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From: | Marcus D. Leech |
Subject: | Re: [Discuss-gnuradio] Dynamic range of USRP2-XCVR2450 |
Date: | Tue, 19 Oct 2010 13:18:49 -0400 |
User-agent: | Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.0.7-1.fc12 Thunderbird/3.0.7 |
On 10/19/2010 12:21 PM, Jorge Miguel wrote:
Hi Marcus!In the "features" list for the LTC2284: 72.4dB SNR, 88dB SFDR SFDR is "spur-free dynamic range".
The LTC2284 can be configured for either 1VP-P or 2VP-P. I believe the USRP2 uses 1VP-P configuration. Generally, with ADCs, you ascribe roughly 6dB of dynamic range per bit, this is a 14-bit A/D. The MAX2829 has roughly 93dB of RX gain-control range--that's right on the data sheet, and is "exposed" to the API inside Gnu Radio. When you create a source, you can specify the gain (actually, you can change it dynamically as well). Is it the correct way of calculating the dynamic range?The LTC2284 A/D is a 14-bit A/D. The maximum input voltage the way it's configured is 0.707Vrms. Divide that by the 2^14, and that's roughly your minimum input voltage. In general, though you take a little bit off the top and add a little bit onto the bottom of the range. Google is your friend. I'd suggest looking up "ADC noise floor dynamic range". Plenty of articles out there. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org |
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