BERT - Bit Error Rate Tester
Core function SIM::bert.process()
. More...

Inheritance diagram for SIM::bert:

Public Member Functions
	bert ()

	~bert ()

void	set_prbs (int M)

void	set_poly (const bvec &bpoly)

void	set_symbol_size (int W)

void	set_length (int L)

void	set_threshold (const ivec &T)

void	set_fsm (bert_fsm_state state)

void	set_output (bert_fsm_state yout)

void	set_adr (bert_adr a)

int	get_length (void)

int	get_symbol_size (void)

ivec	get_threshold (void)

ivec	get_cnt (void)

ivec	get_acc_cnt (void)

int	get_metrics ()

bert_fsm_state	get_fsm (void)

bvec	get_state ()

bvec	get_poly ()

bert_fsm_state	get_output (void)

void	clear_counters (void)

ivec	process (const bvec &ce, const bmat &x)

Detailed Description

BERT - Bit Error Rate Tester
Core function SIM::bert.process()
.

For active clock tick ce[i], input symbols x[i,:] are shifted into X LSR and internally generated PRBS symbols y[i,:] are shifted into Y LSR.
When BERT_FSM is in SYNC state, bit differences between x[i,:],y[i,:] symbols are accumulated in counters - accessible by get_cnt(), get_acc_cnt().
Metrics = sum(xor(X,Y)) is a number of bit differences between states of X,Y LSR (X[0:L-1], Y[0:L-1]).
Metrics, together with thresholds [T0,T1,T2] is used in BERT_FSM state transitions.
Instant change of state is possible only in SYNC, nSYNC states.
In RELOAD state BERT acquires number of bits greater of equal with the length internal PRBS generator and after transits to PRESET state.
In transition from RELOAD to PRESET state, data shifted into X synchronize PRBS to the input bit stream by setting the state of PRBS using acquired input bits.
PRESET requires acquisition of L bits before making a transition.
In PRESET state data both shifted into X,Y - yet Y symbols are generated by PRBS
Bit errors are updated only in SYNC state
BERT_FSM can transition to SYNC state if (metrics < T0) but exits SYNC state if (metrics > T1)
For operation BERT counter requires setting:
W - symbol size for X,Y LSR and PRBS LFSR
L - length of X,Y LSR - X.lenght >= PRBS.lenght due to PRBS X pre-setting in RELOAD state
M - PRBS generator index or LFSR taps [bvec]
[T0,T1,T2] - thresholds for state transitions
BER is to be calculated as BER=(err_cnt)/(bit_cnt)
There are two error counters
- instant values with auto reset after readout with get_cnt()
- permanent values accessible via get_acc_cnt()
BER= (T0/L) is estimation of maximum BER value measurable by BERT, since BER>(T1/L) causes transition to nSYNC state

Constructor & Destructor Documentation

SIM::bert::bert ( )

inline

SIM::bert::~bert ( )

inline

Member Function Documentation

void SIM::bert::clear_counters ( void )

reset all counters

ivec SIM::bert::get_acc_cnt ( void )

Get accumulated counters

Returns: - [ivec] [acc_cnt_err, acc_cnt_bit]

ivec SIM::bert::get_cnt ( void )

Get counters

Returns: - [ivec] [cnt_err, cnt_bit]

bert_fsm_state SIM::bert::get_fsm ( void )

Get current FSM state

Returns: - [bert_state] BERT_FSM

int SIM::bert::get_length ( void )

get length of shift registers X,Y

Returns: - [int] length

int SIM::bert::get_metrics ( void )

Get current value of metrics

Returns: - [int] sum(xor(X[],Y[]))

bert_fsm_state SIM::bert::get_output ( void )

get initial/idle output state

Returns: - [bvec] y0 is BERT_FSM

bvec SIM::bert::get_poly ( void )

get connection poly of internal PRBS generator

Returns: - [bvec] poly_gen

bvec SIM::bert::get_state ( )

get state of shift register addressed by last bert.set_adr() command

Returns: - [bvec] state of shift X,Y,PRBS register

int SIM::bert::get_symbol_size ( void )

get size of input X,Y symbol

Returns: - [int] length of the symbol

ivec SIM::bert::get_threshold ( void )

Get metrics thresholds

Returns: - [ivec] [T0,T1,T2]

ivec SIM::bert::process	(	const bvec &	ce,
		const bmat &	x
	)

\ For active clock ticks ce[i] input symbol x[i,:] is compared with internally generated symbol y[i,:].
x[i,:],y[i,:] are shifted into X,Y LSR, metrics is calculated , and using metrics thresholds BERT_FSM state is set.
Bit errors sum(xor(x,y)) are accumulated in error counters when BERT is in the SYNC state.

Parameters

ce	- [bvec] clock_enable vector
x	- [bmat] input binary symbol to be compared with internally generated y[i,:] by PRBS LFSR

Returns: y - [ivec] internal state BERT_FSM ;

void SIM::bert::set_adr ( bert_adr a )

sets indirect register target for get_state()

Parameters

[in] a - [bert_adr] must be BERT_ADDR address

void SIM::bert::set_fsm ( bert_fsm_state state )

sets FSM state

Note: default state is BERT_RESET

Parameters

[in] state - [int] valid state is one of a BERT_FSM states

void SIM::bert::set_length ( int L )

set length of shift X,Y register - see SIM::lsr.set_length()

Note: X.length >= PRBS.lenght due to PRBS X pre-setting in RELOAD state

Parameters

[in] L - [int] size of shift register

void SIM::bert::set_output ( bert_fsm_state yout )

sets initial/idle output state

Parameters

[in] yout - [bert_state] y0 = yout, must be BERT_FSM states

void SIM::bert::set_poly ( const bvec & bpoly )

set predefined bpoly for PRBS - see SIM::lfsr.set_poly()

Parameters

[in] bpoly - [bvec] feedback poly

void SIM::bert::set_prbs ( int M )

set predefined bpoly for PRBS defined by PRBS sequence 2^M-1 -see SIM::lfsr.set_prbs()

Parameters

[in] M - [int] power of PRBS sequence size = 2^M-1

void SIM::bert::set_symbol_size ( int W )

set symbol_size

Parameters

[in] W - [int] number of bits in a symbol

void SIM::bert::set_threshold ( const ivec & T )

set thresholds vector T=[T0,T1,T2] defining a state transition for calculated metrics

Note: see BERT_FSM for state definition; T0>T1>T2; T0/N is max BER to be measured

Parameters

[in] T - [ivec] = [T0,T1,T2]

The documentation for this class was generated from the following files:

C:/jobs/vcc/itpp_sci/include/sim/sim_bert.hpp
C:/jobs/vcc/itpp_sci/sim_lib/code/sim_bert.cpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation