[Elecraft] Blue Tooth - Freq. response

Mon Feb 7 22:48:28 EST 2011

 > There was no way to know from the documentation which
 > type of equalizer the K3 has inside.

Any multi-band EQ beyond two bands - e.g, other than simple high 
boost/cut and/or low boost/cut designs - must, by definition, be
parametric.  I don't think the manual needs to specify the type
of EQ when it has eight bands.  With multi-band EQ the bottom and
top "bands" are typically shelving and the intermediate bands
parametric with the Q designed for minimum ripple (smooth transition
from band to band).

73,

    ... Joe, W4TV

On 2/7/2011 6:02 PM, Brian Alsop wrote:
> Very interesting.  There was no way to know from the documentation which
> type of equalizer the K3 has inside.
>
> 73 de Brian/K3KO
>
> On 2/7/2011 22:20, Joe Subich, W4TV wrote:
>>
>>   >  If one introduced say 6 db in the segment covering 2KHz and up to the
>>   >  next equalizer breakpoint, I don't see how this can mess up decoding.
>>   >  The gain increase is constant in the segment.
>>
>> No, the gain is not constant across the segment, it is tapered so that
>> setting two adjacent ranges to the same level creates a flat response
>> across the "boundary." In the case of 2125/2295 (traditional "high"
>> tones) setting the 1600 Hz band at 0 and the 2400 Hz band at +10 dB
>> will create a measurable "tilt" between the two tones ... a similar
>> tilt will be seen with the 915/1085 Hz tone pair for the 800/1600 Hz
>> bands.
>>
>> It's easy to see the behavior, simply use a stable oscillator like the
>> XG-2. Set the RxEQ to boost only the 2400 Hz band by +16 dB, zero the
>> dBV meter at 1 KHz and measure the level at 2.125 and 2.295 KHz. The
>> difference will be at least 2 dB (I measure 2.2 to 2.3 dB "tilt" at
>> both 2125/2295 and 915/1085).
>>
>> The behavior of a parametric EQ (which the K3 is) is very different
>> than a shelving EQ.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 2/7/2011 3:26 PM, Brian Alsop wrote:
>>> Joe,
>>>
>>> We very specifically singled out FSK-D for this request. No other
>>> digital mode would be impacted.
>>>
>>> If one introduced say 6 db in the segment covering 2KHz and up to the
>>> next equalizer breakpoint, I don't see how this can mess up decoding.
>>> The gain increase is constant in the segment.
>>>
>>> 73 de Brian/K3KO
>>>
>>> On 2/7/2011 20:17, Joe Subich, W4TV wrote:
>>>>
>>>> But you don't want the equalizer in digital modes as that messes
>>>> up the response and results in poorer decoding. The only change
>>>> that makes sense in any of the digital modes is (flat) level and
>>>> that can be done with CONFIG: LIN OUT.
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>> On 2/7/2011 2:19 PM, Brian Alsop wrote:
>>>>> Add "in equalizer" to the request. Right now it knows to turn it off in
>>>>> FSK-D.
>>>>>
>>>>> 73 de Brian/K3KO
>>>>>
>>>>> On 2/4/2011 22:41, Joe Subich, W4TV wrote:
>>>>>>
>>>>>>>> Unfortunately, one can't bump up audio output in FSK-D.
>>>>>>
>>>>>> What do you mean "can't bump up audio output in FSK-D?" The speaker
>>>>>> or headphone level is controllable with the AF gain and the Line Out
>>>>>> is controllable with the CONFIG:LIN OUT setting.
>>>>>>
>>>>>> 73,
>>>>>>
>>>>>>
>>>>>
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