> I figured I could include that entire range within the FM filter
> bandwidth (which I still can do), AND also hear all 10 KHz of those
> signals (which I've learned I cannot do).
Your ears are much better than mine if you can actually copy a full
10 KHz wide audio pile-up. I have enough trouble keeping up with
4 KHz or so (200 Hz to 4.2 KHz) if I open everything up in SSB mode.
Note the K3 limits HI in CW to "Pitch + 1400 Hz" thus if one likes
a 500 Hz tone, the highest frequency passed in CW is 1900 Hz. The
*widest* bandwidth possible in CW is by using an 800 Hz sidetone
which results in 2.2 KHz ... whether the "roofing filter" is 2.7,
2.8, 6 or 13 KHz wide.
73,
... Joe, W4TV
On 9/26/2012 9:46 PM, Dale Boresz wrote:
> Joe,
>
> Understood. I wanted to be able to simultaneously hear and see 12 Khz or
> so of cw signals, thinking that I could more quickly identify the
> station being worked. For example, if I know the dx station is listening
> from 14.010 to 14.020 (admittedly pretty wide), I figured I could
> include that entire range within the FM filter bandwidth (which I still
> can do), AND also hear all 10 KHz of those signals (which I've learned I
> cannot do). Oh well; the FM filter will still let me hear a wider swath
> of the pile-up than my present 2.8KHz filter will...
>
> 73, Dale
> WA8SRA
>
>
> On 9/26/2012 9:25 PM, Joe Subich, W4TV wrote:
>>> The only reason I had for putting the FM filter in the 2nd receiver
>>> was to be able to hear more of the split in a broad pileup situation
>>> (like the extremely large split widths that we saw a few months ago
>>> with 7O6T),
>> The width of the roofing filter has nothing at all to do with hearing
>> more of the pile-up (unless you're talking about literally "listening"
>> to all the signals at one time like a pile-up tape). The P3's pick-
>> up point is ahead of any roofing filter - it can "see" up to 200 KHz
>> at a time. The K3 transmitter and receiver can be split anywhere in
>> the band and if the KRX3 is used with a separate antenna the K3 and
>> KRX3 can literally transmit on one band and listen on another.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 9/26/2012 8:58 PM, Dale Boresz wrote:
>>> Joe,
>>>
>>> Good observations, all. I agree that 4.2 KHz is certainly good enough
>>> for communications audio.
>>>
>>> The only reason I had for putting the FM filter in the 2nd receiver was
>>> to be able to hear more of the split in a broad pileup situation (like
>>> the extremely large split widths that we saw a few months ago with
>>> 7O6T), figuring that being able to simultaneously hear the wider
>>> bandwidth and see it on the P3 would be a great combination. I'll just
>>> have to be a bit quicker with the VFO-B knob ;-)
>>>
>>> 73, Dale
>>> WA8SRA
>>>
>>>
>>> On 9/26/2012 8:10 PM, Joe Subich, W4TV wrote:
>>>> The limit occurs several places ... adjust the "HI" setting and one
>>>> will find 4.20 is the maximum available. There is also an analog
>>>> lowpass filter in the audio (headphone and speaker) between the DAC
>>>> and the headphone/speaker amplifiers.
>>>>
>>>> I'm sure this limitation derives from the roughly 10 KHz clock/sample
>>>> rate used for the DAC ... Nyquist says the maximum frequency can not
>>>> be more than half the sample (clock) rate. 4.2 KHz is plenty good
>>>> enough for communications audio ... and not bad for AM with fading,
>>>> noise, and interference typical of medium and high frequencies.
>>>>
>>>> The FM filter still provides noticeably better double sideband AM
>>>> response (4.2 - 4.5 KHz with DSP/LPF skirts) than the AM filter
>>>> (3.0-3.3 KHz depending on the IF filter response).
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>> On 9/26/2012 7:23 PM, Don Wilhelm wrote:
>>>>> Sorry, but yes, the K3 audio is limited at 4 kHz, no matter whether it
>>>>> is to the headphones or to the speaker. Please do not "shoot the
>>>>> messenger". but that information is in the archives of this reflector in
>>>>> several places - it has been discussed periodically.
>>>>>
>>>>> If you want to lobby for extended audio response, that is fine, but I am
>>>>> just saying what the limits are today. Whether those can be extended or
>>>>> not is for the DSP designer to answer.
>>>>>
>>>>> 73,
>>>>> Don W3FPR
>>>>>
>>>>> On 9/26/2012 7:11 PM, Dale Boresz wrote:
>>>>>> On 9/26/2012 1:35 PM, Edward R Cole wrote:
>>>>>>> ... But I learned that audio is limited to 4-KHz
>>>>>>> regardless of IF filter so I ended up selling the extra 13-KHz filter.
>>>>>>>
>>>>>>> ...
>>>>>>>
>>>>>>> 73, Ed - KL7UW
>>>>>> I really hope that this does not apply to received audio to the
>>>>>> headphones or loudspeaker! I just purchased two FM filters (one for
>>>>>> sub-receiver to monitor wide splits) specifically to open up the receive
>>>>>> passband (audio included) for SWL and BCB reception. I have no intention
>>>>>> of actually transmitting FM or AM for that matter -- just want the wider
>>>>>> audio bandwidth for receive.
>>>>>>
>>>>>> So... is the received audio bandwidth *really* limited to 4 KHz?
>>>>>>
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