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authorAndreas Bogk <andreas@pt141.(none)>2009-01-15 17:17:29 +0100
committerAndreas Bogk <andreas@pt141.(none)>2009-01-15 17:17:29 +0100
commit7ebd609b4f4139f4dac8627ac00678de89ef4575 (patch)
tree44cc5b2816c8096e6e22781ee4332d840c5658a4 /viterbi_generator/tests/utils
parent602a3c8aa8a3d9bd4d93deda6ac932404f39584d (diff)
Viterbi generator by Piotr Krysik.
Diffstat (limited to 'viterbi_generator/tests/utils')
-rw-r--r--viterbi_generator/tests/utils/make_increment.m70
-rw-r--r--viterbi_generator/tests/utils/make_next.m54
-rw-r--r--viterbi_generator/tests/utils/make_previous.m54
-rw-r--r--viterbi_generator/tests/utils/make_start.m63
-rw-r--r--viterbi_generator/tests/utils/make_stops.m67
-rw-r--r--viterbi_generator/tests/utils/viterbi_detector.m218
-rw-r--r--viterbi_generator/tests/utils/viterbi_init.m38
7 files changed, 564 insertions, 0 deletions
diff --git a/viterbi_generator/tests/utils/make_increment.m b/viterbi_generator/tests/utils/make_increment.m
new file mode 100644
index 0000000..91cc0ae
--- /dev/null
+++ b/viterbi_generator/tests/utils/make_increment.m
@@ -0,0 +1,70 @@
+function [ INCREMENT ] = make_increment(SYMBOLS,NEXT,Rhh)
+%
+% MAKE_INCREMENT:
+% This function returns a lookuptable containing the
+% metric increments related to moving from state n to m.
+% The data is arranged so that the increment accosiated
+% with a move from state n to m is located in
+% INCREMENT(n,m). To minimize computations only legal
+% transitions are considdered.
+%
+% SYNTAX: [ INCREMENT ] = make_increment(SYMBOLS,NEXT,Rhh)
+%
+% INPUT: SYMBOLS: The table of symbols corresponding the the state-
+% numbers.
+% NEXT: A transition table containing the next legal
+% states, as it is generated by the code make_next.
+% Rhh: The autocorrelation as estimated by mf.m.
+%
+% OUTPUT: INCREMENT:
+% The increment table as described above.
+%
+% SUB_FUNC: None
+%
+% WARNINGS: There is no syntax checking on input or output.
+%
+% TEST(S): By hand, against expected values.
+%
+% AUTOR: Jan H. Mikkelsen / Arne Norre Ekstrøm
+% EMAIL: hmi@kom.auc.dk / aneks@kom.auc.dk
+%
+% $Id: make_increment.m,v 1.6 1997/09/22 11:39:34 aneks Exp $
+
+% IN THIS PEACE OF CODE THE SYNTAX CHECKING IS MINIMAL
+% THIS HAS BEEN CHOSEN TO AVOID THE OVERHEAD. RECALL THAT
+% THIS CODE IS EXECUTED EACH TIME A BURST IS RECEIVED.
+
+% FIND THE NUMBER OF SYMBOLS THAT WE HAVE
+%
+[M,Lh]=size(SYMBOLS);
+
+% INITIALIZE THE INCREMENT MATRIX
+%
+INCREMENT=zeros(M);
+
+% RECALL THAT THE I SEQUENCE AS IT IS STORED IN STORED AS:
+% [ I(n-1) I(n-2) I(n-3) ... I(n-Lh) ]
+%
+% ALSO RECALL THAT Rhh IS STORED AS:
+% [ Rhh(1) Rhh(2) Rhh(3) ... Rhh(Lh) ]
+%
+% THE FORMULA TO USE IS:
+% INCREMENT(n,m)
+% =
+% real(conj(I(n))*(I(n-Lh)*Rhh(Lh)+I(n-Lh+1)*Rhh(Lh-1)+...+I(n-1)*Rhh(1))
+%
+% THEY CAN THUS BE MULTIPLIED DIRECTLY WITH EACH OTHER
+
+% LOOP OVER THE STATES, AS FOUND IN THE ROWS IN SYMBOLS.
+%
+for n=1:M,
+ % ONLY TWO LEGAL NEXT STATES EXIST, SO THE LOOP IS UNROLLED
+ %
+ m=NEXT(n,1);
+
+ INCREMENT(n,m)=real((conj(SYMBOLS(m,1))*SYMBOLS(n,:))*Rhh(2:Lh+1).');
+ m=NEXT(n,2);
+
+ INCREMENT(n,m)=real((conj(SYMBOLS(m,1))*SYMBOLS(n,:))*Rhh(2:Lh+1).');
+end
+
diff --git a/viterbi_generator/tests/utils/make_next.m b/viterbi_generator/tests/utils/make_next.m
new file mode 100644
index 0000000..f5af8dc
--- /dev/null
+++ b/viterbi_generator/tests/utils/make_next.m
@@ -0,0 +1,54 @@
+function [ NEXT ] = make_next(SYMBOLS)
+%
+% MAKE_NEXT:
+% This function returns a lookuptable containing a mapping
+% between the present state and the legal next states.
+% Each row correspond to a state, and the two legal states
+% related to state n is located in NEXT(n,1) and in
+% NEXT(n,2). States are represented by their related
+% numbers.
+%
+% SYNTAX: [ NEXT ] = make_next(SYMBOLS)
+%
+% INPUT: SYMBOLS: The table of symbols corresponding the the state-
+% numbers.
+%
+% OUTPUT: NEXT: The transition table describing the legal next
+% states asdescribed above.
+%
+% SUB_FUNC: None
+%
+% WARNINGS: None
+%
+% TEST(S): The function has been verified to return the expected
+% results.
+%
+% AUTOR: Jan H. Mikkelsen / Arne Norre Ekstrøm
+% EMAIL: hmi@kom.auc.dk / aneks@kom.auc.dk
+%
+% $Id: make_next.m,v 1.3 1997/09/22 08:13:29 aneks Exp $
+
+% FIRST WE NEED TO FIND THE NUMBER OF LOOPS WE SHOULD RUN.
+% THIS EQUALS THE NUMBER OF SYMBOLS. ALSO MAXSUM IS NEEDED FOR
+% LATER OPERATIONS.
+%
+[ states , maxsum ]=size(SYMBOLS);
+
+search_matrix=SYMBOLS(:,2:maxsum);
+maxsum=maxsum-1;
+
+% LOOP OVER THE SYMBOLS.
+%
+for this_state=1:states,
+ search_vector=SYMBOLS(this_state,1:maxsum);
+ k=0;
+ for search=1:states,
+ if (sum(search_matrix(search,:)==search_vector)==maxsum)
+ k=k+1;
+ NEXT(this_state,k)=search;
+ if k > 2,
+ error('Error: identified too many next states');
+ end
+ end
+ end
+end \ No newline at end of file
diff --git a/viterbi_generator/tests/utils/make_previous.m b/viterbi_generator/tests/utils/make_previous.m
new file mode 100644
index 0000000..678fa43
--- /dev/null
+++ b/viterbi_generator/tests/utils/make_previous.m
@@ -0,0 +1,54 @@
+function [ PREVIOUS ] = make_previous(SYMBOLS)
+%
+% MAKE_PREVIOUS:
+% This function returns a lookuptable containing a mapping
+% between the present state and the legal previous states.
+% Each row correspond to a state, and the two legal states
+% related to state n is located in PREVIOUS(n,1) and in
+% previous(n,2). States are represented by their related
+% numbers.
+%
+% SYNTAX: [ PREVIOUS ] = make_previous(SYMBOLS)
+%
+% INPUT: SYMBOLS: The table of symbols corresponding the the state-
+% numbers.
+%
+% OUTPUT: PREVIOUS:
+% The transition table describing the legal previous
+% states asdescribed above.
+%
+% SUB_FUNC: None
+%
+% WARNINGS: None
+%
+% TEST(S): Verified against expected result.
+%
+% AUTOR: Jan H. Mikkelsen / Arne Norre Ekstrøm
+% EMAIL: hmi@kom.auc.dk / aneks@kom.auc.dk
+%
+% $Id: make_previous.m,v 1.3 1997/09/22 08:14:27 aneks Exp $
+
+% FIRST WE NEED TO FIND THE NUMBER OF LOOPS WE SHOULD RUN.
+% THIS EQUALS THE NUMBER OF SYMBOLS. ALSO MAXSUM IS NEEDED FOR
+% LATER OPERATIONS.
+%
+[ states , maxsum ]=size(SYMBOLS);
+
+maxsum=maxsum-1;
+search_matrix=SYMBOLS(:,1:maxsum);
+
+% LOOP OVER THE SYMBOLS.
+%
+for this_state=1:states,
+ search_vector=SYMBOLS(this_state,2:maxsum+1);
+ k=0;
+ for search=1:states,
+ if (sum(search_matrix(search,:)==search_vector)==maxsum)
+ k=k+1;
+ PREVIOUS(this_state,k)=search;
+ if k > 2,
+ error('Error: identified too many previous states');
+ end
+ end
+ end
+end \ No newline at end of file
diff --git a/viterbi_generator/tests/utils/make_start.m b/viterbi_generator/tests/utils/make_start.m
new file mode 100644
index 0000000..83275fd
--- /dev/null
+++ b/viterbi_generator/tests/utils/make_start.m
@@ -0,0 +1,63 @@
+function [ START ] = make_start(Lh,SYMBOLS)
+%
+% MAKE_START:
+% This code returns a statenumber corresponding to the start
+% state as it is found from Lh. The method is to use the table
+% of symbolic start states as it is listed in the report made
+% by 95gr870T. For the table lookups are made in SYMBOLS. in
+% order to map from the symbol representation to the state number
+% representation.
+%
+% SYNTAX: [ START ] = make_start(Lh,SYMBOLS)
+%
+% INPUT: SYMBOLS: The table of symbols corresponding the the state-
+% numbers.
+% Lh: Length of the estimated impulseresponse.
+%
+% OUTPUT: START: The number representation of the legal start state.
+%
+% SUB_FUNC: None
+%
+% WARNINGS: The table of symbolic representations has not been verified
+% but is used directly as it is listed in the report made
+% by 95gr870T.
+%
+% TEST(S): The function has been verified to return a state number
+% which matches the symbolic representation.
+%
+% AUTOR: Jan H. Mikkelsen / Arne Norre Ekstrøm
+% EMAIL: hmi@kom.auc.dk / aneks@kom.auc.dk
+%
+% $Id: make_start.m,v 1.2 1997/09/22 11:40:17 aneks Exp $
+
+% WE HAVEN'T FOUND IT YET.
+%
+START_NOT_FOUND = 1;
+
+% OBTAIN THE SYMBOLS FROM Lh. THIS IS THE TABLE LISTED IN THE REPORT MADE
+% BY 95gr870T. (SATEREPRESENTATION IS SLIGHTLY CHANGED).
+%
+if Lh==1,
+ start_symbols = [ 1 ];
+elseif Lh==2,
+ start_symbols = [ 1 -j ];
+elseif Lh==3,
+ start_symbols = [ 1 -j -1 ];
+elseif Lh==4,
+ start_symbols = [ 1 -j -1 j ];
+elseif Lh==5,
+ start_symbols = [ 1 -j -1 j 1];
+else
+ fprintf('\n\nError: Illegal value of Lh, terminating...');
+end
+
+% NOW MAP FROM THE SYMBOLS TO A STATE NUMBER BY SEARCHING
+% SYMBOLS.
+%
+START=0;
+while START_NOT_FOUND,
+ START=START+1;
+ if sum(SYMBOLS(START,:)==start_symbols)==Lh,
+ START_NOT_FOUND=0;
+ end
+end
diff --git a/viterbi_generator/tests/utils/make_stops.m b/viterbi_generator/tests/utils/make_stops.m
new file mode 100644
index 0000000..98734c9
--- /dev/null
+++ b/viterbi_generator/tests/utils/make_stops.m
@@ -0,0 +1,67 @@
+function [ STOPS ] = make_stops(Lh,SYMBOLS)
+%
+% MAKE_STOPS:
+% This code returns a statenumber corresponding to the set of
+% legal stop states as found from Lh. The method is to use the table
+% of symbolic stop states as it is listed in the report made
+% by 95gr870T. For the table lookups are made in SYMBOLS. in
+% order to map from the symbol representation to the state number
+% representation.
+%
+% SYNTAX: [ STOPS ] = make_stops(Lh,SYMBOLS)
+%
+% INPUT: SYMBOLS: The table of symbols corresponding the the state-
+% numbers.
+% Lh: Length of the estimated impulseresponse.
+%
+% OUTPUT: STOPS: The number representation of the set of legal stop
+% states.
+%
+% SUB_FUNC: None
+%
+% WARNINGS: The table of symbolic representations has not been verified
+% but is used directly as it is listed in the report made
+% by 95gr870T.
+%
+% TEST(S): The function has been verified to return a state number
+% which matches the symbolic representation.
+%
+% AUTOR: Jan H. Mikkelsen / Arne Norre Ekstrøm
+% EMAIL: hmi@kom.auc.dk / aneks@kom.auc.dk
+%
+% $Id: make_stops.m,v 1.2 1997/09/22 11:44:21 aneks Exp $
+
+% OBTAIN THE SYMBOLS FROM Lh. THIS IS THE TABLE LISTED IN THE REPORT MADE
+% BY 95gr870T. (SATEREPRESENTATION IS SLIGHTLY CHANGED).
+%
+if Lh==1,
+ stop_symbols = [ -1 ];
+ count=1;
+elseif Lh==2,
+ stop_symbols = [ -1 j ];
+ count=1;
+elseif Lh==3,
+ stop_symbols = [ -1 j 1 ];
+ count=1;
+elseif Lh==4,
+ stop_symbols = [ [ -1 j 1 j ] ; [ -1 j 1 -j ] ];
+ count=2;
+elseif Lh==5,
+ stop_symbols = [ [ -1 j 1 j -1] ; [ -1 j 1 -j -1] ; [ -1 j 1 j 1] ; [ -1 j 1 -j 1] ];
+ count=2;
+else
+ fprintf('\n\nError: Illegal value of Lh, terminating...');
+end
+
+% NOW THAT WE HAVE THE SYMBOL REPRESENTATION THE REMAINING JOB IS
+% TO MAP THE MSK SYMBOLS TO STATE NUMBERS
+%
+index = 0;
+stops_found=0;
+while stops_found < count,
+ index=index+1;
+ if sum(SYMBOLS(index,:)==stop_symbols(stops_found+1,:))==Lh,
+ stops_found=stops_found+1;
+ STOPS(stops_found)=index;
+ end
+end
diff --git a/viterbi_generator/tests/utils/viterbi_detector.m b/viterbi_generator/tests/utils/viterbi_detector.m
new file mode 100644
index 0000000..31e8f93
--- /dev/null
+++ b/viterbi_generator/tests/utils/viterbi_detector.m
@@ -0,0 +1,218 @@
+function [ rx_burst METRIC] = viterbi_detector(SYMBOLS,NEXT,PREVIOUS,START,STOPS,Y,Rhh)
+%
+% VITERBI_DETECTOR:
+% This matlab code does the actual detection of the
+% received sequence. As indicated by the name the algorithm
+% is the viterbi algorithm, which is a MLSE. At this time
+% the approch is to use Ungerboecks modified algorithm, and
+% to return hard output only.
+%
+% SYNTAX: [ rx_burst ]
+% =
+% viterbi_detector(SYMBOLS,NEXT,PREVIOUS,START,STOPS,Y,Rhh)
+%
+% INPUT: SYMBOLS: The table of symbols corresponding the the state-
+% numbers. Format as made by make_symbols.m
+% NEXT: A transition table containing the next legal
+% states, as it is generated by the code make_next.m
+% PREVIOUS: The transition table describing the legal previous
+% states as generated by make_previous.m
+% START: The start state of the algorithm.
+% STOPS: The legal stop states.
+% Y: Complex baseband representation of the matched
+% filtered and down converted received signal, as it
+% is returned by mf.m
+% Rhh: The autocorrelation as estimated by mf.m
+%
+% OUTPUT: rx_burst: The most likely sequence of symbols.
+%
+% SUB_FUNC: make_increment
+%
+% WARNINGS: None.
+%
+% TEST(S): Tested with no noise, perfect syncronization, and channel
+% estimation/filtering. (Refer to viterbi_ill.m)
+%
+% AUTOR: Jan H. Mikkelsen / Arne Norre Ekstrøm
+% EMAIL: hmi@kom.auc.dk / aneks@kom.auc.dk
+%
+% $Id: viterbi_detector.m,v 1.7 1997/11/18 12:41:26 aneks Exp $
+
+% KNOWLEDGE OF Lh AND M IS NEEDED FOR THE ALGORITHM TO OPERATE
+%
+[ M , Lh ] = size(SYMBOLS);
+
+% THE NUMBER OF STEPS IN THE VITERBI
+%
+STEPS=length(Y);
+% INITIALIZE TABLES (THIS YIELDS A SLIGHT SPEEDUP).
+%
+METRIC = zeros(M,STEPS);
+SURVIVOR = zeros(M,STEPS);
+
+% DETERMINE PRECALCULATABLE PART OF METRIC
+%
+INCREMENT=make_increment(SYMBOLS,NEXT,Rhh);
+%INCREMENT
+% THE FIRST THING TO DO IS TO ROLL INTO THE ALGORITHM BY SPREADING OUT
+% FROM THE START STATE TO ALL THE LEGAL STATES.
+%
+PS=START;
+
+% NOTE THAT THE START STATE IS REFERRED TO AS STATE TO TIME 0
+% AND THAT IT HAS NO METRIC.
+%
+S=NEXT(START,1);
+
+METRIC(S,1)=real(conj(SYMBOLS(S,1))*Y(1))-INCREMENT(PS,S);
+SURVIVOR(S,1)=START;
+
+S=NEXT(START,2);
+METRIC(S,1)=real(conj(SYMBOLS(S,1))*Y(1))-INCREMENT(PS,S);
+SURVIVOR(S,1)=START;
+
+PREVIOUS_STATES=NEXT(START,:);
+
+% MARK THE NEXT STATES AS REAL. N.B: COMPLEX INDICATES THE POLARITY
+% OF THE NEXT STATE, E.G. STATE 2 IS REAL.
+%
+COMPLEX=0;
+
+for N = 2:Lh,
+ if COMPLEX,
+ COMPLEX=0;
+ else
+ COMPLEX=1;
+ end
+ STATE_CNTR=0;
+ for PS = PREVIOUS_STATES,
+ STATE_CNTR=STATE_CNTR+1;
+ S=NEXT(PS,1);
+ METRIC(S,N)=METRIC(PS,N-1)+real(conj(SYMBOLS(S,1))*Y(N))-INCREMENT(PS,S);
+ SURVIVOR(S,N)=PS;
+ USED(STATE_CNTR)=S;
+ STATE_CNTR=STATE_CNTR+1;
+ S=NEXT(PS,2);
+ METRIC(S,N)=METRIC(PS,N-1)+real(conj(SYMBOLS(S,1))*Y(N))-INCREMENT(PS,S);
+ SURVIVOR(S,N)=PS;
+ USED(STATE_CNTR)=S;
+ end
+ PREVIOUS_STATES=USED;
+end
+% AT ANY RATE WE WILL HAVE PROCESSED Lh STATES AT THIS TIME
+%
+PROCESSED=Lh;
+
+% WE WANT AN EQUAL NUMBER OF STATES TO BE REMAINING. THE NEXT LINES ENSURE
+% THIS.
+%
+
+if ~COMPLEX,
+ COMPLEX=1;
+ PROCESSED=PROCESSED+1;
+ N=PROCESSED;
+ for S = 2:2:M,
+ PS=PREVIOUS(S,1);
+ M1=METRIC(PS,N-1)+real(conj(SYMBOLS(S,1))*Y(N)-INCREMENT(PS,S));
+ PS=PREVIOUS(S,2);
+ M2=METRIC(PS,N-1)+real(conj(SYMBOLS(S,1))*Y(N)-INCREMENT(PS,S));
+ if M1 > M2,
+ METRIC(S,N)=M1;
+ SURVIVOR(S,N)=PREVIOUS(S,1);
+ else
+ METRIC(S,N)=M2;
+ SURVIVOR(S,N)=PREVIOUS(S,2);
+ end
+ end
+end
+
+% NOW THAT WE HAVE MADE THE RUN-IN THE REST OF THE METRICS ARE
+% CALCULATED IN THE STRAIGHT FORWARD MANNER. OBSERVE THAT ONLY
+% THE RELEVANT STATES ARE CALCULATED, THAT IS REAL FOLLOWS COMPLEX
+% AND VICE VERSA.
+%
+N=PROCESSED+1;
+while N <= STEPS,
+ for S = 1:2:M-1,
+ PS=PREVIOUS(S,1);
+ M1=METRIC(PS,N-1)+real(conj(SYMBOLS(S,1))*Y(N)-INCREMENT(PS,S));
+ PS=PREVIOUS(S,2);
+ M2=METRIC(PS,N-1)+real(conj(SYMBOLS(S,1))*Y(N)-INCREMENT(PS,S));
+ if M1 > M2,
+ METRIC(S,N)=M1;
+ SURVIVOR(S,N)=PREVIOUS(S,1);
+ else
+ METRIC(S,N)=M2;
+ SURVIVOR(S,N)=PREVIOUS(S,2);
+ end
+ end
+ N=N+1;
+ for S = 2:2:M,
+ PS=PREVIOUS(S,1);
+ M1=METRIC(PS,N-1)+real(conj(SYMBOLS(S,1))*Y(N)-INCREMENT(PS,S));
+ PS=PREVIOUS(S,2);
+ M2=METRIC(PS,N-1)+real(conj(SYMBOLS(S,1))*Y(N)-INCREMENT(PS,S));
+ if M1 > M2,
+ METRIC(S,N)=M1;
+ SURVIVOR(S,N)=PREVIOUS(S,1);
+ else
+ METRIC(S,N)=M2;
+ SURVIVOR(S,N)=PREVIOUS(S,2);
+ end
+ end
+ N=N+1;
+end
+
+
+% HAVING CALCULATED THE METRICS, THE MOST PROBABLE STATESEQUENCE IS
+% INITIALIZED BY CHOOSING THE HIGHEST METRIC AMONG THE LEGAL STOP
+% STATES.
+%
+BEST_LEGAL=0;
+for FINAL = STOPS,
+ if METRIC(FINAL,STEPS) > BEST_LEGAL,
+ S=FINAL;
+ BEST_LEGAL=METRIC(FINAL,STEPS);
+ end
+end
+
+% UNCOMMENT FOR TEST OF METRIC
+%
+% METRIC
+% BEST_LEGAL
+% S
+% pause
+
+% HAVING FOUND THE FINAL STATE, THE MSK SYMBOL SEQUENCE IS ESTABLISHED
+%
+
+IEST(STEPS)=SYMBOLS(S,1);
+N=STEPS-1;
+while N > 0,
+
+% if(N>STEPS-40),
+% previo=ceil(S/2)
+% end
+ S=SURVIVOR(S,N+1);
+ IEST(N)=SYMBOLS(S,1);
+ N=N-1;
+end
+
+% THE ESTIMATE IS NOW FOUND FROM THE FORMULA:
+% IEST(n)=j*rx_burst(n)*rx_burst(n-1)*IEST(n-1)
+% THE FORMULA IS REWRITTEN AS:
+% rx_burst(n)=IEST(n)/(j*rx_burst(n-1)*IEST(n-1))
+% FOR INITIALIZATION THE FOLLOWING IS USED:
+% IEST(0)=1 og rx_burst(0)=1
+%
+rx_burst(1)=IEST(1)/(j*1*1);
+for n = 2:STEPS,
+ rx_burst(n)=IEST(n)/(j*rx_burst(n-1)*IEST(n-1));
+end
+
+% rx_burst IS POLAR (-1 AND 1), THIS TRANSFORMS IT TO
+% BINARY FORM (0 AND 1).
+%
+
+rx_burst=(rx_burst+1)./2;
+
diff --git a/viterbi_generator/tests/utils/viterbi_init.m b/viterbi_generator/tests/utils/viterbi_init.m
new file mode 100644
index 0000000..a43b801
--- /dev/null
+++ b/viterbi_generator/tests/utils/viterbi_init.m
@@ -0,0 +1,38 @@
+function [ SYMBOLS , PREVIOUS , NEXT , START , STOPS ] = viterbi_init(Lh)
+% VITERBI_INIT:
+% This function returns the tables which are used by the
+% viterbi demodulator which is implemented in the GSMsim
+% package.
+%
+% SYNTAX: [ SYMBOLS , PREVIOUS , NEXT , START , STOPS ]
+% =
+% viterbi_init(Lh)
+%
+% INPUT: Lh: The length of the channel impulse response
+% minus one.
+%
+% OUTPUT: SYMBOLS: Statenumber to MSK-symbols mapping table.
+% PREVIOUS: This state to legal previous state mapping table.
+% NEXT: This state to legal next state mapping table.
+% START: The start state of the viterbi algorithm.
+% STOPS: The set of legal stop states for the viterbi
+% algorithm.
+%
+% GLOBAL: None
+%
+% SUB_FUNC: make_symbols,make_previous,make_next,make_start,make_stops
+%
+% WARNINGS: None
+%
+% TEST: Verified that the function actually runs the subfunctions.
+%
+% AUTHOR: Jan H. Mikkelsen / Arne Norre Ekstrøm
+% EMAIL: hmi@kom.auc.dk / aneks@kom.auc.dk
+%
+% $Id: viterbi_init.m,v 1.4 1998/02/12 10:52:15 aneks Exp $
+
+SYMBOLS = make_symbols(Lh);
+PREVIOUS = make_previous(SYMBOLS);
+NEXT = make_next(SYMBOLS);
+START = make_start(Lh,SYMBOLS);
+STOPS = make_stops(Lh,SYMBOLS);
personal git repositories of Harald Welte. Your mileage may vary