[VU+ Duo2] Wrong frequency displayed for DVB-C channels

[abu baniaz]

Can you expalin why there are .125, .375, .500 and .750 entries in the cables.xml file?

 

[Huevos]

Can you expalin why there are .125, .375, .500 and .750 entries in the cables.xml file?

No idea, I didn't create the file. Satellites.xml is rounded to the nearest MHz value.

That makes two things that have to be changed then.

I've never seen an STB that takes frequency input in anything but MHz values. Why make a user enter 6 figures when only 3 are required?

 

[Huevos]

Can you expalin why there are .125, .375, .500 and .750 entries in the cables.xml file?

Now I'm even more confused

Cables.xml has stuff like this in it...

<transponder frequency="218750000" symbol_rate="6952000" fec_inner="3" modulation="5" inversion="1"/>
<transponder frequency="219000000" symbol_rate="6952000" fec_inner="3" modulation="5" inversion="1"/>

Two entries pointing at the same transponder.

 

[abu baniaz]

There are at least three ways to look it. If answer is given in one view and it is intepreted in another view there will always be confusion.

Programming
Hardware issues
End user's interaction

Most software is written to fulfil user's requirements, so hopefully discussion can remain in that context.

Oh yes, step scan allows you to scan in less than 1 MHz intervals when it works.

 

[Huevos]

Is there any reason to have multiple entries for the same transponder? IMO, that really is adding to confusion, and causing double scanning. That file is being edited by all different people so it is a mixture of styles. Some providers have been rounded to nearest MHz value, while others are using kHz. Where it is definitely wrong is where both styles have been used (causing multiple entries).

 

[abu baniaz]

Nobody maintains that file. We are even missing the 6887 entries for the UK ( I'll ask PaphosAL to get generate a list for us). You do a wonderful job on the satellite section, however you do not use a cable tuner. The cable providers are all different. With all due respect, you are assuming that they have been rounded off.

When the exact values for the provider are known, then those should be used. Even ABM uses the rational numbers, not nearest integers.

For "blind scanning" then, yes no need for the exact figures as they will be picked up on the integer entry. We should even use automatic entries for the values that we can. That will make scanning easier

 

[amadeus99]

Abu, I contribute and maintain the NOS cable operator entry on cable.xml, I can confirm that the frequency on the file is in Hz.

 

[Huevos]

With all due respect, you are assuming that they have been rounded off.

Look at lines 6248 and 6249. Two entries pointing at the same transponder. There are others like this. Just means the receiver will double scan the same transponder. Bandwidth is 8MHz in this part of the band so it is impossible they are different transponders.

Getting an accurate list would be a good start.

Yes, ABM does write sub-MHz values to lamedb, because that is what is carried in the SI tables.

 

[Huevos]

Abu, I contribute and maintain the NOS cable operator entry on cable.xml, I can confirm that the frequency on the file is in Hz.

Yes, they are in hertz, but, what is being discussed here is false precision.

the number of significant figures used in the presentation of data should be limited to what is warranted by the precision of those data. For example, if an instrument can be read to tenths of a unit of measurement, results of calculations using data obtained from that instrument can only be confidently stated to the tenths place, regardless of what the raw calculation returns or whether other data used in the calculation are more accurate. Even outside these disciplines, there is a tendency to assume that all the non-zero digits of a number are meaningful; thus, providing excessive figures may lead the viewer to expect better precision than actually exists.

 

[Rob van der Does]

How could frequency in Hz be of any interest when the bandwidth is 8MHz?

 

[abu baniaz]

It is no point discussing this further until the end goal is defined. When one person talks about A and another person talks about B, there will always be confusion. No progress will be made.

 

[Huevos]

How could frequency in Hz be of any interest when the bandwidth is 8MHz?

When we did the Blindscan plugin one of the biggest improvements was removing those long numbers that no one understood.

 

[Rob van der Does]

Exactly .

 

[abu baniaz]

Exactly .

It is not permissible to be exact. We must round to nearest integer.

 

[abu baniaz]

An article on nearest integer. explains why rounding upwards is done and not down.

https://en.wikipedia.org/wiki/Nearest_integer_function

 

[Rob van der Does]

The article shows that rounding-off is being done, not specific rounding-up or rounding-down. Also see

https://en.wikipedia.org/wiki/Rounding

So 1.49 is rounded-off as 1, and 1.50 is rounded off as 2 (i.o.w. the normal mathematical rounding-off).

 

[amadeus99]

Since this long discussion is inconclusive, may I suggest to follow other images approach to truncate the frequency to MHz.