RDS and TMC display

Projects General Guidance
1

Hello

I have a tmc receiver http://www.ebay.co.uk/itm/Royaltek-GPS-RDS-TMC-Traffic-Receiver-Develop-Module-/170561018797
I try to get the data to be text but it crashe in my head :~ So i started over again.
Will anyone help me get started with some code how I can sort out the TMC data (2) for example! And display it in text!

Here is the code i use to get data:
#include <SoftwareSerial.h>

SoftwareSerial rds(3,4); // RX, TX
void setup()
{
Serial.begin(9600);
rds.begin(9600);
}
void loop()
{
if (rds.available()) Serial.write(rds.read());
}

And here is the data:
$RTTMC,0,E203,052F,77CD,202042
$RTTMC,2,E203,2520,5033,205332
$RTTMC,0,E203,052C,E67B,535247
$RTTMC,2,E203,2521,7065,6C0D37
$RTTMC,2,E203,2520,5033,205332
$RTTMC,8,E203,8521,4151,F25240
$RTRDS,99.8,9,3,2,1,1,1,100,0,0,0,06D
$RTTMC,2,E203,2521,7065,6C0D37
$RTTMC,0,E203,0529,6174,205039
$RTTMC,0,E203,052A,6468,33204C
$RTTMC,2,E203,2520,5033,205332
$RTTMC,8,E203,8521,4151,F25240
$RTTMC,0,E203,052F,77CD,202042
$RTRDS,99.8,9,3,2,1,1,1,100,0,0,0,06D

2

Hello again!

I have make a string function to get the frequency out from the string: $RTRDS,99.8,7,3,2,1,1,1,100,0,0,0,0*63

void loop()
{
String s = checkRDS();
if(s && s.substring(0, 6) == "$RTRDS")
{
Serial.print("Frequency ");
Serial.print(s[7]);
Serial.print(s[8]);
Serial.print(s[9]);
Serial.print(s[10]);
Serial.println("MHz");
}

And it works but now the frequency are 99.8 but if it change to 100.1 I only get "100."
How can i do to get everything between the comma?