CHU is a HF time signal station operated by the National Research Council of Canada. It operates 24/7 and announces the hour and minute each minute of every day on frequencies 3,330, 7,850 and 14,670 KHz. This is the Canadian counter part to WWV and WWVH. In the strictest sense of the term, it is a broadcasting station, although many would also classify it as an HF utility station as well. Many countries had HF time signal radio stations at one time, but there are fewer now. Back in the day before GPS, these time signals were critically important to anyone needing coordinated event timing. We used the carrier frequency from WWVH as our frequency standard for test equipment. WWV and WWVH also transmitted a very accurate 1 KHz tone for the same purpose. According to the CHU web site:
Normally CHU’s emission times are accurate to 10-4 s, with carrier frequency accuracy of 5×10-12, compared to NRC’s primary clocks, which are usually within 10 microseconds and 1×10-13 compared to UTC.
Additionally, every minute between 31 and 39 seconds, CHU broadcasts FSK time code with a Bell 103 standard (2225 Hz mark, 2025 Hz space) at 300 bits/second (IRIG time code). This could be used as a backup for GPS time clocks on automation systems, if GPS were to fail for some reason. One would have to write a little software program to decode the hex output and reset the computer clock once per minute accordingly. That should not be too hard. LINUX information and software can be found here. More on CHU time code here.
In my location 3,330 KHz is audible 24/7. That signal is transmitted with a carrier power of 3 KW into a non-directional vertical dipole antenna as is 14,670 KHz. The 7,850 KHz signal is transmitted with a carrier power of 10 KW into the same type antenna.
There is some discussion of adding an additional time station transmitter in western Canada and of changing the modulation from AM to DRM or at least adding some type of DRM service.
Or rather occupied bandwidth. During a recent Alternative Inspection of an FM station, there was some question as to the accuracy of the modulation monitor. Truth be told, a modulation monitor is no longer required at a radio station, so long as the station ensures that they comply with relevant FCC regulations for their service. Many modulation monitors continue on, however, as air monitor receivers.
That is all well and good, however, many modulation monitors are notoriously inaccurate and tend to the overly sensitive side of the equation. If used when setting the modulation levels, this can lead to under modulation, which, as we all know leads to disaster, destruction and bad ratings…. Because the volume knob on every radio in the entire metro, Total Survey Area (TSA), or even the whole country has been broken off and listeners are unable to compensate for the low audio levels from an under modulated FM transmitter.
FCC 73.1560 gives the maximum FM deviation as +/- 75 KHz from the carrier, with some allowance for SCA injection levels, up to +/- 78 KHz. This is the definition of 100 percent modulation of an FM carrier. Thus the entire occupied bandwidth is 150 KHz, leaving a guard band of 50 KHz between signals. That is, unless IBOC is employed, then the guard band is -100 KHz which is good science no matter how one looks at it. On a spectrum analyzer, it looks something like this:
This shows that the 5 second average occupied bandwidth of 90 percent of the transmitted energy is within 153 KHz, which is slightly high but within the margin of error of the measurement device. The vertical lines represent the -10 dB signal level as referenced to the carrier. Thus this station is in compliance with FCC rules regarding modulation in spite of the face that the analog modulation monitor shows it being 10-20 percent over. Had it actually been 110 percent, the occupied bandwidth would have been 165 KHz and 120 percent would have read 180 KHz.
Thus, before buying the latest squash-o-matic FM processor and setting it for full tilt boogy, a good engineer may want to check the occupied bandwidth with something other than the old analog FM modulation monitor in the rack.
I enjoy listening to radio, however, there seems to be a dearth of good programming on the conventional frequencies. Somehow, personality-less robo programmed hit music and right wing talk radio just doesn’t seem to cut it anymore. Thus, I have taken to listening to the shortwaves. Truth be told, the availability of good programming is dwindling there as well, but good things can still be found. Here is my list of interesting and or entertaining programs found on the shortwave:
Radio Australia International – 9580 KHz mornings from 6-9am EST (11-1400 UTC). There are a variety of good programs on this station including Asia-Pacific, Saturday Night Country and others. Good to listen to with my morning cup of coffee.
WBCQ – Several good selections here including Alan Weiner World Wide (Fridays 8-9pm), World of Radio (Glen Hauser, Thursdays 5:30-6pm), Marion’s Attic (Sunday 5-6pm), Le Show (Harry Shearer, Sundays 7-8pm) Amos n’ Andy (Tuesdays 5-5:30pm). New 41 Meter Frequency 7490 KHz is clearer than previous frequency. 5110 KHz is hit or miss in this location, however Area 51 is worth a listen (Saturdays and Sundays 7-11pm) if reception is good. Check their schedule on line as program time change.
WWCR – 12160 KHz 12-3pm EST (17-2000 UTC) Alex Jones, entertaining if not a bit over the top, tends to rant, makes some good points when calm. Other programs like World Wide Country Radio, The Pat Boone Show, etc are available at various times on various frequencies.
CBC North – 9625 KHz Continuous Sackville feed of CBC Radio One, mostly in English, occasionally in Inuktitut or French. Good for news from the Great White up.
CFRX – 6070 KHz shortwave feed of News/Talk CFRB Toronto. Conservative news talk programming Canadian style, some good trivia games and whatnot.
WEWN – 15610 KHz Catholic Mass (8-9am Sundays) although lately they have been re-runs, which is goddamned annoying.
There are others from overseas, but many of the English broadcasting services are being scaled back or eliminated. A few broadcasts that one is sure to come across when tuning around; The Voice of Russia (bland, predicable, promos sound like they are recorded in the bathroom), Radio Romania (meh), China Radio International (100% propaganda), Radio Havana, Cuba (campy, mildly entertaining in an absurd way), etc.
Pirate Shortwave broadcasters roam around in the 6890-6970 KHz range. They are irregular in schedule, low power and often contain an obscure dialog or some selection of 80’s hair band music. Still, if one has some time, they can be entertaining too.
A good source of information on shortwave broadcasts is Short-wave.info which has a pretty accurate searchable database and a great feature called “Find out what stations are broadcasting on a frequency of (fill in frequency) Now.” That is very helpful for figuring out what a station is without waiting for station ID or if broadcasting in another language.
With winter coming and the sun spot cycle on the upswing, the HF bands should be open for business.