To illustrate the difference in equipment requirements depending on orbit:
AO-10 and AO-40 require relatively high-gain antennas (Yagis or dishes) and tracking systems to use them.
Some of the LEO satallites, especially the FM repeater satellite UO-14 (AO-27 is the same type/orbit but runs lower downlink power and isn't on 24/7) are acessible using a $200-300 dual-band handheld with a good whip antenna. Spend $60-70 for an Arrow antenna and you can get EXCELLENT results.
2000+ mile range with 5 watts and an entirely handheld setup - Talk about cool.:)
From Ithaca, NY, I have heard a station in Mexico and one in Edmonton, AB on a regular basis via UO-14. I've even heard California.
Andy, N2YPH
I need to replace my antenna... The old one sucked and broke. Only $10 though.:)
Illegal or not, most amateurs will not transmit there as it's reserved for weak-signal work, and who knows, they might want to run moonbounce themselves sometime in the future.:)
If 432.1 were in repeater or FM simplex territory, no one would care.
Either way - The satellite has two uplinks and this only affects one of them.
It has a single low-duty-cycle beacon in the 2.3 GHz band. No reception capability anywhere close to the 802.11 bands. Most of the uplinks/downlinks are in the 2 meter and 70 cm amateur bands.
802.11 is just not suited well for space-based communications anyway...
NO amateur satellites are there - The cost of launch is simply too prohibitive, and it raises groundstation equipment requirements too much.
The highest-flying amateur satellites (AO-10 and AO-40) are in highly elliptical orbits. Almost all others are in various low-earth orbits, circling the Earth every 80-100 minutes.
Do a freshmeat search for "predict" - It's an excellent satellite position prediction package for Linux.
Sounds like all that needs to be done is some further subdivision of the Art and Collectible forums.
I've had no problem selling stuff on eBay - If you list it right, it gets found in a search along with all the other stuff.
I like the large businesses because there are some items I know I'm always going to be able to find cheap on eBay. (Cornelius kegs for homebrewing, a top for the convertible I'm planning on buying, cell phone faceplates, etc.)
I think you missed a key point - It's only sellers who gross over $1k/month that eBay is offering this too, not eBay's entire userbase.
eBay takes a commission from every sale - So those sellers are far, far beyond even paying customers at many sites as far as the revenue they bring into the company.
Meanwhile, Yahoo and MSN are free services, or if they charge, they don't charge nearly as much as the amounts of commissions eBay skims from the qualifying classes of sellers.
Standard fan designs are VERY inefficient at even a small backpressure. Which is why you can't make a "poor man's supercharger" for cars using regular 'ole electric fans.
I remember reading the specs on a 48V 500CFM (approx.) fan - Flow dropped to 0 at less than 0.3-0.4 psi of backpressure.
Even when the compressor is not running, those pipes are still cold due to thermal inertia. As soon as they get warm again, the compressor turns on again.
So the air coming out will not change too much in temperature - The compressor is simply cycled to maintain coil temperature at just above freezing.
Try APRS... A lot of the old TNCs are firmware-upgradable to include built-in APRS.
Control operator rules rock.
on
Field Day 2002
·
· Score: 2
I've always been too lazy to get my code license. (Partly a chicken and egg issue - HF equipment costs $$$, which I'm reticent to spend w/o a code license. Don't wanna bother with code if I don't have the equipment.)
As a result, my first HF experience was operating as W2CXM my senior year in college. Contesting is FUN.
N2YPH
Re:Radio Interference anyone?
on
Field Day 2002
·
· Score: 2
Heck, I would say that FM is more of a danger than SSB/CW - Why?
Inherently, most amplifiers designed for FM use are nonlinear. Which means lots of harmonics.
In a well-designed amp this is irrelevant, since filtering kills the harmonics. But such an amp inherently requires more filtering than a linear one used for SSB. (CW can also be sent through a nonlinear amp.)
Why use nonlinear amps? They're far more efficient.
Not the point.
on
Field Day 2002
·
· Score: 3, Insightful
Hams aren't used for emergency notification of the public. Hams primarily provide communications infrastructure to those who REALLY need it in an emergency situation.
For example, hams will often assist police/fire departments. In NYC post 9/11, the Red Cross made heavy use of hams to maintain communications between all of their mobile units and their command post.
Another emergency organization in addition to ARES and RACES is SKYWARN - In this case, hams provide the "eyes and ears" on the ground to the NOAA. Not too heavily used/needed in the Northeast, but in places like Tornado Alley it's a different story.
In fact, broadcasting is verboten on the amateur bands - So theoretically emergency notification is against FCC rules. (Not like the FCC would care in such a situation. In fact, I believe there are clauses in FCC rules saying that the rules don't apply for emergencies.) Nonetheless, I agree that amateur radio is not the proper medium for emergency notification, but that is not the goal of the amateur emergency organizations.
Re:Emergency broadcast???
on
Field Day 2002
·
· Score: 3, Interesting
I don't have any personal experience with the NYC 'net, but I do know that the various amateur emergency organizations were mobilized for well over six weeks.
It's not always the phone/cell systems that ham radio is designed to replace - Hams are also used to augment already allocated emergency frequencies. (Police, fire). I believe the Red Cross made VERY heavy use of hams for their communications. Simply put, they needed a dispatch-style system that landlines/cells weren't suited to.
In addition, a few years back there was a NASTY ice storm in upstate NY - Many cell tower antennas iced up and ceased operation, and hams came into play then too.
Tompkins County Amateur Radio Club
on
Field Day 2002
·
· Score: 2
The TCARC (Tompkins County, NY - It's upstate in the Finger Lakes region. Think Ithaca) will be setting up at the fire station in Etna, NY this weekend.
Hams looking for the place, try the TCARC repeater on 146.97- once you get into the area if you have trouble finding the location. The other major repeater is W2CXM (Cornell ARC) on 146.61- - But it's usually pretty quiet.
One of the most popular uses of packet radio seems to be accessing the local "DX Cluster"
It's basically a system that allows people to report stations they hear, allowing someone looking for their final multipliers in a contest to know where to look for a station.
The interesting thing about this is that you're not allowed to advertise yourself on the clusters. As a result, if you appear, it's because someone else put you there. You'd think that the DX clusters would die as everyone would keep their "rare finds" secret so as to keep ahead, but instead, the DX clusters are INSANELY active during contests, which says a lot of good things about the ham radio community in general.
DX spots are wonderful when your club is hunting down their last multiplier (Santa Barbara) in the final hours of the ARRL SSB Sweepstakes.
N2YPH
And keeping your Collins 30S-1 happy for nearly 48 hours of continuous operation is no simple trick.:) I'd say the hardest part of the contest was maintaining power levels. Also, our rotor was broken so we had to send guys up onto the tower to rotate our Force12 while we hit the brake release on the rotor.
Re:country ?
on
Field Day 2002
·
· Score: 3, Informative
Given that you used 73 to say Goodbye, I'm guessing you're a ham.
Radio is both international and local. There are international contests, but there's nothing stopping people from operating locally.
Due to the emergency communications focus of Field Day and the fact that 99.999% of all emergencies are relatively local (In fact, a nationwide catastrophe has yet to happen...), it makes sense that it's just the USA. Other countries might also hold similar contests during the year, too.
N2YPH
A little bit more...
on
Field Day 2002
·
· Score: 5, Interesting
This is probably in the ARRL link.
Field Day is themed about emergency communications, although it couldn't be considered "practice" for emergencies. (Running/participating in emergency nets, etc.) - That's what ARES/RACES drills are for.
Field Day is purely a contest - BUT it is a contest that was designed with emergencies in mind. Most ARRL (and international) contests have various operator classes - In the case of Field Day, operator classes are based on how your station is powered. I think there's also a rule stating that you can't operate from your own station.
So basically, all Field Day entrants MUST be using equipment brought to the operating position for the event, not stuff that is there at all times. (I think people HAVE operated in tents from backyards, but people prefer to go hardcore and do some mountaintopping, or go to a firehouse, etc. where they can set up with their club. Club operations from community firehouses, etc. seem to be the most common Field Day arrangements.)
As a result, Field Day makes sure there are plenty of operators in this country with portable (or semi-portable at least) equipment that can be set up in a matter of hours. Bonus points to those who can operate for a weekend without a single bit of help from AC mains.
I was thinking of making the trek back up to school for Field Day, but I need to do some car shopping instead. I wish it were a few weeks later.:)
Note: Philips is concerned with protecting their money.
But what's good for the consumer is good for Phillips . Happens to bad for the RIAA, but Phillips obviously doesn't care too much for them, because the RIAA's pushes at DRM, etc. hurt sales of Phillips products.
The one bad thing about the C-x000 series cameras is that they're a bit bulky. Not as big as an SLR, but not as small as your average point-and-shoot camera.
I also have a Canon Digital Elph (PowerShot S100) - Light on features, but the portability is wonderful in some situations. Doesn't do external lenses, though, at least not easily.
I agree that one should choose the camera and then get the media type that follows.
That said, my personal favorite in the digicam arena is Olympus, specifically their C-x000 series cameras (C-2000,C-3000, and I think now the C-4000)
The 2000 series is 2.1 megapixels, the 3000 series is 3.3 megapixels and adds sound recording capability and a few other little things over the 2000 series. The 4000 series is in the 4-megapixel range I think.
All of them support a tube that screws on around the lens and provides a 46mm (or is it 41mm) standard threaded mount that allows you to attach filters (not too necessary with a digital, except for maybe a polarizer) and add-on wide-angle/zoom lenses (I recommend Tiffen lenses - They're cheap and Tiffen is a well-known brand) Currently I have the tube with a step-up ring to 49mm, as I had quite a number of 49mm filters and attachments from the small lens on my old SLR film camera.
In addition to the magnetic strips mentioned in one of the other replies, some cards have RFID chips embedded into them. Thus, to get into a building, you don't have to swipe the card, you just hold it close to a sensor. Much more reliable than magstripes, and a bit more convenient.
Neither will work with a cheapo lamination system.
Tivo doesn't make money off the hardware. (In fact, the hardware is made by Phillips and Sony, and I think I saw once that TiVo actually PAYS Phillips and Sony a small subsidy per box.)
TiVo's revenue stream is from their *service* - I have a friend that works for them, and he basically says that their attitude is that it's anything goes for hackers, in fact they secretly cheer them on.
BUT, that's as long as the hackers don't go near their revenue stream. Try to screw with their channel guide service/etc., and they will most definately NOT be supporting it. (I think someone basically said that TiVo went to some lengths to shut down people who did such things.)
Hackers upgrading mean: a) TiVo doesn't have to pay the small subsidy on new boxes. b) If the hacker installs a network card, it means they stop using the TiVo dialup system for updates.
Personally, I use gogo - LAME plus 3DNow! optimizations. Great quality, and WICKED FAST.
My SCSI 8x reader couldn't keep up even on my old 800 MHz Athlon. (And yes, it rips at 7.5-8x, unlike my Creative IDE DVD drive which rips at 0.5x - Creative sucks!)
Required antenna size for a given gain is inversely proportional to the frequency used.
Also, as the frequency goes higher, it becomes much harder to generate power. At 70-95 GHz, you're talking single-digit milliwatts in most cases.
For example: I can build a 100-watt amplifier for the HF frequencies (1.8-30 MHz, approximately - I think in terms of the ham bands) for $100 or less. It might be 200-300 watts at that price range. (500W+ if I'm willing to accept nonlinear operation, i.e. I'm running Morse. Of course, at that point, I'm spending serious $$$ in the power supply too)
A 1-watt 2.4 GHz amplifier runs around $400 commerically. I've seen supposed designs for running 1W at $100, but most modern 802.11 cards are too integrated to allow access to the T/R switching line, which makes the cheap amp designs useless.
So to get effective range, you ABSOLUTELY need a high-gain antenna. At 70-95 GHz, even a 1-foot dish is high-gain though. The beamwidth will likely be less than a degree.
Slashdot Mirror
To illustrate the difference in equipment requirements depending on orbit:
:)
:)
AO-10 and AO-40 require relatively high-gain antennas (Yagis or dishes) and tracking systems to use them.
Some of the LEO satallites, especially the FM repeater satellite UO-14 (AO-27 is the same type/orbit but runs lower downlink power and isn't on 24/7) are acessible using a $200-300 dual-band handheld with a good whip antenna. Spend $60-70 for an Arrow antenna and you can get EXCELLENT results.
2000+ mile range with 5 watts and an entirely handheld setup - Talk about cool.
From Ithaca, NY, I have heard a station in Mexico and one in Edmonton, AB on a regular basis via UO-14. I've even heard California.
Andy, N2YPH
I need to replace my antenna... The old one sucked and broke. Only $10 though.
As to use of 432.1 - It's iffy.
:)
Illegal or not, most amateurs will not transmit there as it's reserved for weak-signal work, and who knows, they might want to run moonbounce themselves sometime in the future.
If 432.1 were in repeater or FM simplex territory, no one would care.
Either way - The satellite has two uplinks and this only affects one of them.
It has a single low-duty-cycle beacon in the 2.3 GHz band. No reception capability anywhere close to the 802.11 bands. Most of the uplinks/downlinks are in the 2 meter and 70 cm amateur bands.
802.11 is just not suited well for space-based communications anyway...
The satellite is NOT in geosynchronous orbit.
NO amateur satellites are there - The cost of launch is simply too prohibitive, and it raises groundstation equipment requirements too much.
The highest-flying amateur satellites (AO-10 and AO-40) are in highly elliptical orbits. Almost all others are in various low-earth orbits, circling the Earth every 80-100 minutes.
Do a freshmeat search for "predict" - It's an excellent satellite position prediction package for Linux.
Sounds like all that needs to be done is some further subdivision of the Art and Collectible forums.
I've had no problem selling stuff on eBay - If you list it right, it gets found in a search along with all the other stuff.
I like the large businesses because there are some items I know I'm always going to be able to find cheap on eBay. (Cornelius kegs for homebrewing, a top for the convertible I'm planning on buying, cell phone faceplates, etc.)
I think you missed a key point - It's only sellers who gross over $1k/month that eBay is offering this too, not eBay's entire userbase.
eBay takes a commission from every sale - So those sellers are far, far beyond even paying customers at many sites as far as the revenue they bring into the company.
Meanwhile, Yahoo and MSN are free services, or if they charge, they don't charge nearly as much as the amounts of commissions eBay skims from the qualifying classes of sellers.
It's simply being moved.
Standard fan designs are VERY inefficient at even a small backpressure. Which is why you can't make a "poor man's supercharger" for cars using regular 'ole electric fans.
I remember reading the specs on a 48V 500CFM (approx.) fan - Flow dropped to 0 at less than 0.3-0.4 psi of backpressure.
Even when the compressor is not running, those pipes are still cold due to thermal inertia. As soon as they get warm again, the compressor turns on again.
So the air coming out will not change too much in temperature - The compressor is simply cycled to maintain coil temperature at just above freezing.
Try APRS... A lot of the old TNCs are firmware-upgradable to include built-in APRS.
I've always been too lazy to get my code license. (Partly a chicken and egg issue - HF equipment costs $$$, which I'm reticent to spend w/o a code license. Don't wanna bother with code if I don't have the equipment.)
As a result, my first HF experience was operating as W2CXM my senior year in college. Contesting is FUN.
N2YPH
Heck, I would say that FM is more of a danger than SSB/CW - Why?
Inherently, most amplifiers designed for FM use are nonlinear. Which means lots of harmonics.
In a well-designed amp this is irrelevant, since filtering kills the harmonics. But such an amp inherently requires more filtering than a linear one used for SSB. (CW can also be sent through a nonlinear amp.)
Why use nonlinear amps? They're far more efficient.
Hams aren't used for emergency notification of the public. Hams primarily provide communications infrastructure to those who REALLY need it in an emergency situation.
For example, hams will often assist police/fire departments. In NYC post 9/11, the Red Cross made heavy use of hams to maintain communications between all of their mobile units and their command post.
Another emergency organization in addition to ARES and RACES is SKYWARN - In this case, hams provide the "eyes and ears" on the ground to the NOAA. Not too heavily used/needed in the Northeast, but in places like Tornado Alley it's a different story.
In fact, broadcasting is verboten on the amateur bands - So theoretically emergency notification is against FCC rules. (Not like the FCC would care in such a situation. In fact, I believe there are clauses in FCC rules saying that the rules don't apply for emergencies.) Nonetheless, I agree that amateur radio is not the proper medium for emergency notification, but that is not the goal of the amateur emergency organizations.
I don't have any personal experience with the NYC 'net, but I do know that the various amateur emergency organizations were mobilized for well over six weeks.
It's not always the phone/cell systems that ham radio is designed to replace - Hams are also used to augment already allocated emergency frequencies. (Police, fire). I believe the Red Cross made VERY heavy use of hams for their communications. Simply put, they needed a dispatch-style system that landlines/cells weren't suited to.
In addition, a few years back there was a NASTY ice storm in upstate NY - Many cell tower antennas iced up and ceased operation, and hams came into play then too.
The TCARC (Tompkins County, NY - It's upstate in the Finger Lakes region. Think Ithaca) will be setting up at the fire station in Etna, NY this weekend.
Hams looking for the place, try the TCARC repeater on 146.97- once you get into the area if you have trouble finding the location. The other major repeater is W2CXM (Cornell ARC) on 146.61- - But it's usually pretty quiet.
One of the most popular uses of packet radio seems to be accessing the local "DX Cluster"
:) I'd say the hardest part of the contest was maintaining power levels. Also, our rotor was broken so we had to send guys up onto the tower to rotate our Force12 while we hit the brake release on the rotor.
It's basically a system that allows people to report stations they hear, allowing someone looking for their final multipliers in a contest to know where to look for a station.
The interesting thing about this is that you're not allowed to advertise yourself on the clusters. As a result, if you appear, it's because someone else put you there. You'd think that the DX clusters would die as everyone would keep their "rare finds" secret so as to keep ahead, but instead, the DX clusters are INSANELY active during contests, which says a lot of good things about the ham radio community in general.
DX spots are wonderful when your club is hunting down their last multiplier (Santa Barbara) in the final hours of the ARRL SSB Sweepstakes.
N2YPH
And keeping your Collins 30S-1 happy for nearly 48 hours of continuous operation is no simple trick.
Given that you used 73 to say Goodbye, I'm guessing you're a ham.
Radio is both international and local. There are international contests, but there's nothing stopping people from operating locally.
Due to the emergency communications focus of Field Day and the fact that 99.999% of all emergencies are relatively local (In fact, a nationwide catastrophe has yet to happen...), it makes sense that it's just the USA. Other countries might also hold similar contests during the year, too.
N2YPH
This is probably in the ARRL link.
:)
Field Day is themed about emergency communications, although it couldn't be considered "practice" for emergencies. (Running/participating in emergency nets, etc.) - That's what ARES/RACES drills are for.
Field Day is purely a contest - BUT it is a contest that was designed with emergencies in mind. Most ARRL (and international) contests have various operator classes - In the case of Field Day, operator classes are based on how your station is powered. I think there's also a rule stating that you can't operate from your own station.
So basically, all Field Day entrants MUST be using equipment brought to the operating position for the event, not stuff that is there at all times. (I think people HAVE operated in tents from backyards, but people prefer to go hardcore and do some mountaintopping, or go to a firehouse, etc. where they can set up with their club. Club operations from community firehouses, etc. seem to be the most common Field Day arrangements.)
As a result, Field Day makes sure there are plenty of operators in this country with portable (or semi-portable at least) equipment that can be set up in a matter of hours. Bonus points to those who can operate for a weekend without a single bit of help from AC mains.
I was thinking of making the trek back up to school for Field Day, but I need to do some car shopping instead. I wish it were a few weeks later.
Note: Philips is concerned with protecting their money.
But what's good for the consumer is good for Phillips . Happens to bad for the RIAA, but Phillips obviously doesn't care too much for them, because the RIAA's pushes at DRM, etc. hurt sales of Phillips products.
The one bad thing about the C-x000 series cameras is that they're a bit bulky. Not as big as an SLR, but not as small as your average point-and-shoot camera.
I also have a Canon Digital Elph (PowerShot S100) - Light on features, but the portability is wonderful in some situations. Doesn't do external lenses, though, at least not easily.
I agree that one should choose the camera and then get the media type that follows.
That said, my personal favorite in the digicam arena is Olympus, specifically their C-x000 series cameras (C-2000,C-3000, and I think now the C-4000)
The 2000 series is 2.1 megapixels, the 3000 series is 3.3 megapixels and adds sound recording capability and a few other little things over the 2000 series. The 4000 series is in the 4-megapixel range I think.
All of them support a tube that screws on around the lens and provides a 46mm (or is it 41mm) standard threaded mount that allows you to attach filters (not too necessary with a digital, except for maybe a polarizer) and add-on wide-angle/zoom lenses (I recommend Tiffen lenses - They're cheap and Tiffen is a well-known brand) Currently I have the tube with a step-up ring to 49mm, as I had quite a number of 49mm filters and attachments from the small lens on my old SLR film camera.
In addition to the magnetic strips mentioned in one of the other replies, some cards have RFID chips embedded into them. Thus, to get into a building, you don't have to swipe the card, you just hold it close to a sensor. Much more reliable than magstripes, and a bit more convenient.
Neither will work with a cheapo lamination system.
Tivo doesn't make money off the hardware. (In fact, the hardware is made by Phillips and Sony, and I think I saw once that TiVo actually PAYS Phillips and Sony a small subsidy per box.)
TiVo's revenue stream is from their *service* - I have a friend that works for them, and he basically says that their attitude is that it's anything goes for hackers, in fact they secretly cheer them on.
BUT, that's as long as the hackers don't go near their revenue stream. Try to screw with their channel guide service/etc., and they will most definately NOT be supporting it. (I think someone basically said that TiVo went to some lengths to shut down people who did such things.)
Hackers upgrading mean:
a) TiVo doesn't have to pay the small subsidy on new boxes.
b) If the hacker installs a network card, it means they stop using the TiVo dialup system for updates.
As the 'net adapter upgrade means they have to pay minimal costs for the upgrade.
Or use an encoder based on LAME.
Personally, I use gogo - LAME plus 3DNow! optimizations. Great quality, and WICKED FAST.
My SCSI 8x reader couldn't keep up even on my old 800 MHz Athlon. (And yes, it rips at 7.5-8x, unlike my Creative IDE DVD drive which rips at 0.5x - Creative sucks!)
Required antenna size for a given gain is inversely proportional to the frequency used.
Also, as the frequency goes higher, it becomes much harder to generate power. At 70-95 GHz, you're talking single-digit milliwatts in most cases.
For example: I can build a 100-watt amplifier for the HF frequencies (1.8-30 MHz, approximately - I think in terms of the ham bands) for $100 or less. It might be 200-300 watts at that price range. (500W+ if I'm willing to accept nonlinear operation, i.e. I'm running Morse. Of course, at that point, I'm spending serious $$$ in the power supply too)
A 1-watt 2.4 GHz amplifier runs around $400 commerically. I've seen supposed designs for running 1W at $100, but most modern 802.11 cards are too integrated to allow access to the T/R switching line, which makes the cheap amp designs useless.
So to get effective range, you ABSOLUTELY need a high-gain antenna. At 70-95 GHz, even a 1-foot dish is high-gain though. The beamwidth will likely be less than a degree.