" polarization="1" fec_inner="4" system="0" modulation="1" />
........

so it looks like the source for the data is not right. How does one inform the data provider?

[BrianG61UK]

The difference between 11306 and 11307 isn't worth worrying about.
After all the various manufacturing tolerances and frequency drifts in your hardware, you're likely to be more than 1MHz off-frequency anyway.

[smipx]

Fair enough Brian but the satellites.xml file "ought" to at least be right I would have thought. If that one is wrong then who knows what other ones are wrong (perhaps enough to abe a problem for some)??

[smipx]

if oe-alliance satellites.xml is wrong then I have to ask the obvious question. Where do they populate their data from because that must be wrong too (I am guessing it is human error).

I don't want folk to think I am getting hung up on this :-) I just saw a discrepency, observed a picture break up on a recording and put 2 and 2 together and made 99

[Huevos]

According to SI tables it is 11305.

[smipx]

clearly it's not that critical then 11305 +- 2 or 3 will work I guess :-)

[smipx]

It's why we have leap years and the 29th February occasionally after all.

[Huevos]

+2 is too much. Scan with ABM Freesat and it will do it correct.