Hello, rear radar :-)

[BioSehnsucht]

Would it be feasible to design a phased array radar unit that was still relatively compact (2-4x the volume would probably still be manageable, in terms of hiding it behind a bumper), that could steer a narrower than usual beam from side to side (and perhaps top to bottom) and thus not only cover more area reliably but also with more precision versus a regular radar module?

 

[mongo]

Would it be feasible to design a phased array radar unit that was still relatively compact (2-4x the volume would probably still be manageable, in terms of hiding it behind a bumper), that could steer a narrower than usual beam from side to side (and perhaps top to bottom) and thus not only cover more area reliably but also with more precision versus a regular radar module?

A phased array is basically a series of normal single emitters arranged and phased to alter the beam pattern. To make it steerable, you need additional elements in the axis of steering. So if you also wanted vertical aiming, you would need a few rows of elements vertically.

Element size is tied to beam width is tied to frequency and antenna size. Higher frequency and larger size yield smaller beam patterns (for single elements and for arrays of elements).

Assuming an electrically steered unit, if one used the entire bumper, it might be possible to achieve the max beam steering of +/- 60 degrees left/right (maybe more with a curved array). Element creation/ physical design (absorber? ) might get you a decent vertical roll off such that the beam is focused in a roughly level plane for object detection.

 

[Zarwin]

As an update to my previous post about the location of the BT radios, I discovered one other thing interesting this morning when checking the car again. The BT naming has meaning. The last character designates the location.

C - Center or Console
D - Driver B-Pillar
P - Passenger B-Pillar
R - Rear (Bumper)

EDIT: This will of course cause massive confusion with RHD cars , should have used Port/Starboard

For those new to the thread, this is in reference to my post earlier

Also, this morning I noticed the dew on the B-pillars had a peculiar (not so peculiar) dry spot.

 

[lunitiks]

Also, this morning I noticed the dew on the B-pillars had a peculiar (not so peculiar) dry spot.

 

[MarcusMaximus]

...OR: They're actually going to bounce bluetooth signal off of cars as an alternate form of radar.

 

[lunitiks]

...OR: They're actually going to bounce bluetooth signal off of cars as an alternate form of radar.

...AND: Since it's tilted slightly upwards, they're going to bounce some of the bluetooth signals off of overhead signs, reflecting it in a downwards angle to cars behind the car behind you as an alternate form of humor

 

[BigD0g]

What happens if I approach from the front? I'm confused why they need a special rear BT setup if they don't need a front BT setup...

 

[Zarwin]

...OR: They're actually going to bounce bluetooth signal off of cars as an alternate form of radar.

Seems like a silly thought at first but who knows, lol. I just had the car out and parked in a packed parking lot. Walked away and at roughly 200 feet(60m) from the car, with no line of sight to the car (lots of other cars in the way) I still had one of the side radios and the back radio connected to my phone. I'll go out after work and see how far those things can connect to my phone. Not terribly scientific of course since it's just connecting to a phone, but I can also get the RSSI values at different distances for my phone which might be interesting.

 

[lunitiks]

Mods - what's up with keeping my original thread title? Please change it to "Hello, rear bluetooth-antenna". Or "Goodbye, rear radar" LOL!

@Zarwin, I love your experimental nature. Please continue.

Anyone: Why would Tesla bother to install such a "chunk" in the rear bumper? Model X for instance, has tiny bluetooth antennas everywhere, also in the rear bumper, center. What's with the form factor? What are they building in there?

 

[mongo]

Mods - what's up with keeping my original thread title? Please change it to "Hello, rear bluetooth-antenna". Or "Goodbye, rear radar" LOL!

@Zarwin, I love your experimental nature. Please continue.

Anyone: Why would Tesla bother to install such a "chunk" in the rear bumper? Model X for instance, has tiny bluetooth antennas everywhere, also in the rear bumper, center. What's with the form factor? What are they building in there?

If you want it changed, the most effective way is to report your first post and put the request in the comment.

 

[mongo]

Anyone: Why would Tesla bother to install such a "chunk" in the rear bumper? Model X for instance, has tiny bluetooth antennas everywhere, also in the rear bumper, center. What's with the form factor? What are they building in there?

I think it is also the near field RDIF/card reader, hence the large size for the antenna. Why also on the rear sensor? Guessing commonality.

 

[lunitiks]

What do you mean @mongo? I see no such box on the B-pillars...?

 

[mongo]

What do you mean @mongo? I see no such box on the B-pillars...?

Am I inventing a parallel universe again? I assumed that since the Bluetooth node were at the same locations as the RFID readers, they were the same module.

 

[lunitiks]

Am I inventing a parallel universe again? I assumed that since the Bluetooth node were at the same locations as the RFID readers, they were the same module.

Clearly they're not the same form factor at least. Look at the pillar images upthread, compare it to the black box on page 7.

 

[Zarwin]

I think it is also the near field RDIF/card reader, hence the large size for the antenna. Why also on the rear sensor? Guessing commonality.

That would make sense, but RFID it isn't enabled anywhere except the driver side B-pillar according to the manual. I just checked to make sure this was accurate and it is. Tried it on the passenger B-pillar and of course had to try it on the rear bumper as well. Doesn't do anything unless it's on the driver side B-pillar. Still makes sense that it is combined in the same module though.

EDIT: And this would make sense for the center console as well since RFID to enable drive is in the same place as the console BT it seems

 

[mongo]

That would make sense, but RFID it isn't enabled anywhere except the driver side B-pillar according to the manual. I just checked to make sure this was accurate and it is. Tried it on the passenger B-pillar and of course had to try it on the rear bumper as well. Doesn't do anything unless it's on the driver side B-pillar. Still makes sense that it is combined in the same module though.

Yeah, I'm off, the rear module does not have any secondary communication function. The B pillar version is dual role BLE + RFID. The chunky size may be to ensure the spacing requirement from the antenna?

 

[Joerg]

For RHD it makes sense to include the RF(/BT) on the right side and only to make it active thru software later for those markets. On the back it might be handy to unlock if you approach from behind and first want to open trunk?

 

[mongo]

For RHD it makes sense to include the RF(/BT) on the right side and only to make it active thru software later for those markets. On the back it might be handy to unlock if you approach from behind and first want to open trunk?

I had the same trunk thought, but there is no button that I know of for it. Oh! Unless it uses the backup camera, and you wave your hand or some such...

 

[BioSehnsucht]

A phased array is basically a series of normal single emitters arranged and phased to alter the beam pattern. To make it steerable, you need additional elements in the axis of steering. So if you also wanted vertical aiming, you would need a few rows of elements vertically.

Element size is tied to beam width is tied to frequency and antenna size. Higher frequency and larger size yield smaller beam patterns (for single elements and for arrays of elements).

Assuming an electrically steered unit, if one used the entire bumper, it might be possible to achieve the max beam steering of +/- 60 degrees left/right (maybe more with a curved array). Element creation/ physical design (absorber? ) might get you a decent vertical roll off such that the beam is focused in a roughly level plane for object detection.

Well, some googling later and apparently some R&D has been done way back in 2014 but I can't find much concrete info about it or any progress updates on commercializing.

Researchers unlock potential of phased-array radar for automotive deployment

With Phased-Array Radar Technologies, UC San Diego Electrical Engineers Aim to Make Car Travel Safer

A 77–81-GHz 16-Element Phased-Array Receiver With - Beam Scanning for Advanced Automotive Radars - IEEE Journals & Magazine

I wish you didn't have to pay for access to IEEE, might be something interesting in there.

100 degree field of view (I'm guessing this means +-50 degrees from straight ahead) and up to 100m distance.

From the picture of the chip, it looks pretty small, but it's not clear if that's just the RF processing (phase shifting, etc) or the antennas too (seems too small to include the antennas). Though since it's being developed for automotive applications, surely it can't be too big ...

From Radar for Pedestrian Safety image doesn't seem like the overall package is much larger than typical radars, but I'm just guessing from the size of the screw holes.

 

[run-the-joules]

I had the same trunk thought, but there is no button that I know of for it. Oh! Unless it uses the backup camera, and you wave your hand or some such...

There's a button on the trunk.