Topband: CW Speaker Mystery - My Experience

[Joe Subich, W4TV]

On 2026-02-07 12:19 PM, Tree wrote:

> Many people are copying signals way below the noise level with their
> DSP radios and FT8.
That depends on the way one defines the noise level.  FT8 (and the rest
of Joe Taylor's modes) measure the noise floor in an SSB (2.5 - 2.7 KHz)
bandwidth.  However, the actual detection bandwidth for each tone is
in the 5 Hz range.  If one adjusts for the detection bandwidth, the
"-24 dB" minimum s/n of FT8 is more like +3dB for tone vs. noise.

> How is that possible if that signal just isn't there?
The signal is quite obviously there ... it's a matter of how one defines
the noise.

73,

    ... Joe, W4TV

On 2026-02-07 12:19 PM, Tree wrote:
>> So is the takeaway that the older superhet top line rigs are then the
> optimum for 160-meter DX?
> 
> I guess this begs a question about FT8.  Many people are copying signals
> way below the noise level with their DSP radios and FT8.  How is that
> possible if that signal just isn't there?
> 
> Tree N6TR
> 
> On Sat, Feb 7, 2026 at 8:08 AM Rick Kunath via Topband <
> topband at contesting.com> wrote:
> 
>> So is the takeaway that the older superhet top line rigs are then the
>> optimum for 160-meter DX?
>>
>> Or is there something else about the SDR that wins out?
>>
>> Ir seems like hearing is what it is all about down here.
>>
>> And an excellent review, thank you.
>>
>> Rick Kunath, K9AO
>>