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Freeview-T UHF Antenna in strong signal area

 

 

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johanschuld at gmail

Apr 20, 2012, 3:45 AM

Post #1 of 7 (1676 views)
Permalink
Freeview-T UHF Antenna in strong signal area

Hi All,

Continuing on my recent post about making my Nova-TD500 work properly, I
have now observed the following.

1: HVR4000 = Perfect reception on all Channels
2: Nova-TD500 = Poor reception, barely watchable
3: HVR2000 = Reasonable reception, however TV3 is very bad or does not even
work.
4: Set Top Box = Perfect reception on all Channels

Which makes me think that possibly it's "Dual" cards that need a better
signal than a single tuner card, although to me it seems a bit unlikely.

Anyway, as I have identified that my antenna, antenna position and cable
are all in average condition, I decided to do the whole thing properly and
replace the antenna and possibly add a masthead amp.

I live in Te Atatu Peninsula, Auckland where UHF signal strength is
supposed to be quite strong as it's close to the transmitter. Our house is
fitted with a medium/low-gain antenna (kinda like this one, but maybe even
smaller: http://www.freetv.co.nz/webapps/p/61418/52840/306850). No masthead
amp, no diplexer fitted (so just one antenna connected). However, an VHF
antenna above it. Line of sight very blocked by a big and dense tree 10m
from the antenna.

Now I'm not an antenna expert but I know enough about them to know these
things can be quite critical. Simply fitting a high-gain antenna (a long
one) with a masthead amp might just create a too strong signal. Well, at
least with analog that was the case so I assume digital will have similar
issues(?) so I'm wondering what the right plan of attack is.

If I look around the area, some houses have the really small antenna like
we have, and some have a big high-gain antenna. I wonder if the big ones
are placed because of similar DVB receiving issues? But they are a bit too
expensive to just try it out. So I was thinking the following, in order of
preference/trying out.

1: Get a medium/high gain antenna and mount and cable it properly. Get rid
of the soon to be useless VHF antenna.
2: Put a mast head amp in. (I like the Kingray ones)
3: Relocate the antenna to the other side of the house which has line of
sight and effectively divides the required cable length by 3 at least.

Are there any antenna experts here which can comment?


sultanoswing at gmail

Apr 20, 2012, 3:59 AM

Post #2 of 7 (1698 views)
Permalink
Re: Freeview-T UHF Antenna in strong signal area [In reply to]

On 20 April 2012 22:45, Johan Schuld <johanschuld [at] gmail> wrote:
>
> Hi All,
>
> Continuing on my recent post about making my Nova-TD500 work properly, I have now observed the following.
>
> 1: HVR4000 = Perfect reception on all Channels
> 2: Nova-TD500 = Poor reception, barely watchable
> 3: HVR2000 = Reasonable reception, however TV3 is very bad or does not even work.
> 4: Set Top Box = Perfect reception on all Channels
>
> Which makes me think that possibly it's "Dual" cards that need a better signal than a single tuner card, although to me it seems a bit unlikely.
>
> Anyway, as I have identified that my antenna, antenna position and cable are all in average condition, I decided to do the whole thing properly and replace the antenna and possibly add a masthead amp.
>
> I live in Te Atatu Peninsula, Auckland where UHF signal strength is supposed to be quite strong as it's close to the transmitter. Our house is fitted with a medium/low-gain antenna (kinda like this one, but maybe even smaller: http://www.freetv.co.nz/webapps/p/61418/52840/306850). No masthead amp, no diplexer fitted (so just one antenna connected). However, an VHF antenna above it. Line of sight very blocked by a big and dense tree 10m from the antenna.
>
> Now I'm not an antenna expert but I know enough about them to know these things can be quite critical. Simply fitting a high-gain antenna (a long one) with a masthead amp might just create a too strong signal. Well, at least with analog that was the case so I assume digital will have similar issues(?)  so I'm wondering what the right plan of attack is.
>
> If I look around the area, some houses have the really small antenna like we have, and some have a big high-gain antenna. I wonder if the big ones are placed because of similar DVB receiving issues? But they are a bit too expensive to just try it out. So I was thinking the following, in order of preference/trying out.
>
> 1: Get a medium/high gain antenna and mount and cable it properly. Get rid of the soon to be useless VHF antenna.
> 2: Put a mast head amp in. (I like the Kingray ones)
> 3: Relocate the antenna to the other side of the house which has line of sight and effectively divides the required cable length by 3 at least.
>
> Are there any antenna experts here which can comment?
>
> _______________________________________________
> mythtvnz mailing list
> mythtvnz [at] lists
> http://lists.ourshack.com/mailman/listinfo/mythtvnz
> Archives http://www.gossamer-threads.com/lists/mythtv/mythtvnz/


I'm no antenna expert, but a couple of thoughts:
1) It's more than just signal which can be affecting the various tuner
cards' performances - drivers and firmware being a potential biggie.
2) Getting rid of VHF aerial and tree could help. I however, I assume
you don't want the VHF aerial for FM radio reception, and that the
tree won't be movable.
3) Options 1 and 3 sounds reasonable and cheap. Probably save cash on
option 2 for now.

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mythicalbeast at slingshot

Apr 20, 2012, 4:44 AM

Post #3 of 7 (1656 views)
Permalink
Re: Freeview-T UHF Antenna in strong signal area [In reply to]

>
> I live in Te Atatu Peninsula, Auckland where UHF signal strength is
> supposed to be quite strong as it's close to the transmitter. Our
> house is fitted with a medium/low-gain antenna (kinda like this one,
> but maybe even
> smaller: http://www.freetv.co.nz/webapps/p/61418/52840/306850). No
> masthead amp, no diplexer fitted (so just one antenna connected).
> However, an VHF antenna above it. Line of sight very blocked by a big
> and dense tree 10m from the antenna.
>
>
> Now I'm not an antenna expert but I know enough about them to know
> these things can be quite critical. Simply fitting a high-gain antenna
> (a long one) with a masthead amp might just create a too strong
> signal. Well, at least with analog that was the case so I assume
> digital will have similar issues(?) so I'm wondering what the right
> plan of attack is.
>

> _______________________________________________

The general consensus is the nova 500 is a bad radio. Thankfully the
freeview set-top box has to meet a specification that is not just price.

Normal high gain antenna (long yagi) is more directional..this is not
necessarily good/better for urban canyon, trees, roofs & partial
blockage by land.

Masthead amps are a last resort..the better brands GME-Kingray have
selectable gain in diff bands.

DVB_T modulation (cofdm) is very immune to multi-path because of low
symbol rate.
So a high gain & wide angle antenna like ganged array, commonly referred
to (incorrectly) as a phased array, works very well in multi-path urban
environs..
And this style of antenna is small (diff shape) & cheap. So antenna
people don't use them.

You can get the ganged array in (at least) 12dB & 18dB gain versions.

Coax matters. Make sure the run is low loss UHF. RG-6 using waterproof
(grease filled) crimp F connectors.




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stephen_agent at jsw

Apr 20, 2012, 5:34 AM

Post #4 of 7 (1694 views)
Permalink
Re: Freeview-T UHF Antenna in strong signal area [In reply to]

On Fri, 20 Apr 2012 22:59:50 +1200, you wrote:

>On 20 April 2012 22:45, Johan Schuld <johanschuld [at] gmail> wrote:
>>
>> Hi All,
>>
>> Continuing on my recent post about making my Nova-TD500 work properly, I have now observed the following.
>>
>> 1: HVR4000 = Perfect reception on all Channels
>> 2: Nova-TD500 = Poor reception, barely watchable
>> 3: HVR2000 = Reasonable reception, however TV3 is very bad or does not even work.
>> 4: Set Top Box = Perfect reception on all Channels
>>
>> Which makes me think that possibly it's "Dual" cards that need a better signal than a single tuner card, although to me it seems a bit unlikely.
>>
>> Anyway, as I have identified that my antenna, antenna position and cable are all in average condition, I decided to do the whole thing properly and replace the antenna and possibly add a masthead amp.
>>
>> I live in Te Atatu Peninsula, Auckland where UHF signal strength is supposed to be quite strong as it's close to the transmitter. Our house is fitted with a medium/low-gain antenna (kinda like this one, but maybe even smaller: http://www.freetv.co.nz/webapps/p/61418/52840/306850). No masthead amp, no diplexer fitted (so just one antenna connected). However, an VHF antenna above it. Line of sight very blocked by a big and dense tree 10m from the antenna.
>>
>> Now I'm not an antenna expert but I know enough about them to know these things can be quite critical. Simply fitting a high-gain antenna (a long one) with a masthead amp might just create a too strong signal. Well, at least with analog that was the case so I assume digital will have similar issues(?)  so I'm wondering what the right plan of attack is.
>>
>> If I look around the area, some houses have the really small antenna like we have, and some have a big high-gain antenna. I wonder if the big ones are placed because of similar DVB receiving issues? But they are a bit too expensive to just try it out. So I was thinking the following, in order of preference/trying out.
>>
>> 1: Get a medium/high gain antenna and mount and cable it properly. Get rid of the soon to be useless VHF antenna.
>> 2: Put a mast head amp in. (I like the Kingray ones)
>> 3: Relocate the antenna to the other side of the house which has line of sight and effectively divides the required cable length by 3 at least.
>>
>> Are there any antenna experts here which can comment?
>>
>> _______________________________________________
>> mythtvnz mailing list
>> mythtvnz [at] lists
>> http://lists.ourshack.com/mailman/listinfo/mythtvnz
>> Archives http://www.gossamer-threads.com/lists/mythtv/mythtvnz/
>
>
>I'm no antenna expert, but a couple of thoughts:
>1) It's more than just signal which can be affecting the various tuner
>cards' performances - drivers and firmware being a potential biggie.
>2) Getting rid of VHF aerial and tree could help. I however, I assume
>you don't want the VHF aerial for FM radio reception, and that the
>tree won't be movable.
>3) Options 1 and 3 sounds reasonable and cheap. Probably save cash on
>option 2 for now.

I would have to agree with option 3. UHF needs line of sight much
more than VHF, and is worse affected by trees.

You have to realise that digital channels rarely have "poor" reception
- it is usually good enough or none, that being the basic difference
between anything digital and anything analogue. So "poor" reception
is usually a period of digital reception where the data is good enough
to produce a valid signal, then a period of dropout where the digital
data is too bad to be repaired, and then another good period. The
difference in signal level and quality between receiving 100% and not
can be quite small, and wind in your tree is entirely sufficient to
cause that level of change.

The TD-500 seems to have less sensitivity (ie needs a higher signal
level) than some other tuners. So a signal that is OK for the
HVR-4000 may not be for the TD-500. It may only be just OK for the
HVR-4000, but just OK works for digital signals where for an analogue
signal you would get a degraded picture. One explanation for the
lower sensitivity is that the TD-500 has dual tuners, and therefore
must have a splitter on the board. Hence the signal level is
necessarily going to be reduced to each tuner. The HVR-4000 only has
a single tuner, so that gets the full signal from its antenna cable.

You should also consider your cabling. Do you have a splitter and
then cables from that to all of the tuners, set top boxes and the TV?
If so, then even a fairly good signal from the antenna will be
significantly reduced at each of the tuners. Does the TD-500 work if
you directly plug it into the antenna without anything else connected
and no splitter? Have you tried swapping around the cables? Cables
are often the weak point in any setup and can be damaged (eg by
running the vacuum over them, or kids or the dog playing).

When you had the UHF antenna installed, did the installers replace the
cable from the roof, or just use the existing cable from the VHF
antenna? If so, it may not be cable rated for UHF. Check and see if
it is labeled RG-6, which is what it should be for UHF.

Also, the different UHF channels can be far enough apart that the
antenna is better tuned to some than others - typically the highest
frequency channel is received worst. Since TVNZ is usually the lowest
frequency multiplex, it is usually best received. Reception testing
should be done on the worst multiplex, usually Kordia. You need to
check on the frequencies from your transmitter and find out which is
the highest.

Here in Palmerston North, before the recent frequency change, I used
to be able to receive TVNZ OK from rabbits ears, but always needed the
full antenna for Kordia and usually for Mediaworks. I have not tested
with rabbits ears since the change, but I would expect better
reception on the new lower frequencies.

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paulgir at gmail

Apr 20, 2012, 1:28 PM

Post #5 of 7 (1648 views)
Permalink
Re: Freeview-T UHF Antenna in strong signal area [In reply to]

from the antenna.
>
> Now I'm not an antenna expert but I know enough about them to know these
> things can be quite critical. Simply fitting a high-gain antenna (a long
> one) with a masthead amp might just create a too strong signal. Well, at
> least with analog that was the case so I assume digital will have similar
> issues(?) so I'm wondering what the right plan of attack is.
>
> If I look around the area, some houses have the really small antenna like
> we have, and some have a big high-gain antenna. I wonder if the big ones
> are placed because of similar DVB receiving issues? But they are a bit
> too
> expensive to just try it out. So I was thinking the following, in order
> of
> preference/trying out.
>
> 1: Get a medium/high gain antenna and mount and cable it properly. Get
> rid
> of the soon to be useless VHF antenna.
> 2: Put a mast head amp in. (I like the Kingray ones)
> 3: Relocate the antenna to the other side of the house which has line of
> sight and effectively divides the required cable length by 3 at least.
>
> Are there any antenna experts here which can comment?

I'm in Kaukapakapa and have 50km line of site path to Waiatarua,with only
One nearby hill in the way.My signal is pretty good,considering.I recently
installed
91 element beam antenna (the long style) to improve things.These are
available
From Jaycar for around $100 and that is the retail best price I found.
I was informed that in areas that the signal is blocked by
buildings,hills,trees etc,
a phased array (the flat style) will perform better.Jaycar has these for
$86.
If you know someone that can get a trade discount at electrical
wholesalers,you
can get them around $10 cheaper.

http://www.jaycar.co.nz/productView.asp?ID=LT3182&form=CAT2&SUBCATID=1016#4

http://matchmaster.co.nz/uhf-tv-antennas/phased-array/02mm-ee06

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johanschuld at gmail

May 4, 2012, 4:13 AM

Post #6 of 7 (1541 views)
Permalink
Re: Freeview-T UHF Antenna in strong signal area [In reply to]

>
>
>
> 1: Get a medium/high gain antenna and mount and cable it properly. Get rid
> of the soon to be useless VHF antenna.
> 2: Put a mast head amp in. (I like the Kingray ones)
> 3: Relocate the antenna to the other side of the house which has line of
> sight and effectively divides the required cable length by 3 at least.


Hi All,

Sorry for the somewhat late reply to my original thread but things have got
in the way with playing around. I have got back to it in the meantime
though and got some interesting result. So I thought I'd share.

I decided to get another antenna after the current one fell apart when I
tried to move it after I removed the VHF antenna. Got a "antsig" 42 Element
one. No mast head amp, no splitters, no diplexers. Directly from the aerial
to my mythbox.

1: HVR4000 still perfect signal
2: Nova TD500 signal!!
3: HVR2200 no lock what so-ever

That's where I got to before I got sidetracked for a couple of weeks. I've
been watching HD-TV occasionally to see how it performs and after some good
results I decided to give the Nova-TD500 the highest input priority.. 2
days later.. unwatchable recordings. Artifacts all over the place. It was
not even bad weather?

So I've been experimenting. primarily using the HVR4000 as "femon" seems
to work quite well with it. I tried taking some elements off the antenna
(making it a 21 element) as I thought it might have too much signal. I also
tried a mast head amp and played with the gain just to see what the effect
is.

HVR4000 half ant (21 element, no mast head amp) (NovaTD500 & HVR2200 would
not get a lock)
status SCVYL | signal 21% | snr 99% | ber 69 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 99% | ber 5 | unc 0 | FE_HAS_LOCK

HVR4000 half ant (21 element), mast head amp on 100% (NovaTD500 & HVR2200
would not get a lock)
status SCVYL | signal 21% | snr 97% | ber 737 | unc 26 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 98% | ber 761 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 98% | ber 403 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 98% | ber 563 | unc 1 | FE_HAS_LOCK

HVR4000 full ant (42 element), no amp (NovaTD500 would get a lock, HVR2200
would not)
status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK

Interestingly (and a bit as expected), best reception seems to be with not
using an amp and using 42 elements. I'm not sure if the signal level and
snr actually correct, but the "BER" (Bit Error Rate) and "UNC" (number of
uncorrected blocks?) seem to be actually work. I've left the antenna with
42 elements and no mast head amp.

I'm still at a bit of a loss here. I know I can improve things still more
by moving the aerial to the other side of the house and replacing the cable
with a new (so known good) one, but I'm not convinced. It should not be
that hard? I have NEVER had reliable reception with DVBT on my mythbox.
(well.. apart from the HVR4000). Maybe just get 2 of those :)

Just to try, I have put the HVR2200 in a Win7 box. Installed the drivers
and had clear TV. Sometimes some artifacts but only just after tuning. I
would like to try the "firmware" that the win7 drivers use on my mythbox
but have not found a way to extract them. Has anyone done something
similar? (currently using these
http://www.steventoth.net/linux/hvr22xx/firmwares/4019072/NXP7164-2010-03-10.1.fw
)

Cheers
Johan


stephen_agent at jsw

May 4, 2012, 7:28 AM

Post #7 of 7 (1518 views)
Permalink
Re: Freeview-T UHF Antenna in strong signal area [In reply to]

On Fri, 4 May 2012 23:13:22 +1200, you wrote:

>>
>>
>>
>> 1: Get a medium/high gain antenna and mount and cable it properly. Get rid
>> of the soon to be useless VHF antenna.
>> 2: Put a mast head amp in. (I like the Kingray ones)
>> 3: Relocate the antenna to the other side of the house which has line of
>> sight and effectively divides the required cable length by 3 at least.
>
>
>Hi All,
>
>Sorry for the somewhat late reply to my original thread but things have got
>in the way with playing around. I have got back to it in the meantime
>though and got some interesting result. So I thought I'd share.
>
>I decided to get another antenna after the current one fell apart when I
>tried to move it after I removed the VHF antenna. Got a "antsig" 42 Element
>one. No mast head amp, no splitters, no diplexers. Directly from the aerial
>to my mythbox.
>
>1: HVR4000 still perfect signal
>2: Nova TD500 signal!!
>3: HVR2200 no lock what so-ever
>
>That's where I got to before I got sidetracked for a couple of weeks. I've
>been watching HD-TV occasionally to see how it performs and after some good
>results I decided to give the Nova-TD500 the highest input priority.. 2
>days later.. unwatchable recordings. Artifacts all over the place. It was
>not even bad weather?
>
>So I've been experimenting. primarily using the HVR4000 as "femon" seems
>to work quite well with it. I tried taking some elements off the antenna
>(making it a 21 element) as I thought it might have too much signal. I also
>tried a mast head amp and played with the gain just to see what the effect
>is.
>
>HVR4000 half ant (21 element, no mast head amp) (NovaTD500 & HVR2200 would
>not get a lock)
>status SCVYL | signal 21% | snr 99% | ber 69 | unc 0 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 99% | ber 5 | unc 0 | FE_HAS_LOCK
>
>HVR4000 half ant (21 element), mast head amp on 100% (NovaTD500 & HVR2200
> would not get a lock)
>status SCVYL | signal 21% | snr 97% | ber 737 | unc 26 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 98% | ber 761 | unc 0 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 98% | ber 403 | unc 0 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 98% | ber 563 | unc 1 | FE_HAS_LOCK
>
>HVR4000 full ant (42 element), no amp (NovaTD500 would get a lock, HVR2200
>would not)
>status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
>status SCVYL | signal 21% | snr 100% | ber 0 | unc 0 | FE_HAS_LOCK
>
>Interestingly (and a bit as expected), best reception seems to be with not
>using an amp and using 42 elements. I'm not sure if the signal level and
>snr actually correct, but the "BER" (Bit Error Rate) and "UNC" (number of
>uncorrected blocks?) seem to be actually work. I've left the antenna with
>42 elements and no mast head amp.
>
>I'm still at a bit of a loss here. I know I can improve things still more
>by moving the aerial to the other side of the house and replacing the cable
>with a new (so known good) one, but I'm not convinced. It should not be
>that hard? I have NEVER had reliable reception with DVBT on my mythbox.
>(well.. apart from the HVR4000). Maybe just get 2 of those :)
>
>Just to try, I have put the HVR2200 in a Win7 box. Installed the drivers
>and had clear TV. Sometimes some artifacts but only just after tuning. I
>would like to try the "firmware" that the win7 drivers use on my mythbox
>but have not found a way to extract them. Has anyone done something
>similar? (currently using these
>http://www.steventoth.net/linux/hvr22xx/firmwares/4019072/NXP7164-2010-03-10.1.fw
>)
>
>Cheers
>Johan

If those signal level % values were from the TD-500, I would say they
were way too low. But as far as I can tell, the numbers from each
card are only comparable to the same exact model of card. For the
TD-500, if I am remembering correctly, you need > 65% signal level
before it will record reliably.

When you are getting lock on the HVR-4000 and TD-500, is that at the
same time, or are you moving the cable between them? If so, then
adding the necessary splitter and its 6? db drop in the signal levels
is going to cause problems.

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