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[aprssig] FREQ Object Formats (clarified)

Bob Bruninga bruninga at usna.edu
Tue May 8 03:04:50 UTC 2012

>> The example "FFF.FFF +" is only listed as an example 
>> in the SECOND 10-byte field, which ONLY applies to a
>> separately explicitly listed frequency.
> Wait, are you saying that the table below isn't just 
> EXAMPLES of the nuggets of information that can be
> transmitted in a frequency comment,

Don't know how you can possibly infer that. See the word "example" in line 1 above.  Nor how anyone can miss the word "Examples:" which precedes the list.

>  I... was under the (apparently mistaken) impression 
> that a frequency specification comment could include 
> any combinations of:
> Tnnn or tnnn
> Cnnn or cnnn
> Dnnn or dnnn
> 1750
> +nnn or -nnn
> + (and by extrapolation) -
> Rnnm or Rnnk
> (and maybe more)

Yes, but ONLY in their respective columns.  That is why there are so many examples of correct usage.

See the EXAMPLES.  the first field is for TONE and the second one is for OFFSET (if needed) or RANGE. 

> and if I wanted to I could build a packet that said:
> 146.850MHz Toff -060 R20m PCARS Repeater

Which is exactly correct. In this case the OFFSET is where it is supposed to be and the R20m which is human readable additional info only can slide to the left.

> And if so, then the specification, IMHO, definitely 
> needs quite a bit of clarification work if any ones-
> and-zeros literally logical programmer is expected to 
> pick up on what's legal and what's not.

Sorry, I though it was obvious.  Ill try to add more clarification.

Bob, Wb4APR

>> 1st 10-BYTES  Frequency Description
>> ----------    ---------------------------------------
>> FFF.FF MHz    Freq to nearest 10 KHz
>> FFF.FFFMHz    Freq to nearest  1 KHz
>> Examples:
>> 146.52 MHz Enroute Alabama
>> 147.105MHz AARC Radio Club
>> 146.82 MHz T107 AARC Repeater (Tone of 107.2)
>> 146.835MHz C107 R25m AARC     (CTCSS 107.3, range 25 mi)
>> 146.805MHz D256 R25k Repeater (DCS code and range 25 km)
>> 146.40 MHz T067 +100 Repeater (67.8 tone, +1.00 MHz offset)
>> 145.50 MHz t077 Simplex       (Tone 77.4Hz, NARROW band)
>> 2nd 10-BYTES  Optional Added fields  (with leading space)
>> ----------    --------------------------------------------
>> _Txxx RXXm    Optional PL tone and nominal range in miles
>> _Cxxx RXXm    Optional CTCSS tone and range in miles
>> _Dxxx RXXk    Optional DCS code and nominal range in km
>> _1750 RXXk    Optional 1750 tone, range in km, wide FM
>> _l750 RXXk    Optional 1750 tone NARROW (lower case L not 1
>> _Toff RXXk    Optional NO-PL, No DCS, no Tone, etc.
>> _Txxx +060    Optional Offset of +600 KHz (up to 9.90 MHz)
>> _Exxm Wxxm    East & West range if different (N,S,E,W)
>> _txxx RXXm    Lower case first letter means NARROW mod
>> _FFF.FFFrx    Alternate rx Frequency if not standard offset
>> _FFF.FFF +    Alternate Frequency and standard shift

> Which would even mean that a 1750 tone must only 
> express range in kilometers, and never miles?   

Again, one should infer the examples in the first column and the ones in the right column and they may be mixed in any way as long as they remain in the correct column.  After these columns, evreything is considered free text for human consumption.

Bob, Wb4APR

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