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[aprssig] FREQ Object Formats

Andre aprs at pe1rdw.demon.nl
Tue May 8 00:15:43 UTC 2012


On Tue, 08 May 2012 01:41:15 +0200, Lynn W. Deffenbaugh (Mr)  
<ldeffenb at homeside.to> wrote:

> On 5/7/2012 7:25 PM, Bob Bruninga wrote:
>> 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.   
>> It
>> is NOT part of the original FFF.FFFMHz format.  What I was referring to
>> below, is that it is also NOT parseable as part of the "xyz" part of an
>> OBJECT NAME either.
>>
>> Let me say it again, the only parsable offsets are +xxx or -xxx where  
>> xxx is
>> in 10's of KHz.
>
> 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,  
> but are EXPLICTLY the ONLY combinations that are LEGAL?  I surely didn't  
> read it that way and was under the (apparently mistaken) impression that  
> a frequency specification comment could include any combinations of:
>
> FFF.FF MHz or FFF.FFFMHz
> FFF.FFFrx
> Tnnn or tnnn
> Cnnn or cnnn
> Dnnn or dnnn
> 1750
> +nnn or -nnn
> + (and by extrapolation) -
> Rnnm or Rnnk
> (and maybe more)
>
> and if I wanted to I could build a packet that said:
>
> 146.850MHz Toff -060 R20m PCARS Repeater
>
probably would need to set a limit for what is machine readable text and  
what only human readable, right now it is set to 10 bytes or 20 bytes with  
the second 10 bytes being rx frequentie followed by rx or 2 blocks of 4  
bytes seperated by a space eventhough the shown exsamples breaks that  
asumption by also alowing only one 4 byte block.
in that light Toff makes no sense too, not mentioned means not used in my  
book but maybe that is because I'm used to repeater directories asuming  
not needing a tone unless mentioned.

> even though that particular sequence is not explicitly listed.  Did I  
> completely miss the boat on this one?   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.
>
> Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
>
> PS.  From http://www.aprs.org/info/freqspec.txt:
>
>>      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 of 107.3 and range of 25 mi)
>>      146.805MHz D256 R25k Repeater (DCS code and range of 25 km)
>>      146.40 MHz T067 +100 Repeater (67.8 tone and +1.00 MHz offset)
>>      145.50 MHz t077 Simplex       (Tone of 77.X Hz and 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 kilometers
>>      _1750 RXXk    Optional 1750 tone, range in km, wide modulation
>>      _l750 RXXk    Optional 1750 tone narrow modulation (lower case L)
>>      _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 range and West range if different (N,S,E,W)
>>      _txxx RXXm    Lower case first letter means NARROW modulation
>>      _FFF.FFFrx    Alternate receiver 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?   I don't think you really mean that....
>
And worse only set an offset when using a pl tone but not for 1750 hz
-- 
73 Andre PE1RDW



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