Unable to perform IQ sampling normally

RE: Unable to perform IQ sampling normally

honghuahh — Thu, 22 Aug 2024 10:54:21 GMT

OK，thanks. Maybe there is too much noise. Recently, we did another test. The postion that couldn't be received before can now be received again. We ' ll do some more tests later.

RE: Unable to perform IQ sampling normally

Simonr — Mon, 19 Aug 2024 12:48:40 GMT

I had a chat with the developer in charge of direction finding today, and they are not aware of any issues with the changing the antenna switching pattern. We ran a quick test today, using the configuration you mention, and did not see any issues with static const uint8_t ant_patterns[] = { 0xC, 0x9, 0xE, 0xD, 0x8, 0xA, 0x2, 0x0, 0x5, 0x6, 0x1, 0x4 };

Note that the order of the entries in the device tree should not be changed when using the Nordic antenna matrix. (The enable-gpio-patterns sequence that is). If the GPIOs are set up differently the radio will apply antenna-enable-patterns, but other antennas on the matrix are selected. So if you always also change the dfegpio0-gpios, you should only change the ant_patterns, as that works out of the box on our end.

The only other possibility we see is that there is too much noise in your testing environment that the two devices aren't able to connect, but then again it would be strange that it works with the default antenna pattern.

Best regards,

Simon

RE: Unable to perform IQ sampling normally

honghuahh — Sat, 03 Aug 2024 14:41:14 GMT

OK，thanks. We found that there is noise when switching the antennas, but we are not sure if this is the main reason.

RE: Unable to perform IQ sampling normally

Simonr — Fri, 02 Aug 2024 07:59:08 GMT

Hi again

I've not heard back from the devs yet, and the expert on this is away until August 19th I'm afraid, so I'll try getting hold of him then and fill you in again then unless someone else chimes in before then.

Best regards,

Simon

RE: Unable to perform IQ sampling normally

Simonr — Mon, 29 Jul 2024 10:52:18 GMT

Yep, I agree there must be something we're missing and have made an inquiry internally to find out what that might be. I'll get back to you when I hear back from the devs. Unfortunately some of the team is currently out of office, so it might take a while. I'll get back to you on Friday at the latest with an update in any case.

Best regards,

Simon

RE: Unable to perform IQ sampling normally

honghuahh — Fri, 26 Jul 2024 13:18:27 GMT

Can you confirm with your developers or testers whether different switching patterns will affect the connection of the device? If so, what could be the possible reasons for this.

We use our own antenna board, and also find that different switching patterns will affect the connection. An antenna switching patterns can work normally at a certain position, but the connection may be disconnected at other positions.

However, when we do not sample IQ data, that is, do not switch the antennas, any antenna can be connected normally. It seems that switching antennas will affect the connection.

But we have not yet found an antenna switching patterns that can be normally connected at all positions.

RE: Unable to perform IQ sampling normally

Simonr — Thu, 25 Jul 2024 08:41:33 GMT

Yes, it should be possible to get usable IQ samples from other antenna switching patterns as well, but the default one is the optimal one since it does one corner at a time.

I'm afraid the accurate Chinese description doesn't help much since I don't know Chinese, but I think what you need to do here is to make sure you match up the antenna switches to the pattern you're actually setting. You need to make sure the correct switch is used so that the application switches to the right antenna when doing sampling on the central side. I'm guessing the disconnections are caused by a timeout because the device switches to the incorrect antennas and thus not catching the expected data.

Best regards,

Simon

RE: Unable to perform IQ sampling normally

honghuahh — Wed, 24 Jul 2024 02:38:06 GMT

These pictures show the connection between nRF52833 DK and Antenna Board

RE: Unable to perform IQ sampling normally

honghuahh — Tue, 23 Jul 2024 13:07:44 GMT

Have you set this custom antenna pattern on both sides of the connection or just on the central side?

I use AOA mode and just set this custom antenna pattern on the central side

How have you connected the antenna array to the nRF52833 DK on your end?

Pin Header, I will upload a picture later to show the connection

So when you change the antenna pattern without changing the switch pattern they won't match

the antenna pattern is passed as a parameter to this interface，so the switch pattern will change according to the antenna pattern

Is there a specific reason you're playing around with the antenna switching patterns here?

We want to use our own Antenna Board and antenna pattern, so we need to verify different antenna switching patterns.
According to the code process,
changing the value of static const uint8_t ant_catterns will also change the SWITCHPATTERN register, so I hope to confirm with you whether changing the antenna switching patterns can still obtain IQ sampling values normally

To describe it accurately, I will explain it in Chinese

我们打算使用我们自己设计的天线，天线切换的顺序也是我们自己定义的，所以我们想用 nRF52833 DK 和 PCA20054 Antenna Board 做验证，看看天线切换的顺序是否可以改变，但是现在我们改变天线切换顺序，板子的连接都不正常了。

根据代码流程，改变 static const uint8_t ant_patterns 的值， SWITCHPATTERN 寄存器也会跟着改变，所以希望和你们确认，改变天线的切换顺序是否还能正常获取IQ采样值

RE: Unable to perform IQ sampling normally

Simonr — Tue, 23 Jul 2024 08:22:36 GMT

Have you set this custom antenna pattern on both sides of the connection or just on the central side? How have you connected the antenna array to the nRF52833 DK on your end? The different antennas are connected to specific antenna switches, so they need to match in order to switch correctly. So when you change the antenna pattern without changing the switch pattern they won't match and likely cause these CRC errors. Is there a specific reason you're playing around with the antenna switching patterns here?

Best regards,

Simon

RE: Unable to perform IQ sampling normally

honghuahh — Tue, 23 Jul 2024 03:58:24 GMT

I use this ant_patterns and gpio，it cannot establish a connection

But when I change the order of gpio, it works well

It's possible that gpio28 and gpio29 have different features compared to gpio3 and gpio4, or pcb design issues

Have you made any progress on this issue now?

RE: Unable to perform IQ sampling normally

honghuahh — Wed, 17 Jul 2024 05:19:37 GMT

Ok, thanks for your reply

RE: Unable to perform IQ sampling normally

Naeem Maroof — Tue, 16 Jul 2024 14:29:36 GMT

Hi,

We have received your query, and the ticket will be assigned to one of our engineers. Please bear that it may take few days to get an answer as we have high load during this time.

Apologies for inconveniences.

Regards,

Naeem

RE: Unable to perform IQ sampling normally

honghuahh — Tue, 16 Jul 2024 03:32:44 GMT

I did some tests.

When static const uint8_t ant_patterns[] = {0xC, 0x9, 0xE, 0xD, 0x8, 0xA,
0x2, 0x0, 0x5, 0x6, 0x1, 0x4 };

The position of the two boards is shown below. The central can collect some IQ data, and the packet CRC ERROR often occurs. After a period of time, the connection will be disconnected

Then move the central position to the position shown in the figure, and the connection will immediately disconnect,

and IQ data cannot be collected

But when I used the original

static const uint8_t ant_patterns[] = { 0x2, 0x0, 0x5, 0x6, 0x1, 0x4,
0xC, 0x9, 0xE, 0xD, 0x8, 0xA };

central is in the top two positions, the connection and IQ sampling are normal, this phenomenon is very strange, why the connection is related to the order of antenna switching