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Author Topic: What part of bandwidth don't YOU understand?  (Read 5618 times)
KE7IZL
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« Reply #30 on: July 30, 2011, 04:56:25 PM »

BPSK31 though has ultra narrow band. Even if your SSB receiver receives 10 well spaced paralell BPSK31 transmissions in its passband, if you are using decoding software like MultiPSK, just click the one on the waterfall you want to decode (as well as reply to). The radio's 2 to 3 khz bandwidth doesn't matter. The bandwidth of the digital transmission itself (and RX bandpass FFT filter on the software) are what matter.
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W8JX
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« Reply #31 on: July 30, 2011, 05:07:44 PM »

Even if your SSB receiver receives 10 well spaced paralell BPSK31 transmissions in its passband, if you are using decoding software like MultiPSK, just click the one on the waterfall you want to decode (as well as reply to). The radio's 2 to 3 khz bandwidth doesn't matter. The bandwidth of the digital transmission itself (and RX bandpass FFT filter on the software) are what matter.

In theory anyway. The problem with this is that is "assumes" all signals are same strength too. Through in a strong signal or two in or near this bandpass to swamp AGC and this theory goes out the window. Theory and reality do not mesh that often.
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N2RRA
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« Reply #32 on: July 30, 2011, 07:26:19 PM »

Even if your SSB receiver receives 10 well spaced paralell BPSK31 transmissions in its passband, if you are using decoding software like MultiPSK, just click the one on the waterfall you want to decode (as well as reply to). The radio's 2 to 3 khz bandwidth doesn't matter. The bandwidth of the digital transmission itself (and RX bandpass FFT filter on the software) are what matter.

In theory anyway. The problem with this is that is "assumes" all signals are same strength too. Through in a strong signal or two in or near this bandpass to swamp AGC and this theory goes out the window. Theory and reality do not mesh that often.

All this may be true but low signal to noise ratio and narrow band width modes using software is very effective in noisy conditions ,weak signal and doesn't need excess bandwidth or power. With 25 watts or less can work the world.

All though the thread is about using SSB mode as the issue people are having trouble with understanding.


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W8JX
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« Reply #33 on: July 30, 2011, 10:29:16 PM »


All though the thread is about using SSB mode as the issue people are having trouble with understanding.


Well Digi is mostly AFSK modulation is SSB mode.
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K7NSW
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« Reply #34 on: July 31, 2011, 03:29:33 PM »

Sometimes QRM is really accidental.  I was wintering in Arizona.  I found a dead cw freq, listened for a minute,  and called QRL three times.  No response.  Called CQ, etc - the usual.  No response.  Radio off and went to cut the lawn.  Received a friendly e-mail a few days later.  A guy in the midwest.  He copied W1AW on that freq and was doing code practice.  He also heard me and I messed up his code practice.  He was in the middle between me and ARRL HQ.  The band was open to Connecticut for him but closed for me.  So I sinned in ignorance, no fault of mine.  Patience and a forgiving heart are still virtues - that is why the e-mail to me was friendly.  Still do not know what I could have done differently.  Life is not always fair or the way we want it - oh well.
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N2RRA
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« Reply #35 on: August 01, 2011, 10:28:07 AM »

Sometimes QRM is really accidental.  I was wintering in Arizona.  I found a dead cw freq, listened for a minute,  and called QRL three times.  No response.  Called CQ, etc - the usual.  No response.  Radio off and went to cut the lawn.  Received a friendly e-mail a few days later.  A guy in the midwest.  He copied W1AW on that freq and was doing code practice.  He also heard me and I messed up his code practice.  He was in the middle between me and ARRL HQ.  The band was open to Connecticut for him but closed for me.  So I sinned in ignorance, no fault of mine.  Patience and a forgiving heart are still virtues - that is why the e-mail to me was friendly.  Still do not know what I could have done differently.  Life is not always fair or the way we want it - oh well.

I see your point but still not the same. This same scenario does happen on SSB but you can prevent the interference from a QSO much easier. In CW filtering a signal 50Hz to 500 Hz can be eliminated completely is possible but not in SSB. In CW it's not like you can just jump in and mention the interference with everybody if you know what I'm saying.

If there's a NET which has a group of people from all over the U.S. ,or across seas someone is going to hear you ask if "frequency is in use" in SSB. There shouldn't be any problem in telling that person "yes...thanks for asking". Even if the station was 1KHz away someone in the group should react to prevent further interruption.

In the scenario of two stations in QSO could be harder ,but what W1IT is talking about is that same group of people knowing that your having a QSO for the last 30-45 minutes 2KHZ away and they still start their NET. Then they have the nerve to come down and state that your interfering with them. It's B.S.!

Why can't they just move 1KHz higher?



« Last Edit: August 01, 2011, 10:30:25 AM by N2RRA » Logged
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