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From: | Marcus Müller |
Subject: | Re: [Discuss-gnuradio] Distance Measurement |
Date: | Mon, 13 Jul 2015 11:14:59 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
Hi Manuel, I haven't taken a very detailed look at your flowgraph (the symbol rate being 10e6 with a sampling rate of 400kHz seems odd), but:
To be honest, I think the fact that you didn't notice that your temporal resolution wasn't nearly sufficient is a bit of a bad sign; I sometimes find myself "panicking" about something that doesn't work, and I always found it helpful to then take a moment, sit down, drink a coffee, take a sheet of paper and do some math or drawings or such things to find out what I expect my system to do. Your radar is a bit odd -- the whole real signal / complex-to-magnitude is a very atypical approach for radar, because range resolution (ie. the smallest distance change you can measure) is proportional to unambiguous bandwidth for pulse radars (and basically, all radar types); so usually, you try to squeeze the maximum bandwidth out of your system and avoid throwing away half of it by only considering real signals! This also makes your usage of the RRC a bit questionable, but you might have other reasons to use it (shapers for pulse radars are often something like Chebychev windows). By the way, the theoretical lower limit for a simple one-way pulse radar's range resolution is (complex sampling! ), which gives us for your case. So you really need to increase your sampling rate by a factor of at least 100, if you don't want to run around more than 7.5m. Best regards, Marcus On 07/13/2015 03:56 AM, Manuel David Lozano Amezquita wrote:
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