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Channel 7 Perth very poor reception


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I don't usually watch Channel 7 but with the Olympics coming up thought I'd check it out today, all channels that they broadcast.

The reception was dreadful with pixelation and sometimes even said "no signal"

All the other Perth channels both SD and HD are fine with 10/10 quality and signal strength.

Channel 7 issues on both TVs in the house so not TVs at fault. I have F connected high quality cabling installed with a masthead amp. If I turn the gain down on the masthead amp Channel 7 just disappears totally, so a weak signal from Ch7 seems to be the issue.

 I am in Edgewater, fairly low down on the Lake Joondalup side and probably do not have LOS to Bickley but it is ONLY Channel 7 channels that I have issues with.

Any ideas ?

 

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Harry,

TV stations use computers to continuously monitor the transmitted signal strength along with lots of other transmitter test points. Their main transmitter is in Television Rd Bickley but they can also transmit from another tower in Welshpool Rd Carmel, which is used by TEN.

Just make sure that the plug pack for the masthead amplifier is connected between one of the TVs and the splitter and that the power is on. (Some splitters will only accept the power on one of the TVs  cable.

"Channel 7" is actually transmitted on channel 6.The most likely cause is poor connection to the antenna, input of the masthead amplifier, output of the masthead amplifier or the splitter. Do you have an antenna which was used for analog channel 2 and would be 2 m wide at at the back? If so replace it with a Band 3 antenna.

I say channel 6 requires a metallic connection but as the channel number increases more signal can be capacitively coupled across a tiny gap.

I live in the Warwick area and there is no problems here.

Alanh 

 

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Thanks. I think it is the antenna as I have had it for well before we all went digital. All other cabling, connectors sockets, masthead amp etc are all fairly recent after a house renovation.

I will replace it.

Initially I did think that CH7  was doing something in preparation for its multi channel Olympic coverage.

Will let you know if the new antenna fixes the problem.

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Some VHF Antennas have a bad problem with roll off at the bottom end of the band. The performance was not that good. As it seems that you only have problems with Channel 7 (VHF Ch.6) I would say that the antenna performance at this frequency is bad. As you have said, try a new antenna, I think this will fix your problem.

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Harry,

Unless you watch West TV on channel 44, buy an antenna which is for band 3 VHF only, then all the antenna will be used to receive your programs. Many installers use VHF/UHF ones and half the antenna will go unused.

 

Alanh

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Well I have tried a new antenna and Seven has improved but no where near perfect, still get some pixelation. When I look at the signal on my TVs Digial setup , all channels except for CH6 (Seven) are 10 signal strength and 9 or 10 on quality. Channel 6 (Seven) has 9 signal signal strength and the quality varies between 1 or 2 and 7 and its it does not stay on anyone of them for long and the quality goes up and down as if say soemone was standing in front of the Antenna and waving something in front of it to block CH6 on and off (nothing Ican see that does that , although there is a tree 20 to 300 meters away, but all other channels re unaffected.

 Interference ? but from what ?

Looks like my Olympic viewing will not be good. And don't say stream it on the Internet, my area is considered poor for ADSL by the Govt site  ( a long way from the exchange) and indeed it is, I get average 4Mb/sec (and thats between 4 adults) , NBN not in sight for 9 months ( if ever) and then it will be the FTTN version. I did think about Vivid Wireless but no LOS to the nearest transmitter even though it is only 500 meters from me.

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Quite weird, reception fairly good  until late PM and then once dark down the toilet again varying between totaly pixelated or "no signal".

Earlier I rotated the antenna to be 90 degrees off direction both East and then ahain 90 degrees West and all the channels  except CH6 (Seven) received loud and clear depoite the orientation..

I am still a total loss as to understand just why CH6(Seven) is so bad. I wil try a couple of things tomorrow. I have 4G filter on the msthead amp so unlikleyinterference from there. The other sid eof the Lake in Wanneroo is a large Tesltra tower with also of stuff on it some of which look like microwave as weel as Mobile Phone Antenna, wondering if something from there is interfering with Seven ? Will also raise height of Antenna by a meter or so, currently the Antenna is below the height of the double storey house opposite on the high side of the road, behind them even higher is a road. If height is the issue not sure why Seven only effected. Also will bypass the masthead amp and see if that makes any difference.

 btw my wife says some of her friends who live locally also have issues with Seven. As always with females technical information is somewhat lacking.

 I will get to the bottom of it

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Harry,

We are on VHF 12 in one area and were having troubles with antennas not doing the complete band VHF6-12. This caused us the exact problems you were asking about. The one channel at the end of the band is having problems. BTW how is your ABC reception...

Interference in the VHF band is more likely to be caused by impulse noise, e.g. sparking and arcing. Well known DTV VHF reception killers are old refrigerators, electric fences, cheap Chinese downlights, and Christmas lights...I doubt that the Telstra tower would be causing you problems.

Can I ask, you are watching VHF, not UHF? Your autotune hasn't locked in some other Channel 7 TX from somewhere else? There is a TX site closer to you called Perth Coastal which although only low power might have been accidentally picked up..

Edited by steveb
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VHF , this Perth

2 minutes ago, steveb1503559504 said:

Harry,

 

We are on VHF 12 in one area and were having troubles with antennas not doing the complete band VHF6-12. This caused us the exact problems you were asking about. The one channel at the end of the band is having problems. BTW how is your ABC reception...

Interference in the VHF band is more likely to be caused by impulse noise, e.g. sparking and arcing. Well known DTV VHF reception killers are old refrigerators, electric fences, cheap Chinese downlights, and Christmas lights...I doubt that the Telstra tower would be causing you problems.

Can I ask, you are watching VHF, not UHF? your autotune hasn't locked in some other Channel 7 TX from somewhere else?

VHF. ABC is 100% perfect. How to check auto tune ? , 2 TVs , both have same issue. I don't think here is another VHF Seven near here but will check. How to stop that if that is the case ?

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The reason I asked about he ABC is that they are on VHF12 at the other edge of the band...I thought if you were having problems with them it could be bandwidth related.

We had a case where a viewers reception stopped at the same time every night.....long story...it turned out it was a cheap dehumidifier that they had purchased for a new baby....electric fan motor was sparking its head off.....stopped DTV reception.....and it was just on our station.

To check your autotune you will need to have a look somewhere, usually in the Now/Next, and see what channel is indicated. If it isn't there you might have to look at the full eps. If that isn't it you may have to go into the TV's menus and look for a channel list. 

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5 minutes ago, Harry1503559513 said:

VHF , this Perth

VHF. ABC is 100% perfect. How to check auto tune ? , 2 TVs , both have same issue. I don't think here is another VHF Seven near here but will check. How to stop that if that is the case ?

No other VHF for Seven. Govt MySwitch says should be "good" reception here. I will try the  UHF channels to the North of me , might be better LOS.

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Harry,

You have not said what type of antenna you tried and what brand and model the masthead amplifier is.
The only real way to fix this problem is to get an antenna installer who has a digital field strength meter to measure the strength of each channel where the antenna is and follow the signal levels through your antenna system to find out where the signal is disappearing.

Since your antenna system is old, corrosion is a common cause due to the amount of salt in the air in seaside areas. The sun has a go at cables.

There is no UHF translators designed to cover your area. Scarborough and the CBD are much lower power and have directional transmitting antennas.

The 697 MHz low pass filter will have little effect.

Electronic retailers don't sell sensitive antennas, you want one who only sells antennas to antenna installers.

Go to SCiteq in Wangara http://www.sciteq.com.au/shop/odrok-dv310-vhf-10-element-tv-aerial/ is a similar antenna to the one I have. If you need a masthead amplifier http://www.sciteq.com.au/product-category/rf-distribution/amplifiers-2/page/2/ A new Kingray MDA15V, and don't forget to ensure you have the accompanying 14 V plug pack power supply.

Don't forget that the myswitch website will also tell you which direction to point the antenna. Click on the Antenna setup guide in the green block. The cable in the above antenna is furtherest from the transmitter.

 

Alanh

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SCiteq does also sell retail.

If you use the above antenna you must disconnect the amplifier first and remove any plug pack which feeds an injector between the TV and the wall.

I should add that the MDA15V will not require any additional filters because it already contains filters to remove any signal which is not on channels 6 - 12.

Alanh

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8 hours ago, alanh said:

Since your antenna system is old, corrosion is a common cause due to the amount of salt in the air in seaside areas. The sun has a go at cables.

Was old now have new, was some corrosion when I took out the old...new antenna did help a bit with Seven. All cables/connectors etc  are new. 

UHF transmitter , there is one at Yanchep and myswitch says I am in a medium area for reception.

New Antenna is Hills Tru Band Black Arrow Digital VHF/UHF High Gain TV Antenna

Amp is Digimatch VHF/UHF/HDTV Masthead Amplifier from Jaycar http://www.jaycar.com.au/digimatch-vhf-uhf-hdtv-masthead-amplifier/p/LT3270

Remember it is only CH6 (Seven) that has issue and suffer variable reception

Edited by Harry
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Harry,

You said you are in Edgewater, but I did not have your specific address. Two Rocks is a very low power transmitter set for Two Rocks residents.

The myswitch site shows the Two Rocks signal as variable and weak or non existent in Edgewater area. It would need a high gain UHF antenna with an amplifier on a tall pole  (with the antenna 10 m above the ground), where as where as Perth main transmitters is generally much stronger with some small spots of low signal.

The Two Rocks transmitters are UHF only so you would waste your money with a VHF/UHF antenna, because half of the antenna is unused. The Jaycar amplifier is a poor choice because it does not contain any of the filtering.

I suggest you use an antenna installer who can measure the signal levels and tell them that you only want a band 3 antenna. The only thing on UHF is West TV. If you add UHF to the antenna like the Hills model mention, half of that antenna is UHF which is only used for West TV. If you want to use Hills who are in Balcatta, they have a DY10 which is similar to the other antenna I recommended.

Alanh

 

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mySwitch is a reception guide, not a panacea.

A method of measuring the strength & quality of the signals from the antenna under test is required to determine whether or not a masthead amplifier is required. If an amplifier has garbage going into it, the output of the amplifier is a higher level of garbage, not better reception.

This test process may require a selection of antennas to determine the most suitable, and will usually require checking the mounting location & height for best performance, particularly where signals are blocked by buildings or terrain. Selective attenuation can also occur when blocking of signal is a potential issue, whereby only one channel appears to be affected.

Your problem could also be related to an electronic appliance generating interference only on channel 7's frequency. It's unlikely, unless you go around turning power off to electronic devices in yours or other people's places, whether this could be effectively isolated.

 

On 7/28/2016 at 3:43 PM, Harry1503559513 said:

quality varies between 1 or 2 and 7

 

That's poor. This quality measurement is after all error correction on the received signal has been performed, & suggests to me that the signal is close to failure all the time, explaining the picture/sound breakup you are experiencing when the signal quality goes "over the cliff".

 

In my opinion you need someone with the right equipment & expertise to sort this. You might get there yourself, but at what cost?

Edited by I am not a duck
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2 hours ago, I am not a duck said:

mySwitch is a reception guide, not a panacea.

A method of measuring the strength & quality of the signals from the antenna under test is required to determine whether or not a masthead amplifier is required. If an amplifier has garbage going into it, the output of the amplifier is a higher level of garbage, not better reception.

This test process may require a selection of antennas to determine the most suitable, and will usually require checking the mounting location & height for best performance, particularly where signals are blocked by buildings or terrain. Selective attenuation can also occur when blocking of signal is a potential issue, whereby only one channel appears to be affected.

Your problem could also be related to an electronic appliance generating interference only on channel 7's frequency. It's unlikely, unless you go around turning power off to electronic devices in yours or other people's places, whether this could be effectively isolated.

 

 

That's poor. This quality measurement is after all error correction on the received signal has been performed, & suggests to me that the signal is close to failure all the time, explaining the picture/sound breakup you are experiencing when the signal quality goes "over the cliff".

 

In my opinion you need someone with the right equipment & expertise to sort this. You might get there yourself, but at what cost?

Thanks.

 I have now eliminated the masthead amp as any connection to the issue. I bypassed it and although signal quality and strength reduced across the board, especially the ABC, they were all reasonable, however the CH6 (Seven) remained bad so I can say that whatever the issue is with CH6(Seven), bypassing the amp proved the AMP is not contributing to the problem.

I was wondering if ADSL2 could interfere with the CH6, the unshielded twisted pair telephone cable runs right next to the TV coax cable for quite a way. I will test this out tomorrow by turning of the modem/router and disconnecting the POTS telephone. Weather too bad to be up on the roof playing with the antenna.

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Harry,

You are guessing. Channel seven has no loss of signal power. You can try your phone lines etc which will only have an effect if the shield in the coax cable is not connected in both ends.

Keep going this way and you will miss the Olympics. Get in a professional with a digital field strength meter.

Alanh

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38 minutes ago, alanh said:

Harry,

You are guessing. Channel seven has no loss of signal power. You can try your phone lines etc which will only have an effect if the shield in the coax cable is not connected in both ends.

Keep going this way and you will miss the Olympics. Get in a professional with a digital field strength meter.

Alanh

At the moment it is not costing me any dollars to try and work it out. I never usually watch Channel Seven so bugger it (sour grapes), If I can't fix it then since all other channels are fine I will miss the Olympics on  Seven, but then in my experience FTA broadcasters do a terrible job at these events with most action focussed on celebrity panels and  show only sports in which Australia has a potential medal. I will go and watch it at my son's house, he has a bigger TV than me and also has the fastest NBN fibre connection so watching "minority sports" is an option together with VPN to other countries Olympic feeds.

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1 hour ago, alanh said:

Harry,

You are guessing. Channel seven has no loss of signal power. You can try your phone lines etc which will only have an effect if the shield in the coax cable is not connected in both ends.

Keep going this way and you will miss the Olympics. Get in a professional with a digital field strength meter.

Alanh

I think I may not have communicated the issue clearly. CH6(Seven) signal strength is always good whether via the masthead amp or not. It is the QUALITY which is bad which to me means that there is likely interference and packets are dropping. I am no way any expert in these matters but surely a field strength meter only measures the strength of the signal NOT the Quality which needs a digital tuner to measure. I am willing to be corrected on that but I can't see how a meter can measure the  digital packet quality without some sort of tuner/debug/error detect software involved.

 My Quality varies constantly on CH6(Seven( varying from good to poor, very poor and non extistent), I might take a video of the  signal screen  page on my TV to show you. It is in constant motion sliding across the screen from poor to good and back again. btw disconnected the landline and no difference.

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1 hour ago, Harry1503559513 said:

I am no way any expert in these matters but surely a field strength meter only measures the strength of the signal NOT the Quality which needs a digital tuner to measure.

Neither am I, however, having installed or repaired thousands of antenna set ups since digital TV started, I have some knowledge of this.

Proper digital signal analysers are capable of measuring parameters to enable successful installation of either terrestrial or satellite systems, & have the capability to give the necessary information to achieve this.

1 hour ago, Harry1503559513 said:

I might take a video of the  signal screen  page on my TV to show you. It is in constant motion sliding across the screen from poor to good and back again

Not necessary, as I know exactly of which you speak (It's one of the methods I use to demonstrate to customers why their reception is patchy, & how, when repaired, much improved the signal now is.)

You may have electrical interference on VHF channel 6, or it could also be a poor quality incoming signal, either because the signal is passing through or around obstructions, or there is a reflected signal from somewhere (which in the analogue days would give rise to ghosting & other artefacts.)

You could purchase something like this entry level meter to assist in your quest.

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On 28/07/2016 at 8:37 PM, steveb1503559504 said:

Harry,

We are on VHF 12 in one area and were having troubles with antennas not doing the complete band VHF6-12. This caused us the exact problems you were asking about. The one channel at the end of the band is having problems. BTW how is your ABC reception...

Interference in the VHF band is more likely to be caused by impulse noise, e.g. sparking and arcing. Well known DTV VHF reception killers are old refrigerators, electric fences, cheap Chinese downlights, and Christmas lights...I doubt that the Telstra tower would be causing you problems.

Can I ask, you are watching VHF, not UHF? Your autotune hasn't locked in some other Channel 7 TX from somewhere else? There is a TX site closer to you called Perth Coastal which although only low power might have been accidentally picked up..

Now I may be getting somewhere. I just autotuned and then manual (to double check) tuned CH6 and when it first scanned it shows 2 Perth Channel 7s, making a total of 7 subchannels. I double checked again using a set top box, same thing and also with the other TV. All the same on scanning. Now ther is no other VHF CH6 so it cannot be the issue you alluded to but what if there was a reflection somewhere and it is picking up that ?

 

3 hours ago, I am not a duck said:

Neither am I, however, having installed or repaired thousands of antenna set ups since digital TV started, I have some knowledge of this.

Proper digital signal analysers are capable of measuring parameters to enable successful installation of either terrestrial or satellite systems, & have the capability to give the necessary information to achieve this.

Not necessary, as I know exactly of which you speak (It's one of the methods I use to demonstrate to customers why their reception is patchy, & how, when repaired, much improved the signal now is.)

You may have electrical interference on VHF channel 6, or it could also be a poor quality incoming signal, either because the signal is passing through or around obstructions, or there is a reflected signal from somewhere (which in the analogue days would give rise to ghosting & other artefacts.)

You could purchase something like this entry level meter to assist in your quest.

In light of what I just replied to Steveb  above this starts to seem like refection , if so how to eliminate it ?

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