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laforge, 02/19/2016 10:49 PM
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{{>toc}}
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h1. TRF6151C
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This is the Texas Instruments RF Chip TRF6151C (Rita)
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It includes a VCO, Mixers, etc.
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Data sheet is available from http://www.52rd.com/bbs/Detail_RD.BBS_8719_68_1_1.html but registration to the chinese forum
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is required for download.
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h2. TSP
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The TSP to the TRF6151 uses three wires:
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* CLOCK (regular CLK_13M)
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* STROBE (generated by TPU)
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* DATA (provided by TPU at falling edge of CLOCK, TRF samples data at rising edge of CLOCK)
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[[Image(Rita:trf6151_tsp.png)]]
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h2. Analog I/Q baseband output
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During development I've taken some measurements of the I/Q output of the TRF6151. This signal
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is fed to the [[TWL3025]] baseband ADC inputs.
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The green and black graph of the diagrams below are the "I" channel positive and negative signal.
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The magenta graph (M1) is the difference signal computed by the Scope.
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All voltages have to be multiplied by a factor of 10, as 10:1 probes were used.
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h3. baseband output in idle mode listening on paging channel
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This is zoomed out to a very long timebase to see the Rx activity at 1.8 second intervals,
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which apparently was the paging channel for the paging group of that IMSI.
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[[Image(Rita:trf6151_iq_rx_paging_channel.png)]]
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h3. multiple consecutive bursts
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This shows multiple consecutive received bursts.  
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You can see that there is a DC offset when the TRF6151 is powered up, but you can't really see data on that DC offset
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[[Image(Rita:trf6151_iq_rx_burst_distance.png)]]
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h3. a single burst
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[[Image(Rita:trf6151_rx_iq_one_burst.png)]]
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h3. bits of a burst
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[[Image(Rita:trf6151_rx_iq_bits_of_burst.png)]]
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