Date   

Re: Future version 1.27 of the "World Map" #future

Brian Morrison
 

On Wed, 11 May 2022 22:15:50 -0700
"Radioman ZeroZero" <radioman@...> wrote:

A pc clock cannot maintain time accurately.  It is all very well
setting a very accurate time but after half an hour it will have
drifted.
If you're running something like Fedora Linux then you can use chronyd
to supervise the system clocks, it's far better than ntpd on its own.

There are also packages like oscillatord which can discipline PC clocks
from a 1pps GPSDO signal.

I'm not sure what amateur radio part of the hobby requires a
super accurate time.
Accuracy is addictive, once you have it you can find things to do with it ;-)

--

Brian G8SEZ


Re: Future version 1.27 of the "World Map" #future

Brent Seres/ VE3CUS
 

I use NTP on my PC to sync with CHU or WWV and it works well

 Brent 
VE3CUS





-------- Original message --------
From: jdow <jdow@...>
Date: 2022-05-12 07:27 (GMT-05:00)
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Future version 1.27 of the "World Map" #future

On 20220512 02:14:17, David J Taylor via groups.io wrote:
On 12/05/2022 06:15, Radioman ZeroZero wrote:
A pc clock cannot maintain time accurately.  It is all very well setting a very
accurate time but after half an hour it will have drifted.  I'm not sure what
amateur radio part of the hobby requires a super accurate time.
--
Thanks Steve M0ZEH

Steve,

Reference NTP software (but not all so-called "atomic clock" programs) does not
only set the time initially, but it also measures the drift rate and adjusts
the clock rate so that accurate time is maintained even with a drifting
undisciplined clock.

There's more here:  https://www.satsignal.eu/ntp/setup.html#why

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv

Technical extreme quibble:

In order to get approximately 1 kHz clocks a timer, not atypically running off a US TV receiver color subcarrier crystal, is divided by 3580. This obviously gives a frequency about 545 ppm off to which the clock's accuracy of maybe as bad as 100 ppm is added. The best you can do is dither this divider so that on the average you get 1 kHz with as many 0s after the decimal point as you wish. If the oscillator is perfectly on 5e6/88*63 Hz you can work out the dither pattern to give arbitrary accuracy from 3.57954545454545... MHz. In a simple case with an imprecise computer oscillator, if the clock alternates between 3580 and 3579 for the setting you move the accuracy down to about 46 ppm from the basic process and whatever the clock might be. If you compare with an external precision timer you can work out a dither pattern for the divisor that leads to greater long term accuracy. Unfortunately this sort of bassakwards approach is required because the timer clock has no software adjustment potential so you cannot slide the oscillator right in with a D/A converter feeding a VCXO input.


{^_-}  Did anybody manage to stay awake through that nonsense?


Re: Future version 1.27 of the "World Map" #future

jdow
 

On 20220512 02:14:17, David J Taylor via groups.io wrote:
On 12/05/2022 06:15, Radioman ZeroZero wrote:
A pc clock cannot maintain time accurately.  It is all very well setting a very
accurate time but after half an hour it will have drifted.  I'm not sure what
amateur radio part of the hobby requires a super accurate time.
--
Thanks Steve M0ZEH

Steve,

Reference NTP software (but not all so-called "atomic clock" programs) does not
only set the time initially, but it also measures the drift rate and adjusts
the clock rate so that accurate time is maintained even with a drifting
undisciplined clock.

There's more here:  https://www.satsignal.eu/ntp/setup.html#why

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv

Technical extreme quibble:

In order to get approximately 1 kHz clocks a timer, not atypically running off a US TV receiver color subcarrier crystal, is divided by 3580. This obviously gives a frequency about 545 ppm off to which the clock's accuracy of maybe as bad as 100 ppm is added. The best you can do is dither this divider so that on the average you get 1 kHz with as many 0s after the decimal point as you wish. If the oscillator is perfectly on 5e6/88*63 Hz you can work out the dither pattern to give arbitrary accuracy from 3.57954545454545... MHz. In a simple case with an imprecise computer oscillator, if the clock alternates between 3580 and 3579 for the setting you move the accuracy down to about 46 ppm from the basic process and whatever the clock might be. If you compare with an external precision timer you can work out a dither pattern for the divisor that leads to greater long term accuracy. Unfortunately this sort of bassakwards approach is required because the timer clock has no software adjustment potential so you cannot slide the oscillator right in with a D/A converter feeding a VCXO input.


{^_-}  Did anybody manage to stay awake through that nonsense?


Re: Future version 1.27 of the "World Map" #future

David J Taylor
 

On 12/05/2022 06:15, Radioman ZeroZero wrote:
A pc clock cannot maintain time accurately.  It is all very well setting a very
accurate time but after half an hour it will have drifted.  I'm not sure what
amateur radio part of the hobby requires a super accurate time.
--
Thanks Steve M0ZEH
Steve,

Reference NTP software (but not all so-called "atomic clock" programs) does not
only set the time initially, but it also measures the drift rate and adjusts
the clock rate so that accurate time is maintained even with a drifting
undisciplined clock.

There's more here: https://www.satsignal.eu/ntp/setup.html#why

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv


Re: Future version 1.27 of the "World Map" #future

jdow
 

On 20220511 23:56:07, Alan G4ZFQ wrote:
On 12/05/2022 05:15, Radioman ZeroZero wrote:
not sure what amateur radio part of the hobby requires a super accurate time.

Steve,

Super accurate, not many. http://www.dxatlas.com/faros/ is one that measures propagation delay, it actually contains it's own NTP clock.
The Kiwi radio network uses GPS PPS to use TOA station location.

Meinberg as mentioned is one that sets PC time and maintains it  to within miliseconds.

73 Alan G4ZFQ

I've run across a reference of an ntp server that maintains time by fiddling with the counter settings. If you have a 3.57954545454 MHz timer oscillator (5e6/88*63) then it fiddles the time keeping divider up and down from 3579 to account for the fractional part and apply further correction so that long term timing is in the microsecond range if you can supply it with an accurate time tick. The pro radio astronomers use an even fancier setup to make precision time using motherboards that reference time to 100 MHz or higher oscillators in the PCs. (I wonder how many replace the timer oscillator with a TCVCXO and lock the loop. I bet the VLB array uses this sort of technique.)

PCs have a lot more potential than most people realize, especially for a hardware hacker.

{^_^}


Re: Future version 1.27 of the "World Map" #future

jdow
 

As long as the temperature is fairly stable a PC can do remarkably with a normal NTP installation. The Linux PC used as a router here maintains our ntp install and maintains time within +/- 30 ms across multiple time sources. At the moment it has chosen a GPS locked source and is within +/- 6 ms jitter on teh link and an offset of about 0.34 ms. It is +/- 8 ms across the 5 sites it monitors. Modulo your definition of accurately that's surprisingly good considering it does not vary all that much. It applies corrections to the PC's timers so that they tick off accurate 1ms ticks with jitter in the sub-microsecond range that is intentionally used to keep the clock accurate.

On my Windows PC I am running an old ntp tool that does not touch the timers and instead jam sets 1ms plus, zero, or minus corrections as needed once a minute. (This PC's clock is pretty pathetic, too.) I should probably get a proper ntp for the machine. I believe NIST has one.


{^_^}

On 20220511 22:15:50, Radioman ZeroZero wrote:

A pc clock cannot maintain time accurately.  It is all very well setting a very accurate time but after half an hour it will have drifted.  I'm not sure what amateur radio part of the hobby requires a super accurate time.
--
Thanks Steve M0ZEH


Re: Future version 1.27 of the "World Map" #future

Alan G4ZFQ
 

On 12/05/2022 05:15, Radioman ZeroZero wrote:
not sure what amateur radio part of the hobby requires a super accurate time.
Steve,

Super accurate, not many. http://www.dxatlas.com/faros/ is one that measures propagation delay, it actually contains it's own NTP clock.
The Kiwi radio network uses GPS PPS to use TOA station location.

Meinberg as mentioned is one that sets PC time and maintains it to within miliseconds.

73 Alan G4ZFQ


Re: Future version 1.27 of the "World Map" #future

Charles Suckling
 

Steve

Depends what you mean by 'super accurate'. 

WSJT-X  (and clones) need time to be accurate  to within a second or two.  Most stations using this use Meinberg or similar to keep PC clocks on time, or if internet is not available they use  GPS derived time. 

73

Charlie DL3WDG

On Thu, 12 May 2022 at 07:15, Radioman ZeroZero <radioman@...> wrote:
A pc clock cannot maintain time accurately.  It is all very well setting a very accurate time but after half an hour it will have drifted.  I'm not sure what amateur radio part of the hobby requires a super accurate time.
--
Thanks Steve M0ZEH


Re: Future version 1.27 of the "World Map" #future

Simon Brown
 

Very accurate clocks are available for PCs.

 

You may be surprised how much ‘ham’ software is used by the military, I’ll say no more in this respect for obvious reasons.

 

Timestamping packets is a good example of the use of an accurate clock, see this project https://blog.adafruit.com/2021/09/08/time-card-an-open-source-pcie-gnssatomic-time-reference/ which I’ve been following.

 

Simon Brown

https://www.g4eli.com

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Radioman ZeroZero
Sent: 12 May 2022 06:16
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Future version 1.27 of the "World Map" #future

 

A pc clock cannot maintain time accurately.  It is all very well setting a very accurate time but after half an hour it will have drifted.  I'm not sure what amateur radio part of the hobby requires a super accurate time.
--
Thanks Steve M0ZEH


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Re: Future version 1.27 of the "World Map" #future

Radioman ZeroZero
 

A pc clock cannot maintain time accurately.  It is all very well setting a very accurate time but after half an hour it will have drifted.  I'm not sure what amateur radio part of the hobby requires a super accurate time.
--
Thanks Steve M0ZEH


Re: Future version 1.27 of the "World Map" #future

Simon Brown
 

Thanks,

 

This does save me time – were I to have found the time in the first place.

 

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Frank
Sent: 11 May 2022 19:58
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Future version 1.27 of the "World Map" #future

 

Hi

as info and save a few lines of code for Simon.... and free time for dog walking.... ;-) ;-)

 

I always use with USB GPS on the /P location and laptop PC without internet the BktTimeSync PC APP by IZ2BKT.

It works perfectly and directly adjusts the clock and the whole PC with the GPS data on the COM.

It goes either with GPS with internet or/and COM or USB socket.

 

Never had a TimeSync problem except that since my USB GPS is ten years old, it is not as sensitive if inside home, compared to my cell phone which receives all satellites even in the basement!

 

Perhaps it would be more interesting to be able to use cell phone GPS in some way, to be paired with the PC, but I wouldn't know how...


73


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Re: World Map - Rotator COM Ports

 

Sorry, being busy all the day long.

It is a Idiom Press RotorCard, DCU protocol.

On 2022-05-11 05:18, Simon Brown wrote:

What is the rotator controller you’re talking to?

 

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Max Mucci, N5NHJ via groups.io
Sent: 11 May 2022 01:33
To: main@SDR-Radio.groups.io; SDR-Radio@groups.io
Subject: Re: [SDR-Radio] World Map - Rotator COM Ports

 

Logs attached.

 

On 2022-05-10 19:20, Max Mucci, N5NHJ via groups.io wrote:

I'll check it out tonight. I'll also update the VSPE installation (first..) just in case.

Thanks!

73, Max

On 2022-05-10 19:15, Simon Brown wrote:

So,

 

For those who had a problem, please try: https://1drv.ms/u/s!AovWaZDu7HrdgYBDVujIHq2ooWHKKg?e=7AMYA4

 

Simon Brown

https://www.g4eli.com

https://www.sdr-radio.com

 


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-- 73 de Max, N5NHJ (I8NHJ) one of EL2PP, 1A0KM, JT1Y, E30GA, T77V, TT8MM, T32R, K5K, XR0X, S05X, 4O3T, BS7H, K4M, PJ7E, PJ7DX, 6Y1V, C6ANA, VP5/I8NHJ, ZF2NH, KP4/N5NHJ and...

-- 73 de Max, N5NHJ (I8NHJ) one of EL2PP, 1A0KM, JT1Y, E30GA, T77V, TT8MM, T32R, K5K, XR0X, S05X, 4O3T, BS7H, K4M, PJ7E, PJ7DX, 6Y1V, C6ANA, VP5/I8NHJ, ZF2NH, KP4/N5NHJ and...

-- 73 de Max, N5NHJ (I8NHJ) one of EL2PP, 1A0KM, JT1Y, E30GA, T77V, TT8MM, T32R, K5K, XR0X, S05X, 4O3T, BS7H, K4M, PJ7E, PJ7DX, 6Y1V, C6ANA, VP5/I8NHJ, ZF2NH, KP4/N5NHJ and...


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-- 73 de Max, N5NHJ (I8NHJ) one of EL2PP, 1A0KM, JT1Y, E30GA, T77V, TT8MM, T32R, K5K, XR0X, S05X, 4O3T, BS7H, K4M, PJ7E, PJ7DX, 6Y1V, C6ANA, VP5/I8NHJ, ZF2NH, KP4/N5NHJ and...


Re: Future version 1.27 of the "World Map" #future

jdow
 

On 20220511 11:57:46, Frank wrote:
Hi
as info and save a few lines of code for Simon.... and free time for dog walking.... ;-) ;-)
 
I always use with USB GPS on the /P location and laptop PC without internet the BktTimeSync PC APP by IZ2BKT.
It works perfectly and directly adjusts the clock and the whole PC with the GPS data on the COM.

It goes either with GPS with internet or/and COM or USB socket.

 
Never had a TimeSync problem except that since my USB GPS is ten years old, it is not as sensitive if inside home, compared to my cell phone which receives all satellites even in the basement!
 
Perhaps it would be more interesting to be able to use cell phone GPS in some way, to be paired with the PC, but I wouldn't know how...

73

Modulo required accuracy this may be good or bad. Cogitate a little while on the effects of multipath on GPS accuracy, especially when you only get the signal via a bounce path. (If you are interested in nanoseconds.)


{o.o}


Re: Future version 1.27 of the "World Map" #future

jdow
 

Well, for most uses add about 3 or 4 ms to the time mark data read and average out a 7 ms peak to peak jitter and it should be modestly accurate maybe down to usual ntp accuracy.


{^_^}

On 20220511 07:14:51, Simon Brown wrote:

I doubt it, it’s a USB device.

 

NMEA data is generated every second, but this can’t be used as PPS.

 

Simon Brown

https://www.g4eli.com

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Dirk
Sent: 11 May 2022 12:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Future version 1.27 of the "World Map" #future

 

jdow,
does the GPS receiver from Amazon really have a PPS output, that I could use without destroying the receiver?


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Re: Future version 1.27 of the "World Map" #future

jdow
 

Dunno - read the data on the site. That's all I know. Although I bought one for "old times sake" given that I know what the Phase 2B satellite looks like close up and its Delta launch pad (thanks to Hal Greenlee). I may know more before long.

{^_^}

On 20220511 04:57:00, Dirk wrote:

jdow,
does the GPS receiver from Amazon really have a PPS output, that I could use without destroying the receiver?


Re: Future version 1.27 of the "World Map" #future

EA7HGL
 

Greetings Simon and fellow members.
Thank you for including this function, I currently use the CLOCK program from F6CTE, and at the beginning of operating in digital I synchronize the clock with the GPS in the port (USB-Serial).
In relation to the precision, well ................... enough to not have problems with the FT8 for example.
If we want to go more than that precision, it is fine as an exercise and with the desire to reach the best accuracy, although my recommendation was born from reading that future version 1.2.7 and I thought it was a detail that would make the software even more pleasant so kindly provided by Simon.
Very grateful to both Simon and all of you for making this hobby a step beyond the commercial.
Greetings.

Antonio D. (EA7HGL).

P.D: Excuse my bad english.


Re: Future version 1.27 of the "World Map" #future

Frank
 

Hi
as info and save a few lines of code for Simon.... and free time for dog walking.... ;-) ;-)
 
I always use with USB GPS on the /P location and laptop PC without internet the BktTimeSync PC APP by IZ2BKT.
It works perfectly and directly adjusts the clock and the whole PC with the GPS data on the COM.

It goes either with GPS with internet or/and COM or USB socket.

 
Never had a TimeSync problem except that since my USB GPS is ten years old, it is not as sensitive if inside home, compared to my cell phone which receives all satellites even in the basement!
 
Perhaps it would be more interesting to be able to use cell phone GPS in some way, to be paired with the PC, but I wouldn't know how...

73


Re: Future version 1.27 of the "World Map" #future

David J Taylor
 

On 11/05/2022 12:33, jdow wrote:
The performance counter has been available for a very long time.
GetSystemTimePreciseAsFileTime() is an added function that means you do not
have to invent your own. Remember that this only reads the time when you call
the function. This may be several ms from when the data came in on an io port
buffer. There are no free lunches, unfortunately.

{^_^}
Yes, and the delay is usually much more predictable on Linux systems than on
Windows. The performance counter doesn't give time of day, of course, but can
be useful for approximate interval measurements.

PTP can overcome these limitations, at the expense of dedicated network devices.

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv


Re: Future version 1.27 of the "World Map" #future

David J Taylor
 

On 11/05/2022 10:43, Simon Brown wrote:
With these NMEA devices the resolution comes from the chipset. As below, the time is 09h37m52s, the milliseconds value is always returned as zero. Not all NMEA sentences are returned by every device, mine doesn’t return the timestamps.
They are easy to read – just open the COM port and read the text.
$GPGLL,5006.3037,N,00507.6798,W,*093752.000*,A,A*47
$GPGLL,5006.3035,N,00507.6796,W,*093753.000*,A,A*4A
$GPGLL,5006.3032,N,00507.6792,W,*093754.000*,A,A*4E
Simon Brown
https://www.g4eli.com <http://www.g4eli.com/>__
https://www.sdr-radio.com <https://www.sdr-radio.com/>
It's worse than that - the delay between the UTC second edge and the NMEA output can (and does) vary according to the length of the sentence and the amount of processing required inside the GPS device. Where possible, I recommend using the highest baud rate and the minimum number of sentences. $GPRMC is usually enough - it include time, date and location.

On battery operated devices I tend to select all GNSS constellations (GPS, GLONASS and Galileo) even though it may use more battery. With a limited view, it increases the number of satellites which may be visible.

73,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-taylor@...
Twitter: @gm8arv


Re: Future version 1.27 of the "World Map" #future

Simon Brown
 

I doubt it, it’s a USB device.

 

NMEA data is generated every second, but this can’t be used as PPS.

 

Simon Brown

https://www.g4eli.com

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Dirk
Sent: 11 May 2022 12:57
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Future version 1.27 of the "World Map" #future

 

jdow,
does the GPS receiver from Amazon really have a PPS output, that I could use without destroying the receiver?


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