IWR6843: Carrier sensing function for Japan needed?

Hi,

An expert will comment shortly. Thank you for your patience.

Best,

Nate

Hi,

Our field team believes that this requirement is unnecessary if the transmit power is below 10 mW. Does that match your expectation? They are currently investigating it in greater detail.

Best

Nate

Hello Nate

Thanks for your response. It would be great to get more clear informations here. I'm at the moment also in contact with a laboratory what is possible but we had already similiar issues in the past for 24GHz radar sensors and Jack Cha who initiated the base topic had the same problems when he talked with his client for a certification in Japan for a 60GHz system.

Thank you Ueli,

Please ping this thread if you don't hear back by EOD on Thursday.

Best,

Nate 

Hello Nate

I got a feedback from our laboratory and it seems that the references you mentioned to in the last topic are only valid for lower frequency systems. The requirements for 57 to 64GHz are defined in volume 2 of the standard and the rules here are different to the snippet you posted:

It seems that there is a need for a interference prevention function and we have also a limitation when it comes to transmission times (10% duty cycle). But at the moment I've no plan what is really needed to show compliance for such a interference prevention function. Does TI have more information here?

Best,

Ueli

Hello Nate

Thanks for the update. Great that you have connections directly to Japan what were able to clear this things up.

Best, Ueli

By the way

Is it somehow possible to work with higher EIRP limits and duty cycles by adding an interference prevention function?

Best, Ueli

Hi Ueli,

This is exactly what I am curious about too :). I'm asking around internally, but I don't think I will get an answer in a reasonable amount of time. Can you ping this thread again in a week or two if you don't hear back? If you're able to work with Jack Cha to get more information about specific requirements for the carrier sense function, maybe we can figure it out together. My current line of thought revolves around whether we need to be able to detect power at the entire frequency band, or if it's limited to just a carrier frequency of 60 GHz. If we can limit the carrier frequency to only 60 GHz, then maybe it is possible.

Best,

Nate

Hello Nate

I checked the topic with our laboratory and they say that the information of your field team in Japan is wrong.

It seems that there are three different categories for the use of 60GHz (FMCW low power, Pulse radar, and 60GHz high power) Pulse radar is not relevant for us why I only list the two other categories:

1. FMCW (low power)
Frequency: 57 ~ 64GHz
OBW: 7GHz
Antenna power (conducted): 10dBm
EIRP: 13dBm
Transmission time restriction: 3.3ms or less per 33ms
Carrier sensing: /
Interference prevention function: 6-2.5

2. 60GHz high power
Frequency: 57 ~ 66GHz
OBW: 9GHz
Antenna power (conducted): 250mW
EIRP: 40dBm
Antenna gain: >10dBi
Transmission time restriction: /
Carrier sensing: Yes
Interference prevention function: 6-2.5

The lab clearly say's that there is always a need for an IPF function for both categories. The point here is that they can't check it during a certification. Here we as manufacturer need to provide a statement what we sign what say's that we can be sure that we receive our transmitted signal. For me this is quiet difficult to reach for an FMCW radar because we have no modulation. But it can be that we can define a statement what will work here.

When you want to go to the high power categorie you do not have the duty cycle restriction but you need to implement a carrier sensing functionality what listens to the RX channels and only starts sending if there are no other transmitters sending in the same band.

It would be great when you can recheck this with your team and maybe give me a hint for the statement we need for the IPF.

Best  Ueli

Hi Ueli,

Perhaps you could make a statement using this information in this document?

https://www.ti.com/lit/an/swra662a/swra662a.pdf

I will ask internally for thoughts about the statement, but expect at least a week before a response.

Best,

Nate