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i9000 has provision for optional ext antenna??

was watching the below linked video "hardware tour" and about halfway thru, the narrator shows a socket next to the microSDHC card, indicating it's a socket for the optional external antenna?????
the antenna socket reference is at the 2.45 mark
http://www.youtube.com/watch?v=qM0T3cBoIro&feature=related

Don't know about it being there. But there's definitely an SMA connector of some sort in the beginning of this video:
http://www.youtube.com/watch?v=gydoCVSTNFc

the way those components pop together, that poster that wanted to swap components from overseas models to add FFC and a flash might be onto something

doesnt the korean version of the galaxy s have tv, im sure i saw somewhere that it has and the antenna for the tv is on the right side if you have the phone facing away from you.

yeah, but the tv antenna is up at the top corner, like you said, upper right corner when screen faces away from you
this connector is next to the microSDHC card slot about 1.5" down

larryccf said:
yeah, but the tv antenna is up at the top corner, like you said, upper right corner when screen faces away from you
this connector is next to the microSDHC card slot about 1.5" down
Click to expand...
Click to collapse
nothing that a piece of ribbon connector cant solve, right?

started to think you were on the mark re the ribbon cable
then was watching this video again http://www.youtube.com/watch?v=lt9XNnjAcBc - at about 1:59 it shows a larger socket on the upper edge of the black subframe -
it'd be nice if the one i suspect is an optional radio antenna socket is that after all, and meant for a cradle (like sony ericsson had) that incorporated an external antenna connection

larryccf said:
started to think you were on the mark re the ribbon cable
then was watching this video again http://www.youtube.com/watch?v=lt9XNnjAcBc - at about 1:59 it shows a larger socket on the upper edge of the black subframe -
it'd be nice if the one i suspect is an optional radio antenna socket is that after all, and meant for a cradle (like sony ericsson had) that incorporated an external antenna connection
Click to expand...
Click to collapse
just watched the video and its shown clearly for about 2:10 to 2:26

It is a radio antenna socket, I have on my phone to, unfortunately I don`t have a picture to show you right now.

I believe it is an external GPS antenna Socket...
Mine has it, and probably every phone has it...

this is an GPS antenna socket ... it is MMCX socket, you can find external antenna on dealextreme : http://www.dealextreme.com/details.dx/sku.14926

The internals seem to come apart very easily - they look like they are just modules with open contact bridges that just tape in place...?

Practically every phone I've ever owned included one of these external antenna jacks (FME-Female I believe), usually hiding beneath a little rubber cover. This dates back to my first, a Nokia 6190 built in 1998 which (of course) had no GPS back then. Since the GPS (at the bottom) and cellular antennas (on the top) are separate, I can't imagine this would improve GPS signals.
It's always given me a little assurance that even in the worst dead spots, I could technically snap on an inexpensive external antenna or signal booster to get a GSM connection.
For those wondering, I've confirmed the jack is, in fact, hiding under the rubber cover on the Vibrant version of the Galaxy S. Note: the rubber cover is kinda tough to pry out, but it pops back on easy enough.
Example: Cellphone Signal Booster Pack, $30

I know people might wonder why bother, but for some of you who own Renault and Peugeot vehicles in Europe, they have heat reflecting windscreens which scuppers sat-nav use in many cases hence the reason why MMC and MMCX connectors came about.
Personally, I found it easier to have a magnetic aerial and booster in the car like this
http://www.totalpda.co.uk/Carcomm/Carcomm-GPS-Re-Radiator-Antenna.7477.html

Is there any external (portable) antenna for Galaxy S when hiking on the hillside or working at a mountain area (low signal, very2 low)....?

multi basys car kit from Carcomm

Hi All,
just got the second part of this car kit turn up today from totalpda
The kit does not come with a window mount so you will have to source one, but the fixings do have the standard "AMPS" pattern 4 hole screw mounting, so pretty much anything on the 'bay will "do"
There are 2 cables - one for 12/24v DC, terminated in two open wires , and an antenna cable with the usual ..er...FME(?) trailing plug attached to it . The base plate also comes with an in-line fuse holder to make things safer, but you have to provide your own scotch-loks or terminal strip ! theres no provision for connection to an external microphone or line in of the car stereo (Ive been *****ing to carcomm since the HTC TYTN for the latter) However,I have a bluetooh enabled stereo now so this no longer bothers me
The antenna coupler is (I assume) capacitively connected (via an air gap) to the radio antenna but produced a very useful 5dBm CPICH power improvement when wired up to a tri-band band glass mount antenna (verified in the Desires extended engineering hidden menu)
flaws? well just one major goof!
A few times I have used the rear facing camera on my phones, suitably cradled, to capture video of bad driving or other crimes committed in front of me .
no chance of doing that now! the antenna booster section obscures it totally!!
overall though - rather good - although I would have liked to have seen composite video out so i can feed the sat nav output into my flip up TV screen like I "jury rigged" my old htc raphael
hope that helps someone out there - any questions just ask and I will try to answer them
regards
Rob
--
MW0CQU

Photos would be good, thanks

Photos would be good, thanks
Click to expand...
Click to collapse
a fair point, well made ;-)
ok lts see if this will work:
First pic - The empty cradle straight on
the two wires are DC power and antenna cable as described above
Second pic - A side view. odd angles due to door pillar and me being too lazy to unstick the mount. The antenna bulge is part of the "front" plate the back piece is thin and rectangular in section. the whole concept of the multi-basys is to have interchangable front pieces as you change phones over time.
Third pic - Phone fitted , showing a Map
Fourth pic - showing the flaw in that you can put the unit horizontal but you cant use it to video things happening in front of you as the antenna bulge obscures 50% of the view of the camera
hope that helps
Cheers
Rob
--
MW0CQU

G Tablet Hardware Breakdown (with pics)

So, I posted this in two of the posts buried deep within the bowels of the original thread, but I think it's a good idea to have it separated into it's own thread.
There are 4 screws under the rubber feet on back of the tablet that help hold the device together. Aside from these 4 screws, there are 3 plastic clips per side that hold the case closed.
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When you break the case open, you'll see the 2-cell, 7.4V battery, the motherboard, and the metal inner frame. The frame is held in place by screws around the perimeter, including 1 screw that is covered by the motherboard.
The EMF shield simply snaps off, revealing the hardware within. The Tegra 2 chip is of the T20 series, and the board is populated with 512MB of RAM, and the 2 chips composing the 16GB flash storage. The WIFI/Bluetooth module is made by USI. Audio is processed by a Realtek ALC5623 chip, through two separate speakers which are built into small enclosures.
Also, there are spaces for a 3G modem and what could be assumed to be a GPS unit left unpopulated.
There is nothing interesting to be seen on the back side of the main board except that it can be noted that there is space for an additional 512MB of ram to be added to the board and an EMF shield to be placed around it.
There is a hard-reset button on the main board, located next to the battery and below the 3G pads. There is also an unpopulated space for a second button.
Although not pictured, the screen is a standard netbook screen (which explains the viewing angles). It is manufactured by AU Optronics, model B101AW06. It is controlled by a Texas Instruments LVDS83B.
The capacitive functions are handled by Tango S32s. There is an AMTEL chip on the board with them. I'm assuming it's an interface between the main board and the capacitive controllers.
---
On the whole, this is a very well built device. There is room to upgrade for those daring enough to take on the task. It will be interesting to see what people do the device when it becomes more mass market in the coming weeks.
---
Updates:
The chipset for the wifi/bt module is a Broadcom BCM4329.

I found this if someone wants to give it a try it can make your tablet a cdma 3g device for use with either sprint or verizon. http://www.alibaba.com/product-gs/284022690/CDMA_Module.html
View attachment 442763

It looks like that touch controller is capable of more than just the two points that it currently allows. Apparently its software controlled how much it can sense.

t3h_g3n3r4l,
can you take a look at the front facing part of the frame, and see what is behind the 4 front buttons? I was wondering if you could use nail polish remover to remove the paint behind the buttons (so some light would shine through). How hard was it to remove the main board from the case?
Thanks!

cttwarnock said:
t3h_g3n3r4l,
can you take a look at the front facing part of the frame, and see what is behind the 4 front buttons? I was wondering if you could use nail polish remover to remove the paint behind the buttons (so some light would shine through). How hard was it to remove the main board from the case?
Thanks!
Click to expand...
Click to collapse
There's a circuit board down there. I didn't bother to see what all was on it though. It might be possible to use some sort of SMD LED backlight and use light-piping to etch lit buttons in whatever color you want. The only downside is that you'd most likely lose the ambient light sensor functionality.
It was fairly easy to pull the main board. All of the wiring connectors use positive force to keep them together as opposed to locking connectors, so it was just a matter of pulling everything loose, which wasn't difficult.
The hardest part was getting into the case. When pulling it apart, it's easiest to start at the corner diagonally opposite the volume button working towards the front panel buttons, then down the side with the volume controls, then down the side with the dock connector, then finally the edge with the USB ports.
Marine6680 said:
It looks like that touch controller is capable of more than just the two points that it currently allows. Apparently its software controlled how much it can sense.
Click to expand...
Click to collapse
Interesting. I wonder if the AMTEL chip on the board with those sensor chips is actually what is limiting us the two-point multitouch, as opposed to Android. It looked like a microcontroller chip (I think maybe a PIC), I just never really bothered to read all of the etchings on it.
Looks like I need to open this thing up again and see what else I can discover.

I can't stop thinking about those pads for the additional 512mb of memory. Sourcing the chips and some extremely steady hands could pay off in spades.
Sent from my DROIDX using XDA App

amathophobia said:
I can't stop thinking about those pads for the additional 512mb of memory. Sourcing the chips and some extremely steady hands could pay off in spades.
Sent from my DROIDX using XDA App
Click to expand...
Click to collapse
You can't directly solder to the chips. A toaster oven, otoh, should do the trick.

cttwarnock said:
t3h_g3n3r4l,
can you take a look at the front facing part of the frame, and see what is behind the 4 front buttons? I was wondering if you could use nail polish remover to remove the paint behind the buttons (so some light would shine through). How hard was it to remove the main board from the case?
Thanks!
Click to expand...
Click to collapse
I would love to see someone do this!!!!!

t3h_g3n3r4l said:
You can't directly solder to the chips. A toaster oven, otoh, should do the trick.
Click to expand...
Click to collapse
I have hand soldered to a surface before, there's actually lots of tutorials online of how to get good at it, it becomes an art form to some. usually comes down to using the right amount of flux paste in the right areas.
If I can get one of these devices, and someone can find a source for those chips I am 100% sure that I can get those chips on.
same with the 3G and GPS modules
If you all find it, I will solder. but, y'know, make 100% damn sure their right first.
also, even if I DO get them on the board, will the device even recognize the hardware? It might right of the bat, but more likely, we'll have to modify the kernel, which hey, I'm hardware, not software, someone's gotta be with me on the other half of this project if the need arises.
EDIT: http://www.mouser.com/ProductDetail...GPS-SG-T/?qs=sGAEpiMZZMuD5AK9w5s05iDvClDmkWN6 this might work for that gps space... I'd really have to get my hands on the hardware to see if it's compatible...
EDIT EDIT: http://www.alibaba.com/product-free/109064341/LEA_5S.html actually I think this would work better.

cttwarnock said:
t3h_g3n3r4l,
can you take a look at the front facing part of the frame, and see what is behind the 4 front buttons? I was wondering if you could use nail polish remover to remove the paint behind the buttons (so some light would shine through). How hard was it to remove the main board from the case?
Thanks!
Click to expand...
Click to collapse
when I get mine I will break out the multimeter and see if there are any loose spots i could drain power to some led's for. that takes care of the light source, but making the light shine through is a whole other problem. making it shine through the pre-existing plastic is also going to be finicky, you want to make sure you arent going to damage anything that would break the capacitive touch screen.

Lemcott said:
I have hand soldered to a surface before, there's actually lots of tutorials online of how to get good at it, it becomes an art form to some. usually comes down to using the right amount of flux paste in the right areas.
If I can get one of these devices, and someone can find a source for those chips I am 100% sure that I can get those chips on.
same with the 3G and GPS modules
If you all find it, I will solder. but, y'know, make 100% damn sure their right first.
also, even if I DO get them on the board, will the device even recognize the hardware? It might right of the bat, but more likely, we'll have to modify the kernel, which hey, I'm hardware, not software, someone's gotta be with me on the other half of this project if the need arises.
EDIT: http://www.mouser.com/ProductDetail...GPS-SG-T/?qs=sGAEpiMZZMuD5AK9w5s05iDvClDmkWN6 this might work for that gps space... I'd really have to get my hands on the hardware to see if it's compatible...
EDIT EDIT: http://www.alibaba.com/product-free/109064341/LEA_5S.html actually I think this would work better.
Click to expand...
Click to collapse
Interesting. I might have to give the whole solder to a grid array package another look.
I also agree that the uBlox GPS would be the better choice.

Lemcott said:
I have hand soldered to a surface before, there's actually lots of tutorials online of how to get good at it, it becomes an art form to some. usually comes down to using the right amount of flux paste in the right areas.
If I can get one of these devices, and someone can find a source for those chips I am 100% sure that I can get those chips on.
same with the 3G and GPS modules
If you all find it, I will solder. but, y'know, make 100% damn sure their right first.
also, even if I DO get them on the board, will the device even recognize the hardware? It might right of the bat, but more likely, we'll have to modify the kernel, which hey, I'm hardware, not software, someone's gotta be with me on the other half of this project if the need arises.
EDIT: http://www.mouser.com/ProductDetail...GPS-SG-T/?qs=sGAEpiMZZMuD5AK9w5s05iDvClDmkWN6 this might work for that gps space... I'd really have to get my hands on the hardware to see if it's compatible...
EDIT EDIT: http://www.alibaba.com/product-free/109064341/LEA_5S.html actually I think this would work better.
Click to expand...
Click to collapse
An easier route may be to resolder what looks to be the Mini-PCI express port back on. That would let you pop in all sorts of cards, notably a 3G+GPS card. Step one is finding out if its mini-pci express. From the pics they look close.

SMT soldering is not too difficult by hand with the proper set up. I had to learn to do it while in the military, everything from SMT repair to repairing boards with bullet holes through the middle. The only chips that need an oven to solder are the ones with a grid of contacts on the bottom surface of the chip like CPUs.

People used to add memory to the original xbox. Not sure if the process the same.
http://www.youtube.com/watch?v=Vi3Bi2i2bEg
There are a lot of diagrams and source info on adding mini pci cards on mydellmini.com.
http://www.mydellmini.com/forum/dell-mini-1010/12234-serious-talk-about-mini-pci-e-slots-4.html
http://www.mydellmini.com/forum/del...s/4635-sdhc-mini-pcie-adapter-would-work.html
Hope these can be of some help.
Sent from my DROIDX using Tapatalk

amathophobia said:
People used to add memory to the original xbox. Not sure if the process the same.
http://www.youtube.com/watch?v=Vi3Bi2i2bEg
There are a lot of diagrams and source info on adding mini pci cards on mydellmini.com.
http://www.mydellmini.com/forum/dell-mini-1010/12234-serious-talk-about-mini-pci-e-slots-4.html
http://www.mydellmini.com/forum/del...s/4635-sdhc-mini-pcie-adapter-would-work.html
Hope these can be of some help.
Sent from my DROIDX using Tapatalk
Click to expand...
Click to collapse
I believe the Viewsonic uses BGA memory, which means the solder points aren't exposed and unfortunately you can't use a soldering iron on them. Ovens have to be used to solder them.
It would be interesting to find out if the Mini-PCIe connector would work though.
EDIT:
The next time someone has one of these tablets apart, would you please measure the height of the standoffs for the Mini-PCIe? If I can get that info, I'll order a connector and give it a try. Might be nice to add 3G/GPS for (relatively) cheap.

KorbenD said:
I believe the Viewsonic uses BGA memory, which means the solder points aren't exposed and unfortunately you can't use a soldering iron on them. Ovens have to be used to solder them.
Click to expand...
Click to collapse
That was my original point. I think it can also be done with solder paste and a heat gun, but you may as well go ahead and bake the whole thing at that point. I would be much more comfortable soldering to the USB host and adding some additional ports/gadgets than I would be with breaking out a heat gun and torching my brand new tablet.

Guys i like where this is going.....lets keep on it this!
Any updates?
Getting 3g/gps and possibility of the keys to light up......this would be killer!

Kov695 said:
Guys i like where this is going.....lets keep on it this!
Any updates?
Getting 3g/gps and possibility of the keys to light up......this would be killer!
Click to expand...
Click to collapse
Not lately. I've been completely wrapped up with school. I have the feeling it will be 2 or 3 more weeks before I get the free time to do anything with my tab other than just load firmware and use it.

did pci-e can use turbo memory？

looks like there might be room near the usb ports for a stripped down usb hub and 3g modem. We could get both 3G data and voice with skype or fring

[Q] Can we build a better antenna?

The signal on this phone is way worse than my old Motorola Milestone. The only time I see green for cell signal in "battery use" is when I'm outside, whereas on the Droid it was almost always solid green. I'm never out of signal but I understand that the better the signal, the less battery use by the radio.
I found a thread in the Incredible S section and a video on youtube that tried to make the antenna in the cover better by sticking aluminum foil onto the back, extending from the pins on the cover.
To test, I first tried taking off the cover (lost signal) and putting 2 thin strips of aluminum directly on the contact pins on the phone to see if I could get signal without the cover. It worked.
I then built 2 random network of strips extending the pins on the cover (without touching the other pin's extension network) and sticking them down with tape. I made contact between the aluminum foil and the pins, and with itself always non-shiney to non-shiney side. I think the shiny side might be coated with something that isn't conductive.
Now the cover is back on but I'm not sure it's making any difference. Still -87db to -97db while holding the phone in the house.
Has anyone else tried this? I might try thin copper wire next.
Any wisdom on how the stock back cover works as an antenna? Isn't it plastic? Is it just the small gold pins?
Let's build a better antenna
Sent from my Sensation using XDA App

I'm not very good but I agree with you the signal are very week
In my house I get 1 bar of signal whereas if just step one foot out of my house the signal bar goes full
Sent from my HTC Sensation using xda premium

You can make one new antenna, but you must remove old one, or else, your new one can not work as you expected. I think original one should not worse than some standard, so flash a new radio package should have some improve one this problem. I have GPS signal weak problem some months ago, but after I flash latest radio package, GPS can be locked within several minutes without a valid data connection. Before that time, my GPS can not be locked within ten minutes.

Take a look over at the HTC Titan forums, there were a few guys over there looking into signal problems and they had all sorts of ideas while I had a Titan. The titan is pretty much a sensation xl with wp7 and the titan, xl and our sensations antennae all work in the same way with the contacts on the phone and battery cover. Hope this helps.
Sent from my HTC Sensation XE using xda premium

sparx180 said:
Take a look over at the HTC Titan forums, there were a few guys over there looking into signal problems and they had all sorts of ideas while I had a Titan. The titan is pretty much a sensation xl with wp7 and the titan, xl and our sensations antennae all work in the same way with the contacts on the phone and battery cover. Hope this helps.
Sent from my HTC Sensation XE using xda premium
Click to expand...
Click to collapse
Thanks, I'll try a search there. Do you remember anything working?
I'm interested to know how the stock antenna/battery cover works first. That'll help me understand how we could improve it.
Sent from my Sensation using XDA

Flyview said:
Thanks, I'll try a search there. Do you remember anything working?
I'm interested to know how the stock antenna/battery cover works first. That'll help me understand how we could improve it.
Sent from my Sensation using XDA
Click to expand...
Click to collapse
They were using copper strips on the outside of the case that worked but obviously was ugly. But last time I checked they were looking into scraping away the top layer of oxidized contacts to get a better contact with the phone. But Titan mobile signal and WiFi signal is waay worse than sensation. Mine was so bad I sold mine and got my XE so I'm sure someone over there could fill you in or you could find something worth experimenting with.
Sent from my HTC Sensation XE using xda premium

hello,
i've tried such things when i had a sensation. I gave up since the problem wasn't that bad for me and for some more effective measures to be taken the phone itself had to be modified in a way that warranty service people would not like.
Anyway, the antennas on sensation are, as you know, located in it's back cover. Those small exposed copper pins make contact to the corresponding locations on the phone. If one would crack open the sensation's back cover and rip off it's 3 layer construction, one would see that those copper pads are linked with some small copper conductor, forming the antenna system. Unlike older htc phones i've hacked, sensation uses a different antenna layout. If I were to try to improve it, i would go by the following steps/rules:
1. Any antenna on these type of devices, is actually a bridge between 2 points, as opposed to more traditional antenna design that has a ground pin (cold connection) and the so called hot wire - the antenna itself. These 2 are separated in normal designs, but since the nature of the wavelengths involved in gsm communications these 2 wires are actually bridged and form something called a ground loop.
2. here's a typical setup for a phone implying the same antenna system like sensation. (click for a larger version)
The small pads (blocks) are pairs used for each wireless functions. So let's say that green is gsm, blue is bluetooth/wlan and red is gps. In the right side, the phone side (without the cover) you can see that these section have their ground connections linked together. If you were to use a multimeter on the phone side and try to measure each point for continuity (with the ground connection - ex. metallic shield of the microusb connector) you will find the ones corresponding to ground.
If you look into the left side, the battery cover part, you will see that each pair has it's pins linked together. At first, if you connect the cover to the phone, it would appear that you actually short circuit everything there and it looks like a huge mess. That's true, but the manner in witch the short circuit is made, creates a ground loop. These are sensible to RF signals and although hated in other areas (hum noise on some audio equipments, etc) they are essential here as they are actually what the phone uses as an antenna.
3. note that since i currently don't have a sensation, the simple graphic representation placed above may not be 100% accurate to what you will find in this particular phone. The ideea remains the same. One must use a multimeter, placed on continuity tester to measure the points on the battery cover then - the ones on the phone. You try to place your probes on those pins - the multimeter beeps, then you've found a pair. On the phone itself you'll find more pins that "beep" when measured together, once you found all of them, you'll figure out what's the phone's ground pins for these antennas.
4. Once you have a pretty good ideea on what is linked to what and how the connections are made, it's time to figure out what antenna does what function. With the back cover removed, you should try to connect each pins corresponding to a pair, you can use a small copper wire (careful not to touch anything else). If you see gsm/bluetooth/wlan/gps working, you would have found what what each pair of pins does.
5. redesigning the whole antenna system would involve placing some copper foil as material for the bridge between the pins. Small copper wire isn't good here, you need something with a greater conductive surface.
6. Experiment, you may notice some improvements but take care how you mix the parts of your custom antenna to the original battery cover. In reality, the results will be less spectacular since the whole design is, if i am to say,well ... badly engineered. The fact that these antennas are almost all the time covered by your hand when holding the phone, doesn't help either. It just proves that simpler designs (like the hd2 for example) are superior in both sensitivity and stability in this matter.
One important note, however. It is recommended that you use surgical gloves and/or use a wrist strap to reduce the amount of static electricity produces by your body and induced on those small antennas. Some of them are very sensible to these things, you may actually further reduce their performance by damaging (reducing overall gain though transistor degradation) the small and delicate input stage of their RF transceivers.

facdemol said:
hello,
i've tried such things when i had a sensation. I gave up since the problem wasn't that bad for me and for some more effective measures to be taken the phone itself had to be modified in a way that warranty service people would not like.
Anyway, the antennas on sensation are, as you know, located in it's back cover. Those small exposed copper pins make contact to the corresponding locations on the phone. If one would crack open the sensation's back cover and rip off it's 3 layer construction, one would see that those copper pads are linked with some small copper conductor, forming the antenna system. Unlike older htc phones i've hacked, sensation uses a different antenna layout. If I were to try to improve it, i would go by the following steps/rules:
1. Any antenna on these type of devices, is actually a bridge between 2 points, as opposed to more traditional antenna design that has a ground pin (cold connection) and the so called hot wire - the antenna itself. These 2 are separated in normal designs, but since the nature of the wavelengths involved in gsm communications these 2 wires are actually bridged and form something called a ground loop.
2. here's a typical setup for a phone implying the same antenna system like sensation. (click for a larger version)
The small pads (blocks) are pairs used for each wireless functions. So let's say that green is gsm, blue is bluetooth/wlan and red is gps. In the right side, the phone side (without the cover) you can see that these section have their ground connections linked together. If you were to use a multimeter on the phone side and try to measure each point for continuity (with the ground connection - ex. metallic shield of the microusb connector) you will find the ones corresponding to ground.
If you look into the left side, the battery cover part, you will see that each pair has it's pins linked together. At first, if you connect the cover to the phone, it would appear that you actually short circuit everything there and it looks like a huge mess. That's true, but the manner in witch the short circuit is made, creates a ground loop. These are sensible to RF signals and although hated in other areas (hum noise on some audio equipments, etc) they are essential here as they are actually what the phone uses as an antenna.
3. note that since i currently don't have a sensation, the simple graphic representation placed above may not be 100% accurate to what you will find in this particular phone. The ideea remains the same. One must use a multimeter, placed on continuity tester to measure the points on the battery cover then - the ones on the phone. You try to place your probes on those pins - the multimeter beeps, then you've found a pair. On the phone itself you'll find more pins that "beep" when measured together, once you found all of them, you'll figure out what's the phone's ground pins for these antennas.
4. Once you have a pretty good ideea on what is linked to what and how the connections are made, it's time to figure out what antenna does what function. With the back cover removed, you should try to connect each pins corresponding to a pair, you can use a small copper wire (careful not to touch anything else). If you see gsm/bluetooth/wlan/gps working, you would have found what what each pair of pins does.
5. redesigning the whole antenna system would involve placing some copper foil as material for the bridge between the pins. Small copper wire isn't good here, you need something with a greater conductive surface.
6. Experiment, you may notice some improvements but take care how you mix the parts of your custom antenna to the original battery cover. In reality, the results will be less spectacular since the whole design is, if i am to say,well ... badly engineered. The fact that these antennas are almost all the time covered by your hand when holding the phone, doesn't help either. It just proves that simpler designs (like the hd2 for example) are superior in both sensitivity and stability in this matter.
One important note, however. It is recommended that you use surgical gloves and/or use a wrist strap to reduce the amount of static electricity produces by your body and induced on those small antennas. Some of them are very sensible to these things, you may actually further reduce their performance by damaging (reducing overall gain though transistor degradation) the small and delicate input stage of their RF transceivers.
Click to expand...
Click to collapse
Awesome!!! Thanks bud. I'm gonna bust out the multimeter.
So the antenna is basically some copper inside the cover connecting two adjacent pins? I assume just connecting them straight isn't the best antenna (or else they would have just done that on the phone). [EDIT: Ah, for the other two antennas, they are indeed linked with a straight piece of copper. The GSM antenna is two small contacts that I assume are somehow linked through the inside of the cover] Is this connection actually long (distance) within the cover?
Also, what are those "extensive modifications" that would actually create a big difference? I bought my phone second hand so I don't think I have warranty (or do I?). Is it building a traditional ground + hot wire antenna?

Ok, here is what I found. I'm pretty sure I used the multimeter correctly. Didn't have a continuity setting per se, but there was one in the resistance category that had an arrow pointing to a plus and it worked like in example 1 here.
What I found on the cover, is pretty much what we expected.
What I found on the phone is kind of surprising: each pair is connected to itself. Each pin is connected to the ground already as well, EXCEPT for 1 near the top.
Thoughts on how the ground loop is generated and what to try bridging with copper foil next?
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the design i've draw in the previous post, took the simplest design when using a ground loop in a phone like the sensation. As you can see, in reality, things are a bit more complex. Since you have those pins already connected one to another and those pairs to the phone ground (usb metallic shield) you already have a ground loop inside the phone and you actually extend it when you place the back cover.
Without trying to be more technical about multilayer pcb design or ground planes on a pcb, let's see what can be done about the gsm antenna and it's performance.
1. a logical first step would be to identify the pins corresponding to this antenna. Try to make some sort of cable with one end that can be fitted over those pins on the phone and the other end to an external antenna (piece of metal, if needed, use a simple metallic spoon or fork). The cable has to have 2 smaller cables inside, one for each pin. Once you find where are the pins for the gsm antenna we can proceed further. You may want to try other means to identify this, it's just that you may need a cable later on this "guide" so i've suggested to have one ready.
2. it's kind of difficult to experiment with high frequency antenna designs since there are no hobby tools capable of measuring these kind of frequencies (in the 0.8 - 1.8 - 2.4 Ghz area) and neither their amptitude in a given circuit. Since the phone itself has some means to measure this, we'll .. aah, use the phone. Signal bars, dB meters, whatever you find relevant. Another thing i do when i experiment, is to .. oversize things for more visible and clearer results. Of course, if, let's say you have a broken old phone and want to see if it still works, you won't remove it's battery and plug it to a car battery - you will blow it up. That's not one of those things were you want to oversize. Helpfully, antennas are of different nature. So, when you have to decide if a particular type of antenna is helpful, make a bigger one just like it. If the bigger one works, and the smaller one doesn't - then the design works but it's a size problem. If the bigger one doesn't work, then surely the smaller one won't work either here so you shouldn't try to make one to fit in the phone.
3. So, you got your pins right and know what's the gsm ones. Let's talk about some of the most simplest designs. Since RF energy is invisible and.. without any tools, impossible to measure, i'll be making an analogy with magnets and magnetic forces because they are of a similar origin but you can observe the effect of magnetic forces applied to an object even if you don't see the actual magnetic fields.
So, here are the 2 examples we’ll be talking today.
As you can see in the picture, the first one is a simple metallic plate and the second one contains 2 plates, one smaller then the other (about ¼) separated and not touching each other. Below each design, you have a representation of what would you see if we were to look at them from their profile, with the antennas standing vertically. Let’s talk about how they work. In case of RF energy, you would have a RF field, a spatial area on witch these waves propagate. If you place a metallic object in this field, an amount of this field’s energy will be passed to the metallic object (the process is called “induction”). We can measure this since this process generates a bunch of free moving electrons inside our metallic object. The stronger the field or the larger the surface area -> we “aquire” more electrons. If the field is too strong, a lot of electrons are being induced, they kind of “rub” on each other and surrounding molecules (it’s called brownian effect) so we produce heat - a microwave oven works like this. If we still were to pump up a greater field and to induce more energy, we will produce more heat. If we still try to induce more energy, we will obtain nuclear fusion. If we find ourselves rather more insistent and still try, we will obtain energy-matter convesions (like einstein's e=mc2) and if we still try to induce more and more energy, the matter we create will collapse under it's own gravitational field, thus we'll obtain a small black hole and surely we'll get banned from XDA for this. But to scale things down a bit and still talk about some lonely electrons, based on the general definition of the electric current, our electrons constitute a small electric current induced in the metallic object by that RF field. In a phone, that electric current is what’s being filtered and amplified. All forms of RF fields work just like this, so in the phone’s case, gsm, wlan, bluetooth etc. Thus, we need to “aquire” (it’s not the most physically correct term.. I know, but I try to keep it simple) more electrons. That’s the role of any antenna. The first design works great in areas were you have a relatively good field strength (phone signal) since it offers a big contact surface with the electromagnetic waves. This however is not always enough in places where you have a weaker field since the longer the distance to the source, the more the waves dissipate over a greater surface and from the point of view of a single receiving device – loose energy. The second design is a hybrid between those satellite dishes you may see on top of some buildings and some high gain antenna designs use in wi-fi networking. Simply adding a second metallic plate to the larger one, changes things quite a bit. I’ll get back on it after another schematic, showing how these 2 designs receive those badly needed electrons.
So, you can see, the red square (we’ll call it emitter) and our antennas. In the first case, the red thing emits and the black thing (antenna, profile view) receives those red curved lines (field energy). Because of this, a bit of red “appears” inside the black thing.
The second case looks a bit more complicated and yep.. it is. Remember that some time ago, I’ve talked about comparing RF fields with magnetic fields for the sake of simplicity. Well.. it’s time to do that stuff.. Imagine the red thing as a strong magnet. You have 2 iron plates at some distance from the magnet. You also glue these to keep them secure and not attracted by the magnet. In this setup, we say that we’ve “placed the metallic things inside the magnetic field generated by the magnet” (or something like this). The metallic plates are subjected to the force of the magnetic field, we can observe this easily because we have to keep them secured in place, not to move near the magnet. It’s the equivalent of the RF field described above. BUT something extra is also happening. While being attracted to the magnet the plates also become temporarely magnetized. So, they, themselves, will attract other metallic objects. This means that they have created a magnetic field of their own. The smaller plate, closer to the magnet, produces a larger secondary field, it’s effects reaches the second larger plate and get’s added up to the magnet’s field. Thus, the larger plate, receives a greater magnetic field in this case as opposed to the first example were only one plate is being used. The larger plate will also produce a magnetic field of it’s own, it will also reach the smaller plate, it will be induced in it, then the smaller plate will “re-emit” it to the larger one … and it’s kind of complicated even here.
The fact is, and it’s important, if we get back to waves.. it can go the other way around. Some bunch of electrons moving inside a metal plate will also create a RF field. So, maybe it’s easier to understand now, it’s actually rather difficult to design antennas since they act in both ways. They receive a part of the RF field, but they also can emit at the same time, a part of the energy they just received. The second design incorporates this facts.
4. After all of this.. how do we link those phone pins to these plates? Well that’s simple. In the first case, we will solder of at least secure 2 wires to 2 opposing corners of that plate. Those will be linked to the phone’s pins (polarity doesn’t count here). In the second case, some experiments must be done. First connect the larger plate to the phone, just like in the first case. Observe if you have any improvements, try to also connect the smaller plate to one corner or the other (by another wire). See what produces best results.
5. How big is .. big? When experimenting with larger antennas, I suggest that the larger plate to be around 50cm – 80cm in diagonal.
6. Materials… My choice would be copper. Thickness is very less relevant. Since copper foil is harder to get, you may also use aluminum foil if you manage to secure wires on it. Copper can be found on electronics store as prefabricated “blank” PCB’s. They are pretty cheap also. You can easily solder a wire on them. If you get these things, go for a single plated one, not the ones that have both sides covered with copper.
7. If you find a design that works for you in the large scale, then will try to find a way to make it smaller and fit it the phone's back case. But if the larger one doesn't work, if any large antenna design doesn't improve things much, the smaller ones surely won't help either and the problem must be searched in other places (phone's firmware, hardware etc).

I'm sorry I've got nothing useful to input in this but a guy on here before was suggesting to create a fractal antenna? something that maximizes the area of the back cover. I googled it a bit and though it was a good idea but I totally have no ideas about how to do such.

You can get stickers that you stick inside your back cover that are supposed to improve the signal. I've read mixed reviews as to whether this actually works...
http://www.phoneaccessoriesuk.co.uk/htc-sensation/268-htc-sensation-signal-booster.html

fractal antennas are better in the respect that they minimize the space requirements for antenna modules inside the phone. However, that's not diy stuff
One could try to reproduce the design with various house hold items but at this scale, when talking efficiency a simple copper plate would outperform any household fractal antenna system.
In general, although there are phones with fractal antennas, they are more efficient in higher wavelengths (lower frequencies). For example,you may have seen frigate class military vessels at sea. They have some tall 6-7 meters antennas (not the radar dishes, or "tv antenna like" yagi ones) that look like a simple rod or an extended version of your car's fm radio. They use fractal designs, and what you see as the "antenna tube" is only the flexible, weather proof casing of the actual fractal antenna inside. But they operate on a different band/wavelength.
@chrisw99 those things are actually what i was talking when suggesting my second example for antenna design. The phone's antenna acts like the bigger plate in that example and these stickers do the job of the smaller plate. Actually in theory they should work but because of the fact each phone has a slightly different antenna or placement for the RF module and these stickers try to be the "one size fits all" type, in reality your mileage may vary.

While I like the idea of building a better antenna (I’m going fiddle w/ this tonight after work), this phone has had much better signal, GPS and Wi-Fi then my Nexus 1 could ever dream of having. GPS is instantaneous on|off (N1 would stay on for up to a min after app close), Wi-Fi connects immediately (N1 would show connection but lag before my icon turned green). I have been VERY happy w/ all aspects if it’s signal.

Ahhh, great info to wake up to haha.
The GSM pins, I forgot to mention, are definitely the bottom ones.
I agree, the wifi has great reception (except when touched; very top pins). Is the wifi antenna still propogating through the cover? Or is it just the little strip of contact?
Sent from my Sensation using XDA

normally wifi antenna should be linked to a small copper foil inside 2 layers of the battery cover. That cover seems to be made out of about 2-3-4 layers of plastic, glued together in some way. One thing i never understood, why the holes in the housing?.
If i remember well, when i had the sensation i was most impressed with the gps performance. That was above any other phone i used before. Wifi performance was not that good, especially when browsing in landscape and covering the antenna with one hand. I also had one hd2 and gsm performance was kind of worse in low carrier coverage areas. Things like hd2 having 1-2 lines of signal indicator, sensation - none.
The wireless performance of the sensation is kind of mixed, some people compaining some never having any problems.

What do you think about rewiring the antennas to switch the wifi and GSM? I.e., cover up the contacts and run wires to the other antenna from the now covered original contact points.
P.s. keeping the phone in 2G mode gives me substantially better signal (ex. -69db instead of -83db).
The only reason I want to improve the signal is for battery use for the radio. I haven't actually had no signal anywhere I've gone...yet. Am I correct in thinking more power is given to the radio under "low" signal conditions though?
Sent from my Sensation using XDA

yes, that is correct. Under poor signal, the phone's tranceiver will require more power to operate. The amplifier stage inside the transceiver will need to increase it's overall gain in order to compensate, that uses more power. However, in modern phones we're talking about 1-2mA (max. 3mA) variations in stand by. That's rather small, if we also take notice of the fact that even so, the phone won't draw 2-3mA extra all the time, only when updating it's status with the corresponding GSM cell in your area (that's why they call it "cellular network"). On older phones (i mean really old) yes, that used to be a problem since individual GSM antennas were further apart from each other, phones back then needed to have stronger transceivers inside, that were able to cope with the increased distance. A small fact: the miniaturization of phones today was possible not primarily because of evolution of electronic stuffs that go inside a phone, but because carriers upgraded their networks and newer phones didn't need powerful RF transceivers inside - along with with all their required circuitry. The second most important thing is the development of high performance li-ion / polymer cells and only at third place, the evolutions in cpu/mcu or other highly intergrated circuits that now equip even the most basic phones. Since the bulky old transceivers were gone, we had a lot of space inside to put new things like cameras or bluetooth/wlan transceivers.
About switching gsm with wlan, first of all you must test how big is the improvement. Don't switch it yet, instead place a larger copper aluminum plate for the gsm antenna and check out if it improves things. If you find out that a 0.5 meter plate improves signal reception by only 20%.. well i don't think it will be relevant at the small scale, when you switch the antennas.

Really? Only 2-3mA draw difference between perfect and low signal? I might be mistaken but I remember my old phone's battery draining quicker under low signal.
I'm going to try aluminum first, that's all I have. Does it matter how long the connecting wires are?
P.s. my signal goes down considerably during a call. -69 to -90db! Just tested outside in my backyard.
Sent from my Sensation using XDA

yes, only a few miliamps. I've conducted some tests at hardware level for this. For example, the HD2 (latest phone i've test using this, here's the topic: http://forum.xda-developers.com/showthread.php?t=1018833 ) has a standby consumption of about 4-5mA (ranging from 0.2 - 6 mA). Standby means screen off, all wireless off (except gsm), processor in low power state. If i remove the antenna, the phone will still have about 1 line on the network signal indicator. Power consumption will increase with 2-3 mA. But that's about it.
The measurements are being done using a professional multimeter directly linked in series with the phone's battery.
The situation will be different if you use the phone in order to make.. phone calls. With full signal, once you make a phone call the phone's transceiver must begin to emit to a nearby carrier antenna, therefore a lot more power will be used. While having the screen off, consumption will jump from 2-3 mA to about 210-240mA during a call. If you have low signal, you can add another 100mA. (that's much...).
So if you make frequent phone calls or use the 3g networks all the time (always on type of connection) you will increase your power consumption with about 40-50%. Stand by and some rare phone calls won't have a noticeable impact, but actively using 3g and making phone calls.. well, that's another story.
Yes, it's normal for signal to drop a little when on a phone call, especially on poor carrier coverage areas. In fact, the signal is constant but your phone's RF transceiver is using very much power to transmit and due to something called supply voltage collapse (voltage drop occurring when a large amount of energy is being drawn from the battery) the receiving part will lose some of it's sensitivity.
2G signal is actually more stronger then 3G from the user's point of view. 2G was developed first, there are more 2g antennas then 3G ones, they covered a greater area with better antenna density. It's far easier and cheaper to build and install a 2g antenna then the more complicated 3G, 3.5G or 4G ones. 2G frequency emission require less power from both antenna and connecting phone then that of 3G.
as an interesting fact, a dual core cpu phone will have a maximum consumption of about 550-600mA. This is only occurring at full load (all wireless on, benchmarks, full screen brightness, etc). From a simple calculation based on the fact that this measurement was done on a 4V battery (about 60-70% charge) we can deduct that a modern phone consumes a maximum of about 2.2Watts

PX5 Xtrons (GS): DAB+ USB Adapter no more recognized.

Since few days ago, I started to experience somo problem with the USB DAB+ adapter. Sometimes it was not detected at both cold or hot startup. Then, since yesterday the DAB adapter is not detected anymore by the HU. It was correctly working before I switched off the car. After few minutes, I started again but no more connection to the adapter is performed.
I know that some GS units, has problem with USB at low outside temperatures. This is my case during winter, but now we have more than 25°C and, when it happens, I found that all USB are not working.
The adapter is connected to the rear of the HU (OTG) USB port. In this case, all the other USB are working, thus it could be the adapter or a bad connection.
Any ideas ?
Thanks

Car was sitting under the sun for the whole day. I checked several time if DAB was working again, without success. No it started to work again...

I doubt that this is a temperature related issue. Maybe a loose wire. Have you checked all physical connections?

realzoulou said:
I doubt that this is a temperature related issue. Maybe a loose wire. Have you checked all physical connections?
Click to expand...
Click to collapse
Found the issue. All 4 pins on the usb were disconnected. Probably vibration and temperature variations caused it. Resoldered and it is working again.
I discovered another interesting thing. When the radio screen is off the signal is max but when is on, then the signal is attenuated a lot. Probably the screen controller is generating interferences on the same DAB frequency. One solution could be to move the dongle far from the head unit and to use some metal sheet as shield. I will test better the issue, switching off the screen in the few places were in my city il loss the signal. The screenshot below are taken from my Note 10 running dab app inside the car. Anyone has similar experience?View attachment 5029233
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View attachment 5029231
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Good that you found the problem and were able to fix it.
For the noise that a screen backlight can cause to the DAB signal, see the posts from @DrRobin in the DAB-Z thread, especially post#2424
His unit is a Xtrons TA709IPL

realzoulou said:
Good that you found the problem and were able to fix it.
For the noise that a screen backlight can cause to the DAB signal, see the posts from @DrRobin in the DAB-Z thread, especially post#2424
His unit is a Xtrons TA709IPL
Click to expand...
Click to collapse
Moving it won't help much, without suppressing the noise, noise will travel down the cable.
Supress by decoupling via capacitors and inductors on the supply lines and supply for the USB, at the source.

marchnz said:
Moving it won't help much, without suppressing the noise, noise will travel down the cable.
Supress by decoupling via capacitors and inductors on the supply lines and supply for the USB, at the source.
Click to expand...
Click to collapse
Did you solve theproblem in this way ?
I have a px5 xtrons too.
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royalhawk2002 said:
Did you solve theproblem in this way ?
I have a px5 xtrons too.
Click to expand...
Click to collapse
Offering suggestions to an electronic problem. I'd start with obtaining an oscilloscope and measuring noise in various parts of the device. No doubt the chinese have cut corners to save the last cent, usually power supply noise suppression.

marchnz said:
Offering suggestions to an electronic problem. I'd start with obtaining an oscilloscope and measuring noise in various parts of the device. No doubt the chinese have cut corners to save the last cent, usually power supply noise suppression.
Click to expand...
Click to collapse
You can see from the pictures below that with the screen light at max the signal strength is low and the opposite with the screen light at minimum. I found a schematic that was related to a sdr based dongle with similar problems. It was encapsulated in an aluminium encloser with good results. The resistance is 1Mohm.
More info here:
https://m.imgur.com/a/pQ8dM
View attachment 5029471
View attachment 5029473
Inviato dal mio SM-N970F utilizzando Tapatalk

I moved my DAB dongle to the boot, rapped it in copper tape and earthed it really well. I also added ferrites to the lead, this helped, but didn’t fix the problem.
I then used a spectrum analyser and found a strong signal at DAB frequencies coming out of the front of the head unit when the screen was on, same as you found. THe noise is then picked up by the antenna.
Wrapping copper tape round the head unit on the metal part just near the front and connecting to the metal of the car cut the noise out of the head unit, see my earlier post for details.
I have two different Xtrons units in different cars, one is noisy (fixed with the copper tape) and the other is clean, it must be the backlight circuit.

DrRobin said:
I moved my DAB dongle to the boot, rapped it in copper tape and earthed it really well. I also added ferrites to the lead, this helped, but didn’t fix the problem.
I then used a spectrum analyser and found a strong signal at DAB frequencies coming out of the front of the head unit when the screen was on, same as you found. THe noise is then picked up by the antenna.
Wrapping copper tape round the head unit on the metal part just near the front and connecting to the metal of the car cut the noise out of the head unit, see my earlier post for details.
I have two different Xtrons units in different cars, one is noisy (fixed with the copper tape) and the other is clean, it must be the backlight circuit.
Click to expand...
Click to collapse
Thanks. Could you please provide a link to your post?
Did you add ferrites to the usb or to the car harness?
My antenna is on the roof, a shark fin type, with GPS, fm radio and dab. It is very far from the head unit...
In any case I don't think the issue is on the antenna, because I did some test with the dongle attached to my note 10 and a different antenna.
The interesting thing is that with this setup I have an unstable signal while I seat inside the car, when the head unit is on, but instead I have full signal going around inside my house. I was expecting that in the car was better because I am out in front of my house.
See the picture for the setup.
I will do other tests in the afternoon, if I can.
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View attachment 5029625

Moved the dongle in the box helped a bit. Now I have a better signal strength but is not the max. Same dongle, with same antenna connected to my note 10 with HU switched off, give a much better signal.
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Here the interferences, with screen on and off. Exactly on the dab frequency...damn!
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Hi,
Here is the link
https://forum.xda-developers.com/showpost.php?p=81667595&postcount=2465
(In case the board won't let me post a url, it is on this forum)
topic=81667595
page 247
postcount=2465
I put a clamp on ferrite round the USB cable at both ends, but in hindsight this didn't do anything.
I think your problem is exactly the same as mine, the head unit backlight emits noise at DAB frequencies, you could test that, connect your DAB dongle to your Note 10 with the Xtrons head unit off, it works correclty. Now switch the head unit on and see the signasl drop on the Note. Now turn off the display on the head unit, signal comes back.
Wrapping the head unit with copper tape and earthing it really made the difference in my car.
Good luck,
Robin

DrRobin said:
Hi,
Here is the link
https://forum.xda-developers.com/showpost.php?p=81667595&postcount=2465
(In case the board won't let me post a url, it is on this forum)
topic=81667595
page 247
postcount=2465
I put a clamp on ferrite round the USB cable at both ends, but in hindsight this didn't do anything.
I think your problem is exactly the same as mine, the head unit backlight emits noise at DAB frequencies, you could test that, connect your DAB dongle to your Note 10 with the Xtrons head unit off, it works correclty. Now switch the head unit on and see the signasl drop on the Note. Now turn off the display on the head unit, signal comes back.
Wrapping the head unit with copper tape and earthing it really made the difference in my car.
Good luck,
Robin
Click to expand...
Click to collapse
Thanks for the info. I already made the tests you suggested and everything is confirmed. I will try first to identify and shield the internal power supply for the lcd, I have a schematic and I have an idea on where is located. Then, if it doesn't work, I will proceed to shield the head unit. I will do pictures to help other users.
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royalhawk2002 said:
Thanks for the info. I already made the tests you suggested and everything is confirmed. I will try first to identify and shield the internal power supply for the lcd, I have a schematic and I have an idea on where is located. Then, if it doesn't work, I will proceed to shield the head unit. I will do pictures to help other users.
Inviato dal mio SM-N970F utilizzando Tapatalk
Click to expand...
Click to collapse
That is fantastic. I have 2 Xtrons units in two cars, an older Android 8, that doesn't cause any interference and the newer featured in the post which creates terrible noise around 200MHz. I did some looking and found that LEDs and their PSU can be noisy at these frequencies, so I guess the later Xtrons units are just a problem. It is not good that they sell a head unit and DAB stick that creates so much noise to make it useless, I did contact them and sent them my findings, but didn't get any sensible response.
Since the noise was coming out of the screen I thought it would be difficult to get rid of unless I put a screen rfi filter on and then the touch screen probably wouldn't work. I did notice that if I touched the metal case of the Xtrons unit with my hands the noise dropped a little, so assumed that it wasn't very well earthed. I tried the copper tape not really expecting it to work, but had to take a piece of tape to bare metal to get a good earth. It took a couple of goes to make sure the head unit and cradle were really well earthed, but the results were fantastic, the noise dropped away to almost nothing on my spectrum analyser.
Unfortunately I didn't get any screen shots from the analyser, but used a SDR-Play to view the spectrum, although a cheap DTV USB stick would also show the same thing if you have one available?

DrRobin said:
That is fantastic. I have 2 Xtrons units in two cars, an older Android 8, that doesn't cause any interference and the newer featured in the post which creates terrible noise around 200MHz. I did some looking and found that LEDs and their PSU can be noisy at these frequencies, so I guess the later Xtrons units are just a problem. It is not good that they sell a head unit and DAB stick that creates so much noise to make it useless, I did contact them and sent them my findings, but didn't get any sensible response.
Since the noise was coming out of the screen I thought it would be difficult to get rid of unless I put a screen rfi filter on and then the touch screen probably wouldn't work. I did notice that if I touched the metal case of the Xtrons unit with my hands the noise dropped a little, so assumed that it wasn't very well earthed. I tried the copper tape not really expecting it to work, but had to take a piece of tape to bare metal to get a good earth. It took a couple of goes to make sure the head unit and cradle were really well earthed, but the results were fantastic, the noise dropped away to almost nothing on my spectrum analyser.
Unfortunately I didn't get any screen shots from the analyser, but used a SDR-Play to view the spectrum, although a cheap DTV USB stick would also show the same thing if you have one available?
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Yes I have the sdr dongle that I am using for my tests. See pictures in above posts. In any case I am thinking to shield the backlight psu with a sheet of metal soldered on the nearest ground point. I will try also to use shielded wire as much as possible inside the unit, exchanging the actually installed, if not shielded. Another test I would like to do is to change the source of the antenna amplifier power...actually is connected to the wire coming out from the hu...probably the 200 mhz interference is transferred to the outside antenna with that wire, contributing to attenuate the signal.
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Today I had the time to make the work. So I did;
1) locate the LED power supply. The problem was not in the power supply, but the LED panel itself. I did some measurements with the spectrum analyser and I found that the highest strength of the interference was coming from the around the screen where the led strip is located and not near the power supply.
2) Noted that the lcd controller board is mounted on the back of the screen without any shield. Then I decided to shield first the board and connect it to the chassis.
3) I put a plastic foil molded on the board to insulate it from the shield. Before that, I fixed a screw on one of the board holes that are connected to ground.
4) Then I put some aluminium tape all around the board, also on the plastic sides of the screen frame. The screw in step 3 was connected to the aluminium shield.
5) connected a wire from the screw in step 3 to the chassis.
6)Covered almost all the unit with aluminium tape, taking care to make all the strips touching one to the other in order to have one whole shield as result.
7) switched on the unit and...no more interferences found even at max screen intensity.
Hereafter some pictures. Now i have the signal strength to max. Hope it helps. I want to thank @DrRobin for the suggestion.View attachment 1
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This is brilliant that you found this source of interference and actually fixed it.
I have a GS px5 unit now with the same problem but I have installed a powered roof antenna which now gives me full signal.
I did once try a shark fin antenna on the roof but it didn’t work which must be because of the interference and I would actually still like to have a shark fin antenna so I think I will do this shielding that you two guys have done.
Did either of you try just shielding the back of the screen to see if that fixed the problem before you installed your ground connections and covered the whole units in tape? The reason I ask is because it is the cheap LED lights that they will have used that will be causing the problem. If they would have used some certified LED lights then they would have had shielding on them and wouldn’t have caused any problems.

ab1702 said:
This is brilliant that you found this source of interference and actually fixed it.
I have a GS px5 unit now with the same problem but I have installed a powered roof antenna which now gives me full signal.
I did once try a shark fin antenna on the roof but it didn’t work which must be because of the interference and I would actually still like to have a shark fin antenna so I think I will do this shielding that you two guys have done.
Did either of you try just shielding the back of the screen to see if that fixed the problem before you installed your ground connections and covered the whole units in tape? The reason I ask is because it is the cheap LED lights that they will have used that will be causing the problem. If they would have used some certified LED lights then they would have had shielding on them and wouldn’t have caused any problems.
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Click to collapse
Look at points 1 to 3 and to the second picture above.
I have a shark fin antenna, for fm, dab and GPS and it is working well
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