Re: [wsjt-devel] FT4 Frequency on 40-m

[jan0]

Paul,The term for the performance parameter you're asking about is "co-channel 
rejection" and, as Steve points out, it's very messy to analyze analytically, 
as it's a very nonlinear function of many variables.  Even validating 
simulation results via experiment can be tricky.Ed N4II.
 Original message From: Paul Kube  Date: 
7/29/19  3:31 PM  (GMT-05:00) To: WSJT software development 
 Subject: Re: [wsjt-devel] FT4 Frequency on 
40-m TOK, thanks Steve. If I get inspired maybe I'll fire up ft8sim and ft4sim 
and run some experiments.73, Paul K6POOn Mon, Jul 29, 2019 at 9:35 AM Steven 
Franke via wsjt-devel  wrote:Paul,I don’t 
know the answer to your question(s).In addition to frequency separation and 
signal strength difference, one would have to consider overall signal strength 
(not just difference), the DT difference between the two signals, and the delay 
and Doppler spread on each of the two channels that are involved. There are too 
many dimensions in that parameter space!  Steve k9anOn Jul 28, 2019, at 8:06 
PM, Paul Kube  wrote:Steve --Related to this, and to 
another recent thread on replying to CQ's on the caller's frequency: What is 
the decoding probability a FT8 (or FT4) signal when being interfered with by 
another FT8 (or FT4) signal, as a function of frequency separation and signal 
strength difference? Seems clear that it would not be appropriate to model the 
interfering signal as additive Gaussian noise, so is this even something that 
you can solve or nicely approximate analytically? I'd be interested to know.73, 
Paul K6POOn Sun, Jul 28, 2019 at 7:38 AM Steven Franke via wsjt-devel 
 wrote:Hi Gene,FT8 is WAY MORE sensitive! 
(~8db)That number is not right. On the additive white Gaussian noise (AWGN) 
channel, the 50% decode probability of FT8 occurs at SNR=-20.8 dB and the 50% 
decode probability of FT4 occurs at SNR=-17.5 dB.  The sensitivity difference 
is therefore 3.3 dB. On channels with severe Doppler spreading, the threshold 
SNR is higher for both modes, and the difference between FT8 and FT4 will 
decrease somewhat because FT4’s larger tone separation tends to give it an 
advantage in those cases.It might be of interest to some to consider that FT8 
uses symbols with duration 160 ms to send 3 bits apiece. FT4 uses symbols with 
duration 48 ms to send 2 bits apiece. For a given average transmitter power, 
the energy that is transmitted per bit for FT8 is larger than the energy 
transmitted per bit for FT4 by the factor (160/3)/(48/2) = 2.22. Thus, the 
theoretical sensitivity difference (ignoring any differences in signal 
detection, synchronization or LDPC decoding efficiency) is 10*log10(2.22) = 
3.46 dB, very close to the actual difference of 3.3 dB that I quoted above.I 
have no strong feelings one way or the other about your main point, but I think 
that it’s preferable to base the discussion on accurate numbers.FT4 is awesome 
for MORE contacts (i.e. contests).I’m sticking with FT8 for QUALITY. 73 de 
W8NET Miles / “Gene”Secretary, Portage County Amateur Radio Service (PCARS)3905 
Century Club - Master #47DV2/W8NET in the PhilippinesLicensed since 1974Steve, 
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Re: [wsjt-devel] FT4 Frequency on 40-m

[Paul Kube]

TOK, thanks Steve. If I get inspired maybe I'll fire up ft8sim and ft4sim
and run some experiments.

73, Paul K6PO

On Mon, Jul 29, 2019 at 9:35 AM Steven Franke via wsjt-devel <
wsjt-devel@lists.sourceforge.net> wrote:

> Paul,
>
> I don’t know the answer to your question(s).
>
> In addition to frequency separation and signal strength difference, one
> would have to consider overall signal strength (not just difference), the
> DT difference between the two signals, and the delay and Doppler spread on
> each of the two channels that are involved. There are too many dimensions
> in that parameter space!
>
> Steve k9an
>
> On Jul 28, 2019, at 8:06 PM, Paul Kube  wrote:
>
> Steve --
>
> Related to this, and to another recent thread on replying to CQ's on the
> caller's frequency:
>
> What is the decoding probability a FT8 (or FT4) signal when being
> interfered with by another FT8 (or FT4) signal, as a function of frequency
> separation and signal strength difference? Seems clear that it would not be
> appropriate to model the interfering signal as additive Gaussian noise, so
> is this even something that you can solve or nicely approximate
> analytically? I'd be interested to know.
>
> 73, Paul K6PO
>
> On Sun, Jul 28, 2019 at 7:38 AM Steven Franke via wsjt-devel <
> wsjt-devel@lists.sourceforge.net> wrote:
>
>> Hi Gene,
>>
>> FT8 is WAY MORE sensitive! (~8db)
>>
>>
>> That number is not right. On the additive white Gaussian noise (AWGN)
>> channel, the 50% decode probability of FT8 occurs at SNR=-20.8 dB and the
>> 50% decode probability of FT4 occurs at SNR=-17.5 dB.  The sensitivity
>> difference is therefore 3.3 dB.
>>
>> On channels with severe Doppler spreading, the threshold SNR is higher
>> for both modes, and the difference between FT8 and FT4 will decrease
>> somewhat because FT4’s larger tone separation tends to give it an advantage
>> in those cases.
>>
>> It might be of interest to some to consider that FT8 uses symbols with
>> duration 160 ms to send 3 bits apiece. FT4 uses symbols with duration 48 ms
>> to send 2 bits apiece. For a given average transmitter power, the energy
>> that is transmitted per bit for FT8 is larger than the energy transmitted
>> per bit for FT4 by the factor (160/3)/(48/2) = 2.22. Thus, the theoretical
>> sensitivity difference (ignoring any differences in signal detection,
>> synchronization or LDPC decoding efficiency) is 10*log10(2.22) = 3.46 dB,
>> very close to the actual difference of 3.3 dB that I quoted above.
>>
>> I have no strong feelings one way or the other about your main point, but
>> I think that it’s preferable to base the discussion on accurate numbers.
>>
>>
>> FT4 is awesome for MORE contacts (i.e. contests).
>>
>> I’m sticking with FT8 for QUALITY.
>>
>> 73 de W8NET Miles / “Gene”
>> Secretary, Portage County Amateur Radio Service (PCARS)
>> 3905 Century Club - Master #47
>> DV2/W8NET in the Philippines
>> Licensed since 1974
>>
>>
>> Steve, K9AN
>>
>>
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Re: [wsjt-devel] FT4 Frequency on 40-m

[Edfel Rivera]

Hi All:

Just a reflection about FT4 and FT8, sensitivity and cycle times.  From my
experience, FT4, is less sensitive than FT8. Please note my QTH is in
Caribbean far distant than stations in the mainland.  My opinion is that IF
FT4 could be improved (maybe a v2 of the mode) regarding sensitivity from
my point of view, cycle time could extend to 8.5 or even 9.5 seconds which
still is a BIG improvement over FT8 15 seconds.  Just looking for "happy
medium"  between the two metrics (sensitivity and speed). For me quality of
worked stations is more important than quantity.   But again maybe there is
a mix of those two attributes that could work for both types of operators,
and have FT4 that may work better for distant QSO's. Just remember that FT8
is a great mode that improved enormously vs JT65.

Regards!

and 73'

Edfel
KP4AJ

On Mon, Jul 29, 2019 at 12:35 PM Steven Franke via wsjt-devel <
wsjt-devel@lists.sourceforge.net> wrote:

> Paul,
>
> I don’t know the answer to your question(s).
>
> In addition to frequency separation and signal strength difference, one
> would have to consider overall signal strength (not just difference), the
> DT difference between the two signals, and the delay and Doppler spread on
> each of the two channels that are involved. There are too many dimensions
> in that parameter space!
>
> Steve k9an
>
> On Jul 28, 2019, at 8:06 PM, Paul Kube  wrote:
>
> Steve --
>
> Related to this, and to another recent thread on replying to CQ's on the
> caller's frequency:
>
> What is the decoding probability a FT8 (or FT4) signal when being
> interfered with by another FT8 (or FT4) signal, as a function of frequency
> separation and signal strength difference? Seems clear that it would not be
> appropriate to model the interfering signal as additive Gaussian noise, so
> is this even something that you can solve or nicely approximate
> analytically? I'd be interested to know.
>
> 73, Paul K6PO
>
> On Sun, Jul 28, 2019 at 7:38 AM Steven Franke via wsjt-devel <
> wsjt-devel@lists.sourceforge.net> wrote:
>
>> Hi Gene,
>>
>> FT8 is WAY MORE sensitive! (~8db)
>>
>>
>> That number is not right. On the additive white Gaussian noise (AWGN)
>> channel, the 50% decode probability of FT8 occurs at SNR=-20.8 dB and the
>> 50% decode probability of FT4 occurs at SNR=-17.5 dB.  The sensitivity
>> difference is therefore 3.3 dB.
>>
>> On channels with severe Doppler spreading, the threshold SNR is higher
>> for both modes, and the difference between FT8 and FT4 will decrease
>> somewhat because FT4’s larger tone separation tends to give it an advantage
>> in those cases.
>>
>> It might be of interest to some to consider that FT8 uses symbols with
>> duration 160 ms to send 3 bits apiece. FT4 uses symbols with duration 48 ms
>> to send 2 bits apiece. For a given average transmitter power, the energy
>> that is transmitted per bit for FT8 is larger than the energy transmitted
>> per bit for FT4 by the factor (160/3)/(48/2) = 2.22. Thus, the theoretical
>> sensitivity difference (ignoring any differences in signal detection,
>> synchronization or LDPC decoding efficiency) is 10*log10(2.22) = 3.46 dB,
>> very close to the actual difference of 3.3 dB that I quoted above.
>>
>> I have no strong feelings one way or the other about your main point, but
>> I think that it’s preferable to base the discussion on accurate numbers.
>>
>>
>> FT4 is awesome for MORE contacts (i.e. contests).
>>
>> I’m sticking with FT8 for QUALITY.
>>
>> 73 de W8NET Miles / “Gene”
>> Secretary, Portage County Amateur Radio Service (PCARS)
>> 3905 Century Club - Master #47
>> DV2/W8NET in the Philippines
>> Licensed since 1974
>>
>>
>> Steve, K9AN
>>
>>
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>>
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Re: [wsjt-devel] FT4 Frequency on 40-m

[Steven Franke via wsjt-devel]

Paul,

I don’t know the answer to your question(s).

In addition to frequency separation and signal strength difference, one would 
have to consider overall signal strength (not just difference), the DT 
difference between the two signals, and the delay and Doppler spread on each of 
the two channels that are involved. There are too many dimensions in that 
parameter space!  

Steve k9an

> On Jul 28, 2019, at 8:06 PM, Paul Kube  wrote:
> 
> Steve --
> 
> Related to this, and to another recent thread on replying to CQ's on the 
> caller's frequency: 
> 
> What is the decoding probability a FT8 (or FT4) signal when being interfered 
> with by another FT8 (or FT4) signal, as a function of frequency separation 
> and signal strength difference? Seems clear that it would not be appropriate 
> to model the interfering signal as additive Gaussian noise, so is this even 
> something that you can solve or nicely approximate analytically? I'd be 
> interested to know.
> 
> 73, Paul K6PO
> 
> On Sun, Jul 28, 2019 at 7:38 AM Steven Franke via wsjt-devel 
> mailto:wsjt-devel@lists.sourceforge.net>> 
> wrote:
> Hi Gene,
> 
>> FT8 is WAY MORE sensitive! (~8db)
> 
> That number is not right. On the additive white Gaussian noise (AWGN) 
> channel, the 50% decode probability of FT8 occurs at SNR=-20.8 dB and the 50% 
> decode probability of FT4 occurs at SNR=-17.5 dB.  The sensitivity difference 
> is therefore 3.3 dB. 
> 
> On channels with severe Doppler spreading, the threshold SNR is higher for 
> both modes, and the difference between FT8 and FT4 will decrease somewhat 
> because FT4’s larger tone separation tends to give it an advantage in those 
> cases.
> 
> It might be of interest to some to consider that FT8 uses symbols with 
> duration 160 ms to send 3 bits apiece. FT4 uses symbols with duration 48 ms 
> to send 2 bits apiece. For a given average transmitter power, the energy that 
> is transmitted per bit for FT8 is larger than the energy transmitted per bit 
> for FT4 by the factor (160/3)/(48/2) = 2.22. Thus, the theoretical 
> sensitivity difference (ignoring any differences in signal detection, 
> synchronization or LDPC decoding efficiency) is 10*log10(2.22) = 3.46 dB, 
> very close to the actual difference of 3.3 dB that I quoted above.
> 
> I have no strong feelings one way or the other about your main point, but I 
> think that it’s preferable to base the discussion on accurate numbers.
> 
>> 
>> FT4 is awesome for MORE contacts (i.e. contests).
>> 
>> I’m sticking with FT8 for QUALITY. 
>> 
>> 73 de W8NET Miles / “Gene”
>> Secretary, Portage County Amateur Radio Service (PCARS)
>> 3905 Century Club - Master #47
>> DV2/W8NET in the Philippines
>> Licensed since 1974
> 
> Steve, K9AN
> 
> 
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Re: [wsjt-devel] FT4 Frequency on 40-m

[Paul Kube]

Steve --

Related to this, and to another recent thread on replying to CQ's on the
caller's frequency:

What is the decoding probability a FT8 (or FT4) signal when being
interfered with by another FT8 (or FT4) signal, as a function of frequency
separation and signal strength difference? Seems clear that it would not be
appropriate to model the interfering signal as additive Gaussian noise, so
is this even something that you can solve or nicely approximate
analytically? I'd be interested to know.

73, Paul K6PO

On Sun, Jul 28, 2019 at 7:38 AM Steven Franke via wsjt-devel <
wsjt-devel@lists.sourceforge.net> wrote:

> Hi Gene,
>
> FT8 is WAY MORE sensitive! (~8db)
>
>
> That number is not right. On the additive white Gaussian noise (AWGN)
> channel, the 50% decode probability of FT8 occurs at SNR=-20.8 dB and the
> 50% decode probability of FT4 occurs at SNR=-17.5 dB.  The sensitivity
> difference is therefore 3.3 dB.
>
> On channels with severe Doppler spreading, the threshold SNR is higher for
> both modes, and the difference between FT8 and FT4 will decrease somewhat
> because FT4’s larger tone separation tends to give it an advantage in those
> cases.
>
> It might be of interest to some to consider that FT8 uses symbols with
> duration 160 ms to send 3 bits apiece. FT4 uses symbols with duration 48 ms
> to send 2 bits apiece. For a given average transmitter power, the energy
> that is transmitted per bit for FT8 is larger than the energy transmitted
> per bit for FT4 by the factor (160/3)/(48/2) = 2.22. Thus, the theoretical
> sensitivity difference (ignoring any differences in signal detection,
> synchronization or LDPC decoding efficiency) is 10*log10(2.22) = 3.46 dB,
> very close to the actual difference of 3.3 dB that I quoted above.
>
> I have no strong feelings one way or the other about your main point, but
> I think that it’s preferable to base the discussion on accurate numbers.
>
>
> FT4 is awesome for MORE contacts (i.e. contests).
>
> I’m sticking with FT8 for QUALITY.
>
> 73 de W8NET Miles / “Gene”
> Secretary, Portage County Amateur Radio Service (PCARS)
> 3905 Century Club - Master #47
> DV2/W8NET in the Philippines
> Licensed since 1974
>
>
> Steve, K9AN
>
>
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Re: [wsjt-devel] FT4 Frequency on 40-m

[Gene Marsh via wsjt-devel]

Hi Steve, 

I didn’t calculate everything - and thank you for doing “my work” for me.  ;)

In the real world, we need more empirical data to support my thought = FT8 is 
superior for weak signal/DX/“valuable” contacts (and, of course, “value” is 
purely subjective).  We know is “better” qualitatively, but in the real world, 
how much?  We don’t have the history for FT4 DX pileups. In fact, we have only 
a smattering of good FT8 data. 

I *believe*, in more than 8000+ FT8 contacts (vs ~175 FT4 contacts!), FT8 is 
clearly better than FT4 for weak signals.  But, how much value can be used for 
a QUANTITATIVE assessment (rare DX vs many more contacts).  I need more data. 

Thanks for your response!

I’m staying tuned

73 de W8NET Miles / “Gene”
Secretary, Portage County Amateur Radio Service (PCARS)
3905 Century Club - Master #47
DV2/W8NET in the Philippines
Licensed since 1974

> On Jul 28, 2019, at 10:32 AM, Steven Franke  wrote:
> 
> Hi Gene,
> 
>> FT8 is WAY MORE sensitive! (~8db)
> 
> That number is not right. On the additive white Gaussian noise (AWGN) 
> channel, the 50% decode probability of FT8 occurs at SNR=-20.8 dB and the 50% 
> decode probability of FT4 occurs at SNR=-17.5 dB.  The sensitivity difference 
> is therefore 3.3 dB. 
> 
> On channels with severe Doppler spreading, the threshold SNR is higher for 
> both modes, and the difference between FT8 and FT4 will decrease somewhat 
> because FT4’s larger tone separation tends to give it an advantage in those 
> cases.
> 
> It might be of interest to some to consider that FT8 uses symbols with 
> duration 160 ms to send 3 bits apiece. FT4 uses symbols with duration 48 ms 
> to send 2 bits apiece. For a given average transmitter power, the energy that 
> is transmitted per bit for FT8 is larger than the energy transmitted per bit 
> for FT4 by the factor (160/3)/(48/2) = 2.22. Thus, the theoretical 
> sensitivity difference (ignoring any differences in signal detection, 
> synchronization or LDPC decoding efficiency) is 10*log10(2.22) = 3.46 dB, 
> very close to the actual difference of 3.3 dB that I quoted above.
> 
> I have no strong feelings one way or the other about your main point, but I 
> think that it’s preferable to base the discussion on accurate numbers.
> 
>> 
>> FT4 is awesome for MORE contacts (i.e. contests).
>> 
>> I’m sticking with FT8 for QUALITY. 
>> 
>> 73 de W8NET Miles / “Gene”
>> Secretary, Portage County Amateur Radio Service (PCARS)
>> 3905 Century Club - Master #47
>> DV2/W8NET in the Philippines
>> Licensed since 1974
> 
> Steve, K9AN
> 
> 
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Re: [wsjt-devel] FT4 Frequency on 40-m

[Christoph Berg]

Re: Roy Gould 2019-07-27 

> It does not seem to me that there is any reason that FT4 and FT8 cannot
> operate together in the same channel. If this is so, then why have separate
> channels for them?

FT8 is quite good at decoding even overlapping signals in parallel.
However, from my experience, what it does not like, is when some
strong signal (dis)appears halfway through the RX cycle, probably
because of the TRX's AGC changing. If the same strong signal is there
all the time on the next cycle, decoding works.

If FT4 were on the same channel, that would happen all the time,
making decoding weak FT8 signals very difficult.

Christoph


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Re: [wsjt-devel] FT4 Frequency on 40-m

[Edfel Rivera]

Hi All:

My experience from the Caribbean for example 6M  no FT4 QSO so far. Tried
80m and similar experience,  although I can hear some stations.  No QSO.
For users working the magic bad, at distant locations FT4 is out the scene
unless conditions are excellent.  Just my experience,  However, will test
more the FT4 mode.

73'

Edfel
KP4AJ

On Sun, Jul 28, 2019 at 10:38 AM Steven Franke via wsjt-devel <
wsjt-devel@lists.sourceforge.net> wrote:

> Hi Gene,
>
> FT8 is WAY MORE sensitive! (~8db)
>
>
> That number is not right. On the additive white Gaussian noise (AWGN)
> channel, the 50% decode probability of FT8 occurs at SNR=-20.8 dB and the
> 50% decode probability of FT4 occurs at SNR=-17.5 dB.  The sensitivity
> difference is therefore 3.3 dB.
>
> On channels with severe Doppler spreading, the threshold SNR is higher for
> both modes, and the difference between FT8 and FT4 will decrease somewhat
> because FT4’s larger tone separation tends to give it an advantage in those
> cases.
>
> It might be of interest to some to consider that FT8 uses symbols with
> duration 160 ms to send 3 bits apiece. FT4 uses symbols with duration 48 ms
> to send 2 bits apiece. For a given average transmitter power, the energy
> that is transmitted per bit for FT8 is larger than the energy transmitted
> per bit for FT4 by the factor (160/3)/(48/2) = 2.22. Thus, the theoretical
> sensitivity difference (ignoring any differences in signal detection,
> synchronization or LDPC decoding efficiency) is 10*log10(2.22) = 3.46 dB,
> very close to the actual difference of 3.3 dB that I quoted above.
>
> I have no strong feelings one way or the other about your main point, but
> I think that it’s preferable to base the discussion on accurate numbers.
>
>
> FT4 is awesome for MORE contacts (i.e. contests).
>
> I’m sticking with FT8 for QUALITY.
>
> 73 de W8NET Miles / “Gene”
> Secretary, Portage County Amateur Radio Service (PCARS)
> 3905 Century Club - Master #47
> DV2/W8NET in the Philippines
> Licensed since 1974
>
>
> Steve, K9AN
>
>
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Re: [wsjt-devel] FT4 Frequency on 40-m

[Steven Franke via wsjt-devel]

Hi Gene,

> FT8 is WAY MORE sensitive! (~8db)

That number is not right. On the additive white Gaussian noise (AWGN) channel, 
the 50% decode probability of FT8 occurs at SNR=-20.8 dB and the 50% decode 
probability of FT4 occurs at SNR=-17.5 dB.  The sensitivity difference is 
therefore 3.3 dB. 

On channels with severe Doppler spreading, the threshold SNR is higher for both 
modes, and the difference between FT8 and FT4 will decrease somewhat because 
FT4’s larger tone separation tends to give it an advantage in those cases.

It might be of interest to some to consider that FT8 uses symbols with duration 
160 ms to send 3 bits apiece. FT4 uses symbols with duration 48 ms to send 2 
bits apiece. For a given average transmitter power, the energy that is 
transmitted per bit for FT8 is larger than the energy transmitted per bit for 
FT4 by the factor (160/3)/(48/2) = 2.22. Thus, the theoretical sensitivity 
difference (ignoring any differences in signal detection, synchronization or 
LDPC decoding efficiency) is 10*log10(2.22) = 3.46 dB, very close to the actual 
difference of 3.3 dB that I quoted above.

I have no strong feelings one way or the other about your main point, but I 
think that it’s preferable to base the discussion on accurate numbers.

> 
> FT4 is awesome for MORE contacts (i.e. contests).
> 
> I’m sticking with FT8 for QUALITY. 
> 
> 73 de W8NET Miles / “Gene”
> Secretary, Portage County Amateur Radio Service (PCARS)
> 3905 Century Club - Master #47
> DV2/W8NET in the Philippines
> Licensed since 1974

Steve, K9AN


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Re: [wsjt-devel] FT4 Frequency on 40-m

[Gene Marsh via wsjt-devel]

No!

FT8 is WAY MORE sensitive! (~8db)

FT4 is awesome for MORE contacts (i.e. contests).

I’m sticking with FT8 for QUALITY. 

73 de W8NET Miles / “Gene”
Secretary, Portage County Amateur Radio Service (PCARS)
3905 Century Club - Master #47
DV2/W8NET in the Philippines
Licensed since 1974

> On Jul 27, 2019, at 5:47 PM, Roy Gould  wrote:
> 
> Gentlemen:
> 
> Bandwidth and weak signal performance are important considerations when 
> comparing the relative merits of FT8 and FT4. Perhaps an even more important 
> consideration is which of these is the most fun to operate.
> 
> I have been using FT4 since the release of 2.1.0 and find that I like it a 
> lot better than FT8. It is twice as fast and features such as Best S+P are 
> great. I have abandoned FT8 in favor of FT4. I anticipate that others will 
> come to the same conclusion and eventually FT4 will replace FT8.
> 
> I do not like having FT4 on the same frequency as W1AW (7.0475 MHz). I often 
> copy the code practice and the bulletins from W1AW. I do not usually copy 
> these CW broadcasts by ear. I use them for code practice for CW programs such 
> as Fldigi and CW Decoder. I have these programs copy the bulletins for me as 
> if this was a digital mode signal. I would like to be able to receive W1AW 
> without interference from any other nearby signals.
> 
> It does not seem to me that there is any reason that FT4 and FT8 cannot 
> operate together in the same channel. If this is so, then why have separate 
> channels for them?
> 
> Therefore, I propose that the default 40-m frequency for FT4 be 7.074 MHz.
> 
> What do you think?
> 
> 73, Roy, W7IDM
> 
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Re: [wsjt-devel] FT4 Frequency on 40-m

[Jim Shorney]

On Sat, 27 Jul 2019 15:47:17 -0600
Roy Gould  wrote:

> I have been using FT4 since the release of 2.1.0 and find that I like it a
> lot better than FT8. It is twice as fast and features such as Best S+P are
> great. I have abandoned FT8 in favor of FT4. I anticipate that others will
> come to the same conclusion and eventually FT4 will replace FT8.


I would be happy if the majority of stateside ops moved to FT4 so I could more 
easily hear and work the very weak DX on FT8. FT4 is too fast and less 
sensitivity are issues for some.

 
> I do not like having FT4 on the same frequency as W1AW (7.0475 MHz). I
> often copy the code practice and the bulletins from W1AW. I do not usually
> copy these CW broadcasts by ear. I use them for code practice for CW
> programs such as Fldigi and CW Decoder. I have these programs copy the
> bulletins for me as if this was a digital mode signal. I would like to be
> able to receive W1AW without interference from any other nearby signals.


That's what CW filters are for. 


> Therefore, I propose that the default 40-m frequency for FT4 be 7.074 MHz.


Good heavens no. It is already enough of a zoo the way it is.


73
-Jim
NU0C


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[wsjt-devel] FT4 Frequency on 40-m

[Roy Gould]

Gentlemen:

Bandwidth and weak signal performance are important considerations when
comparing the relative merits of FT8 and FT4. Perhaps an even more
important consideration is which of these is the most fun to operate.

I have been using FT4 since the release of 2.1.0 and find that I like it a
lot better than FT8. It is twice as fast and features such as Best S+P are
great. I have abandoned FT8 in favor of FT4. I anticipate that others will
come to the same conclusion and eventually FT4 will replace FT8.

I do not like having FT4 on the same frequency as W1AW (7.0475 MHz). I
often copy the code practice and the bulletins from W1AW. I do not usually
copy these CW broadcasts by ear. I use them for code practice for CW
programs such as Fldigi and CW Decoder. I have these programs copy the
bulletins for me as if this was a digital mode signal. I would like to be
able to receive W1AW without interference from any other nearby signals.

It does not seem to me that there is any reason that FT4 and FT8 cannot
operate together in the same channel. If this is so, then why have separate
channels for them?

Therefore, I propose that the default 40-m frequency for FT4 be 7.074 MHz.

What do you think?

73, Roy, W7IDM
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