Another NMEA 0183 post

[oakleyb]

How many devices can 1 output from GPS serve, 1 or many ?

thanks

 

[prv]

More than one, not quite many. Four is often suggested as a rule of thumb, though it will vary depending on the particular devices and how good your wiring is.

Pete

 

[LadyInBed]

More than one, not quite many. Four is often suggested as a rule of thumb, though it will vary depending on the particular devices and how good your wiring is.

Pete

Yes, good wire and short distance helps.

 

[oakleyb]

ok great thats good news thanks for the replies

 

[Gypsy]

As PRV says it depends on the listening device. But aalso the talker. The pure differential input devices are 600ohm impedance so you may find the talker is unable to drive all 4 like that. Others may be high impedance and there will be little problem. Even a mix of Hi/Lo can help.

The only way is to add them one by one and look out for lapses in data. Better still if you can monitor the NMEA on one of the listeners to look for bad characters in messages.

 

[nigelmercier]

... Better still if you can monitor the NMEA on one of the listeners to look for bad characters in messages.

Or buy/borrow an oscilloscope.

 

[Fantasie 19]

Fascinating - I would have thought that as the output from the GPS is digital (rather than analog) providing your wiring/connections are right you could connect as many as down stream devices as you like.. how come the limitation??

 

[nimbusgb]

Bus loading, impedance, capacitance, current available from the driving end, data frequency, soooooo much affects digital transmission on a wire.

Digital it may be but it still suffers the problems of an AC signal on a pair of wires. If anything 'digital' suffers from the effects of 'rounding', the nice sharp square transitions get smoothed out.

 

[nigelmercier]

Or as my Electronics Lecturer used to say: "The signal doesn't know it's digital!"

 

[Fantasie 19]

Or as my Electronics Lecturer used to say: "The signal doesn't know it's digital!"

Brilliant - cheers guys... learn something new every day...