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From: | Marcus D. Leech |
Subject: | Re: [Discuss-gnuradio] Multi-N210 synchronization issue |
Date: | Sun, 06 Nov 2011 16:20:34 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.23) Gecko/20110928 Fedora/3.1.15-1.fc14 Thunderbird/3.1.15 |
On 11/06/2011 03:12 PM, Khalid Jamil wrote:
Actually, this is entirely independant of UHD and the devices it connects to. The selector() must necessarily disconnect then reconnect, and this must necessarily create a phase hit. Near as I can tell, the selector object (which is a synthetic object defined in GRC, but not, as far as I can tell, available anywhere else in Gnu Radio) will case a phase-hit regardless of what the source is.Thanks Marcus. So, it is the "select" block that is causing UHD device to reset every time. The reason I am using "Select" block is to avoid large file sizes, as the interested signals can occur any time for short periods of time. So, I have to run the program all the time, record a calibrating signal and then wait for experiment data to occur and record this to file sinks. Continuous recording can fill the hard disk very quickly; 1MS/s for eight channels, something like 32MB/s or 2GB/min. Any ideas on how can I record IQ data for discrete non-continuous intervals of time without causing the system to re-tune. Thanks, Khalid.
If this were my problem to solve, I might use the "record" button to drive an adder which when you're not recording, adds some large out-of-range value to the output data, otherwise the data is in {-1.0,1.0}. Then I'd dump my data over a FIFO, and use a C/C++ program to do "data slicing" on the resulting data, then use the data magnitude to decide if it's "real" or not. That is but one approach.
You could dump your "record" variable to an external file, and have your recording program look for the value of that variable, and start recording when it sees the variable set to True (or 1, or oranges, or kobe-beef, or battleships, or whatever).
Another way is to simply have your file-sink write to "/dev/null" until it's time to write real data. The filename can be changed dynamically
and it "just works". -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
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