After having torn down and subsequently efficiently reassembled two Aukey dashcams, the DRA1 and (extra just lately) DRA5, I had two choices for what to do with them: donate them or preserve them (I suppose I might additionally “promote them”, however that’d actually stretch the that means of “open field”, wouldn’t it?). Thus far, I’ve stored them. And in preparation for probably urgent them into service, I’ve bought two equipment for every:
I ordered three of the latter, truly motivated partly by a amount low cost provide from the vendor, and with a teardown in thoughts.
These modestly priced units (presently listed on eBay for $8.99 every) are extra than simply passive antennas; they embrace processing ICs that merge and reconcile the indicators coming from a number of GPS satellites and output a serial information stream (strictly talking, within the type of NEMA sentences) that informs the dashcam of its real-time location for show, datalogging to a SD card, and so forth. In actual fact, trendy receiver ICs are as an alternative known as GNSS (international navigation satellite tv for pc system) units as a result of they comprehend not solely GPS but additionally Galileo, GLONASS and different providers. Maxim Built-in’s (now Analog Gadgets’) MAX7269 is a consultant instance.
My unit arrived absent any directions and packaged solely in a transparent plastic bag.
Right here’s what it seems like unbagged, as-usual, alongside a 0.75″ (19.1 mm) diameter U.S. penny for measurement comparability functions:
You’d be understandably confused in case you seemed on the connector and questioned if the GPS receiver outputs stereo audio (or to be actual, on this specific case, acts as a stereo headset with a further mono microphone output, or as a balanced-input headset). It definitely seems like a standard 3.5mm audio plug, doesn’t it? Scan GPS receivers on eBay or elsewhere and also you’ll discover each four- (TRRS) and three- (TRS) conductor variations; I wanted to ensure that I purchased the variant anticipated by the Aukey dashcams…however maintain that thought.
Generally in these teardown initiatives figuring out the parts as soon as I get inside is the largest problem. And different instances, simply getting inside is the toughest half. This was a type of latter conditions, because it turned out. However I’m getting forward of myself. The 1st step was to peel off the sticker on the underside of the receiver, which revealed a coin-shaped magnet beneath, presumably meant to “stick” the receiver to a bit of metallic on the within of the car (once more, I’m considerably guessing, as a result of….no documentation…):
However all that sticker peeling didn’t truly get me inside. So, my consideration was subsequent drawn to a seam across the sides of the receiver:
The seam was asymmetrical (horizontal on two sides, curved on the others), so I used to be skeptical that it was something greater than beauty, however I figured it wouldn’t harm to strive anyway…
I’m not like different, luckier of us with their fancy, expensive sonic blades ;-), so I as-usual needed to resort to field cutters and screwdrivers-as-chisels (I nearly additionally broke out the hacksaw):
When the side-seam consideration didn’t get me wherever (I used to be on the time working beneath the eventually-incorrect assumption that the highest a part of the case was snapped or glued to the rest and would finally yield), I turned my consideration to the bottom-side circumference seam; which you’ll, looking back, faintly see within the earlier pictures after I eliminated the sticker:
However regardless of how a lot of the outer case I used to be capable of break free, and the way lengthy I utilized a warmth gun to the assemblage, I couldn’t get that prime off:
Taking a breather, I peered inside and noticed one other seam:
Redirecting my implements-of-destruction consideration to it acquired me the place I wished to be:
Seems, my screwdriver jabbing had inadvertently additionally jostled the Faraday cage inside unfastened (together with creating different injury which you’ll shortly see, however none to me, fortunately):
The PCB lifted proper out:
Revealing…properly, not a lot, until you’re into low-noise amplifiers. Particularly, there are two SOT-23-6 packaged AT2659S units from an organization referred to as Zhongkewei, and alternate-sourced (Google knowledgeable me) by Maxim Built-in/Analog Gadgets. What about these scoring marks on the PCB, by the best way (resembling those on both aspect of part F1)? These had been from my screwdriver and the neanderthal who was wielding it.
Flip the PCB over and also you see a squarish system hooked up to the opposite aspect, a ceramic patch antenna to be exact:
All of which leaves me with two questions:
- The place’s the GPS receiver chip? It doesn’t matter what I attempted, I couldn’t get the ceramic patch antenna to budge, so I can solely assume this specific IC is mounted on the non-visible aspect of the PCB, in-between the PCB and the antenna.
- Why was a four-conductor plug obligatory? Look carefully on the soldered connections between the wire and the PCB and inform me what number of you depend. Three, proper? Which is smart…energy and floor coming from the dashcam, plus serial information headed to the dashcam. If this had been an A-GPS design, the place the receiver’s GPS-sourced location information is augmented by mobile tower-sourced location information coming both from the dashcam itself or (for instance) a cellphone Bluetooth-connected to the dashcam, a fourth wire (and conductor mated to it) carrying a serial information stream headed in the wrong way may make sense, however that’s not the case right here.
That each one mentioned, and as I’ve admitted earlier than, RF stuff isn’t my specific forte…due to this fact why I depend on my readers to fill within the information gaps. Hold forth within the feedback, please!
—Brian Dipert is the Editor-in-Chief of the Edge AI and Imaginative and prescient Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the corporate’s on-line publication.
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