[ntp:questions] OT: GPS18x LVC failure

Unruh unruh-spam at physics.ubc.ca
Tue Oct 13 02:37:48 UTC 2009


E-Mail Sent to this address will be added to the BlackLists <Null at BlackList.Anitech-Systems.invalid> writes:

>Rick Jones wrote:
>> Has anyone asked Garmin about the specs vs what they've seen?

><http://www8.garmin.com/support/pdf/iop_spec.pdf>
><BlockQuote>
>3 Physical Protocols
>3.1 Serial Protocol
>The Serial Protocol is based on RS-232.
> The voltage characteristics are compatible with most hosts;
>  however, the device transmits positive voltages only,
>  whereas the RS-232 standard requires both positive
>  and negative voltages.
> Also, the voltage swing between mark and space may not be
>   large enough to meet the strict requirements of the RS-232
>   standard.
>  Still, the device voltage characteristics are compatible
>   with most hosts as long as the interface cable is wired
>   correctly.
></BlockQuote>

I suspect that this is the remains of the 18LVC. the measurements show that the
18x does not follow these guidelines, and so the question that needs to be asked
of Garmin is why there is a difference between the written specs and the physical
device. The PPS seems to be TTL however.
Note that those specs are dated 2006 which was before the 18x was built or
released.



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