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Re: 10 kHz-150 kHz Band Sweep from EN70 Indiana
D R
Hi Gedas,
Can you post a recording direct from SDRC, please? It would be nice to be able to dive into the waterfall and look at some of the weak signals close up, although it was easy enough to pick out all the US Navy stations (and some French Navy as well). A five minute duration is ample, and it keeps the filesize down to about 200MB. I've added another recording I've just made - the solar panels are gone, the storms aren't too bad, and the LORAN transmitter is back on, but well below its normal power output, so it's all reasonably clear. DDH47 on 147.3kHz is worth a look, as you can decode it with FLDigi (settings: RTTY - Custom - 85Shift, 50baud, 5-0-1.5, Auto, 72char. Use CW or LSB, filter centred on signal.) I haven't checked it myself to see whether it was actually sending anything worth decoding, but I could always do a much longer recording if you want to try it out (German weather forecasts can make rivetting reading ;) ). Regards, Dave
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Re: SNR meter, bandwidth and gain adjustment for transverters
jdow
But S-Meter is not SNR meter. Although the SNR meter
should be approximated from the S-Meter reading.
toggle quoted messageShow quoted text
{^_-}
On 20210705 13:57:05, Conrad, PA5Y
wrote:
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Re: SNR meter, bandwidth and gain adjustment for transverters
jdow
On 20210705 12:09:22, Bob Dengler wrote:
Please, Bob, distinguish what you mean with reference to time domain or spectral domain. It all makes SO MUCH more sense in time domain. Then terms like "quasi peak" make sense. It's meter rise time written usefully. That term makes no sense in the frequency domain.At 7/5/2021 10:43 AM, you wrote:On Mon, Jul 5, 2021 at 09:26 AM, Bob Dengler wrote: I strongly disagree. How else is one supposed to make total channel power measurements for radiometry? SDRs aren't just for communications, & any developer that codes their SDR apps otherwise is hamstringing their full potential. Right now the only apps I know of that can do this are HDSDR & SDRuno. HDSDR is compatible with all my SDRs so that covers my needs, but it would be nice if SDRC could display & record average channel power readings as well as HDSDR is fairly useless for NBFM monitoring (no de-emphasis). I'll have to go through the forum archives to see if this has been requested, & do so if not. Bob NO6B Please define "average power". I've also seen the term "integrated power" bandied about in the Flex forums. There is no established definition for either term.We can choose to split hairs on average vs. sample vs. RMS. I think for purposes of amateur radiometry, any of the above will do. If I'm wrong someone please chime in.The function of an S-meter is not to report the "total power" or "average power" or "integrated power" in the passband, it is to report the highest voltage measured anywhere in the passband, irrespective of any nebulous "total power" contained within the filter. That's what Simon's S-meter does.OK, fair enough. An S-meter, as described above, is useless to me. I would like to see the option of switching the S-meter function in SDRC to an average channel power meter. :) Thanks Bob NO6B Please PLEASE *P*L*E*A*S*E* guys distinguish between frequency domain behavior and time domain behavior. Frequency domain behavior gets in there when Simon discusses picking one small frequency bin to represent the whole bandwidth of interest. {o.o}
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Re: SNR meter, bandwidth and gain adjustment for transverters
jdow
WTFF is "Continuum mode". You are losing your
audience by inventing terms that make no sense. Do you mean time
domain where everything flows along in a sampled stream? If so
then time domain makes more sense to the engineers designing
things. It's instantly understandable.
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{+_+}
On 20210705 12:27:26, sm6fhz wrote:
Hi.
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Re: SNR meter, bandwidth and gain adjustment for transverters
jdow
I'm sorry guys - my autisim has kicked in and I have to get this off
my chest before I explode.
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As originally conceived the S-Meter was an indication of channel power. Meter ballistics and capacitor charge and discharge created a quaisi-peak reading over time. It takes a little time for the meter reading to rise and it generally if not originally takes longer to fall. This served multiple purposes. I'm not sure which came first, protecting the operator's ears or providing a relative power indication for the operator. I suspect the latter was easier to implement before the days of AGC systems. Certainly IF alignment is facilitated by reading audio output power with any AGC disabled. Probably somebody figured that would be handy for operators to give some relative power readings during active communications. In some radios special meter calibration was used to give quasi accurate readings 6dB/S-unit. That did not sell so we got the 2 dB per S-Unit of the ProII coming out of the mess. (I have one so I pick on it's shortcomings.) The important point above is that the S-Meter responds to instantaneous power changes slowly. This gives it the IARU's quasi-peak sort of performance much like a VU meter provides, as perhaps distinct from a Durrough meter. The value you see on the meter bears a fairly good indication, if the meter is accurate, of you real ability to communicate. Once we move to the spectral domain from the time domain this "quasi-peak" loses meaning. It has to be applied between successive spectral computations. Since there are FFT peculiarities such as windowing involved it is difficult enough to be called impossible or at least quite impractical to make real accurate readings for say a 2.4 kHz bandwidth out of a spectrum with 10 Hz bins. Fortunately in most cases one filters incoming data before switching to baseband processing. In the case of SSB it's a zero IF receiver so filtering after conversion can be used but power can be derived in much the same way. Take the IF filter output IQ values, square each one, and add them together. That is a real power value in dB relative to a dooby value. With a calibrated source the dooby value can become a real dBm value. (For AM demodulation the square root of that power value becomes your AM output without the distortion products the usual diode demodulators provide.) Once you have that power value derived from I^2 + Q^2 you can filter it per the IARU quasi peak requirements and get correct S-Meter readings and behavior. Do note that the I^2 + Q^2 reading above is NOT necessarily well related to selecting the highest level bin in an FFT output. With broadcast FM it very emphatically does not. I have seen peak spectral element values on a broadcast FM signal vary by more than 20 dB from silence to high modulation level. That is not in any way shape or manner proper S-Meter behavior. Now maybe I can get this out of my head. I hope I did not get abusive above. (This is why I enjoy math. There is only one correct answer or set of answers. It's the way my brain works. And it's made my life "complicated" to say the least.) {O.O}
On 20210705 12:02:37, Bob Dengler wrote:
At 7/5/2021 09:37 AM, you wrote:Bob, Is this Continuum mode? I would need an exact specification were I to add this.Not sure if I understand the question. I'm referring to the channel power or S-meter, which if I understand correctly current indicates peak channel power. It would be nice to have the option to have it read average channel power, then also have the ability to store those readings to a CSV file (2 columns: time & dBm) every x milliseconds. This is exactly what HDSDR offers. Once calibrated with a known noise source or hot/cold load, this allows using an SDR as a radiometer. Also give us one or two significant digits after the dBm decimal point. I'll put the above in the SDRC Requests forum if needed. Thanks! Bob NO6B
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Re: SNR meter, bandwidth and gain adjustment for transverters
Mark Cayton
Joanne,
I didn't "go off the cliff" anywhere. 1) "So if you have a signal that features multiple peaks all about the same amplitude how big is the S-Meter error?" What "error" are you referring to?? There is no "error". In the case you describe (with multiple equal peaks), the S-meter should read the same regardless of whether there are one or a thousand peaks. As I've stated unwaveringly, the S-meter should report the highest value detected anywhere in the passband, no more and no less. What part of that rule is not clear to you? It's clear to me by your very question that you don't have the slightest grasp on that simple rule. 2) "Take an NFM signal modulated by a sine wave. Run up the modulation from zero until there are three spikes showing within the NFM bandwidth that are all the same level. What is the correct measurement? One of the peaks or the proper sum of all three?" What is this "proper sum of all three" value you mention??? Be specific. Your prized "sum" value remains undefined. 3) "Now continue running up the amplitude of modulation into the BFM realms with the signal spread out over 200 kHz bandwidth. What is the correct S-Meter reading?" What is even the point of that question? The S-meter couldn't (and shouldn't) care less about bandwidth. 4) "Does that reading change when the announcer pauses for breath? Should it?" The simple answer is "no", at least not for a transmission with a steady FM carrier, given that by definition the modulation on any FM signal should never exceed the strength of the carrier. Once again - the S-meter should only report the strongest signal measured anywhere in the passband. For an FM (or AM) signal, the strongest signal will always be the carrier. You're asking me these questions, but you (or anyone else) can easily see the answers to every one of those questions by simply opening a session of SDRC and click on any BCFM or BCAM station. If the carrier is steady then the S-meter reading will also be steady, regardless of the amount of modulation and regardless of bandwidth. If anyone has gone off a cliff, it certainly isn't me! Mark
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Re: SNR meter, bandwidth and gain adjustment for transverters
jdow
On 20210705 10:43:26, oldjackbob@... wrote:
On Mon, Jul 5, 2021 at 09:26 AM, Bob Dengler wrote: The total power in a given bandwidth cannot be properly derived from a spectrum display. It can be derived easily from a filter followed by demodulator design. You take the I and Q values, square them, and sum them. That gives you the power in arbitrary units that can be calibrated easily. That is the total, or if you want to be obscure "integrated", power within the receiver's bandwidth. It is also the power as used in an AGC system if it really keeps loudness more or less constant. Picking a single spectrum element can mess AGC systems, too. The function of an S-meter is not to report the "total power" or "average power" or "integrated power" in the passband, it is to report the highest voltage measured anywhere in the passband, irrespective of any nebulous "total power" contained within the filter. That's what Simon's S-meter does. Whereinell do you get that notion? It has NO compatibility with how well you are receiving a signal, the Eb/N0 reading. Per the definition established in IARU Region 1 Technical Recommendation R.1, "the metering system shall be based on quasi-peak detection". Notice the reference to "peak detection". There is no "average power" mentioned anywhere in the definition. A correctly designed S-meter by definition reports only the peak signal strength detected, nothing more and nothing less. They are speaking time domain. You are speaking frequency domain. They are not the same thing. As Simon has stated long ago, if anyone wants anything else reported (such as a "total power") he would be glad to look into that, as a separate meter. But his S-meter has always been in strict compliance with the published definition. He is not compliant with that IARU definition. He has something sort of useful. It is NOT compliant. Mark {^_^}
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Re: 3D waterfall
jdow
Probably they do match in terms of power per pixel.
The number of pixels wide makes a difference in levels.
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{o.o}
On 20210705 09:15:00, Bart AA7VA wrote:
I find it interesting, and played with it for awhile. Wasn't sure where in the band, or band width, was showing, but comparisons with the waterfall soon rectified that.
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Re: 3D waterfall OT
jdow
I wish you had not mentioned that. I had to go
looking. And unfortunately what has been seen cannot be unseen.
AAAAAAIIIIIIIEEEEEEEEEE! My eyes my eyes they burn.
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{+_+}
On 20210705 09:01:10, Gisle Vanem
wrote:
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Re: 3D waterfall OT
jdow
Minimizing does not do what should be done.
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{o.o}
On 20210705 08:49:23, David J Taylor
via groups.io wrote:
On 05/07/2021 16:37, Gisle Vanem wrote:
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Re: SNR meter, bandwidth and gain adjustment for transverters
jdow
So if you have a signal that features multiple peaks
all about the same amplitude how big is the S-Meter error? Take an
NFM signal modulated by a sine wave. Run up the modulation from
zero until there are three spikes showing within the NFM bandwidth
that are all the same level. What is the correct measurement? One
of the peaks or the proper sum of all three? Now continue running
up the amplitude of modulation into the BFM realms with the signal
spread out over 200 kHz bandwidth. What is the correct S-Meter
reading? Does that reading change when the announcer pauses for
breath? Should it? Mark, I think you went off the cliff on that
one.
toggle quoted messageShow quoted text
{^_^}
On 20210705 07:43:04,
oldjackbob@... wrote:
Per the info on Simon's page explaining the operation of the S-meter, "[The signal level] is the peak spectrum FFT bin (output value) which is within the current filter."
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Re: SNR meter, bandwidth and gain adjustment for transverters
Conrad, PA5Y
I did not see this post before. What Ingolf describes is exactly what is needed, and I am sure would attract many new users. I am just building a microwave EME system(4.5m solid dish) and I would be delighted to have such a useful feature.
Regards
Conrad PA5Y
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
On Behalf Of sm6fhz via groups.io
Sent: 05 July 2021 21:27 To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters
Hi.
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Re: SNR meter, bandwidth and gain adjustment for transverters
Conrad, PA5Y
Simon continuum mode is very useful for sun noise measurements or sun>cold sky for the EME boys. However, it is comparative, it does not need to be calibrated. It merely plots received power over time. It would be a very welcome addition indeed. It would of course be great if it could be calibrated as well. But for EME the relative measurements between cold sky and any celestial source can be used for Y factor calculations. This can then be used to see if any improvements are truly effective. Also good for checking that all is still working as expected.
toggle quoted messageShow quoted text
Regards Conrad PA5Y
-----Original Message-----
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown via groups.io Sent: 05 July 2021 18:37 To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters Bob, Is this Continuum mode? I would need an exact specification were I to add this. Simon Brown, G4ELI https://www.sdr-radio.com -----Original Message----- From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Bob Dengler Sent: 05 July 2021 17:26 To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters At 7/5/2021 07:43 AM, you wrote: Per the info on Simon's page explaining the operation of the S-meter,signal level] is the peak spectrum FFT bin (output value) which is within the current filter."That page is found here:Â <https://www.sdr-radio.com/s-meter>https://www.sdr-radio.com/s-meterSimon explains it clearly. There is no correlation of peak FFT bin value to filter bandwidth (or AGC level, or any other consideration), nor should there be. Any modern SDR-based S-meter that changes its reading based on filter bandwidth is doing it wrong.I've said it before: Simon got it right, many others are getting it wrong.Mark I strongly disagree. How else is one supposed to make total channel power measurements for radiometry? SDRs aren't just for communications, & any developer that codes their SDR apps otherwise is hamstringing their full potential. Right now the only apps I know of that can do this are HDSDR & SDRuno. HDSDR is compatible with all my SDRs so that covers my needs, but it would be nice if SDRC could display & record average channel power readings as well as HDSDR is fairly useless for NBFM monitoring (no de-emphasis). I'll have to go through the forum archives to see if this has been requested, & do so if not. Bob NO6B -- - + - + - Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.
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Re: 3D waterfall OT
jdow
No, you aren't the only one. As I see it the ribbon
is a triumph of wasted screen space dedicated to cute rather than
function.
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{o.o}
On 20210705 06:50:26, ronwhat wrote:
Jdow, am I the only one who prefers the old menu system rather than the MS Ribbon? In Word or Excel, I knew where to find any menu item I used…it was always there. Then came the Ribbon, with no option to choose it or the old menu bar. Now it is often a real effort to find which ribbon I need to go to in order to access an item that I don’t use regularly. I think the ribbon function should include option for old style menu listing of all commands, gray out any that are not valid at the point in the program.
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Re: 3D waterfall
jdow
I am thinking of other things like the matrix
display, various data displays, and so forth.
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{o.o}
On 20210705 04:50:45, Jos Stevens
wrote:
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Re: SNR meter, bandwidth and gain adjustment for transverters
Conrad, PA5Y
Well I disagree, SNR improves as you reduce bandwidth, this is just physics. If the metering does not reflect this then the SNR metering is simply wrong. Just use your ears.
Conrad
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
On Behalf Of oldjackbob via groups.io
Sent: 05 July 2021 16:43 To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] SNR meter, bandwidth and gain adjustment for transverters
Per the info on Simon's page explaining the operation of the S-meter, "[The signal level] is the peak spectrum FFT bin (output value) which is within the current filter."
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Re: 3D waterfall
Conrad, PA5Y
Tha’ what? Nowt up wit Yorkshire accent, it wor designed t keeyup sutheners guessin.
Ok looks worse when you write it down.
Regards
Conrad PA5Y(orkshire)
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
On Behalf Of jdow via groups.io
Sent: 05 July 2021 12:34 To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] 3D waterfall
Yorkshire, Yorky(?), accent gets me. "What did he say?" On 20210705 03:29:37, Simon Brown wrote:
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Re: 3D waterfall
Conrad, PA5Y
There was a recent FW update for the FTDX-10 I understand. I have some TX composite noise measurements from Rob Sherwood and it looks very clean, no sure if it is public domain but I am sure if you asked him he would provide it. It is good.
Regards
Conrad PA5Y
From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
On Behalf Of Simon Brown via groups.io
Sent: 05 July 2021 06:16 To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] 3D waterfall
Ah,
Shame – the FTDX-10 has a different PA module to the FTDX-101, I was hoping it would be clean ☹ .
Simon Brown, G4ELI
From:
main@SDR-Radio.groups.io <main@SDR-Radio.groups.io>
On Behalf Of Kriss Kliegle KA1GJU
I just wish operators of FTDX10's could learn how NOT to QRM the band!
- + - + - Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.
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Re: SNR meter, bandwidth and gain adjustment for transverters
Bob Dengler
At 7/5/2021 12:06 PM, you wrote:
Please define 'average channel power'.See SM6FHZ Ingolf's message a few minutes after mine; for quick reference here is the posting: <<https://sdr-radio.groups.io/g/main/message/23048>https://sdr-radio.groups.io/g/main/message/23048>. I think he is asking for a little more than I am but my request is basically the same: recording average channel power over time. By "average channel power" I mean the amount of power a calorimetric power meter would record if the channel power were to be fed to one. There is the issue of integration time: I'd say the average power read by such a power meter over that integration time is what we're looking for. Bob NO6B
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Re: SNR meter, bandwidth and gain adjustment for transverters
sm6fhz
Hi.
I made a request for this (Continuum mode) in 2014 together with a basic specification of possible functions. It can be found here: https://sdr-radio.groups.io/g/main/message/23048 I hope it can make a baseline fore further development of a in dept specification. 73 / Ingolf, SM6FHZ
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