10 replies to this topic

[tsteele]

Hi, I need some advice on DAB+ reception and change to my antenna cabling to get it to work.

I was recently given a DAB+ clock radio, however where I live I've discovered (after much frustration) that my reception is almost zilch.   I'm in Cromer, Northern Beaches, and house is on the backside of a hill.  At first I thought the unit was DOA, but managed to get 1 bar of signal for 10 seconds and the radio tuned in and came on...but basically there is little to no signal.   It's a clock radio, so like most, it has the pathetic little wire antenna at the back.    On my roof is a huge antenna we had replaced approx 2-3 years ago for digital TV.  I think it's a 30ft mast with another small extention on top.  Digital TV works fine (I have 2 antennas, one vhf, one uhf, one pointing to Artarmon, one to central coast).  It also has an amp booster (whatever it's called) in order to get any signal. As a test for the DAB+ radio, I disconnected the aerial lead from the TV, and placed the radio antenna wire into the coax plug and the radio ends up with reasonable signal and picks up all channels well.  

So I want to run some RG6 cabling to my bedroom where I want this clock radio.  In order to split my existing cabling, should I :

1) make a split after the amplified output (near the TV) and run a 11m cable run back to my bedroom.

or

2) split the cable before the amp in the lounge room (closer to my bedroom), and run a shorter 3m run to my bedroom.  If I do this I may or may not need another amp boost just for the radio.

I'd appreciate if anyone could suggest what's best. The amp I have is a Kingray, but not sure exactly what model it is.   I have a photo of it if it helps..

Thanks
Tim

[digital doctor spock]

You will find that your TV aerial is horizontal and DAB polarisation is vertical, so if you intend using an outdoor antenna it should be vertically polarised. However if ti works from your existing TV aerial then RG6 quad shield cable is a very good option, where to split, ideally after the amplified output.

[mtv]

Yes, the difference between horizontal and vertical polarisation can make a huge difference.

Having said that, if it works reliably, it doesn't matter.

The split should be made after the amp.

If there is an existing splitter for more than one TV outlet, use that if it has a spare port, or replace it with one which has extra capacity for your cable. Eg: replace a 2-way splitter with a 3-way splitter, etc.

Be aware that any split will reduce available TV signals too, but if there is sufficient signal strength and signal quality, it should be fine.

Impossible to know exactly without accurate signal measurements.

[alanh]

Commercial Radio Australia is well aware of the poor signal strengths in the northern beaches and is planning to install repeaters. Date unknown.

AlanH

[nbound]

tsteele, on 03 July 2012 - 12:58 PM, said:

In order to split my existing cabling, should I :

1) make a split after the amplified output (near the TV) and run a 11m cable run back to my bedroom.

or

2) split the cable before the amp in the lounge room (closer to my bedroom), and run a shorter 3m run to my bedroom.  If I do this I may or may not need another amp boost just for the radio.

I'd appreciate if anyone could suggest what's best. The amp I have is a Kingray, but not sure exactly what model it is.   I have a photo of it if it helps..

The amp isnt the little black box in the loungeroom. That black box is just a power supply that sends power back up the cable to power an amplifier thats located most likely on your mast, or less likely a splitter amplifier in the roof/under the floor.

The best way to split would be to see if theres an unused port on your main TV splitter (assuming you have more than one outlet), and cable to a new outlet from there.

If not, then yes you could either upgrade the existing splitter or split behind the TV but if signal levels arent great then either could affect the TV, Only one way to find out without test equipment though.

[tsteele]

Thanks for the replies.   Yes I've been quickly learning that the aerial is better in a vertical position for DAB+.  My UHF aerial is vertical though (the VHF is horizontal).  But as some of you have said, yes it appears to be working fine for DAB+ reception in it's current config, so it doesn't matter.

And yes, the amp is on the mast, and the little black box is just the psu for it.  I'm slowly learning..

I currently don't have any split, it's straight from the antenna/amp to the TV.  I was thinking of having the split after the amp (next to TV), I was just wondering about the 11m run back to my bedroom.

As far as I can remember from the antenna install, the signal is strong, so I think I will try installing a 2way split after the PSU connection, and do my 11m run of RG6 cable.  If it affects the TV reception, then I'll have to rethink it.

I was thinking of a basic splitter like this, would this be enough, or do I need something else ?

http://www.jaycar.co...w.asp?ID=LT3044
or
http://dicksmith.com...nector-splitter

[alanh]

tsteele,
If you are getting reliable DTV reception from Bouddi, then you do not need an antenna pointed at Artarmon/Gore Hill/Willoughby for DTV. This is because the programs are identical.

You would be better off turning your VHF antenna vertical and point it at Artarmon. This may be difficult if the antenna you are using is designed to receive analog channel 2.

With the antenna at a height of 10 m changing the polarisation will not be easy or safe.

It would be prudent to ask info@digitalradioplus.com.au or ring them to find out when the repeaters will be on air. If they do your radio may not need an external antenna.

Alanh

[M'bozo]

tsteele, on 03 July 2012 - 12:58 PM, said:

As a test for the DAB+ radio, I disconnected the aerial lead from the TV, and placed the radio antenna wire into the coax plug and the radio ends up with reasonable signal and picks up all channels well.

This could be purely fortuitous reception, based on signal pickup from the antenna mast and attachments, and/or the coaxial cable down to the existing TV outlet, which is then conducted to the wire antenna on the radio.

What happens if you perform this test, and then turn the PSU off?

Is reception still available, or does it deteriorate?

Matching the impedance of the TV antenna system of the house to a wire antenna on a radio, particularly if the specifications for the radio are unknown, and it does not have an external antenna connector, could lead to interesting results.

[tsteele]

Hi Alanh,

I realise that the channels are identical with Artarmon and Bouddi, however they are picking up different frequencies as you would know, and we've found sometimes a particular station works better via one antenna then the other.  

eg: my PVR has picked up 2 channels for station 9 (channel 8 & 33).  We've found that whenever the signal starts to get choppy say when there's bad weather about, Channel 8 (191.5) will show problems - audio breaks up, pixelation of video, and Channel 33 (564.5) works without problems.  Likely as we are on the backside of the hill looking back to Artarmon.  We're not using the analogue tuner in the TV at all (I've disabled it).

However I think that some other channels work work better the other way.  ie: Channels for Stations 7 & 10, work better on the lower digital frequency then the higher frequency digital.  Well they did, but it may have changed.  I don't fully understand how say 7 & 10 are fine from Artarmon, and 9 is not as good. As I say, maybe it's since changed ??

I've just gone and found out that Bouddi transmits the higher digital frequencies, and Artarmon transmits the lower digital frequencies.  It's been a while since I've had a play, but I'll have to look into it again.   I just know that my location is difficult, and the antenna guy admitted it was a more difficult location to sort out.  I think he ended up using 2 antennas just for good measure as that is what we had before.  I really don't understand it well enough.

"What happens if you perform this test, and then turn the PSU off?"

I'll try this out and let you know.  Good idea.

Thanks again for the feedback from everyone.

Tim

[alanh]

tsteele
The signals you are receiving are not from the Central Coast's Bouddi but from Manly's North Head. The Bouddi transmissions are vertically polarised and the Manly transmitters are horizontally polarised. So you need to point the UHF antenna southward and ensure its dipoles are set parallel to the horizon for horizontal polarisation.
Manly transmission channels
ABN 30 543.625 MHz
TCN 33 564.5 MHz
SBS 34 571.5 MHz
TEN 45 648.5 MHz
ATN 48 669.5 MHz

Disconnect your antenna and do an auto scan to remove all channels
Now manually tune the above channels. Now the receiver will obtain from the signals their correct names and not ones starting with 350+.

The Manly translators are to cover the southern end of the Northern Beaches below the escarpment and Bouddi the Northern end. With a band 4+ antenna correctly pointed with the correct polarisation you should get continously reliable reception

To answer your other questions
The reason why TCN reception is poor is because it is radiated from Willoughy and ATN/TEN are radiated from Artarmon. ABC/SBS/TSN are all radiated from Gore Hill. This is under normal conditions and not during maintenance or equipment failure.

If you switch off the PSU you will get nothing. The amplifier has to be bypassed to get the antenna signal unamplified.

Alanh

[andrewlace]

Could you be assuming that after the power supply is the amplified output? It sounds like you are talking about the power supply.  What is the model number of the amplifier/power supply.  Asssuming it starts with ps.... then it is a kingray power supply and it should make little or no difference if you split it before or after the power supply provided the power is still being run to the masthead amplifier (again assuming it has one) usually with a large telescopic mast you'd be wanting a low noise masthead amplifier.