Dashcam GPS Teardown
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- čas přidán 15. 12. 2018
- A look at the GPS module which was part of a Dashcam. A look at a modern process node and the difficulty in analyzing silicon down to the gate level with a optical microscope.
More photos at: electronupdate.blogspot.com - Věda a technologie
The battery is there to keep the last position and satellite data (which are "downloaded" from the GPS satelites while the device is active). This speeds up the fix the next time the device is powered up. It will work without that battery, but depending on signal strength it can take an aweful long time to get a satelite fix in that case. But it can be exchanged. Doesn't have to be the same shape with the tabs. There's usually enough space to put another type in the case.
Yes. The almanac takes 11 minutes to download from the GPS satellites at 50 bits per second, and it’s good for up to 2 weeks.
You need a SEM :)
Don't we all? ;p
those battery's or caps are mostly used to remember the satellites. most of the settings for the gps are stored in a eeprom.
Now we wait with baited breath for the teardown of the rest of the camera...
Short life, but look on the bright side, the old one was probably GPS and GLONAS only, the replacement could listen to GALILEO and BAIDOU as well for more accurate fixes, my latest phone is picking a few satellites from all four constellations already.
Thank you for your videos, I always enjoy watching them.
Thank you so much, been trying to find FCC internal pics for these cheapy modules. This helps alot. Thank you
Fantastic video. Learning a lot here, please keep up the great work.
Electronupdate fans: do a shot every "of course" ^_^
It always amazes me to think about how unbelievably minute the power it's receiving is. The GPS transmitter is 25 watts and that 1cm^2 antenna is probably absorbing 0.2 femtowatts of microwave energy. ONE HUNDRED BILLION TIMES less energy than the star light from an average star falling on the same area.
I agree, that's stunningly amazing!
But then there's these two tiny spaceships on their way to leaving our entire solar system, and we're STILL somehow able to RECEIVE DATA FROM THEM! That is REAL MAGIC...
And with millions transistors smaller than the wavelength of visible light, packed into a consumer device that only lasts a few years.
Those devices use two clever tricks to achieve a vert high gain:
Firstly, they are *superheterodyne* receivers (that's not specific to GPS, pretty much all receivers are superheterodyne today). To explain that simply, the 1575 MHz GPS L1 signal is said to be "downconverted" X MHz lower through a "mixer". Imagine that the mixer converts all signals to 1570MHz lower, the GPS signal will come out of the mixer at 5 MHz. At this frequency it is much easier to amplify and to filter it. Then this signal is sampled by an analog to digital converter: all what happens next is in the digital domain.
Here is the second trick: the signal is said to be *spread spectrum* . A GPS signal actually is very narrow, around 50Hz wide (compare this with a FM radio station that is 200kHz wide), such a signal can get very easily interfered and drowned below the noise floor. To overcome that, the signal is "spreaded" by mixing it with a much wider 1.023MHz wide signal. The signal now occupies around 1MHz of bandwidth and is much less likely to be interfered. Then the receiver will mix the incoming signal with the 1.023MHz wide signal to retreive the narrow signal. To receive the signal the receiver must precisely synchronize its 1.023MHz wide signal with signal of the satellite. The difference of synchronization between signals from the different satellites gives the TDoA( Time-Difference of Arrival) between the different signals from the satellites, which is used to calculate the distances relative to them and the the position is calculated via triangulation. All satellites transmit at the same frequency and are thus amplified by the same circuitry. The digital circuit will simultaneously de-spread the signals from all the satellites and as they are not in sync they do not interfere with each other.
Saw the title and nearly passed by thinking about another teardown etc, yup. But clicked and saw you truly tore it apart!! Those die pics are great :D
This is fascinating to watch, thanks for sharing these tear downs. Have you ever examined a modern gyroscope/accelerometer? I fly miniquads, drone racing type RC flying, and most people in the hobby build their own aircraft and use flight controllers which makes them fairly hi tech toys but most of us only have a vague understanding of what’s inside all of the packages mounted on our flight controllers/video transmitters etc.
I would be happy to send you a 30x30mm flight control board that has a gyro, microprocessor, on screen display chip etc. on it if you want to take a peek inside 😎
BTW this GPS module looks very familiar especially the ceramic patch antenna, we use modules like that when building return to home RC aircraft or even just for transmitting coordinates back to us when flying long range so we know where to look if it goes down lol.
Very good video 👍
That looks like a pretty standard breakout board for whichever gps module they've used. I guess if it fits the case, and soldering a few wires across to the interface board is cheap enough then it's good enough for them.
Thanks for the teardown. Interesting to see that GPS module had pads for what looked a USB connector? Surprised there isn't more to a GPS antenna, just a metal and ceramic sandwich.
In many devices the GPS is a seperate subsystem that comprises the antenna, the RF/processor part, a small battery for timekeeping and outputs its position via a serial link. The GPS module (I mean the green pcb with the antenna) does probably not come from the dash cam manufacturer. As the gps receiver (the blue pcb with the chips) probably supports USB so they they designed the green pc to be able to fit a micro USB connector, in case someone woule need it.
Also, the ceramic in the antenna somehow interacts with electromagnetic waves, you can find a lot more info if you google "ceramic antenna". Those are used because they are way smaller than 1575MHz circularily polarized antennaes.
Power supply- potentially an easy fix, but I'm glad you tore it down instead 👍
Are you sure that “battery” wasn’t actually a supercap?
It might also have been a rechargeable 3V battery like the ML621www.digikey.com/product-detail/en/fdk-america-inc-a-member-of-fujitsu-group/ML621-TZ1/SY103-ND/1202947
Both supercaps and rechargeable batteries come in this form factor.
No, it is supercap. I'm also using them for gps modules, to keep satellite data.
What would stop you from replacing the battery? there was plenty of room for a larger one.
why is the ceramic pink on the gps antenna, is that beryllium oxide?
This was really cool
electronupdate what was max resolution and max sd card this cam supported ??
Nice, thanks for sharing😀👍
you'd love to do a video on a Zing smart night light. This is the coolest and smartest I've seen, I have one apart in my hand now. It has 20 I believe sm5050 rgb's, wifi, bluetooth, li-po battery, PIR. Pricey at $40 us but it does a lot with software app, you might want to check it out. Thx
Home depot sells.
Very crusty hand soldering on that gps module. Never seen a dash cam with separate gps. Wonder why they did that.
Perhaps to partition the product and then try to upsell people on overpriced accessories after they've already bought the camera and are satisfied with it or have committed to buying the camera. This way they can lower the price on the main unit and make it more attractive but drive up the overall profit.
Also on a technical level, why not, GPS is usually a separate subsystem that only needs power+ttl-serial anyway.
Siana Gearz they could upsell by just omitting gps components on the main board. After the fact, they could sell someone a whole new camera if they want gps.
GPS antennas need to be stuck to a precise area of the windshield where there is no GPS-blocking thermal insulating layer, so the antenna MUST be separate from the rest of the unit. The GPS module is completely seperate because, first, this is more flexible (You can have dashcams without GPS) and secondly you can use a dirt-cheap cable instead of a more expensive coaxial cable.
Integrated Electronics my garmin dash cam has gps integrated. Every other dash cam I’ve looked at is the same. There’s no technical requirements to have the gps separate.
I have a dashcam with a separate GPS module, and Integrated Electronics gave you a very good reason for them being separate :P I'm not sure if this is what Integrated Electronics was referring to, but the Ford Fiesta in which I learnt to drive, in around 2008, had an electrically-heated *front* windscreen (for very rapid de-icing/defogging, apparently it's a Ford-only thing called Quickclear: en.wikipedia.org/wiki/Quickclear ), with dozens of very fine wires running up and down the windscreen - fine enough that they didn't interfere with the driver's vision. However that technology is known to attenuate GPS signals (and other RF signals), so if you have a car with that windscreen feature you may well *require* an external GPS unit/antenna that you can place somewhere on the windscreen that doesn't have those heating wires (I think there's a patch behind the rear-view mirror that's void of the heating element), otherwise you would really struggle to get a GPS lock.
I don't know if this is much of an issue any more - perhaps more recent GPS modules are sensitive enough that they can get a lock even from signals that have been attenuated by this technology, or maybe because, as mentioned in another comment on this video, modern units are able to listen for positioning signals from four separate global constellations (i.e. the USA's GPS, Russia's GLONASS, the EU's Galileo, and China's BeiDou - also Japan's QZSS, but that's basically limited to covering Japan), each using their own frequency range(s), that attenuation is less of a concern - but it was definitely a problem for people using GPS receivers 5-10 years ago.
(Incidentally, the fact that we now have 4 global navigation satellite systems in operation [Galileo has only been available since Dec '16, and BeiDou's global coverage has only recently been usable - Wikipedia suggests literally since *last month*: 27th December 2018!] is super cool. I'm currently indoors, in southern England, and yet my very new Android smartphone [Huawei Mate 20 Pro] is able to see 11 GPS satellites, 8 GLONASS satellites, 8 Galileo satellites, and 6 BeiDou satellites!)