[Elecraft] K3 DATA A vs AFSK A
Lynn W. Taylor, WB6UUT
KX3 at ColdRocksHotBrooms.com
Tue Mar 17 20:47:11 EDT 2015
... and it should be LSB because everyone knows: Low Space Means Fine
Teletype.
On 3/17/2015 4:00 PM, Joe Subich, W4TV wrote:
>
> Note: in my comment below Mark-85 Hz should be MARK+85 Hz as AFSK A
> (LSB) reverses the sense of the tones - Mark is the lower of the two
> audio tones but the higher of the RF frequencies.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2015-03-17 6:48 PM, Fred Jensen wrote:
>> Hmmm ... this may be the first time Fred Cady's book has failed me. I
>> understand now "what" each mode does. What's still not clear is "why
>> would I choose one over the other?" Operator/User manuals tend not to
>> answer that question, they are understandably focused on exactly how to
>> operate the equipment.
>>
>> I'm very sure that, when I first set up RTTY, I went to AFSK A because I
>> knew what audio frequency shift keying was and I didn't know what DATA A
>> was. It all worked, so I never changed it or tried out the other
>> choice. I guess if AFSK A is LSB and works with MMTTY in its default
>> configuration, then DATA A is USB and I'd have to reverse the tones in
>> MMTTY.
>>
>> I'll leave it as I've been using it, it works so it obviously doesn't
>> need fixing. I was just curious. I have my "pitch" set at 915 Hz, I
>> can't hear 2,125 Hz. Thanks Joe and Mike.
>>
>> 73,
>>
>> Fred K6DGW
>> - Northern California Contest Club
>> - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
>> - www.cqp.org
>>
>> On 3/17/2015 10:07 AM, Joe Subich, W4TV wrote:
>>>
>>> On 2015-03-17 12:41 PM, Fred Jensen wrote:
>>> > Can you 'splain the difference between AFSK and DATA A?
>>>
>>> AFSK A and DATA A are both audio modes. AFSK A uses LSB
>>> and FC is set to MARK - 85 Hz (the center of the two RTTY
>>> Tones). DATA A is USB and FC is set to 1500 Hz (the center
>>> of the transmit audio passband [200 - 2800 Hz]).
>>>
>>> AFSK A also allows use of the AFSK transmit filter (a tight
>>> filter around the Mark/Space tones to eliminate hum/pops/etc.)
>>> and the use of the Dual Tone filter on receive.
>>
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