[ntp:questions] CHU/IRIG audio drivers.2 / VOACAP / HFCC & ITU
mikehack at u.washington.edu
Mon Feb 5 04:27:26 UTC 2007
Why WWV and WWVH, as well as CHU don't have animated VOACAP charts on their
websites showing expected coverage patterns is a mystery to me.
> You bring up VOACAP, which is specific to antenna configuration at both
> the transmitter and receiver, as well as the 10-cm flux, which at this
> time of the sunspot cycle is miserably low.
To the best of my knowledge, utility broadcasters as well as international
broadcasters can use CIRAF Zones for planning and to resolve interefernce
issues. The HFCC uses CIRAF Zones extensivly for planning, albeit not all
broadcasters post proper CIRAF Zone data.
Sadly, neither the NIST nor the NRC are members of HFCC.
CHU / WWV / WWVH should be listed in the HFCC database.
Broadcasters eating away at Fixed Services is not entirly HFCC's fault --
they only coordinate 80% of the HF broadcast spectrum and users.
> You mention CIRAF zones, which is ironic since CHU 7335 is presently
> victim of IHFB broadcasters in Central America. The broadjammers have
> essentially chewed up all the spectrum from 7100-8100 in ITU Regions 1 and
> 3 (Europe and Asia) and 7300-8100 in Region 2 (North and South America).
> The band 7350-8100 was once allocated to the Fixed Service, but as a
> practical matter the band has been heavily infested with broadcasters even
> before reallocation.
This crowding has to be a European problem, as I have never noticed many out
of band users in the Western Americas.
The FCC ISM band issue aside -- Canada must set aside the US allocations,
and the US must set aside the Canadian allocations ... with respect to the
time and frequency service stations.
> The band 8100-9040 belongs to the Maritime Mobile and Aeronautical Mobile
> Services. The next slot above that is 9040-9400 allocated to the Fixed
> Service. Broadcasters have poached there as well. In any case, that's
> probably too high for the current 7335 users. There is a small slice
> 6765-7000 allocated to the Fixed Service worldwide but the FCC considers
> it an ISM band. It's unknown how Canada allocates it, but do we want CHU
> in an ISM band? There's nowhere to hide.
Technically, I suppose as long as your destination reciver in an HF telecom
link is in or near water -- you can send encrypted RTTY aka SITOR etc.
> A very solid case can be made for the Maritime Mobile users to give up
> some spectrum. Once upon a time Morse telegraphy was the medium of choice,
> but most maritime coast stations have abandoned that mode and rely either
> on Marisat or SITOR, which is much more spectrum efficient and the
> operators don't need Morse training. Using an archaic ITU footnote, the
> maritime coast frequencies are often poached by US military stations using
> encrypted teletype. An especially egregious case even now is the poaching
> of the WWV protected band at 5 MHz by broadcasters that camp on the edges
> of the protected band and splatter sidebands over the WWV signal. Is there
> no shame?
The story behind the story must be an interesting one...
> I once complained to the FCC Maryland monitoring station about
> interference on the 60-kHz WWVB signal. They and the Maine monitoring
> station triangulated to a location in Quebec. They told me they had no
> jurisdiction and directed me to the State Department. So, adjacent channel
> splatter on 5 MHz coming from Costa Rica? Gimme a break.
Joining the HFCC would be enough, at least it would have RCI to help make
> In principle, CHU could join the IHFB consortium and fight VOACAP wars
> with the other broadcasters for frequencies, with a gentleman's agreement
> to protect the 7335 frequency. Problem is at night the adjacent channel
> splatter takes out CHU now.
Yes, but this is an MW and LW issue -- it does not really affect HF users.
WWVB is an LF service, Loran at 100 khz qualifies as longwave ... only just.
> As for western Canada, I hear you. You propose a system similar to how
> European countries manage their national mediumwave/longwave networks.
> They heat up a national loudenboomer on a protected longwave frequency
> near the center of the country (Radio Luxembourg come to mind?) and spot
> several lower power, mediumwave transmitters to fill in the outskirts of
> the coverage area. The problem is, even if the outskirt transmitters are
> synchronized by one means or another, coverage at places nearly
> equidistant from two or more transmitters is very problematic.
The CHU / WWV / WWVH signal formats are very similar.
However, with no hardware base to disenfranchize -- CHU signal innovation is
Canada is considering HD Radio -- however, HD Radio may not support NTP
packets -- or quality time signals of any kind.
DRM-FM may support NTP, but that has yet to happen.
The only way an IRIG subcarrier system would work would be to have the
university or NPR radio station offer the service in conjunction with the EE
& Physics Departments. Most university stations can't even provide proper
RDS time signals. There is no designated RDS helper packet to allow for
automatic IRIG reciver setup.
Even "world class" universities like MIT probably could not maintain a
proper IRIG subcarrier service in Boston -- for various internal and
> CHU has another problem. Unlike WWV and WWVH that were designed to coexist
> on the same frequencies, the CHU signal design of not conducive to
> cochannel frequency sharing. It might be simpler to retail CHU modulation
> via VHF FM broadcast subcarrier in selected metropolitan areas, like the
> BBC does in Singapore. Using the NTP audio drivers, and inexpensive FM
> subcarrier demodulators, no special purpose equipment would be needed.
In Canadian history, minority goverments often get more done than majority
However, I have yet to see the new PM (1yr anniversary) do anything about
RCI's massive multi-decade underfunding catastrophy.
http://cbc.am/rci.htm (a hellishly long read, but educational)
> Obviously there must be a lots of noise going on in Canadian politics on
> this issue, since the problem must certainly have been anticipated on at
> least the last two WARCs, but only announced recently in public. Western
> Canada is about as far from Ottawa as Eastern US is from Fort Collins, so
> the propagation conditions should be about the same. There will be no joy
> in the high latitudes of Canada and Alaska due geomagnetic unrest, so HF
> service might not be an option anyway.
Sadly, neither WinRadio nor most DRM recivers have software code that can
decode CHU or WWV -- useing the same RF sampling techniques and FFTs that
decode the DRM signal.
> The precision time and time interval (PTTI) folks have toys far better
> than anything that can be done at HF. CHU has expensive, redundant and
> precise timecode generators and transmitters that can deliver time
> accurate to 0.1 ms, as claimed on the CHU web. The NTP audio driver can
> deliver that level of performanc, even if the fractious ionosphere wanders
> up and down some 0.3 ms or more.
More people would be customers of HF services if the signal quality were to
DRM on HF helps a lot, but in the rest of the HF bands it is better to have
geographically distributed transmitters and better frequency coordination.
Sadly, you have probably found all of the CHU support software.
> There is a fundamental problem which is often overlooked. Who are the true
> customers of the HF services? The CHU web site mentions the NTP audio
> driver, but does not mention CHU receivers that might be available from
> other sources. I can't find any commercial purpose-built CHU receivers,
> but Google came up with another CHU audio decoder
> http://www.rossi.com/chu/ similar to the NTP audio driver, but designed to
> operate standalone. Are they the only CHU sources?
The re-licenceing of CHU will probably happen.
CHU being forced to move would be a mess -- it took me writing the CHU
proposal to memorize 2 of the 3 frequencies.
That 14mhz one still illudes me...
In spite of most of the text and images in my proposal, CHU-West using a
frequency that is +/- 5 khz (or more) from CHU's primary allocation is fine
My other work: http://cbc.am/radio.htm
> The easiest option would be to re-license as a broadcaster and try to hold
> on to 7335. Next best, move 7335 just below 7000 might be the easiest
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