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From: | Tim Huggins |
Subject: | Re: Setting the OFDM Occupied Carriers |
Date: | Mon, 3 Aug 2020 14:19:00 +0000 (UTC) |
Looks like an alignment issue. If you take 4 subcarriers off each end:(list(range(-22, -21)) + list(range(-20, -7)) + list(range(-6, 0)) + list(range(1, 7)) + list(range(8, 21)) + list(range(22, 23)),)or the same number out in a different way:(list(range(-26, -25)) + list(range(-20, -7)) + list(range(-6, 0)) + list(range(1, 7)) + list(range(8, 21)) + list(range(26, 27)),)then it works. Someone else might know whether the allocator is supposed to handle arbitrary numbers of occupied subcarriers, or whether it has to be a multiple of 8 or something like that.On Tue, Jul 28, 2020 at 4:26 PM Jeff Long <willcode4@gmail.com> wrote:Ok, I see the same thing and haven't figured it out either.On Tue, Jul 28, 2020 at 3:53 PM Tim Huggins <huggins.timothy@yahoo.com> wrote:The signal looks correct, but the plots change from this:to this:Maybe the issue is not with the actual chain, but potentially how I am displaying the results?On Tuesday, July 28, 2020, 3:44:52 PM EDT, Jeff Long <willcode4@gmail.com> wrote:I plugged the shorter list into the occupied_carriers variable in tx_ofdm.grc on 3.8.1.0 and saw what looked like a reasonable signal.On Tue, Jul 28, 2020 at 3:27 PM Tim Huggins <huggins.timothy@yahoo.com> wrote:I am trying to understand the OFDM examples and I'm quickly running into an issue. I was successfully able to modify the occupied carriers in the ofdm_loopback.grc example, however when I copy these changes to the tx_ofdm.grc or rx_ofdm.grc I do not see data on coming out of either the OFDM Receiver (tx_ofdm.grc) or the Stream CRC32 block (rx_ofdm.grc). I have attached a UChar To Float which is connected to a QT GUI Time Sink to view the data (mimicking the loopback example).For example tx_ofdm.grc sets occupied_carriers to:(list(range(-26, -21)) + list(range(-20, -7)) + list(range(-6, 0)) + list(range(1, 7)) + list(range(8, 21)) + list(range(22, 27)),)or([-26, -25, -24, -23, -22, -20, -19, -18, -17, -16, -15, -14, -13, -12, -11, -10, -9, -8, -6, -5, -4, -3, -2, -1, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26],)Modifying this to(list(range(-25, -21)) + list(range(-20, -7)) + list(range(-6, 0)) + list(range(1, 7)) + list(range(8, 21)) + list(range(22, 26)),)or([-25, -24, -23, -22, -20, -19, -18, -17, -16, -15, -14, -13, -12, -11, -10, -9, -8, -6, -5, -4, -3, -2, -1, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25],)results in only zero being displayed. What am I overlooking that results in the data not making through the examples?Thank you,Tim
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