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[aprssig] FREQ Object Formats

Bob Bruninga bruninga at usna.edu
Mon May 7 18:59:25 UTC 2012


> And a close second... is people transmitting a
> frequency OBJECT with the SAME frequency duplicated 
> in the comment of the object. 

That is simply wrong.

> According to the spec (which I'm hoping to change), 
> this second frequency is the RECEIVE frequency.  

But only for CROSS Band or odd-splits.

> I'd like to see the receive frequency always require 
> the FFF.FFFrx and allow the (albeit redundant) specification 
> of the primary frequency in both the object name and 
> position beacon since that's how most of the world is doing it

Then they are doing it wrong.  A complete waste of bandwidth when the
comment text is supposed to convey additional USEFUL information.  Typicaly
the extra bytes should be used for Weekly NET times and monthly Meeting
dates as provided in the spec, not a dublication of the freq which is
already in the packet.

> The current spec at http://www.aprs.org/info/freqspec.txt says:
> If both the object name and the comment contain a frequency, 
> then the name is considered the transmit frequency...
> and the frequency in its comment text is its split receive frequency.

Notice the key word "split" which does not refer to standard offsets.
"Split" only refers to non-standard splits and cross band repeaters in the
context in which I wrote it.  Maybe that needs to be clarified?

> #2) best thing we can do is NOT TRANSMIT ANY OFFSETS IF THE OFFSET IS
> STANDARD.

> This only works, IMHO, if there's a world-wide standard.

But, it does *not* need to be worldwide.  It only needs to be LOCAL.  All
radios sold in areas that have 600 KHz splits all do 600 KHz splits.  All
radios sold in areas that do 500 KHz splits, do 500 KHz splits.  And QSY
Tuning of an APRS radio to a local object is entirely a local process.

> I believe I've read that there is no standard for 70cm repeaters

In the USA, the standard is +/- 5 MHz.  And it amazes me that people feel
the need to indicate MINUS offset when the repeater is above 445 MHz where
the offset can ONLY be MINUS.  And to indicate + offset below 445 MHz where
the offset can only be + or it interferes with the band  plan.

> sake of easy, GLOBAL, interpretation of offsets, I'd propose 
> that we recommend explicit offset transmission.

Not needed in 99% of the cases.  So it is wasteful use of bandwidth.

> The issue with offsets is that some people are beaconing 
> +n.nM to get a MHz offset when the spec says +nnn is in 
> 10KHz units... [there is no] mention of +n.nM (+0.6M for 
> instance) in the specifications...

If people simply followed the spec, everything would work.  And if Kenwood
would implement standard +/- offsets on 70 cm then all our problems would go
away.  Except for the MAJORITY of digipeater manually prepared frequency
beacons that are incorrectly formatted.

Bob, WB4APR





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