How do I discern Maidenhead Locator from GPS lat long info.

[astanapane]

These days i tried to use the $GPVTG sentence and get the speed from there as it is in Km/h

First of all the format of the $GPVTG sentence is as follows.

1. X.XX for the left X before the "dot" when the speed is less than 10km/h
2. XX.XX for the XX before the "dot" when the speed is more than 9 km/h and less than 100km/h
2. XXX.XX for the XXX before the "dot" when the speed is more than 99km/h

For the .XX so the two digits after the "dots" those are the decimal part and stays stable in the $GPVTG sentence.

We need to check when the speed change, where is the dot.

serin2 gps_tx,84,timeout,lostcable,[wait("GPVTG"),wait("N"),_
wait(","),TS[0],TS[1],TS[2],TS[3],TS[4],_
wait(","),SKIP 3]

for i = 1 to 3
    if TS[i]="." then decimal = i   'TOTAL SPEED. find which character is the decimal point 
    next i

select case decimal 'if the gps shows 1.45 it may be 145
                    'for the conversion ASCII to number we can use the -48
    case    1       'decimal position is x.xx
        speed = (10*(TS[0]-48))+(TS[2]-48)
    case    2       'decimal position is xx.xx
        speed = (100*(TS[0]-48))+(10*(TS[1]-48))+(TS[3]-48)
    case    3       'decimal position is xxx.xx
        speed = (1000*(TS[0]-48))+(100*(TS[1]-48))+(10*(TS[2]-48))
    end select     
    
gosub OVERSPEED:


OVERSPEED: 

if SPEED > 1000 then     ' 100Km/h
    high porta.3
    low  porta.2
    low  porta.1    
else
    LOW porta.3
    
if SPEED > 500 then     ' 50Km/h
    high porta.2
    low  porta.1    
else
    LOW porta.2
    
if SPEED > 100  then    ' 10Km/h
    high porta.1
else
    LOW porta.1

endif
    endif
        endif
    return

At the moment the code is working as it is, but i think i need to change the multiplication of 10*, 100* and 1000*, to 1*, 10* and 100*, because as you see at the OVERSPEED: i use 1000 for the 100 km/h, 500 for the 50km/h and 100 for the 10km/h.
But then the dot will change place, or i will not being able to identify the right place of it. Anyhow the code is working for the speed.

Still i need to:

1. Make the Day/Month/Year to work properly, now i think i will not have a problem to solve this.

2. The display data are refreshed, my goal is to make the data stable all the time at the screen and change only the needed values.