Project

General

Profile

Rita » History » Version 4

laforge, 02/19/2016 10:48 PM
add scope captures from the I/Q baseband output

1 4 laforge
[[PageOutline]]
2 4 laforge
3 4 laforge
= TRF6151C =
4 1 laforge
This is the Texas Instruments RF Chip TRF6151C
5 1 laforge
6 1 laforge
It includes a VCO, Mixers, etc.
7 2 laforge
8 2 laforge
== TSP ==
9 2 laforge
10 2 laforge
The TSP to the TRF6151 uses three wires:
11 2 laforge
 * CLOCK (regular CLK_13M)
12 2 laforge
 * STROBE (generated by TPU)
13 2 laforge
 * DATA (provided by TPU at falling edge of CLOCK, TRF samples data at rising edge of CLOCK)
14 2 laforge
15 2 laforge
[[Image(Rita:trf6151_serial_1.png)]]
16 2 laforge
17 2 laforge
[[Image(Rita:trf6151_serial_2.png)]]
18 3 laforge
19 3 laforge
The timings have been confirmed by the measurements below:
20 3 laforge
21 3 laforge
[[Image(Rita:trf6151_tsp.png)]]
22 4 laforge
23 4 laforge
== Analog I/Q baseband output ==
24 4 laforge
25 4 laforge
During development I've taken some measurements of the I/Q output of the TRF6151.
26 4 laforge
27 4 laforge
The green and black graph of the diagrams below are the "I" channel positive and negative signal.
28 4 laforge
The magenta graph is the difference signal computed by the Scope.
29 4 laforge
30 4 laforge
=== baseband output in idle mode listening on paging channel ===
31 4 laforge
32 4 laforge
This is zoomed out to a very long timebae to see the Rx activity at 1.8 second intervals,
33 4 laforge
which apparently was the paging channel for the paging group of that IMSI.
34 4 laforge
35 4 laforge
[[Image(Rita:trf6151_iq_rx_paging_channel.png)]]
36 4 laforge
37 4 laforge
=== multiple consecutive bursts ===
38 4 laforge
39 4 laforge
This shows multiple consecutive received bursts.  
40 4 laforge
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
41 4 laforge
42 4 laforge
[[Image(Rita:trf6151_iq_rx_burst_distance.png)]]
43 4 laforge
44 4 laforge
=== a single burst ===
45 4 laforge
46 4 laforge
[[Image(Rita:trf6151_rx_iq_one_burst.png)]]
47 4 laforge
48 4 laforge
=== bits of a burst ===
49 4 laforge
50 4 laforge
[[Image(Rita:trf6151_rx_iq_bits_of_burst.png)]]
Add picture from clipboard (Maximum size: 48.8 MB)