OK so it's not the microsecond or nanosecond stuff that much of this list
is about, but I've been running an experiment for the past few days
gathering data on how well (or otherwise) a pair of cheap EM2S radio
receiver modules receive the MSF radio signal. I've been trying to see if I
could design
Hi Deirdre,
I'd like to repeat your measurement at a different location (eastern
england).
What did you use to capture the data and write it as a vcd file ?
-adrian
On Tue, Feb 6, 2018 at 6:40 PM, Deirdre O'Byrne
wrote:
> OK so it's not the microsecond or nanosecond stuff that much of this l
In message
, "Deirdre O'Byrne" writes:
>I've been trying to see if I could design a decoding algorithm that
>would be more noise-tolerant than the algorithms I've seen out in
>the wild.
You can: I baptised it "the blame algoritm".
The trick is not to try to accept pulses as valid but t
On Tue, Feb 6, 2018 at 2:37 PM, Poul-Henning Kamp wrote:
> If you look in http://phk.freebsd.dk/phkrel/NTPns.20080902.tgz
> you will find a file called dcf77_blame.c with my code,
> here is a couple of the simpler tests:
>
> /* LSB of minutes must be different from previous minute */
>
I used this cheap (but good for the price!) signal analyser -
http://www.ebay.ie/itm/Hobby-Components-UK-USB-24M-8CH-24MHz-Logic-Analyser/161309221423?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
I used sigrok to do the recording -
https://www.sigrok.org/
Let me know if you collec
rnabioul...@gmail.com said:
> How difficult would it be to complete these modules and integrate them with
> the rest of NTP, as NTP decoder modules? So instead of an AM HF receiver,
> the setup for these signals would be:
The simple way to do that is to use the shared-memory interface. No chan
In message
, Ruslan Nabioullin writes:
>On Tue, Feb 6, 2018 at 2:37 PM, Poul-Henning Kamp wrote:
>> If you look in http://phk.freebsd.dk/phkrel/NTPns.20080902.tgz
>> you will find a file called dcf77_blame.c with my code,
>How difficult would it be to complete these modules and integra
That's the next level of error detection. Unfortunately I notice with MSF
and these cheap receivers it can be difficult to determine what the binary
values being transmitted during the second were, which was my motivation
for the analysis I did.
I notice that there is one significant difference be
Hi
If you want to get even more “nutty", look at the “seed” that you likely
already have
for the computation. In this day and age, you probably know what day / month /
year it is.
Since you might not (say) know the hour, you have a +/- 1 day sort of tolerance
on that. It rolls
into month and
In message
, "Deirdre
O'Byrne" writes:
>With a blame algorithm in place it should be possible to recover these signals.
Yes, easily.
At distance MSF is significantly harder to receive than DCF77.
One of the reasons is that USA also operates two 60kHz transmitters
also very precisely
In message , Bob kb8tq writes:
>If you want to get even more “nutty", look at the “seed” that you likely
>already have
>for the computation. In this day and age, you probably know what day / month /
>year it is.
So, some of us think of that as cheating :-)
>Since you might not (say)
Deirdre,
Great discussion on my favorite topic. I am the guy on the other side of
the lake that curses MSFs interference with WWVB.
I did indeed cheat by using the GPS time and 1 second tick to recreate the
WWVB timecode bits to remove the psk shifts in the received signal here on
the east coast. T
Hi
> On Feb 6, 2018, at 4:19 PM, Poul-Henning Kamp wrote:
>
>
> In message
> ,
> "Deirdre O'Byrne" writes:
>
>> With a blame algorithm in place it should be possible to recover these
>> signals.
>
> Yes, easily.
>
> At distance MSF is significantly harder to receive than DCF77.
>
> Since MSF *is* on 60 KHz, you do indeed get dead spots.
If the two signals are not encoded identically, there should be an
interesting signal when one of the transmitters is off and the other is on.
Has anybody looked for that sort of pattern?
Is there a map of the dead spots? Any time-nuts
Hi
If you look at the papers for the “new” WWVB format, there are plots of where
the
MSF issues are likely to be the greatest. Since both signals are phase and
amplitude
shifted by propagation effects, you will not get stationary nulls. You simply
get zones
where the reception is tough.
Bob
In message <20180206225742.67030406...@ip-64-139-1-69.sjc.megapath.net>, Hal
Murray writes:
>> Since MSF *is* on 60 KHz, you do indeed get dead spots.
>
>If the two signals are not encoded identically, there should be an
>interesting signal when one of the transmitters is off and the oth
Tom,
Thanks for the feedback!
On 6 February 2018 at 20:29, Tom Van Baak wrote:
>
> 2) Not all decoding errors are equal. Since this is a time code instead of
> arbitrary binary data you can use the internal structure of the data to
> your benefit.
>
As I said to Poul-Henning, that is the next
deirdre@gmail.com said:
> MSF disciplined oscillator?! I don't trust these receivers to any better
> than about the 20ms mark, so such a disciplined oscillator would have quite
> a long integration time!
It would be interesting to see if you can find any pattern in your histogram
plots. Sa
Hi
> On Feb 6, 2018, at 3:48 PM, Deirdre O'Byrne wrote:
>
> Tom,
>
> Thanks for the feedback!
>
> On 6 February 2018 at 20:29, Tom Van Baak wrote:
>
>>
>> 2) Not all decoding errors are equal. Since this is a time code instead of
>> arbitrary binary data you can use the internal structure o
>
>
> Did MSF finally go to a BPSK signal format? I heard they were considering
> that.
>
I don't know, though I've ordered a SDR which should be able to receive the
raw signal. I don't see anything about it in the documentation, though.
Regards,
Deirdre.
_
>
>
> Splitting the MSF received signal into 100ms chunks, all of the seconds
> apart from the start-of-minute marker are of the form 0AB1. Using "x"
> to represent a 100ms chunk whose value could not be determined, I notice
> that many of the received seconds were of the form "0AB1x111" or "0A
In message
, "Deirdre
O'Byrne" writes:
>MSF disciplined oscillator?! I don't trust these receivers to any better
>than about the 20ms mark, so such a disciplined oscillator would have quite
>a long integration time!
It's actually more complicated and better than that.
The low-pass fil
Hi
Back in the era of VLF disciplined oscillators, carrier phase was the preferred
approach.
Getting that to work with 100% AM modulation took some effort ….
Bob
> On Feb 7, 2018, at 2:13 AM, Poul-Henning Kamp wrote:
>
>
> In message
> ,
> "Deirdre O'Byrne" writes:
>
>> MSF disci
No doubt! But I'm trying to remain as inexpensive as possible.
That it might be possie to get 5ms (300 carrier periods!) from an
off-the-shelf consumer-grade component not designed for accuracy is pretty
cool IMO.
On 7 Feb 2018 14:31, "Bob kb8tq" wrote:
Hi
Back in the era of VLF disciplined o
In message
, "Deirdre
O'Byrne" writes:
>I've updated my paper, which now contains the attached graph. (I did a
>linear regression analysis to see what the correction for the receivers
>should be, and I applied receiver 2's correction to both receivers to
>generate this graph).
Yes, the
Challenge accepted.
This graph is probably not too useful, for the simple reason that when the
receiver is spitting out mostly noise, the averages are going to be
massively affected.
[image: Inline images 1]
On 7 February 2018 at 01:03, Hal Murray wrote:
>
> deirdre@gmail.com said:
> > MSF
> Hal Murray wrote:
> If the two signals are not encoded identically, there should be an
> interesting signal when one of the transmitters is off and the other is on.
> Has anybody looked for that sort of pattern?
> Is there a map of the dead spots? Any time-nuts live in/near one?
Yes. Here
On 07/02/18 01:16, Bob kb8tq wrote:
>> MSF disciplined oscillator?! I don't trust these receivers to any better
>> than about the 20ms mark, so such a disciplined oscillator would have quite
>> a long integration time!
>
> Once upon a time, that *was* how people did disciplined oscillators. Part o
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