Why can't I get DTV channels?

[ddavidovsky]

Newish TV (Sharp lc-40le275x) with DVB-T/DVB-T2 tuner built in.

Using RG-6 coax which presumably connects to the condo's antenna on the roof and which supplies about 100 analogue channels.

But when tuning DTV, no signal is found.

Some people say a 'digital antenna' is necessary. Others debunk this and say there is no difference between analogue and digital antennas. If all antennas are the same, I'm wondering why DTV doesn't work through the condo's coax cable?

It seems a bit ironic to have to buy an old-fashioned indoor antenna in order to get a higher-quality picture, so before I buy one, I'm trying to understand this.

 

 

 

 

 

[Mrjlh]

Some ideas.  Although in the beginning digital was transmitted in both VHF/UHF, today most are transmitted only in UHF range.  Is your antenna both VHF/UHF? Hard to tell unless you look. Look for a sideways V shape antenna.  And is your antenna pointed in the correct direction of the transmitter?  Check to see if there is an input mode setting for the TV under the menu settings. You might also invest in at table top antenna that also receives HD. Might solve all your problems.

[Jdietz]

If you're getting 100 or so channels it's probably not an antenna you're hooked up to but a satellite system / distribution modulator. So that setup won't support DTV unless it's piped in as well. 

If you're not too far from a broadcasting station any cheap indoor antenna will get you a reasonable signal (which in DTV means a perfect picture)

 

[RichCor]

45 minutes ago, Jdietz said:

If you're getting 100 or so channels it's probably not an antenna you're hooked up to but a satellite system / distribution modulator.

Yep, sounds like it's a private MATV cable system where the operator picks what video content appears on what channels and they are all sequential.

[ddavidovsky]

Thanks for the comments.

There's no access to the roof of this 24 storey block so I don't know what's up there, but it sounds like that's the answer - I guess I'm not hooked up to a regular antenna at all. I have to admit, I never really understood where all those analogue channels were coming from... 

So I have to get an indoor antenna and fiddle around with it to get the DTV channels. I thought those days were over. Oh well...

[Crossy]

10 hours ago, ddavidovsky said:

So I have to get an indoor antenna and fiddle around with it to get the DTV channels. I thought those days were over. Oh well...

 

If you're pretty high up you'll be surprised how well the little antennae sold alongside the digital boxes work, do get the ones meant for digital, the rabbit-ears aren't up to the task.

 

We're 50km from the transmitter and run two TVs of a simple 3-element Yagi mounted only about 8 feet up. As an experiment I tried the tiny loop that came with one of the digital boxes, it received all but two of the channels when upstairs.

[ddavidovsky]

16 minutes ago, Crossy said:

 

If you're pretty high up you'll be surprised how well the little antennae sold alongside the digital boxes work, do get the ones meant for digital, the rabbit-ears aren't up to the task.

 

We're 50km from the transmitter and run two TVs of a simple 3-element Yagi mounted only about 8 feet up. As an experiment I tried the tiny loop that came with one of the digital boxes, it received all but two of the channels when upstairs.

Ok thanks, will get one from AliExpress.

 

According to this map http://dtvservicearea.nbtc.go.th/webpeople/ the Bangkok transmitter is on Baiyoke Tower 2 - the wrong side of the building from me. Not sure if that spells trouble.

[Crossy]

Why go mail order when you can get them in Tesco?

 

At the frequencies we are looking at a few walls won't be an issue, how far from the transmitter are you?

[ddavidovsky]

Too lazy to go out shopping. There's a big choice on AliExpress, delivered to the door, and probably a few hundred baht cheaper. No hurry.

 

Question is whether to get an amplified one. I'm about 6km from the transmitter. Absolutely wrong side of the building, but I have a balcony which might help.

[Crossy]

Have you tried a coat hanger (semi-serious comment)? At only 6km from the transmitter you'll almost be able to run a light off it.

 

Try a foot or so of wire in the antenna socket of the TV. If that works you won't need an amplified antenna.

[ddavidovsky]

Ok, that gave me an idea - I do have a length of spare coax cable, so I just stripped 8 inches or so off one end and bunged the other in the TV antenna socket. It worked. Found 26 DTV channels, all looking pristine, so I guess I'm good.

 

This is definitely solved. Thanks for the help.

[Crossy]

You should have 30 odd channels so a proper antenna is definitely on the cards, but I don't think you need an amplified one

 

Your set should have some sort of signal strength / quality meter, adjusting your wire for best quality on one of the poorer channels then re-scanning may yield more available channels.

 

[KhunBENQ]

12 hours ago, ddavidovsky said:

So I have to get an indoor antenna and fiddle around with it to get the DTV channels. I thought those days were over. Oh well...

No, they came back.

And it's not only a disadvantage.

You need a small antenna only and you are independent.

You can move it everywhere/every-time. No one can charge you.

That the condo coax does not work is no surprise to me.

 

As written: absolutely no need to mail order or the like.

I advice against.

In good shops they might even be willing to exchange/upgrade if it is not working.

That stuff is about everywhere (electronic shops/departments) since DVB/T2 has been introduced in Thailand.

 

 

 

[johng]

14 hours ago, ddavidovsky said:

Some people say a 'digital antenna' is necessary. Others debunk this and say there is no difference between analogue and digital antennas. If all antennas are the same,

There shouldn't be any difference as the frequencies are exactly the same UHF 480-862 MHZ  or CH 21-69

 

Just saw the update with 8 inch of coax LOL  I wish I was so lucky 

 

 

I was able to get signals from Bangkok  both analogue and digital in Na-Jomtien ( 160Kms)  with my homemade  "coat hanger yagi"

 

A shop bought  "Digital antenna"

 

and  the biggest I could find at the time

 

all produced about the same results which was a signal that varied greatly  even when pointed at the local transmitter only 12 KMs away

the signal was not consistent with lots of drop outs..bad enough to not be watchable

 

the building management has now started putting up " very big  antennas"  Beta Digital HD37E at least twice the length of my biggest one ! 

(the Samart D15E with a claim of 9-13 dB gain)  and fed it into the UHF distribution circuit.

 

 now on the same cable we have Banglamung Cable TV  analogue and digital + six  Satellite channels ( Cband) + the Digital terrestrial TV signals all multiplexed together and sent down the same cable...what could go wrong !!

 

 

 

 

[KhunBENQ]

Good job!

 

But don't frighten the topic starter

He is in some high-rise in Bangkok.
Baiyoke tower "around the corner".

So I guess some basic stuff should do it.

 

Such:

 

[Crossy]

For others trying to get DTV working:-

 

https://play.google.com/store/apps/details?id=esrith.nbtc.BRDC&hl=en_GB

 

This page is the PC version, not working (actually very slow) for me today http://dtvservicearea.nbtc.go.th/webpeople/

 

[johng]

22 minutes ago, KhunBENQ said:

But don't frighten the topic starter

He is in some high-rise in Bangkok.
Baiyoke tower "around the corner".

Yes the Bangkok transmitter is quoted at 100 Kilowatts  should be able to cook some chicken with that power 

 

 

some more info on all transmitters here

DVBt2 thai transmitters.PDF

 

Edited May 29, 2017 by johng

[johng]

17 minutes ago, Crossy said:

This page is the PC version, not working for me today http://dtvservicearea.nbtc.go.th/webpeople/

 its working for me    if you don't want to or it cant find your location  then zoom into your location on the map with the  + button on the left hand side  or with the mouse scroll wheel  when you have found yourself on the map  then click on the blue button at top right hand of the screen

    then move mouse pointer to your location and left click  and it should show  the nearest transmitter and you can find the

"technical details"  by clicking on the little down arrow in the grey area of the pop up box.

 

 

[ddavidovsky]

Well I just hauled myself out to an IT mall, a Tesco Lotus, and a couple of seedy open-fronted high-street TV shops. I guess I don't have the requisite shopping skills... The only antennas I saw anywhere were a couple of plasticky looking things in the latter. Didn't like the look of them. Came back empty-handed and exhausted. Which is why I prefer online shopping. Anyway, no hurry.

 

One other thing - maybe it's pushing my luck, but can I feed both cables into the TV at once (that is, the new DTV antenna, plus the original ATV condo cable that comes from the wall) so I can flick between DTV and ATV using the remote? Otherwise I have to reach behind and switch them manually (which is quite tricky on my set as the socket points downwards).

Will the two signals work through a Y-splitter without interfering with each other?

 

If you're wondering why I might need to switch back to ATV at all, it's because we get fed, free of charge, some channels that are actually useful, such as a Malaysian Astrosports which shows Premier League (albeit not too clear). That's basically all I use the TV for - the rest is for the vahine.

[RichCor]

2 minutes ago, ddavidovsky said:

can I feed both cables into the TV at once (that is, the new DTV antenna, plus the original ATV condo cable that comes from the wall) so I can flick between DTV and ATV using the remote?

Otherwise I have to reach behind and switch them manually (which is quite tricky on my set as the socket points downwards).

Will the two signals work through a Y-splitter without interfering with each other?

 

This definitely isn't recommended. If there is channel usage overlap then your 'antenna' will cause interference for everyone else in the building. You're antenna will become a broadcast antenna for the MATV system (not good)

 

To combine the two signals you'd need a special device specifically designed to allows the signals to be merged on a common output without backfeeding on the two inputs.

 

 

If you set doesn't have two F-type cable connector inputs then another cleaner option would be to purchase an external DVB-T2 Digital Tuner and connect it to your set via HDMI. 

[ddavidovsky]

1 hour ago, RichCor said:

 

This definitely isn't recommended. If there is channel usage overlap then your 'antenna' will cause interference for everyone else in the building. You're antenna will become a broadcast antenna for the MATV system (not good)

 

To combine the two signals you'd need a special device specifically designed to allows the signals to be merged on a common output without backfeeding on the two inputs.

 

 

If you set doesn't have two F-type cable connector inputs then another cleaner option would be to purchase an external DVB-T2 Digital Tuner and connect it to your set via HDMI. 

 

Ok, I definitely won't try combining the cables then. That whole issue seems far more fraught than I imagined.

Maybe one day they'll invent a simple coax to HDMI adapter and I can use that.
 

For the time being I'll manually switch the ATV/DTV cables when necessary - I can run a little coax extension cable from the TV so the socket is easier to reach. If I get fed up of doing that, I guess I'll have to get a separate digital tuner as you suggest.

[RichCor]

5 hours ago, ddavidovsky said:

That whole issue seems far more fraught than I imagined.

Maybe one day they'll invent a simple coax to HDMI adapter and I can use that.

They've invented it already. It's called a Set Top Box.

 

DVB-T2 for Terrestrial, DVB-S2 for Satellite, and DVB-C for Cable ...though most cable and sat operators usually provide the box as they need to unscramble/decrypt the content).  

[ddavidovsky]

20 hours ago, RichCor said:

They've invented it already. It's called a Set Top Box.

 

DVB-T2 for Terrestrial, DVB-S2 for Satellite, and DVB-C for Cable ...though most cable and sat operators usually provide the box as they need to unscramble/decrypt the content).  

Sure, but that would be overkill for me. And I would be no better off - the TV only has two HDMI ports and they're both currently in use (Blu-ray player and Raspberry Pi) so I would still end up plugging and unplugging cables in order to see the analogue channels.

 

Never seen a TV with two coax sockets which is what I really need here. If there is some kind of gadget allows combining two coax cables into one input, that would be useful.

[Jdietz]

A coax splitter works both ways.. As long as there's nothing transmitted by the shared cable on the DTV frequencies you're golden.

 

Edited May 30, 2017 by Jdietz

[johng]

There are remote controlled UHF/VHF switches available to choose between 2 or more inputs.

[ddavidovsky]

Thanks for the pointers. Coax switch could be the solution - I had no idea they existed. A manual one would be okay.

Probably rarer than hen's teeth in Thailand though.

One here for $13.50, free shipping:

https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20170530082414&SearchText="coax+switch"

My cables are push-on so I guess I would also need special connectors to fit those threads.

 

[Jdietz]

The one linked is specced for CB frequencies only, TV is quite a bit higher. It 'may' all just work though.

You will need PL-259 connectors to go with these. 

 

Personally I would test a 3 way coax splitter first and see if that gives satisfactory results.

 

http://www.lazada.co.th/coax-coaxial-antenna-y-splitter-adapter-aerial-to-catv-tv-convertersocket-plug-2166117.html?ff=1

[ddavidovsky]

39 minutes ago, Jdietz said:

Personally I would test a 3 way coax splitter first and see if that gives satisfactory results.

 

http://www.lazada.co.th/coax-coaxial-antenna-y-splitter-adapter-aerial-to-catv-tv-convertersocket-plug-2166117.html?ff=1

I was thinking of using something like that but post 20 above warned about some interference issues that sounded parlous.

You said above that nothing would have to be transmitted on the DTV frequencies. But if the DTV coax is attached then surely it's transmitting...?

[Jdietz]

I mean for this to work, the CATV coax can't have any channels mapped onto the DTV channels, that would interfere. 

No harm trying though. It either works, or not.

 

[ddavidovsky]

12 hours ago, Jdietz said:

I mean for this to work, the CATV coax can't have any channels mapped onto the DTV channels, that would interfere. 

No harm trying though. It either works, or not.

 

 

Okay, just to be clear, currently, with the condo's coax plugged in, I can tune about 100 analogue CATV channels and zero DTV channels.

With the indoor antenna coax plugged in, I can tune 26 DTV channels and just a few very fuzzy analogue channels.

The setup gives me the option to tune either the ATV or DTV channels or both.

 

So the solution is for me to plug in the CATV coax and tune it to the analogue channels only, then unplug that and plug in the antenna coax and tune it to the DTV channels only. Then I can plug both coaxes into the TV using the Y-connector and use the TV's remote to switch between ATV and DTV channels without them interfering with each other? That would be ideal.

Edited May 31, 2017 by ddavidovsky