1. ADC I/Q data are saturated with minimum receive Gain 24, any other way to reduce the gain?
2. in receive subsystem page 50 of IWR1443 data sheet, what "saturation detection do"?
3. Can ADC data be averaged before sending to FFT accelerator?
Can anyone answer these questions?
Thanks,
Hello Feng,
If this is on your-own hardware it may be possible. Normally the patch antenna has 8-9db gain, there are losses reflecting off the target. The Rx LNA has 24-48db gain. If you think this is based on your Tx reflecting off a target, you can use the Tx backoff in the ProfileCfg, try to backoff by 10 to 20 db (1db per count).
I have not seen this on the EVM.
Answers Q1 - this is not normal. I would use the mmWave Estimator and Radar Studio and reenter your chirp / system parameters.
With the EVM, and a Corner Reflector .5m equivalent at 8-10 meters, with 30-36db gain, on the EVM I do not get saturation. I have attached a picture.
Answer Q2 - in the production version (ie ES3) for the ASILB version of the AWR radar devices, there is RF monitoring, included that the BSS processor can look at specific RF or digital points, and report errors if the signal level is too high, too low, or detects interference. This information is not yet available from the designers. There is a description of Built in tests for the AWR1642.
Answer Q3 - the ADC buffer can be processed differently through Hardware Accelerator (HWA) Programming, which is customized by the user. There is a digital filter capability, You could create a scaling factor with the filter coefficients (use an impulse tap and vary the value).
I think you should look at the mmWaveSDK capture demo, and capture the raw ADC Buffer data. while the internal data path goes from 12bits, to 18bits throughout the DFE, you can round the output to 12,14, or 16bits. When you capture the signed complex, or signed real data, you can look at the signal levels at the DFE output.
You can route the data directly to L3 memory, without HWA processing to make sure its not an HWA concern.
Hello,
To paste a picture, you need to select Use rich formatting. Then paste a JPG from file, or paste from Word (put your picture in a word file, then copy and paste.
I don't have a corner reflector that is 6" per side, our Lab has a 4.25" per side. I will have to setup a capture demo, to send you the data. There is also another tool, called Radar Studio, but to use this you need the DevPack board, and a TSW1400. It captures the LVDS output from the 1443, 1642 devices. I will try to post a lab result Monday.
The transmitter backoff is a standard mmWave parameter. Please look at the mmWave SDK User Guide. It is in the ProfileCfg. You can save your mmWave Visualizer experiment to a .cfg file, change the Tx backoff parameter to 10 (its currently 0), that should result in 10db less transmit power.
In my case, with a 4.25" triangle reflector, at 2.1meters, RxGain 30, Tx backoff, along bore site of Tx antenna, my IQ count is < 1000.
I have included a screen shot from Radar Studio. We will have to replicate this with mmWave data capture, I will work on that. (probably Monday).
Regards,
Joe Quintal
