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[aprssig] differential corrections available to public (insome places)

Jim Lux jimlux at earthlink.net
Mon Mar 14 17:51:56 UTC 2005

At 08:49 AM 3/14/2005, Robert Bruninga wrote:

> >>> "Jim Lux" <jimlux at earthlink.net> 3/14/05 10:56:52 AM >>>
> >> That may all be old or obsolete, but it is how we were
> >> recommending it back then.  I think we were suggesting
> >> that the RTCM104 be on a different 2m freq so that it
> >> couild be real-time full operations without any QRM to
> >> 144.39.
> >> de WB4APR, Bob
> >But, if it's on a different frequency, then existing TNCs and
> >radios, which are single channel centric, wouldn't be able
> >to gain the benefit of more precise positions.
>All radios can operate with one TX and a different RX.
>Its no different than 2m voice through a repeater. you
>liisten on one freq and TX on another.

But then your radio won't hear all the other APRS stations transmitting on 
144.39.  I was proposing the distribution of real time corrections within 
the framework of APRS, not as a standalone accuracy enhancement (for which 
there are a multitude of other approaches).

I suppose you could set up a high site to transmit two streams, one on 
144.39 with just position reports that you're basically digipeating and the 
other on something else that has both APRS messages and real time 
corrections merged, but it's not clear that the second frequency wouldn't 
wind up just as congested.  I guess it would have dupe's removed, and there 
wouldn't be as much contention from other mobile's transmitting.


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