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h1. TRF6151C

This is the Texas Instruments RF Chip TRF6151C (Rita)

It includes a VCO, Mixers, etc.

Data sheet is available from http://www.52rd.com/bbs/Detail_RD.BBS_8719_68_1_1.html but registration to the chinese forum

is required for download.

h2. TSP

The TSP to the TRF6151 uses three wires:

* CLOCK (regular CLK_13M)

* STROBE (generated by TPU)

* DATA (provided by TPU at falling edge of CLOCK, TRF samples data at rising edge of CLOCK)

!Rita:trf6151_tsp.png!

h2. Analog I/Q baseband output

During development I've taken some measurements of the I/Q output of the TRF6151. This signal

is fed to the [[TWL3025]] baseband ADC inputs.

The green and black graph of the diagrams below are the "I" channel positive and negative signal.

The magenta graph (M1) is the difference signal computed by the Scope.

All voltages have to be multiplied by a factor of 10, as 10:1 probes were used.

h3. baseband output in idle mode listening on paging channel

This is zoomed out to a very long timebase to see the Rx activity at 1.8 second intervals,

which apparently was the paging channel for the paging group of that IMSI.

!trf6151_iq_rx_paging_channel.png!

h3. multiple consecutive bursts

This shows multiple consecutive received bursts.  

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

!Rita:trf6151_iq_rx_burst_distance.png!

h3. a single burst

!trf6151_rx_iq_one_burst.png!

h3. bits of a burst

!trf6151_rx_iq_bits_of_burst.png!