Help!!!!Interfering With Telstra Tower

**best4less** · 28-08-08, 12:00 PM

I have a mate

He may have a piece of equipment that might be Interfering With a Telstra Tower
He had the the Telstra coppers driving around his place with a spectrum analyzer and aerial sticking out there car window for the last couple of weeks

Well yesterday they knocked on his door and said that something is knocking out 3 somethings(carriers,he can't remember right now) from the Telstra tower 200-300 meters away and they have located the source to his house,a 850mhz source.
He told them he had nothing in his house that could do that apart from a few phones that do NextG.Well he offered to turn a few things off around his TV, as they said this is where the source of the signal was coming from,while they waited outside and the 1st thing he turned of was a DVD Player model DM500 if you are familiar with that model

(He was going to say, they were Dreaming if the thought it was hid DVD) and they said that was it

What could be causing such interference within the 850mhz range since there is only a 12 volt plug pack powering it and actually transmitting 300 meters away ?????
Is it possible.

**iwacelect** · 28-08-08, 12:19 PM

hi mate
these plug packs are switch mode and the higher the switching frequency the lighter and smaller the inductor needs to be to filter out rf, now if the electro cap on the output drys up AND you get a dry joint good enough to spark then you have a transmitter ( think marconi)

so therefore i'd say probably,
on the other hand your mates now got a jammer thats transportable, that would confuse the hell out of them

**Twoshots** · 28-08-08, 12:31 PM

Quote:

Originally Posted by iwacelect

hi mate
these plug packs are switch mode and the higher the switching frequency the lighter and smaller the inductor needs to be to filter out rf, now if the electro cap on the output drys up AND you get a dry joint good enough to spark then you have a transmitter ( think marconi)

so therefore i'd say probably,
on the other hand your mates now got a jammer thats transportable, that would confuse the hell out of them

Mmmm get an inverter and go for a drive

**beer4life** · 28-08-08, 12:34 PM

G'Day,
For a start,their test, as described, does not prove a thing !
It may have been fortuitous that the source ceased at the same time !
Even if the source is still persisting, they are most unlikely to come back and say it wasn't your fault after all.
It would require many on/off cycles to confirm.
Having said that, there are many possible theoretical explanations, including;
Operating frequencies/Harmonics between seemingly innocent units that are within their own radiation limits, even to the point that the problem is within their own equipment.
He should demand a log of when the interferrance occurs, to compare with the operating times of his equipment.
A hell-of-a lot more investigation would need to be done, for them to lay the blame at his doorstep. It says little for their equipment if it is not immune to the circumstances as described.
Bin thar, don that.
Kindest Regards, " The Druid ".

**Studio1** · 28-08-08, 12:44 PM

It is possible the DVD player could be interfering.

If it's generating a harmonic that's strong enough to get into the input side of the cellular receiver (and they are pretty damn sensitive) then it may be nuking it.
Even though it's got a plugpack feeding it, chances are it has some kind of switching power supply and they're notoriously noisy, especially with the cheap "Made in China" stuff.
What needs to happen really is for the DVD player and its associated power supply to be submitted for testing. A good specan will determine what if anything it's radiating and at what frequencies.

As IWAC suggests, it could even be the plugpack itself.

**best4less** · 28-08-08, 12:57 PM

MMM Cheep Chinese power supply I'll smash her open and see whats in side

Before

after to come

**ssrattus** · 28-08-08, 01:04 PM

Is this "DVD player" a Dream DM500 satellite receiver?

**TZB** · 28-08-08, 01:22 PM

Yeah those cheap wall warts are notorious for knocking out ADSL signals too.
Having a bit of trouble getting it open B4L ?

**Antennaman** · 28-08-08, 01:22 PM

This is not surprising, as when there were actually RIs that would come out for free and track down interference to radio and television reception, they could tell you some good stories as to strange generators of RF interference.

For example, television masthead amplifiers that are installed by well meaning owners that turn out to be unmodulated free running oscillators owing to inadequate installation practises is not an uncommon source of interference to 3G operations.

There was even an advertising campaign in the papers covering this about the time 3g started. Read the part about who is responsible for this interference in the following article, and this applies to all items, not just the specific case mentioned here.

ACMA - Masthead & distribution amplifiers fact sheet

If it took a couple of weeks to track the interference down, they must be pretty sure of its origin. Moving the offending items from their currently installed position to elsewhere for testing may not prove anything, as the act of moving the offending items could disturb the fortuitous feedback path that is causing this problem.

**best4less** · 28-08-08, 01:23 PM

and apart

Dream DM500

**best4less** · 28-08-08, 03:46 PM

Bloody hell it looks all good in there except for a bad smell LOL
and just 1 cap measuring low in ESR it was a 10uf 50v on the primary side
I best be pulling the box apart and having a look inside that.

My Kingdom for a spectrum analyzer to trace this 850mhz

**bulbous** · 28-08-08, 04:00 PM

Telstra could help here with stressing to the Australian Guvvamint the need for decent regulations relating to garbage emission from all consumer devices. For a few cents in passive components the entire RF spectrum could be cleaned up immensely.

Try tuning across VHF and UHF with an SSB receiver these days - twenty years ago the spectrum was wonderfully clear, now it's a screaming mess !

I don't think it will be the power supply as I don't reckon their will be any RF source in there which will be stable enough.

I would be looking at any high-frequency processor stuff on the MPEG board. There will be a crystal oscillator and PLL stuff hanging off the board.

**best4less** · 28-08-08, 04:51 PM

Maybe i need a lead lined box and stuff it in there LOL

**trash** · 28-08-08, 06:05 PM

I don't know of any telstra police

We have RFI equipment for measuring terrestrial interference etc, but we never go hunting for individual signals.

Sounds like the ACMA. Telstra will know if their is a signal problem from a PIM test which they can run from a script on the mobile base station. This is probably what they've detected. PIM testing is usually -150dBc.

**best4less** · 28-08-08, 06:11 PM

You are dead right they were the ACMA and they did turn the power to the house off while the Telstra people watched it live at the tower and they did say that the
interference did go away

**Studio1** · 28-08-08, 06:59 PM

Quote:

Originally Posted by best4less

and apart

Dream DM500

This stuff is just absolute rubbish. How can anyone produce this? I just shake my head when I see this.

The day that China started to mass produce electronics and all the other crap we see now was the day we sold our souls.
Shame on the governments of Oz and NZ for allowing this sh*t to come in.

Lament mode off.

**eeprommemory** · 28-08-08, 09:34 PM

i have a GME kingray MHU34F antenna booster and it puts out a large signal at 1150mhz.
it drove me nuts.
i unplugged everything and this signal i could receive 500M away was still there.
turn off house power and it goes.
then i turned on all power but lights.
as soon as i turned on the lights i worked out what it was.
the booster plug pack is on the light circuit.
i put my finger on the FET and it stops doing it.
modded it with some tin to cover FET.
bloody cheap untested design.
i bet the makers said "yep looks good lets make em" no testing.

**trash** · 28-08-08, 09:43 PM

Quote:

Originally Posted by Studio1

The day that China started to mass produce electronics and all the other crap we see now was the day we sold our souls.

And they got a good deal, you sold it to them with a discount !

**eeprommemory** · 28-08-08, 09:53 PM

Quote:

Originally Posted by trash

And they got a good deal, you sold it to them with a discount !

DAM does that mean some Chinese junk maker has mine.

28-08-08, 12:00 PM	#1 (permalink)
best4less I'am Not a Bloody Joke iTrader: (8) Join Date: Jan 2008 Location: Australia Posts: 2,526 Spent time on board: 1 Month, 3 Weeks, 2 Days and 12:27:04	Help!!!!Interfering With Telstra Tower I have a mate He may have a piece of equipment that might be Interfering With a Telstra Tower He had the the Telstra coppers driving around his place with a spectrum analyzer and aerial sticking out there car window for the last couple of weeks Well yesterday they knocked on his door and said that something is knocking out 3 somethings(carriers,he can't remember right now) from the Telstra tower 200-300 meters away and they have located the source to his house,a 850mhz source. He told them he had nothing in his house that could do that apart from a few phones that do NextG.Well he offered to turn a few things off around his TV, as they said this is where the source of the signal was coming from,while they waited outside and the 1st thing he turned of was a DVD Player model DM500 if you are familiar with that model (He was going to say, they were Dreaming if the thought it was hid DVD) and they said that was it What could be causing such interference within the 850mhz range since there is only a 12 volt plug pack powering it and actually transmitting 300 meters away ????? Is it possible. __________________ Please wipe your feet before walking all over me

28-08-08, 12:19 PM	#2 (permalink)
iwacelect Senior Member iTrader: (0) Join Date: Jan 2008 Posts: 314 Spent time on board: 5 Days and 13:40:41	hi mate these plug packs are switch mode and the higher the switching frequency the lighter and smaller the inductor needs to be to filter out rf, now if the electro cap on the output drys up AND you get a dry joint good enough to spark then you have a transmitter ( think marconi) so therefore i'd say probably, on the other hand your mates now got a jammer thats transportable, that would confuse the hell out of them __________________ When I explained to the guy what avatar I wanted, that wasn't what I meant!

28-08-08, 12:34 PM	#4 (permalink)
beer4life The Druid. iTrader: (2) Join Date: Feb 2008 Location: The Nether World. Posts: 632 Spent time on board: 1 Month, 3 Weeks, 2 Days and 18:30:59	Winging Telstra. G'Day, For a start,their test, as described, does not prove a thing ! It may have been fortuitous that the source ceased at the same time ! Even if the source is still persisting, they are most unlikely to come back and say it wasn't your fault after all. It would require many on/off cycles to confirm. Having said that, there are many possible theoretical explanations, including; Operating frequencies/Harmonics between seemingly innocent units that are within their own radiation limits, even to the point that the problem is within their own equipment. He should demand a log of when the interferrance occurs, to compare with the operating times of his equipment. A hell-of-a lot more investigation would need to be done, for them to lay the blame at his doorstep. It says little for their equipment if it is not immune to the circumstances as described. Bin thar, don that. Kindest Regards, " The Druid ". __________________

28-08-08, 12:57 PM	#6 (permalink)
best4less I'am Not a Bloody Joke iTrader: (8) Join Date: Jan 2008 Location: Australia Posts: 2,526 Spent time on board: 1 Month, 3 Weeks, 2 Days and 12:27:04	MMM Cheep Chinese power supply I'll smash her open and see whats in side Before after to come __________________ Please wipe your feet before walking all over me

28-08-08, 01:23 PM	#10 (permalink)
best4less I'am Not a Bloody Joke iTrader: (8) Join Date: Jan 2008 Location: Australia Posts: 2,526 Spent time on board: 1 Month, 3 Weeks, 2 Days and 12:27:04	and apart Dream DM500 __________________ Please wipe your feet before walking all over me

28-08-08, 12:44 PM	#5 (permalink)
Studio1 Senior Member iTrader: (0) Join Date: Jan 2008 Location: Inside the toaster Posts: 473 Spent time on board: 3 Days and 7:23:44	It is possible the DVD player could be interfering. If it's generating a harmonic that's strong enough to get into the input side of the cellular receiver (and they are pretty damn sensitive) then it may be nuking it. Even though it's got a plugpack feeding it, chances are it has some kind of switching power supply and they're notoriously noisy, especially with the cheap "Made in China" stuff. What needs to happen really is for the DVD player and its associated power supply to be submitted for testing. A good specan will determine what if anything it's radiating and at what frequencies. As IWAC suggests, it could even be the plugpack itself.

28-08-08, 01:04 PM	#7 (permalink)
ssrattus Super Moderator iTrader: (0) Join Date: Jan 2008 Posts: 1,207 Spent time on board: 3 Weeks, 5 Days and 9:05:36	Is this "DVD player" a Dream DM500 satellite receiver?

28-08-08, 01:22 PM	#8 (permalink)
TZB Member iTrader: (0) Join Date: Jan 2008 Location: Canberra Posts: 84 Spent time on board: 1 Day and 8:05:17	Yeah those cheap wall warts are notorious for knocking out ADSL signals too. Having a bit of trouble getting it open B4L ?

28-08-08, 01:22 PM	#9 (permalink)
Antennaman Member iTrader: (0) Join Date: Jul 2008 Posts: 50 Spent time on board: 13:25:38	This is not surprising, as when there were actually RIs that would come out for free and track down interference to radio and television reception, they could tell you some good stories as to strange generators of RF interference. For example, television masthead amplifiers that are installed by well meaning owners that turn out to be unmodulated free running oscillators owing to inadequate installation practises is not an uncommon source of interference to 3G operations. There was even an advertising campaign in the papers covering this about the time 3g started. Read the part about who is responsible for this interference in the following article, and this applies to all items, not just the specific case mentioned here. ACMA - Masthead & distribution amplifiers fact sheet If it took a couple of weeks to track the interference down, they must be pretty sure of its origin. Moving the offending items from their currently installed position to elsewhere for testing may not prove anything, as the act of moving the offending items could disturb the fortuitous feedback path that is causing this problem.

28-08-08, 03:46 PM	#11 (permalink)
best4less I'am Not a Bloody Joke iTrader: (8) Join Date: Jan 2008 Location: Australia Posts: 2,526 Spent time on board: 1 Month, 3 Weeks, 2 Days and 12:27:04	Bloody hell it looks all good in there except for a bad smell LOL and just 1 cap measuring low in ESR it was a 10uf 50v on the primary side I best be pulling the box apart and having a look inside that. My Kingdom for a spectrum analyzer to trace this 850mhz __________________ Please wipe your feet before walking all over me

28-08-08, 04:00 PM	#12 (permalink)
bulbous Thaumaturgist iTrader: (0) Join Date: Jan 2008 Posts: 308 Spent time on board: 1 Week, 1 Day and 22:54:45	Telstra could help here with stressing to the Australian Guvvamint the need for decent regulations relating to garbage emission from all consumer devices. For a few cents in passive components the entire RF spectrum could be cleaned up immensely. Try tuning across VHF and UHF with an SSB receiver these days - twenty years ago the spectrum was wonderfully clear, now it's a screaming mess ! I don't think it will be the power supply as I don't reckon their will be any RF source in there which will be stable enough. I would be looking at any high-frequency processor stuff on the MPEG board. There will be a crystal oscillator and PLL stuff hanging off the board.

28-08-08, 04:51 PM	#13 (permalink)
best4less I'am Not a Bloody Joke iTrader: (8) Join Date: Jan 2008 Location: Australia Posts: 2,526 Spent time on board: 1 Month, 3 Weeks, 2 Days and 12:27:04	Maybe i need a lead lined box and stuff it in there LOL __________________ Please wipe your feet before walking all over me Last edited by best4less : 28-08-08 at 05:48 PM.

28-08-08, 06:05 PM	#14 (permalink)
trash Senior Member iTrader: (0) Join Date: Jan 2008 Posts: 336 Spent time on board: 2 Days and 16:32:17	I don't know of any telstra police We have RFI equipment for measuring terrestrial interference etc, but we never go hunting for individual signals. Sounds like the ACMA. Telstra will know if their is a signal problem from a PIM test which they can run from a script on the mobile base station. This is probably what they've detected. PIM testing is usually -150dBc.

28-08-08, 06:11 PM	#15 (permalink)
best4less I'am Not a Bloody Joke iTrader: (8) Join Date: Jan 2008 Location: Australia Posts: 2,526 Spent time on board: 1 Month, 3 Weeks, 2 Days and 12:27:04	You are dead right they were the ACMA and they did turn the power to the house off while the Telstra people watched it live at the tower and they did say that the interference did go away __________________ Please wipe your feet before walking all over me

28-08-08, 09:34 PM	#17 (permalink)
eeprommemory Premium Member iTrader: (3) Join Date: Jan 2008 Location: ADL Posts: 123 Spent time on board: 4 Days and 6:35:16	i have a GME kingray MHU34F antenna booster and it puts out a large signal at 1150mhz. it drove me nuts. i unplugged everything and this signal i could receive 500M away was still there. turn off house power and it goes. then i turned on all power but lights. as soon as i turned on the lights i worked out what it was. the booster plug pack is on the light circuit. i put my finger on the FET and it stops doing it. modded it with some tin to cover FET. bloody cheap untested design. i bet the makers said "yep looks good lets make em" no testing. __________________ dangerous toys are lots of fun but you could get hurt!

Sponsored Links

Sponsored Links

Sponsored Links

Sponsored Links

LinkBacks (?) LinkBack to this Thread: http://www.austech.info/electronics/10410-help-interfering-telstra-tower.html
Posted By	For	Type	Date
Austech - Powered by vBulletin	This thread	Refback	28-08-08 12:13 PM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode