BER: Difference between revisions

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This block measures the bit error rate between two streams of packed data. It compares the bits of each streams and counts the number of incorrect bits between them. It outputs the log of the bit error rate, so a value of -X is 10^{-X} bit errors.
This block measures the bit error rate between two streams of packed data. It compares the bits of each streams and counts the number of incorrect bits between them. It outputs the log of the bit error rate, so a value of -X is 10^{-X} bit errors.


When the  is set to false (default), it is in streaming mode. This means that the output is constantly producing the current value of the BER. In this mode, there is a single output BER calculation per chunk of bytes passed to it, so there is no exact timing between calculations of BER. In this mode, the other two parameters to the constructor are ignored.
When <code>Test Mode</code> is set to false (default), it is in streaming mode. This means that the output is constantly producing the current value of the BER. In this mode, there is a single output BER calculation per chunk of bytes passed to it, so there is no exact timing between calculations of BER. In this mode, the other two parameters to the constructor are ignored.


When  is true, the block is in test mode. This mode is used in the ber_curve_gen example and for other offline analysis of BER curves. Here, the block waits until at least are observed and then produces a BER calculation. The parameter helps make sure that the simulation is controlled. If the BER calculation drops below the setting, the block will exit and simply return the set limit; the real BER is therefore some amount lower than this.
<code>Test Mode</code> equals true is used in the ber_curve_gen example and for other offline analysis of BER curves. Here, the block waits until at least<br> <code>BER Min Errors</code> are observed and then produces a BER calculation. The parameter <code>BER Limit</code> helps make sure that the simulation is controlled. If the BER calculation drops below the <code>BER Limit</code> setting, the block will exit and simply return the set limit; the real BER is therefore some amount lower than this.


Note that this block takes in data as packed bytes with 8-bits per byte used. It outputs a stream of floats as the log-scale BER.
Note that this block takes in data as packed bytes with 8-bits per byte used. It outputs a stream of floats as the log-scale BER.
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== Example Flowgraph ==
== Example Flowgraph ==


Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI. Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately. The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.
This flowgraph shows the measurement of BER in an OFDM loopback simulation.
 
[[File:OFDM_loopback_BER_fg.png|800px]]
 
== Example Output ==
 
[[File:OFDM_loopback_BER_out.png|800px]]


== Source Files ==
== Source Files ==


; C++ files
; C++ files
: [https://github.com/gnuradio/gnuradio TODO]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fec/lib/ber_bf_impl.cc]


; Header files
; Header files
: [https://github.com/gnuradio/gnuradio TODO]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fec/lib/ber_bf_impl.h]


; Public header files
; Public header files
: [https://github.com/gnuradio/gnuradio TODO]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fec/include/gnuradio/fec/ber_bf.h]


; Block definition
; Block definition
: [https://github.com/gnuradio/gnuradio TODO]
: [https://github.com/gnuradio/gnuradio/blob/master/gr-fec/grc/fec_ber_bf.block.yml]

Latest revision as of 01:51, 11 February 2024

This block measures the bit error rate between two streams of packed data. It compares the bits of each streams and counts the number of incorrect bits between them. It outputs the log of the bit error rate, so a value of -X is 10^{-X} bit errors.

When Test Mode is set to false (default), it is in streaming mode. This means that the output is constantly producing the current value of the BER. In this mode, there is a single output BER calculation per chunk of bytes passed to it, so there is no exact timing between calculations of BER. In this mode, the other two parameters to the constructor are ignored.

Test Mode equals true is used in the ber_curve_gen example and for other offline analysis of BER curves. Here, the block waits until at least
BER Min Errors are observed and then produces a BER calculation. The parameter BER Limit helps make sure that the simulation is controlled. If the BER calculation drops below the BER Limit setting, the block will exit and simply return the set limit; the real BER is therefore some amount lower than this.

Note that this block takes in data as packed bytes with 8-bits per byte used. It outputs a stream of floats as the log-scale BER.

Parameters

Test Mode
False for normal streaming mode (default); true for test mode.
BER Min Errors
The block needs to observe this many errors before outputting a result. Only valid when test_mode=true.
BER Limit
If the BER calculation falls below this limit, produce this value and exit. Only valid when test_mode=true.

Example Flowgraph

This flowgraph shows the measurement of BER in an OFDM loopback simulation.

OFDM loopback BER fg.png

Example Output

OFDM loopback BER out.png

Source Files

C++ files
[1]
Header files
[2]
Public header files
[3]
Block definition
[4]
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