HEY, CHINA!
Well, well, things are coming to a head. Canada and China are engaged in a diplomatic squabble, and China's true colours are showing. China has been dismissive of Canada, suggesting that such a pipsqueak little country should just keep its mouth shut.
I think it's just about time somebody grabbed a switch and took China out behind the shed. I can think of about 35,000,000 people who are perfect for the job.
(That's the approximate population of Canada.)
And I know how to do it.
China, for all its hideous, almost-uncountable human-rights abuses, its crushing yoke of communism, is rewarded for bad behaviour by way doing huge amounts of business with Canada. As a result, an inordinate amount of the things we purchase in the course of a year has been made in China. What's more, most of the raw materials in the products originated --wait for it--in Canada!
What if we all, collectively said, "Enough is enough" and simply stopped buying chinese crap. No more tissue-thin tee-shirts, or pants with tiny pockets, that don't zip up correctly; no more iPhones (look it up!); no more little piles of junk from the dollar store; no more piles of shoes for midgets.
I think it's time for Canada to look to stop doing business with China. China has proven itself unable to participate on the world stage as an adult; therefore, it needs to be spanked.
Henceforth, I'm going to be checking the labels on everything I buy. If it's made in China--if there's any possibility it was made in China--it's going back onto the shelf. I will buy no Chinese-made electronics, clothing, foodstuffs. I won't see their travelling exhibits or cultural shows. In short: I am going to minimize the amount of business done with China on my behalf.
My new mantra: no more chinese crap!
If enough Canadians stuck by this policy, there would be rapid changes. Dollarama, for example, would have to scramble to replace almost every product on its shelves. Wal-Mart would founder. Our retail landscape would be in for some reconfiguration; but that's not a bad thing.
There are other consequences. China's purchasing of raw materials would somewhat slow down; wouldn't it be wonderful if Canadians suppliers to China began to say, "Sorry, can't help you." We could bring China to its knees in about six months.
China can be dismissive of Canada, but at its own peril. If you look at the percentage of global trade Canada does with China, it's easy to see that the removal of that trade would cause a recession in China. It's easy to see that our trade cannot simply be replaced on the chinese side of the equation; far easier on the Canadian side.
As for Canada? I don't think it would be that bad. It would be a boon for Canadian manufacturers (if there's a demand for something, someone will make it--and incidentally need raw materials)--and the loss of jobs in retail chains that failed to adapt would be made up for by increases in employment among chains that did.
China is a huge consumer of Canadian raw materials, and a huge supplier of cheap crap, highly dependent upon overseas trade. Let's start using that leverage.
-Bill
Friday, 18 January 2019
Friday, 11 January 2019
TELESCOPES
An Introduction
If you're involved in amateur astronomy for any amount of time, you'll start getting interested in a telescope.
These days, there are a number of different types, along with different mounts. We'll explore each of these.
Refractors
Refractors are the oldest type of telescope. They feature a primary, or objective, lens up front, and an eyepiece at the viewing end. You can kit it out with numerous accessories (image erectors, right-angle viewers, finderscopes), but the main design of big lens, little lens, and a shape similar to a baseball bat, usually are the giveaways.
Reflectors
Reflecting telescopes have been around for hundreds of years, in various sub-types. Generally, a reflector can be recognized through its usually more-squat shape, and often the placement of the eyepieces.
Newtonian Reflectors
This sort of telescope, invented by Sir Isaac Newton, features a primary mirror at the end of a long tube. The mirror reflects light back up towards a small secondary mirror, canted at a 45-degree angle, and out the side of the telescope. You can usually spot a Newtonian telescope by the placement of the eyepiece; if they're near the front, it's probably a Newtonian.
Cassegrain Reflectors
This sort of telescope, often referred to as a Catadioptric Telescope, features a mirror mounted flush; the light is bounced off the parabolic primary mirror, up to the secondary mirror, and back down and out through a hole in the primary mirror.
Schmidt-Cassegrain Reflectors
These are similar to cassegrains, except that a correcting 'lens' up front combats spherical aberration. The primary mirror may also be spherical.
Maksutov Reflectors
These are similar to Schmidt-Cassegrains, but the nature of the correcting lens is a little different. Adherents swear by it.
MOUNTS
The telescope mount is just as important as the type of telescope. Again, there are several mount types:
Alt-Azimuth
This is a simple up/down, left/right kind of mount. It's usually the cheapest, and with the advent of computer-controlled mounts, they are much more useful.
Equatorial
This is a more-complicated version, best described as an Alt-Az mount which itself is mounted on a wedge that corresponds to the local latitude. This has the effect of 'tilting' the mount to match the sky; circles in the azimuth will correspond to latitude circles in the sky. This type of mount is unwieldy on larger telescopes.
Dobsonian
This is an exceedingly simple type of mount, usually applied to reflectors more than refractors. Basically, it two arms which come up from a circular, rotating base; each 'arm' cradles a short arm extending from the telescope. This allows the telescope to be moved in altitude and azimuth, manually. Some have turned their 'Dobs' into de-facto equatorial mounts by putting them on a wedge (and taking great care to balance the instrument).
Most people cut their teeth on something like a 60-mm refractor, often on an alt-az mount. I have one of those. I also have one on an equatorial mount; and a four-inch reflector on what I can only describe as a 'bowl-mount'.
If I can offer one piece of advice: don't buy your first telescope at a camera shop or department store. Those tend to be underpowered, overpriced, and on cheap, rickety alt-az mounts. Take some time to peruse Internet ads for telescopes and mounts; it'll give you a feel for the prices of various types of instruments, plus a decent mount. Watch out for "200-power" and "400x" telescopes; generally, magnification that high is useless for astronomical viewing; and if that's what they're emphasizing, you don't want their product.
Have fun! Till next time,
-Bill
An Introduction
If you're involved in amateur astronomy for any amount of time, you'll start getting interested in a telescope.
These days, there are a number of different types, along with different mounts. We'll explore each of these.
Refractors
Refractors are the oldest type of telescope. They feature a primary, or objective, lens up front, and an eyepiece at the viewing end. You can kit it out with numerous accessories (image erectors, right-angle viewers, finderscopes), but the main design of big lens, little lens, and a shape similar to a baseball bat, usually are the giveaways.
Reflectors
Reflecting telescopes have been around for hundreds of years, in various sub-types. Generally, a reflector can be recognized through its usually more-squat shape, and often the placement of the eyepieces.
Newtonian Reflectors
This sort of telescope, invented by Sir Isaac Newton, features a primary mirror at the end of a long tube. The mirror reflects light back up towards a small secondary mirror, canted at a 45-degree angle, and out the side of the telescope. You can usually spot a Newtonian telescope by the placement of the eyepiece; if they're near the front, it's probably a Newtonian.
Cassegrain Reflectors
This sort of telescope, often referred to as a Catadioptric Telescope, features a mirror mounted flush; the light is bounced off the parabolic primary mirror, up to the secondary mirror, and back down and out through a hole in the primary mirror.
Schmidt-Cassegrain Reflectors
These are similar to cassegrains, except that a correcting 'lens' up front combats spherical aberration. The primary mirror may also be spherical.
Maksutov Reflectors
These are similar to Schmidt-Cassegrains, but the nature of the correcting lens is a little different. Adherents swear by it.
MOUNTS
The telescope mount is just as important as the type of telescope. Again, there are several mount types:
Alt-Azimuth
This is a simple up/down, left/right kind of mount. It's usually the cheapest, and with the advent of computer-controlled mounts, they are much more useful.
Equatorial
This is a more-complicated version, best described as an Alt-Az mount which itself is mounted on a wedge that corresponds to the local latitude. This has the effect of 'tilting' the mount to match the sky; circles in the azimuth will correspond to latitude circles in the sky. This type of mount is unwieldy on larger telescopes.
Dobsonian
This is an exceedingly simple type of mount, usually applied to reflectors more than refractors. Basically, it two arms which come up from a circular, rotating base; each 'arm' cradles a short arm extending from the telescope. This allows the telescope to be moved in altitude and azimuth, manually. Some have turned their 'Dobs' into de-facto equatorial mounts by putting them on a wedge (and taking great care to balance the instrument).
Most people cut their teeth on something like a 60-mm refractor, often on an alt-az mount. I have one of those. I also have one on an equatorial mount; and a four-inch reflector on what I can only describe as a 'bowl-mount'.
If I can offer one piece of advice: don't buy your first telescope at a camera shop or department store. Those tend to be underpowered, overpriced, and on cheap, rickety alt-az mounts. Take some time to peruse Internet ads for telescopes and mounts; it'll give you a feel for the prices of various types of instruments, plus a decent mount. Watch out for "200-power" and "400x" telescopes; generally, magnification that high is useless for astronomical viewing; and if that's what they're emphasizing, you don't want their product.
Have fun! Till next time,
-Bill
Wednesday, 2 January 2019
A Tuned Three-Foot Cardboard-Box Loop Antenna
In advanced DX'ing, the user almost always turns, at some point, to a tuned loop antenna. Such an antenna vastly amplifies the incoming signal, and is fairly directional; moreover, it can be tuned for maximum performance.
Over the years, I've constructed a number of cardboard-box loops, and in doing so I've hit on some key construction techniques which can save you time.
This particular loop was constructed from four shipping boxes, each approximately 19" x 15"-- a fairly standard size. I've mounted them each on a 90-degree angle from the one before it, to make a strong core and a large box, approximately 34 inches on a side. Here are some pictures--you can see that I've bound the boxes together with duct tape.
As for the wiring, this, too, is easily accomplished. This procedure is for each corner, to make guide holes for your wires:
- first, measure in a fixed distance from the edge
- second, mark 15 ticks, spaced 5mm to 15mm (I used 10mm).
- now, using a paring or other small knife (in fact, a steak knife works quite well), cut an incision
at each tick mark; make it on a 45-degree angle and about 1 cm deep. Wiggle the knife slightly, to enlarge the hole.
Punch two holes near the first 'corner' you're about to wire. Punch two more near the final hole. You can see what I mean in the finished product:
Take about a foot of one end of your wire, and push it through and around so that it loops between the two holes and then enters the box. (You may have to lift a flap away for this.)
Now, counting from your first corner, wrap 13 turns of wire. Stick with the same hole at each corner, until you reach your starting corner; then move one hole in. Continue in this fashion, then loosely loop the wire through one hole and into the box.
Connect the two loose ends of wire. At this point, your loop should have some basic pickup. If it doesn't, try adding one turn to your wire.
Connect the ends of wire to a tuning capacitor. Try tuning around the band. Remember that for maximum performance, you'll have to re-tune the antenna at every stop.
I note that tuning capacitors are becoming a little scarce. I had the sense to buy up a few, surplus, some years ago; plus I've been cannibalizing old radios as they wear out.
When you are satisfied with the performance of your loop, fasten the far end of wire through the two holes, for a permanent fit.
Other improvements:
You can add some improvements to the loop. One, you'll probably be sitting it on the floor, so protect the underside of it from snagging and stretching. I've used several bands of duct tape, perpendicular to the wires. You might consider adding a cardboard bottom plate.
You can also mount the tuning capacitor, perhaps along the inner core of your loop.
Finally, one benefit: your receiver and even logsheet can rest comfortably on the inside shelf formed by a box. Quite handy--but remember it's in there before you go to move the loop!
Conclusions:
This sort of box design is big--you have no idea how big until you see it physically in front of you. It seems larger than an equivalent framed loop, but it occupies the same dimensions. It can be built in minutes, but is sturdy enough to last a few years. May it give you much entertainment.
-Bill
In advanced DX'ing, the user almost always turns, at some point, to a tuned loop antenna. Such an antenna vastly amplifies the incoming signal, and is fairly directional; moreover, it can be tuned for maximum performance.
Over the years, I've constructed a number of cardboard-box loops, and in doing so I've hit on some key construction techniques which can save you time.
This particular loop was constructed from four shipping boxes, each approximately 19" x 15"-- a fairly standard size. I've mounted them each on a 90-degree angle from the one before it, to make a strong core and a large box, approximately 34 inches on a side. Here are some pictures--you can see that I've bound the boxes together with duct tape.
As for the wiring, this, too, is easily accomplished. This procedure is for each corner, to make guide holes for your wires:
- first, measure in a fixed distance from the edge
- second, mark 15 ticks, spaced 5mm to 15mm (I used 10mm).
- now, using a paring or other small knife (in fact, a steak knife works quite well), cut an incision
at each tick mark; make it on a 45-degree angle and about 1 cm deep. Wiggle the knife slightly, to enlarge the hole.
Punch two holes near the first 'corner' you're about to wire. Punch two more near the final hole. You can see what I mean in the finished product:
Take about a foot of one end of your wire, and push it through and around so that it loops between the two holes and then enters the box. (You may have to lift a flap away for this.)
Now, counting from your first corner, wrap 13 turns of wire. Stick with the same hole at each corner, until you reach your starting corner; then move one hole in. Continue in this fashion, then loosely loop the wire through one hole and into the box.
Connect the two loose ends of wire. At this point, your loop should have some basic pickup. If it doesn't, try adding one turn to your wire.
Connect the ends of wire to a tuning capacitor. Try tuning around the band. Remember that for maximum performance, you'll have to re-tune the antenna at every stop.
I note that tuning capacitors are becoming a little scarce. I had the sense to buy up a few, surplus, some years ago; plus I've been cannibalizing old radios as they wear out.
When you are satisfied with the performance of your loop, fasten the far end of wire through the two holes, for a permanent fit.
Other improvements:
You can add some improvements to the loop. One, you'll probably be sitting it on the floor, so protect the underside of it from snagging and stretching. I've used several bands of duct tape, perpendicular to the wires. You might consider adding a cardboard bottom plate.
You can also mount the tuning capacitor, perhaps along the inner core of your loop.
Finally, one benefit: your receiver and even logsheet can rest comfortably on the inside shelf formed by a box. Quite handy--but remember it's in there before you go to move the loop!
Conclusions:
This sort of box design is big--you have no idea how big until you see it physically in front of you. It seems larger than an equivalent framed loop, but it occupies the same dimensions. It can be built in minutes, but is sturdy enough to last a few years. May it give you much entertainment.
-Bill
Tuesday, 1 January 2019
An Introduction to DX'ing
This week, just to be different, I'm going to introduce you to the hobby of DX'ing--receiving radio stations over long distances. It's a simple hobby, on the face of it; but it could get you into areas you may never touch otherwise, including radio propagation; antenna theory; geography; even cartography. Done regularly, it'll even sharpen your hearing.
Dx'ing is an extremely accessible hobby. All you need is an AM radio (other bands also work; but...), to start with. Digital is great; analogue will do. It's probably best to start in the evening, when there are plenty of stations all over the band.
A note on location: try to be away from televisions and computer equipment. They can be quite radio-noisy. Tablets and phones are also noisy, but only over a short range. Other appliances can cause radio noise, including chargers/AC adapters, blenders and popcorn makers, aquarium heaters, fluorescent tubes, and basically anything using a neon light (see aquarium heaters).
That said, fire up your receiver. I always suggest dropping to the low end of the band and working your way up from there.
Slowly tune your way from frequency to frequency. When you hear something, try orienting the radio for the strongest signal. Oftentimes, you can use this trick to favour one signal over the other. Listen carefully for local references, call letters, station nicknames or slogans--anything that will help you to identify the station. In the United States, callsigns start with 'W' or 'K'. In Canada, it's CB, and CF through CK. Mexican stations are assigned XE callsigns; and Cubans start with CM.
Frequently you will hear Spanish. Don't immediately assume that the station must be from Mexico; there are hundreds, if not thousands, of stations in the United States which broadcast in Spanish. If you hear French, chances are very good that it's from Quebec.
The type of programming will often help in identifying a station. For example, some stations broadcast music, of various genres; some are sports-oriented; some are news, talk or news/talk. Many are religious. You soon get an ear for what a particular format sounds like. In any language.
The Internet is an excellent resource for identifying the stations you hear. Station lists top the... list. One of the best lists out there, for my money, is something called MW List. They have listings for all regions worldwide, one page per frequency, and a fair bit of information on individual stations. During a DX'ing session, I'm constantly referring to it via tablet.
In North America, AM radio stations are 10 KHz apart; in Europe, the spacing is 9 KHz; and many other regions of the world have similar or identical schemes. There are always exceptions, of course.
If this activity catches on with you, you'll probably want to start keeping logs of what you've received. Generally speaking, most log sheets consist of a table, with columns for Date, Time, Frequency, Callsign, Location, Other Notes. When logging an unidentified station, I often include its approximate compass bearing. Many people prefer to do this on a spreadsheet, while many of us still prefer paper. It's totally up to you.
Speaking of station lists, you'll probably want to keep a list of the stations you've received. They tend to be a little more elaborate, as there are so many parameters to a station, which can be tracked. Location, latitude and longitude, daytime and nighttime power, schedule, format, network, etc.
Many DX'ers use a spreadsheet for this. You might be better off going with a program written specifically for this purpose. I can certainly recommend a product: StationBase, authored by me. It will be available in the very near future and is designed specifically for the needs of passive DX'ers (as opposed to active DX'ers--radio amateurs who seek to connect over long distances).
If you're still stuck on this hobby, you'll probably want to look into accessories and better equipment. Headphones are a good one, since DX'ing often occurs late at night, when other family members may be trying to sleep. A better receiver is always good; but the topic is so subjective that I can only advise you to do some research on the Internet. There are all types of receiver in all sorts of price ranges. Hang around the DX'ing message boards, and you'll soon learn which models are favoured by DX'ers. Personally, I swear by my old Realistic DX-200; my DX-440; and a Grundig Satellite Executive Edition, along with a three-foot box loop antenna.
You'll probably get interested in an external antenna at some point. Your basic options are a long-wire antenna, with fixed directionality; or a loop antenna, which can be steered and has quite sharp nulling (points where the signal is stronger or weaker). I'll be posting instructions soon for a strong loop made from cardboard boxes.
Some DX'ers go even more deeply into accessories, using such things as signal preamplifiers, audio filters, computer manipulation of the audio signal, etc.
If you DX over several nights, you'll notice that while the same stations tend to be audible all night, and from night to night, there are variations; and often a signal will pop up that doesn't belong in the usual mix. That's what we listen for. One some frequencies in the AM band, I've heard up to fifteen stations over a 30-year span.
You'll also begin to notice that some frequencies have more action than others. Powerful local stations, for example, may be all that you ever hear on their specific frequencies. You'll find that a number of frequencies are given over to 'clear-channel' stations, on which you can hear many of the major cities in North America.
Having been privileged enough to DX from the West Coast early in life, I found that there are a number of stations that can be heard from coast to coast, under the right conditions. I have about 25 stations that I've heard from both Sooke, and Ottawa.
Some of the more-prominent ones, going from memory, would be:
540 CBU, Vancouver; CBK, Saskatchewan
650 WSM, Nashville;
660 WOR, New York
710 WABC, New York
720 KDWN, Las Vegas;
740 Zoomer Radio, Toronto
760 WJR, Detroit
820 WBAP, Dallas-Ft. Worth
830 WCCO, Minneapolis
870 WWL, New Orleans
1040 WHO, Des Moines
1070 KNX, Los Angeles
1110 KFAB, Omaha
1120 KMOX, St. Louis
1140 WRVA, Richmond
1170 WWVA, Wheeling
In contrast, graveyard channels feature literally hundreds of stations, each with extremely low power, meaning at night those frequencies tend to be just a roar of noise. Some examples: 1230, 1240, 1340, 1400, 1450.
If you indulge in DX'ing over a period of some years, with relatively decent equipment, you will eventually amass thousands of loggings and hundreds to thousands of unique stations. If you live near a coast, you may also pick up trans-oceanic signals--Hawaii, Asia, Europe.
In the winter and spring months, and especially further north, you'll often experience DX during the daytime. It's not unusual to pick up Cincinnati or Boston from here in Ottawa, at midday. I had one day recently where a very specific region in upstate New York was open for about an hour. Needless to say, I took full advantage.
If you're interested in why signal propagation occurs in the AM band, look up the "Kenelly-Heaviside layer," and welcome to atmospheric dynamics.
Incidentally, all of this listening to the radio really sharpens your hearing. I can usually pick one conversation out of a jumble, and follow it, better than the people around me. It's a useful skill to have. It also helps with concentration.
I realize that this essay has only touched upon DX'ing as a legitimate hobby; but getting started literally is as easy as grabbing an AM radio and retiring to a quiet corner of the house. I encourage you to try it at least once in your lifetime.
-Bill
This week, just to be different, I'm going to introduce you to the hobby of DX'ing--receiving radio stations over long distances. It's a simple hobby, on the face of it; but it could get you into areas you may never touch otherwise, including radio propagation; antenna theory; geography; even cartography. Done regularly, it'll even sharpen your hearing.
Dx'ing is an extremely accessible hobby. All you need is an AM radio (other bands also work; but...), to start with. Digital is great; analogue will do. It's probably best to start in the evening, when there are plenty of stations all over the band.
A note on location: try to be away from televisions and computer equipment. They can be quite radio-noisy. Tablets and phones are also noisy, but only over a short range. Other appliances can cause radio noise, including chargers/AC adapters, blenders and popcorn makers, aquarium heaters, fluorescent tubes, and basically anything using a neon light (see aquarium heaters).
That said, fire up your receiver. I always suggest dropping to the low end of the band and working your way up from there.
Slowly tune your way from frequency to frequency. When you hear something, try orienting the radio for the strongest signal. Oftentimes, you can use this trick to favour one signal over the other. Listen carefully for local references, call letters, station nicknames or slogans--anything that will help you to identify the station. In the United States, callsigns start with 'W' or 'K'. In Canada, it's CB, and CF through CK. Mexican stations are assigned XE callsigns; and Cubans start with CM.
Frequently you will hear Spanish. Don't immediately assume that the station must be from Mexico; there are hundreds, if not thousands, of stations in the United States which broadcast in Spanish. If you hear French, chances are very good that it's from Quebec.
The type of programming will often help in identifying a station. For example, some stations broadcast music, of various genres; some are sports-oriented; some are news, talk or news/talk. Many are religious. You soon get an ear for what a particular format sounds like. In any language.
The Internet is an excellent resource for identifying the stations you hear. Station lists top the... list. One of the best lists out there, for my money, is something called MW List. They have listings for all regions worldwide, one page per frequency, and a fair bit of information on individual stations. During a DX'ing session, I'm constantly referring to it via tablet.
In North America, AM radio stations are 10 KHz apart; in Europe, the spacing is 9 KHz; and many other regions of the world have similar or identical schemes. There are always exceptions, of course.
If this activity catches on with you, you'll probably want to start keeping logs of what you've received. Generally speaking, most log sheets consist of a table, with columns for Date, Time, Frequency, Callsign, Location, Other Notes. When logging an unidentified station, I often include its approximate compass bearing. Many people prefer to do this on a spreadsheet, while many of us still prefer paper. It's totally up to you.
Speaking of station lists, you'll probably want to keep a list of the stations you've received. They tend to be a little more elaborate, as there are so many parameters to a station, which can be tracked. Location, latitude and longitude, daytime and nighttime power, schedule, format, network, etc.
Many DX'ers use a spreadsheet for this. You might be better off going with a program written specifically for this purpose. I can certainly recommend a product: StationBase, authored by me. It will be available in the very near future and is designed specifically for the needs of passive DX'ers (as opposed to active DX'ers--radio amateurs who seek to connect over long distances).
If you're still stuck on this hobby, you'll probably want to look into accessories and better equipment. Headphones are a good one, since DX'ing often occurs late at night, when other family members may be trying to sleep. A better receiver is always good; but the topic is so subjective that I can only advise you to do some research on the Internet. There are all types of receiver in all sorts of price ranges. Hang around the DX'ing message boards, and you'll soon learn which models are favoured by DX'ers. Personally, I swear by my old Realistic DX-200; my DX-440; and a Grundig Satellite Executive Edition, along with a three-foot box loop antenna.
You'll probably get interested in an external antenna at some point. Your basic options are a long-wire antenna, with fixed directionality; or a loop antenna, which can be steered and has quite sharp nulling (points where the signal is stronger or weaker). I'll be posting instructions soon for a strong loop made from cardboard boxes.
Some DX'ers go even more deeply into accessories, using such things as signal preamplifiers, audio filters, computer manipulation of the audio signal, etc.
If you DX over several nights, you'll notice that while the same stations tend to be audible all night, and from night to night, there are variations; and often a signal will pop up that doesn't belong in the usual mix. That's what we listen for. One some frequencies in the AM band, I've heard up to fifteen stations over a 30-year span.
You'll also begin to notice that some frequencies have more action than others. Powerful local stations, for example, may be all that you ever hear on their specific frequencies. You'll find that a number of frequencies are given over to 'clear-channel' stations, on which you can hear many of the major cities in North America.
Having been privileged enough to DX from the West Coast early in life, I found that there are a number of stations that can be heard from coast to coast, under the right conditions. I have about 25 stations that I've heard from both Sooke, and Ottawa.
Some of the more-prominent ones, going from memory, would be:
540 CBU, Vancouver; CBK, Saskatchewan
650 WSM, Nashville;
660 WOR, New York
710 WABC, New York
720 KDWN, Las Vegas;
740 Zoomer Radio, Toronto
760 WJR, Detroit
820 WBAP, Dallas-Ft. Worth
830 WCCO, Minneapolis
870 WWL, New Orleans
1040 WHO, Des Moines
1070 KNX, Los Angeles
1110 KFAB, Omaha
1120 KMOX, St. Louis
1140 WRVA, Richmond
1170 WWVA, Wheeling
In contrast, graveyard channels feature literally hundreds of stations, each with extremely low power, meaning at night those frequencies tend to be just a roar of noise. Some examples: 1230, 1240, 1340, 1400, 1450.
If you indulge in DX'ing over a period of some years, with relatively decent equipment, you will eventually amass thousands of loggings and hundreds to thousands of unique stations. If you live near a coast, you may also pick up trans-oceanic signals--Hawaii, Asia, Europe.
In the winter and spring months, and especially further north, you'll often experience DX during the daytime. It's not unusual to pick up Cincinnati or Boston from here in Ottawa, at midday. I had one day recently where a very specific region in upstate New York was open for about an hour. Needless to say, I took full advantage.
If you're interested in why signal propagation occurs in the AM band, look up the "Kenelly-Heaviside layer," and welcome to atmospheric dynamics.
Incidentally, all of this listening to the radio really sharpens your hearing. I can usually pick one conversation out of a jumble, and follow it, better than the people around me. It's a useful skill to have. It also helps with concentration.
I realize that this essay has only touched upon DX'ing as a legitimate hobby; but getting started literally is as easy as grabbing an AM radio and retiring to a quiet corner of the house. I encourage you to try it at least once in your lifetime.
-Bill
Friday, 28 December 2018
BINOCULARS:
Why You Need a Pair
Of all of the accessories carried by the modern amateur astronomer, by far the most useful has to be binoculars. There are a number of reasons why they're the go-to item in every amateur astronomer's toolbox.
One of the first reasons is that binoculars offer stereo vision. Unlike when squinting through a telescope, both of your eyes are engaged. For most people, it's easier to see that way.
Second up, and right behind, is the fact that binoculars are a 'point and shoot' type of product. You want to see what's over there? Then point the binos at it. It's that simple.
Third, binoculars offer a wide field of view and generally good light-gathering characteristics. Surprisingly enough, many astronomical objects cannot be seen by the naked eye because they are too faint, not too small. Binoculars make a vast collection of objects accessible.
With binoculars, you can rapidly sweep a portion of the sky for interesting sights. You'll spot a lot of clumps of stars; you might see a couple of planets; and there are plenty of faint fuzzies within the reach of binoculars.
Binoculars are a great way to familiarize yourself with the night sky. They bring so much into visual range; for example, nearly all of the "faint fuzzies" mentioned last week look fantastic in binos.
In terms of what to look for, you'll want a pair of 7x50s or 10x50s. (The first number refers to the image-multiplying power; the second refers to diameter of each objective lens, in millimetres.)
If your hands shake a bit, go for the lower power. It's not worth trying to get a consistent view through 10x50s.
If you get yourself binoculars, also get a good star chart of some description. Most show all of the brightest stars, and a fair number of faint fuzzies to get you started.
For a flashlight, might I suggest you go with red. Red light interferes less with the night vision you pick up in dark surroundings. That becomes more important when you're dark-adapted, believe me.
When I go out to observe, even with a telescope, I keep my binos within easy reach.
You don't have to spend much; even a cheap pair is better than nothing. Avoid plastic lenses; they suck. Most decent binoculars have glass lenses.
Once you get a pair of binoculars, use them to familiarize yourself with the night sky. There's plenty to see, especially in a dark sky. Try to minimize sources of glare--streetlights, domestic and industrial lighting, etc.
A word to the wise: in densely-populated areas, standing outside with a pair of binoculars is sure to arouse suspicion. People just imagine the worst, and they just know you're spying on them. You may need to seek a location from which you can observe undisturbed.
When you get a pair of binoculars, first make sure you're using them the right way round. The big lenses go in the front, and you look through the little ones--and it's amazing how often Hollywood gets that simple fact wrong!
There are two extremely-valuable adjustments to be made to a pair of binoculars. First off, the spacing between the lenses can be varied, to match the spacing between your eyes. Looking through them, you should see two overlapping circles, and any objects should be converged, if not actually in focus.
Second, most binos have an independent focuser for the right eyepiece (because most people's eyes are just a bit different). The idea is to use the tilt bar on top to achieve sharp focus in the left eye; then use the adjustment to get matching results in the right eye. Generally, you need only rotate the eyepiece to use this feature.
The nicest thing about binoculars is that they are compact and can go anywhere. They last forever (I've got a pair that's twenty years old; they'll be good for another thirty to fifty years; probably they'll outlast me.)
Binoculars: an essential piece of kit.
Why You Need a Pair
Of all of the accessories carried by the modern amateur astronomer, by far the most useful has to be binoculars. There are a number of reasons why they're the go-to item in every amateur astronomer's toolbox.
One of the first reasons is that binoculars offer stereo vision. Unlike when squinting through a telescope, both of your eyes are engaged. For most people, it's easier to see that way.
Second up, and right behind, is the fact that binoculars are a 'point and shoot' type of product. You want to see what's over there? Then point the binos at it. It's that simple.
Third, binoculars offer a wide field of view and generally good light-gathering characteristics. Surprisingly enough, many astronomical objects cannot be seen by the naked eye because they are too faint, not too small. Binoculars make a vast collection of objects accessible.
With binoculars, you can rapidly sweep a portion of the sky for interesting sights. You'll spot a lot of clumps of stars; you might see a couple of planets; and there are plenty of faint fuzzies within the reach of binoculars.
Binoculars are a great way to familiarize yourself with the night sky. They bring so much into visual range; for example, nearly all of the "faint fuzzies" mentioned last week look fantastic in binos.
In terms of what to look for, you'll want a pair of 7x50s or 10x50s. (The first number refers to the image-multiplying power; the second refers to diameter of each objective lens, in millimetres.)
If your hands shake a bit, go for the lower power. It's not worth trying to get a consistent view through 10x50s.
If you get yourself binoculars, also get a good star chart of some description. Most show all of the brightest stars, and a fair number of faint fuzzies to get you started.
For a flashlight, might I suggest you go with red. Red light interferes less with the night vision you pick up in dark surroundings. That becomes more important when you're dark-adapted, believe me.
When I go out to observe, even with a telescope, I keep my binos within easy reach.
You don't have to spend much; even a cheap pair is better than nothing. Avoid plastic lenses; they suck. Most decent binoculars have glass lenses.
Once you get a pair of binoculars, use them to familiarize yourself with the night sky. There's plenty to see, especially in a dark sky. Try to minimize sources of glare--streetlights, domestic and industrial lighting, etc.
A word to the wise: in densely-populated areas, standing outside with a pair of binoculars is sure to arouse suspicion. People just imagine the worst, and they just know you're spying on them. You may need to seek a location from which you can observe undisturbed.
When you get a pair of binoculars, first make sure you're using them the right way round. The big lenses go in the front, and you look through the little ones--and it's amazing how often Hollywood gets that simple fact wrong!
There are two extremely-valuable adjustments to be made to a pair of binoculars. First off, the spacing between the lenses can be varied, to match the spacing between your eyes. Looking through them, you should see two overlapping circles, and any objects should be converged, if not actually in focus.
Second, most binos have an independent focuser for the right eyepiece (because most people's eyes are just a bit different). The idea is to use the tilt bar on top to achieve sharp focus in the left eye; then use the adjustment to get matching results in the right eye. Generally, you need only rotate the eyepiece to use this feature.
The nicest thing about binoculars is that they are compact and can go anywhere. They last forever (I've got a pair that's twenty years old; they'll be good for another thirty to fifty years; probably they'll outlast me.)
Binoculars: an essential piece of kit.
Thursday, 20 December 2018
Faint Fuzzies
In the night sky, the vast majority of the objects you can see with the naked eye are stars, many of them larger and brighter than our own sun.
But, scattered here and there, you can find a few objects that are neither stars nor planets. These are faint objects, best seen in a dark country sky. Hey, that's just the way it is. We've polluted our urban skies to the point where only the brightest stars can be seen.
Here, then, is a brief tour of some of the most-prominent of these "faint fuzzies."
For all of these, it will help to have star charts, or a planetarium program on your phone/tablet. I'm not doing up charts for a blog post.
Mizar and Alcor
Okay, technically, it's not a star, per se—it's two stars. Mizar and Alcor, situated at the bend in the handle of the Big Dipper asterism, can be seen by most people with normal vision as a double star. The bright one is Mizar; the dimmer one is Alcor. Native Americans used to refer to this pair as the "horse and rider."
The Andromeda Galaxy
This is one of the most-distant objects the naked eye can pick out of the sky, at approximately 2.4-million light-years. It is located in the constellation Andromeda (nothing to do with the High Guard, or Captain Hercules), which itself is off the left 'shoulder' of the great Square of Pegasus.
In a dark sky, and using averted vision (looking slightly away from the object, to engage the more light-sensitive rods in our eyes), a fuzzy area up to a degree in diameter (about twice the width of the Full Moon) can be perceived. In binoculars, this object gently glows like a desk lamp. If nothing else, learning to point out Andromeda can make you a hero to your friends (or a total nerd; you have been warned).
The Double Cluster
Hanging in the polar sky, partway between with cosmic 'W' of Cassiopeia and the hydra-like form of Perseus, is the double cluster--two clusters of stars. With the naked eye, one perceives a fuzzy patch, about half the width of the Full Moon. In binoculars, some of the stars in each cluster begin to resolve, giving you a view of two piles of diamond chips, set upon crushed velvet.
The Centaurus Cluster
This is a great globular cluster of stars. Globulars orbit the galaxy; most of them are much further away. The Centaurus cluster shows as a fuzzy patch. In binoculars, it shows up as a larger, brighter fuzzy patch. The reason? It is composed of over a million stars, at a considerable distance.
The Pleiades
This open cluster sits just to the left (east) of the horns of Taurus (itself another open cluster, only closer to us, and less dense). Normally-sighted people can generally perceive six to eight stars in a compact grouping. Some will comment on its dipper-like appearance.
The Great Orion Nebula
This is a huge cloud of gas and dust, including many star-forming regions, in the constellation Orion. Orion itself is prominent in the winter and spring skies as a large X with three stars in the middle. Tracing down slightly from that point, one finds three more stars (the Dagger). One of those stars is fuzzy. It looks magnificent in binoculars or a telescope.
The Northern Coalsack
Thus far, each of the objects described can be detected from the light it emits. This one, on the other hand, can be detected for the light it blocks. The Northern Coalsack, in the Contellation Cygnus, is a large darkening in the middle of the gently-glowing band of the Milky Way.
The Milky Way
It's sad that only a fraction of the population today has seen the Milky Way. It's a grand spectacle in a dark sky; a band of luminescence that shines from pole to pole. It's our own galaxy, and the light you are seeing is from billions of stars, at distances to great for them to be resolved.
This pretty much concludes our tour of faint fuzzies. Next time you find yourself in a dark sky, try looking for a few of them.
-Bill
In the night sky, the vast majority of the objects you can see with the naked eye are stars, many of them larger and brighter than our own sun.
But, scattered here and there, you can find a few objects that are neither stars nor planets. These are faint objects, best seen in a dark country sky. Hey, that's just the way it is. We've polluted our urban skies to the point where only the brightest stars can be seen.
Here, then, is a brief tour of some of the most-prominent of these "faint fuzzies."
For all of these, it will help to have star charts, or a planetarium program on your phone/tablet. I'm not doing up charts for a blog post.
Mizar and Alcor
Okay, technically, it's not a star, per se—it's two stars. Mizar and Alcor, situated at the bend in the handle of the Big Dipper asterism, can be seen by most people with normal vision as a double star. The bright one is Mizar; the dimmer one is Alcor. Native Americans used to refer to this pair as the "horse and rider."
The Andromeda Galaxy
This is one of the most-distant objects the naked eye can pick out of the sky, at approximately 2.4-million light-years. It is located in the constellation Andromeda (nothing to do with the High Guard, or Captain Hercules), which itself is off the left 'shoulder' of the great Square of Pegasus.
In a dark sky, and using averted vision (looking slightly away from the object, to engage the more light-sensitive rods in our eyes), a fuzzy area up to a degree in diameter (about twice the width of the Full Moon) can be perceived. In binoculars, this object gently glows like a desk lamp. If nothing else, learning to point out Andromeda can make you a hero to your friends (or a total nerd; you have been warned).
The Double Cluster
Hanging in the polar sky, partway between with cosmic 'W' of Cassiopeia and the hydra-like form of Perseus, is the double cluster--two clusters of stars. With the naked eye, one perceives a fuzzy patch, about half the width of the Full Moon. In binoculars, some of the stars in each cluster begin to resolve, giving you a view of two piles of diamond chips, set upon crushed velvet.
The Centaurus Cluster
This is a great globular cluster of stars. Globulars orbit the galaxy; most of them are much further away. The Centaurus cluster shows as a fuzzy patch. In binoculars, it shows up as a larger, brighter fuzzy patch. The reason? It is composed of over a million stars, at a considerable distance.
The Pleiades
This open cluster sits just to the left (east) of the horns of Taurus (itself another open cluster, only closer to us, and less dense). Normally-sighted people can generally perceive six to eight stars in a compact grouping. Some will comment on its dipper-like appearance.
The Great Orion Nebula
This is a huge cloud of gas and dust, including many star-forming regions, in the constellation Orion. Orion itself is prominent in the winter and spring skies as a large X with three stars in the middle. Tracing down slightly from that point, one finds three more stars (the Dagger). One of those stars is fuzzy. It looks magnificent in binoculars or a telescope.
The Northern Coalsack
Thus far, each of the objects described can be detected from the light it emits. This one, on the other hand, can be detected for the light it blocks. The Northern Coalsack, in the Contellation Cygnus, is a large darkening in the middle of the gently-glowing band of the Milky Way.
The Milky Way
It's sad that only a fraction of the population today has seen the Milky Way. It's a grand spectacle in a dark sky; a band of luminescence that shines from pole to pole. It's our own galaxy, and the light you are seeing is from billions of stars, at distances to great for them to be resolved.
This pretty much concludes our tour of faint fuzzies. Next time you find yourself in a dark sky, try looking for a few of them.
-Bill
Friday, 14 December 2018
Perihelion - What's it All About?
At this time of year, Earth is rapidly approaching perihelion--its point of closest approach to the sun. This is a consequence of Earth's orbit being elliptical, not circular.
Take a look at this diagram:
In the above diagram, the Earth is a blue ball; the Sun is a yellow ball. Earth is travelling in the counter-clockwise direction. As you can see, we're rapidly approaching the point of closest approach (A). The opposite point, aphelion, is at point (B). The Vernal Equinox, which marks the first day of spring, is at (C); and the autumnal equinox, marking the first day of fall, is at (D).
Now, interestingly enough, the speed at which our planet moves is inversely proportional to its distance from the sun (I know that's not quite true; but it will suffice for now). Right now, our planet is moving faster than usual. This has consequences.
The first consequence is that the planet spends less time between the autumnal and vernal equinoxes (the left-hand side of the image), and more time between the vernal and autumnal equinoxes. You can confirm this by counting the days between the two equinoxes. Now, Earth's orbital eccentricity is small, and so is the effect; but it's there.
This also has the effect of advancing the equation of time (basically put, the difference between the actual time, and the time a sundial would tell you). Right now, Earth is moving faster than usual; this has the effect of pushing both sunrise and sunset 'backward.' And so the equation of time is increasing in the negative direction (you'd have to subtract from the sundial time). Around the vernal equinox, this situation will reverse itself.
A related consequence is that, while the longest and shortest days of the year remain on the solstices, the dates of earliest and latest sunrise and sunset are offset. We've already passed our earliest sunset of the year, for example; but sunrise will continue to get later into late December/early January.
One other consequence to be noted, here: because perihelion falls shortly after the southern solstice (winter in the Northern Hemisphere), Southern-Hemispheric summers are slightly warmer, and the winters slightly colder.
That's enough for now.
-Bill
At this time of year, Earth is rapidly approaching perihelion--its point of closest approach to the sun. This is a consequence of Earth's orbit being elliptical, not circular.
Take a look at this diagram:
In the above diagram, the Earth is a blue ball; the Sun is a yellow ball. Earth is travelling in the counter-clockwise direction. As you can see, we're rapidly approaching the point of closest approach (A). The opposite point, aphelion, is at point (B). The Vernal Equinox, which marks the first day of spring, is at (C); and the autumnal equinox, marking the first day of fall, is at (D).
Now, interestingly enough, the speed at which our planet moves is inversely proportional to its distance from the sun (I know that's not quite true; but it will suffice for now). Right now, our planet is moving faster than usual. This has consequences.
The first consequence is that the planet spends less time between the autumnal and vernal equinoxes (the left-hand side of the image), and more time between the vernal and autumnal equinoxes. You can confirm this by counting the days between the two equinoxes. Now, Earth's orbital eccentricity is small, and so is the effect; but it's there.
This also has the effect of advancing the equation of time (basically put, the difference between the actual time, and the time a sundial would tell you). Right now, Earth is moving faster than usual; this has the effect of pushing both sunrise and sunset 'backward.' And so the equation of time is increasing in the negative direction (you'd have to subtract from the sundial time). Around the vernal equinox, this situation will reverse itself.
A related consequence is that, while the longest and shortest days of the year remain on the solstices, the dates of earliest and latest sunrise and sunset are offset. We've already passed our earliest sunset of the year, for example; but sunrise will continue to get later into late December/early January.
One other consequence to be noted, here: because perihelion falls shortly after the southern solstice (winter in the Northern Hemisphere), Southern-Hemispheric summers are slightly warmer, and the winters slightly colder.
That's enough for now.
-Bill
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