Norm Frequency beacon ?

Norm Frequency beacon ?

[Günther Montag]

Hello friends

does someone know, is there something lik a beacon on the air on shortwave or 
medium wave, ham or radio band, which sends a known fixed exact frequency 
tone in AM, e.g. 1000 Hz or other, for calibration?`
Something like DCF77 on longwave?

We have a real-time pactor program which needs an exact frequency for 
calibration, and not everyone has an DCF77 receiver.

tnx!
-- 
73 de
Günther
dl4mge@darc.de
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Re: Norm Frequency beacon ?

[Matti Aarnio]

On Thu, May 27, 2004 at 01:30:25PM +0200, Günther Montag  wrote:
> Hello friends
> 
> does someone know, is there something lik a beacon on the air
> on shortwave or medium wave, ham or radio band, which sends
> a known fixed exact frequency tone in AM, e.g. 1000 Hz or other,
> for calibration?  Something like DCF77 on longwave?
> 
> We have a real-time pactor program which needs an exact frequency for 
> calibration, and not everyone has an DCF77 receiver.

Dear OM,

I would use GPS disciplined OCXO myself for that.
There have been numerous articles about that in QST, for example.
They are more complex than DCF77 rx, but also versatile, and work
in places where DCF77 doesn't reach -- and as a bonus, you can
get accurate timing well down to microsecond from a commercial
GPS with PPS output.  Adding OCXO disciplining is another story,
of course.

The NCDXF beacon network runs with GPS synced timing, but not with
GPS disciplined frequency, I think.  Those beacons exist all over
the world and frequencies, though.

Alternate methods include asking your local TV network about how
they generate and distribute their TV signals.

In Finland we used to have (during analog link era) a highly accurate
15625 Hz line frequency in TV2 network picture.  Now that they distribute
the signal via digital networks (uncompressed, though) there is noticeably
larger jitter in that timing parameter, and it will end altogether, when
the analog TV system will get decomissioned in a few years time from now.

One possibility might be DVB-T symbol rate clock, which derives itself
from SDH transmission hierarchy master clocks.  But a receiver to extract
that is (if possible) even more complex than GPS-OCXO.   The DVB-T, and
DAB do include a possibility to send the same signal at the same frequency
from multiple transmitters, and a stationary receiver will pick it up just
fine  (mobile receiver is a bit more challenged, though..)


> tnx!
> -- 
> 73 de
> Günther
> dl4mge@darc.de

73 de Matti, OH2MQK 
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Re: Norm Frequency beacon ?

[Thomas Sailer]

On Thu, 2004-05-27 at 14:53, Matti Aarnio wrote:

> I would use GPS disciplined OCXO myself for that.

The program in question derives its timing from the sample clock of the
soundcard, but this frequency must be calibrated against a precise clock
source with a known frequency.

Currently supported methods are:

- The german timecode transmitter DCF77 on 77.5kHz
- TV horizontal synch frequency (which happens to lie in a frequency
  range soundcards can digitize)

I didn't implement any GPS based method because at the time I did this
GPS receivers were still quite uncommon (im my household at least :))

The difficulty with the PPS signal is that not every GPS receiver has it
and it requires some additional hardware to get into the PC. The
simplest method would be to wire it to the parallel port, but
unfortunately "real" parports are disappearing quickly.

NMEA perhaps? Given a long enough calibration period this might well be
precise enough... Does anyone know the timing of the NMEA output? Is it
aligned to the PPS?

> One possibility might be DVB-T symbol rate clock, which derives itself

Too complex FWIW, IMO.

Tom

Re: Norm Frequency beacon ?

[Matti Aarnio]

On Thu, May 27, 2004 at 07:56:40PM +0200, Thomas Sailer wrote:
> On Thu, 2004-05-27 at 14:53, Matti Aarnio wrote:
> > I would use GPS disciplined OCXO myself for that.
> 
> The program in question derives its timing from the sample clock of the
> soundcard, but this frequency must be calibrated against a precise clock
> source with a known frequency.

Yea right...   KISS, and all that.
(I have played with ideas of software defined radio receiver,
 where I digitize IF at around 100 MHz, and preprocess it thru
 decimation hardware at first..  Cheap it ain't, and definitely
 not built-into the PC...  lattest Linux Journal had a story of
 this same theme.)

> Currently supported methods are:
> 
> - The german timecode transmitter DCF77 on 77.5kHz
> - TV horizontal synch frequency (which happens to lie in a frequency
>   range soundcards can digitize)
> 
> I didn't implement any GPS based method because at the time I did this
> GPS receivers were still quite uncommon (im my household at least :))
> 
> The difficulty with the PPS signal is that not every GPS receiver
> has it and it requires some additional hardware to get into the PC.
> The simplest method would be to wire it to the parallel port, but
> unfortunately "real" parports are disappearing quickly.
> 
> NMEA perhaps? Given a long enough calibration period this might well be
> precise enough... Does anyone know the timing of the NMEA output? Is it
> aligned to the PPS?

Cheapest "mouse GPSes" (under 100eur) are now interfaced with USB1.1.
In the days of the serial port the time value output in GGA, GLL, or RMC
was the end of the NMEA line terminating LF character.
With USB this becomes somewhat more fuzzy, and the PPS signal
is not available at all (thru USB, that is.)

Inside the "mouse" there is possibly separate chip to do USB interfacing,
and it talks thru serial line to the GPS.  Possibly...
(I didn't find any GPS receiver that actually itself has USB in chip,
thus I believe it is a case of GPS + USB-serial-port chip.)

> Tom

73 de Matti, OH2MQK

Re: Norm Frequency beacon ?

[Günther Montag]

Thank you all for the interesting suggestions and 
discussion!
Thanks especially to you, Tom, the father of this program!
Will have to think about it and test all the ideas...

-- 
73 de
Günther
dl4mge@darc.de
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BBS Software

[Dave Stubbs]

Hello all,

Would it spark a zealous flame war if I was to ask what is the most 
feature-rich and most popular Packet BBS software out there?  I'm 
looking to offer a full email and news gateway to my club via packet.

Looking forward to your responses,

Dave.
VA3BHF

Re: BBS Software

[Bill Vodall]

> Would it spark a zealous flame war

One could only wish...   Too many folks have turned off packet...

> if I was to ask what is the most
> feature-rich and most popular Packet BBS software out there?  I'm
> looking to offer a full email and news gateway to my club via packet.

Email and News -- you don't need a BBS.  Just hook up a Linux box
with the AX25 system and get it on the air.  Add the UroNode or equivalent
as a friendly user interface and you're in business.

I'm currently using JNOS on Linux as a gateway between Internet Email and
packet mailbox messaging.   The idea is to be able to send an Email note to
ab1xyz@ampr2.net
have have it automatically delievered to ab1xyz's personal TNC mailbox.
There
are probably other tools that will do the Internet to/from Packet gatewaying
but
I'm familar with JNOS and, best of all, the source is available.

HTH.

73,
Bill - WA7NWP

Re: BBS Software

[Dave Stubbs]

Bill Vodall wrote:

> Hi Dave,
> 
> 
>>I was looking at the Linux version of JNOS recently, I compiled and ran 
>>it on a Linux system that already had 3 ethernet interfaces with full 
>>TCP/IP, AX.25, and NET/ROM running in the Linux kernel.  JNOS didn't see 
>>any of these interfaces, so I'm assuming it has it's own network stack 
>>that is different from the OS one?
> 
> 
> Yes.  Think of JNOS as a virtual machine.   It's almost totally separate for the Linux
> box.   You connect the JNOS system to the Linux box with a slip link over
> a pseudo tty using net2kiss and slattach.   A google on those terms should give you
> the necessary incancation -- if not I can forward the relevant parts from my setup.
> 
> 

Ah!

Well, at least that makes sense then, and my conclusions were pretty 
accurate.

My take on the whole situation is that the JNOS on Linux is great for a 
person who used JNOS for many years back in the DOS days and learned it 
well.  I have a suspicion that, for someone like myself who is a new ham 
but who has used Linux daily ever since 1993, I might just be better off 
sticking with the Linux Kernel AX.25 stuff.  It probably offers 
comparable functionality to JNOS, but is much more familiar because it 
is from "my world".

73
Dave
VA3BHF

Re: BBS Software

[Robin Gilks]

> Bill Vodall wrote:
>
>> Hi Dave,
>>
>>
>>>I was looking at the Linux version of JNOS recently, I compiled and ran
>>>it on a Linux system that already had 3 ethernet interfaces with full
>>>TCP/IP, AX.25, and NET/ROM running in the Linux kernel.  JNOS didn't see
>>>any of these interfaces, so I'm assuming it has it's own network stack
>>>that is different from the OS one?
>>
>>
>> Yes.  Think of JNOS as a virtual machine.   It's almost totally separate
>> for the Linux
>> box.   You connect the JNOS system to the Linux box with a slip link
>> over
>> a pseudo tty using net2kiss and slattach.   A google on those terms
>> should give you
>> the necessary incancation -- if not I can forward the relevant parts
>> from my setup.
>>
>>
>
> Ah!
>
> Well, at least that makes sense then, and my conclusions were pretty
> accurate.
>
> My take on the whole situation is that the JNOS on Linux is great for a
> person who used JNOS for many years back in the DOS days and learned it
> well.  I have a suspicion that, for someone like myself who is a new ham
> but who has used Linux daily ever since 1993, I might just be better off
> sticking with the Linux Kernel AX.25 stuff.  It probably offers
> comparable functionality to JNOS, but is much more familiar because it
> is from "my world".

If you are looking for a Kernel solution but want a BBS style interface,
take a look at the Morelia BBS on the Thames Valley IP User Group website
(check the projects link at http://www.tvipug.org). This is written in
python and interfaces to your local news and mail servers and provides via
the kernel AX25 an interface that would be familiar to a *NOS user all the
BBS and node facilities.


-- 
Robin Gilks zl3rob/g8ecj
Internet: g8ecj@gilks.org    http://www.gilks.org

Re: Norm Frequency beacon ?

[Tapio Sokura]

Thomas Sailer wrote:
> The difficulty with the PPS signal is that not every GPS receiver has it
> and it requires some additional hardware to get into the PC. The
> simplest method would be to wire it to the parallel port, but
> unfortunately "real" parports are disappearing quickly.

I'd say most (at least a large part) PCs can read the PPS signal fine 
via a direct connection to serial port DCD line, for example. PPS 
outputs are often TTL, but still work with most PC serial ports. Of 
course this does not help much if you don't have the PPS output on the GPS.

> NMEA perhaps? Given a long enough calibration period this might well be
> precise enough... Does anyone know the timing of the NMEA output? Is it
> aligned to the PPS?

It depends on the GPS, I don't think there is an official standard or 
practice. I'd guess at least the PPS-equipped timing receivers handle 
NMEA in a predefined way to be able to stay on the right second.

   Tapio

Re: Norm Frequency beacon ?

[Dennis Boone]

 > does someone know, is there something lik a beacon on the air on
 > shortw ave or medium wave, ham or radio band, which sends a known fixed
 > exact frequen cy tone in AM, e.g. 1000 Hz or other, for calibration?`
 > Something like DCF77 on longwave?

You might see if you can receive the Canadian or US time and frequency
standards stations, CHU and WWV, in your location:

http://inms-ienm.nrc-cnrc.gc.ca/time_services/shortwave_broadcasts_e.html
http://www.boulder.nist.gov/timefreq/stations/wwv.html

Dennis Boone
KB8ZQZ

Re: Norm Frequency beacon ?

[Ralf Baechle DL5RB]

On Thu, May 27, 2004 at 01:30:25PM +0200, G?nther Montag  wrote:

> does someone know, is there something lik a beacon on the air on shortwave or 
> medium wave, ham or radio band, which sends a known fixed exact frequency 
> tone in AM, e.g. 1000 Hz or other, for calibration?`
> Something like DCF77 on longwave?
> 
> We have a real-time pactor program which needs an exact frequency for 
> calibration, and not everyone has an DCF77 receiver.

A few shortwave stations among them DW have a reputation for a highly
accurate carrier frequency.  There are also the usual time stations such
as WWV on shortwave.  Within Germany ZDF's signal makes a good timebase;
a few years ago description how to build a highly accurate frequency
normal based on this signal have been published.

73 de DL5RB op Ralf

--
Loc. JN47BS / CQ 14 / ITU 28 / DOK A21

Re: Norm Frequency beacon ?

[John Magliacane]

For what it's worth, I'm currently working on a WWVB disciplined
oscillator that generates accurate signals down to 1 kHz and below.
The main oscillator is a VCTCXO operating at 10 MHz.  I believe the
design can also be made to work with other time/frequency standard
stations operating on either 60 or 40 kHz.

The receiver functions essentially as a PLL.  I'm experimenting
with the loop filter at the present time.

After it's complete, I'll try to write something up about it.


73, de John, KD2BD


=====
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	http://www.qsl.net/kd2bd/


	
		
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Re: Norm Frequency beacon ?

[Dave Platt]

> NMEA perhaps? Given a long enough calibration period this might well be
> precise enough... Does anyone know the timing of the NMEA output? Is it
> aligned to the PPS?

That seems to depend on the GPS receiver in question.  As far as I can
tell, there's no requirement that it be well-synchronized, and on one
simple GPS board I bought a few years ago there's no dependable
synchronization.

Re: Norm Frequency beacon ?

[John Coppens]

On 27 May 2004 18:10:10 -0000
"Dave Platt" <dplatt@radagast.org> wrote:

> > NMEA perhaps? Given a long enough calibration period this might well
> > be precise enough... Does anyone know the timing of the NMEA output?
> > Is it aligned to the PPS?
> 
> That seems to depend on the GPS receiver in question.  As far as I can
> tell, there's no requirement that it be well-synchronized, and on one
> simple GPS board I bought a few years ago there's no dependable
> synchronization.

Surely not... I have used GPS for experiments with G3PLX's chirp project
and finally gave up trying to get the NMEA output reliably related to the
PPS pulses. Your luck may vary, mine was a Trimble GPS. I understand the
PPS is hardware generated, and the NMEA depends on the algorithms.

You may have much better results with the TSIP protocol, which can be sent
much more frequently (times/sec). I understand that the relationship
TSIP/PPS is more reliable too. I thought that this protocol was
Trimble-only, but I've read somewhere other manufacturers also support it.

I finally identify the PPS pulse using the PC's clock - which is sync'd to
the internet using the 'chronyd' daemon.

John