No SBS reception.

[Cluey]

hiho,
I've been doing a bit of googling on the problem I'm having and one of the results brought up this forum. Having read a few of the threads here I thought it was worth registering to ask for advice as there seem to be some very helpful people here.

I live in Chadstone (the suburb, the shopping centre is in East Malvern) and a few months ago a friend installed an antenna for me and the neighbour who lives in the flat downstairs. This means there are two outlets from a splitter in my roof. Last week my neighbour mentioned that he wasn't happy with the reception we got for SBS. I'd never noticed this as I don't watch much TV at all and very rarely SBS. But he does as English isn't his first language and SBS has shows in his native tongue.

So this week I got around to seeing what he was talking about and it's bad, very bad. SBS, C31 and NITV are completely unwatchable with my setup but all of the other channels are excellent, I'll make a little table at the end of this post. I only have a USB digital TV tuner for my PC, it detects 33 channels on an auto-scan but a couple of them are radio channels. He is using a DSTB, I don't know if it gets better reception than my setup or not, I'll try and remember to ask him next time I see him.

With my googling I discovered that SBS is transmitted via UHF while the mainstream channels are VHF, so I'm assuming this is the problem. I mentioned a friend did the install of the antenna, he's a licensed electrician and was pretty confident in his ability to do the job. But having read the threads here this was probably a mistake, the posts by mtv have been quite enlightening.
The antenna installed was a bought from Jaycar. I had been into a Jaycar shop and asked them about antennas for my area, this was one they said would work now and in the future after analogue was turned off.

I've read the Specifications page for the antenna and must admit that I'm not sure if it covers the current SBS broadcast. It lists
Channel (6-12) (28-69) and when I look at the it lists SBS1 as being channel 3, which isn't in the listed range.

So I'm posting here before I go any further as I'm not all that sure that the listed channel numbers are referring to the same frequencies.

Thanks for your help.


This is how the tuner software displays the 33 channels it detects. Not being much of a TV watcher I had no idea we had this many available. I'm listing them in the order it has them in, I assume this is frequency based. The first two columns are how the software lists them (LCN=local channel name), third column is signal as represented by the software, it has six 'bars', and my comments if any.

LCN   Name           signal quality/comments
  7   7 Digital       6
 71   7 Digital 1     6 same as above
 72   7TWO            6
 73   7mate           6
 70   7 Digital       6 same as 7/71 (no idea why it comes up three times)
 74   TV4ME           6
  9   Nine Digital    6
 90   GEM             6
 99   GO!             6
 94   EXTRA           6
 95   EXTRA 2         6
  1   ONE             6
 10   TEN Digital     6
 14   TVSN            6
 12   ONE             6 another duplicate
 11   ELEVEN          6
  2   ABC News 24     6
  4   ABC1            6
  5   ABC2 / ABC4     6
  6   ABC1            6
  8   ABC3            6
  3   SBS ONE         0 or 1, no picture or sound
 32   SBS TWO         0 or 1, no picture or sound
 33   SBS 3           0 or 1, no picture or sound
 34   NITV            0 or 1, no picture or sound
 30   SBS HD          0 or 1, no picture or sound
 13   C31             0 or 1, no picture or sound
 15   ABC Dig Music   6
 16   ABC Jazz        6
 37   SBS Radio 1     0 or 1, no sound 95ish% of the time, just broken garbled sounds the rest.
 38   SBS Radio 2     0 or 1, no sound 95ish% of the time, just broken garbled sounds the rest.
 39   SBS Radio 3     0 or 1, no sound 95ish% of the time, just broken garbled sounds the rest.

[mtv]

Cluey,

ALL SBS channels, including NITV are transmitted from Mt Dandenong on RF channel 29, 536.625 MHz which is of course in the range of the antenna, which incidentally is generally fine for your area.

You are getting confused with what the tuner indicates (3) which is the LCN (Logical Channel Number for SBS) also numbers in the 30 range.

You're correct, that SBS (incl NITV) and C31 are UHF and the rest of the channels are VHF.

SBS/NITV will be moving to VHF RF channel 7 after the analogue shutoff, so your antenna will still be suitable. There's no word yet if C31 digital will be moving to VHF or staying on UHF post analogue shutoff.

Anyhow, on to your problem.

I suspect there's a connection problem, either at the antenna, splitter, outlets, or a combination of faults.

Sometimes faulty flyleads from the wall outlet to the tuner will exhibit similar issues.

The same with poorly-shielded coax. Did you installer use RG6 Quadshield coax?

A faulty splitter can do the same. They're not overly common, but I have seen faulty splitters before.... even new ones.

These may be an open circuit, or a short circuit and these faults usually have a far greater effect at UHF frequencies, than VHF frequencies.

I am assuming of course that the antenna was installed ON the roof, not inside the ceiling, as that can also cause reception problems.

I'm also assuming an 'F' type splitter was installed too, along with 'F' type outlets. (F rear with PAL front are fine)

If your electrician friend installed the antenna correctly, he should have used a digital signal meter and checked all channels at the time of installation, which would have indicated there was a problem he needed to resolve.

You need to check all connections for shorts or open circuits and measure signals at the antenna, at the input to the splitter, outputs of the splitter and wall outlets, to determine where the problem is.

Hope this helps.

[Cluey]

Thanks MTV.
It's been a while since I posted this, I guess that shows how infrequently I watch TV! Sorry for the delay.

The cable internally in the flat is RG6, the cable from the antenna to the internal wiring is RG59-U. The joiners were done with the 'F type' connectors.

I'm posting this now as my neighbor has come around and poked me about it, he missed out on watching the soccer last night because it was on SBS.
He's bought a longer mast and thinks just going higher will solve the problems. After unbolting the current one and holding it higher I did manage to get a picture on my PC via the USB tuner.
From what I'd read of your posts, not just in reply to me but to others too, this could solve the problem.

I had meant to get back to you and ask how to test for the open or short circuits, if the taller mast doesn't solve the problems I'll have to investigate further.
I'll update this post when we get it all back together.

[mtv]

Thanks for the update, Cluey.

With digital, antenna height isn't always the answer, but it can be, along with its overall position.

Naturally, if the antenna is very close to a roof, raising it can make a difference, but you really need the ability to read signals accurately whilst making antenna adjustments.

In your area, reception should be fine, providing there are no large obstacles in the signal path.

To test for shorts or open circuits, a multimeter can be used, but not with the antenna or splitters connected as that will give a false reading.

The best method is a professional digital signal meter/spectrum analyser which will display the digital channel power (DCP), the bit error ratio (BER) and the modulation error ratio (MER).

BER is the critical factor which determines how reliable the signal will be. eg: signal quality.

When you say 'joiners' there shouldn't be any joiners..... only a 2-way F type splitter. eg: antenna to splitter input and the two outputs , one to each flat.

I still suspect it's more than just antenna height.

[Antennaman]

the cable from the antenna to the internal wiring is RG59-U.

One of the first things I would be looking at is this cable and connections.

I have come across many versions of this cable that perform less than well at UHF frequencies. The cable may also have deteriorated from being exposed to the environment, making it perform less well at UHF frequencies.

I would suggest replacing this with good quality RG6 quadshield cable to see if it improves things.

It may help if you post the type of antenna being used. Some of the antennas retailed by Jaycar have separate VHF & UHF assemblies, and I have found if these are not installed correctly (or are faulty), there can be issues with reception.

Apart from any advice already given, these points may be worth considering.

A faulty splitter can do the same. They're not overly common, but I have seen faulty splitters before.... even new ones.

These may be an open circuit, or a short circuit and these faults usually have a far greater effect at UHF frequencies, than VHF frequencies.

That's interesting. In my experience, and particularly the open circuit case, I have found the opposite to be so. It seems UHF can jump a very small unsoldered capacitive gap better than VHF (at similar signal levels.)

[mtv]

It may help if you post the type of antenna being used.

The OP posted a link to the antenna in his initial post..... it's a log periodic with a single F connector. eg: no diplexer and no balun.

The antenna installed was a bought from Jaycar.

[mtv]

Cluey,

I'll be in your area this Saturday, if you would like me to check out the problem.

I'll need to know by tomorrow night (Friday) if you do.

[Antennaman]

The OP posted a link to the antenna in his initial post..... it's a log periodic with a single F connector. eg: no diplexer and no balun.

And so he did.

Thank you.

I didn't see that, probably because I wasn't logged on when first viewing the post, & didn't review the post after logging on.

I do not like sites that require a log on to see links, it allows me to make more mistakes than I ordinarily would.

I do not attend here often enough to know the idiosyncratic nature of this place.

[Cluey]

Cluey,

I'll be in your area this Saturday, if you would like me to check out the problem.

I'll need to know by tomorrow night (Friday) if you do.

Sorry MTV I didn't see this until now, things got a bit busier than I usually am so low priority things got left out! It might have been very handy.
Hindsight is always great and in this case it shows I shouldn't have got my mate to do it as he doesn't have one of those signal strength tools, but he'd just lost his job and I thought it would be good for him and cheaper for me. I should know better by now that this isn't always the best way but when you're on a pension saving money always seems like a good idea.

The guy downstairs gets enough reception to watch SBS now, my USB tuner didn't get a picture and doesn't work now because winblows has got upset with me. I need to reinstall it so I'll deal with that later, after I find some time. That's also one of the reasons for the delays in my replies, winblows has been corrupting data when I've asked the computer to sleep so I've lost my browser history twice.
This means I have to remember what I was supposed to be chasing up or reading manually and it's funny how quickly the mind forgets how to do this sort of thing when it normally happens auto-magically.

@ Antennaman
The RG-59U is new, well I guess it's a few months old now but it shouldn't have deteriorated in this time frame.