Re: [time-nuts] Mounting GPS Antenna on Steel Roof

[Brian Kirby]

Attached is a interface for an Oncore VP receiver. You will have to check - I believe the GT and UT use the same connections as the VP.

Brian Kirby wrote:

The inverter is required because the Motorola GPS receiver uses TTL and the PC serial port uses RS232.

Brian KD4FM



Bruce Griffiths wrote:

RS232 uses a positive voltage of +3 to +25 volts to indicate a logic zero, and a negative voltage of -3 to -25 volts to indicate a logic one.

Hal Murray wrote:

Well, I plugged my Oncore UT+ into my PC and it didn't work until I
put a level shifter in... no damage but no data either. So far I've
been lucky in that every device I tried that needed a level shifter

wasn't damaged by the lack of one.

The normal MAX232 type level shifters include an inverter.

So even if the voltage levels work without a level shifter, the signal will be upside down.

To play safe, if one isnt sure that an inverter is required or not an exclusive OR can be used so that the signal can be inverted or not as required.

Bruce

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Oncore Interface.pdf
Description: Adobe PDF document

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