DCA1000EVM+AWR1642BOOST: DDR memory FULL !

Hello Ahmed,

Cont stream option is intended for continuous CW RF transmission. In this mode there are no chirps or frames, its just a continuous wave, and hence no gap in the data. That is why changin chirp or frame config does not impact this mode.

The effective data throughput over a 1Gbps ethernet link is about 300-700Mbps based on capability of the PC used to receive the packets. In continuous mode the data rate is much higher , for example if you are sampling 9Mbps, 4 RX channels, complex 16 bit the data rate would be 1152Mbps which is much higher than what the ethernet can transfer. Hence the DDR memory (2Mbytes) will over flow and that is the limit of the capture. In case of real chirps/frames there is always inter chirp time and inter frame time which reduces the effective data rate and enables continuous capture of Rx data.

Typically for tests that need continuous wave a few clock cycles are enough for analyses. Could you explain why you need non stop capture of RX data in continuous streaming mode? Is there some reason you cannot use the chirp/frame mode?

Regards,
Vivek

Hi Vivek,

thank you for the clarification. Actually, I don't know exactly the difference between the continious mode (no chirps, no frames) and the chirp/frame one. In my case, I need different signals for a period of time( let's say 15 min or more), which is not possible if the DDR will be full. I also will analyse the signal and probably detect peaks etc... 

I am making some signal records in parallel with other records that's why I thought I need the continuous streaming mode. 

I took some records in the chirp/frame mode and it is only for a short period (because of the DDR limit). Is it not possible to record more without interruption ? or once the DDR is full, I should tstart again ? 

what is the best mode you advice me to use in my case (continious or chirp/frame) ? 

thank you in advance,

Ahmed

Vivek,

can you explain me what's the effect if I reduce the number of chirps when taking measurements ? how playing on the chirp parameter could effect the signal quality ?

thanks in advance,
Ahmed

Vivek,

thnaks, I would reduce the periodicity of the frames (want to get each period of time a frame...). But why should I keep the number of chirps (256) always the same, what could be the effect on the signal received ? 

thanks in advance,

Ahmed

hi Vivek,

thanks for the details. Actually, I will use the same config as in the vital signs lab.

(Num ADC samples: 100, num chirps: 2, sampling freq =2000 ksps, chirp duration = 50 us, sampling rate = frame rate, IF sampling rate = 2Mhz).

I want to ask about the sampling along the slow  time axis sampling freq (20 Hz) and the fast time axis sampling freq (2 Mhz) meaning, and what are the exact parameter to configure in the mmwave studio for them ( the chirp duration Tc, interframe sampling rate, bandwidth ) ?? 

thanks in advance,

Ahmed

Hi Kyle,

thanks, I Have already seen it. But I didn't understand why they are using such config to extract to vital signs , for example, why recording data only using two chirps and getting only one in the processing .. ?

thanks,

Ahmed

Hi Kyle,

thanks again, actually I understand the vital signs config and I am using the same in my case to capture signals. but I have one more question concerning the config: 

In the vital signs config, the chirp period is 50 micro seconds and the frame period is  50 ms and in my case (also vital signs case) they are using only one chirp per frame, so why should the frame period is much more higher than the chirp period, is it useless to have a frame with 50 ms which is >>> 50 micro second ? should the frame period be just a bit high than the chirp config ? because otherwise the almost the hole frame will be empty is it just contain one chirp with 50 micro sec (1/1000 * frame period ) ! 

I sow the details in the vital signs lab document and didn't found an explanation to this .

my frame config: ar1.FrameConfig(0, 0, 6000 , 1, 50 , 0 , 1)

my profile config : ar1.ProfileConfig(0, 77, 7.01, 6, 57, 0, 0, 0, 0, 0, 0, 70.106, 1, 100, 2000, 0, 0, 40)

thank you in advance,

Ahmed