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From: | Marcus D. Leech |
Subject: | Re: [Discuss-gnuradio] RFNoc and data rates |
Date: | Thu, 24 Sep 2015 21:31:32 -0400 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
On 09/24/2015 06:37 PM, Simon Olvhammar
wrote:
Yes, in my current Python Gnuradio application I have implemented Dicke-switching by syncing it with external signals that indicate S/R as well as transition state of RF. I have not seen any issues with overlapping fft:s. The switch frequency is 1 Hz and the transition state signal has an interval of perhaps 100us where no storing of ffts is done.You can chose the latency tradeoffs yourself. If you want data delivered to the host faster, you'd likely choose a shorter integration time, by playing with alpha values. But if your Dicke-switching time is on the order of 1s, then you could discard several FFT frames and still have very-high-quality data. There's also a technique called "oblivious synchronous detection" developed by Ken Tapping at DRAO, and I did an implementation of it in my gr-ra_blocks package. If the difference between "sky" and "reference" is more than a few dB, then you can just take buffers of data and "sort them into their houses" (ref or sky) by "slicing" based on the distinct populations of samples, without having to worry about strict synchronization with your (external) switching source--the samples themselves tell you what "house" they belong in.
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