nmea 0183 output from gps help

Hi,
just a question regarding nmea output strings from my gps unit.
I have a jrc gps/sounder combo and I have connected a multi data repeater to it. this displays speed/ depth and temp. have sorted out the speed and temp all works fine but the temp doesn't display properly. my output string from the gps for temp is '$INMTW,+20.8,C*35

the repeater reads something completely different. I was just wondering if most temp output strings on other units have a '+' or '-' before the numerical temp value.
the manufacturer of the repeater says this + is wrong and the repeater can't read it properly. Is this true or shall I return the repeater and but another brand.

Or is there anyway I can change the data string output so there is no '+' in the string.
any help much appreciated.
cheers

 

This website http://www.maperl.com/Hydrography/ shows other $INMTW sentences without the '+'. It is possible that the GPS manufacturer's interpretation of the standard varied from other people's. However, no NMEA parser should struggle with a +/-, so it does seem that the manufacturer of the repeater is being rather unhelpful.

Alternatively, you can use openPilot to read your NMEA stream, then with a few additions to the code you can make it output a new NMEA string without the '+'. You can also use it to display your position (when I've finished re-writing the plotting!), provide track/heading, satellite details, time, speed, temperature, and pretty much anything else you can think of.

Cheers,

Tim B.