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#2
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ELT antenna in composite planes.
Cy,
That reminds me. I recently built and tried out the MicroTrak 300 APRS tracker ( .3 watt transmitter) in my aircraft. It managed over 25 miles direct on a ducky. Not bad for transmission. My ducky is about 9" long. My comparison you quoted was more based on comparing the typical aircraft radio "transmission" range and the similar range of the APRS ducky tracker - both are about 5watts, both VHF. It would be interesting to compare an aircraft tuned ducky reception vs transmission range. Maybe I'll do that someday. All I need is a second standard aircraft radio/antenna and a second aircraft to talk to. On Oct 31, 7:32 pm, "Cy Galley" wrote: Your reference that your 5 watt will work out 60 miles. Unfortunately the old style ELT has only a .1 watt transmitter which is 1/50 the output of your example. I do not have the expertise to tell how this will reduce the distance, but I will bet it does curtail the range quite a bit. -- Cy Galley EAA Safety Programs Editor |
#3
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ELT antenna in composite planes.
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#4
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ELT antenna in composite planes.
Dave,
It was about a couple thousand feet above ground - about what I locally fly. And it was probably more than 60 miles range. Up at 12K msl above Washington state mountains had one digi got me about 100 miles. My rough comparison is with normal radio aircraft reception at say 8000 msl - aircraft to aircraft communication fizzles out about 60? miles. So the ducky isn't bad "transmission" range in direct line of sight situations. But it seems bad in reception. Yeah the current APRS catch is the HAM license. Wish somehow it was easier to get a tracker for GA use. APRS tracking can be a great safety factor. On Oct 31, 10:32 pm, Dave S wrote: wrote: 60 miles coverage on the ground? to what elevation of a receiving antenna? Details.. details.. As for APRS.. while I applaud it, the "catch" is that you have to have a HAM radio licence and ham radio equipment to utilize the existing VHF packet network. Dave |
#5
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ELT antenna in composite planes.
Yeah the current APRS catch is the HAM license. Wish somehow it was easier to get a tracker for GA use. APRS tracking can be a great safety factor. Its not really that difficult, conceptually. Especially when they revise the bandplan to the next narrowing of the bandwidth. Dedicate an aviation channel or two nationwide (I'm sure the band planners can spare ONE or TWO when the next doubling of available frequencies occurs) packet reception. Digipeaters wouldn't really be needed, provided enough igates exist on enough tall towers. If enough aircraft in an area had this, it would also allow tracker equipped aircraft to see OTHER tracker equipped aircraft as a sort of poor man's TIS/TCAS, but the beaconing rate would need to be much faster to support that in real time. There is no monopoly on using APRS on HAM only, and you can put a TNC on theoretically any radio, only infrastructure concerns. Use smart beaconing, so that when traveling straight line, beaconing is minimized, and use corner-pegging logic so that a beaconed datapoint defines when a course change occurs. By setting up a system with smart beaconing you could handle hundreds of beaconing aircraft in an area, with minimal collisions. |
#6
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ELT antenna in composite planes.
One doesn't crash 1000 feet in the air and line of sight is what really
works. That's why they use a satellite which helps immensely when down in the trees and valleys -- Cy Galley EAA Safety Programs Editor Always looking for ideas and articles for EAA Sport Pilot New address - wrote in message ups.com... Dave, It was about a couple thousand feet above ground - about what I locally fly. And it was probably more than 60 miles range. Up at 12K msl above Washington state mountains had one digi got me about 100 miles. My rough comparison is with normal radio aircraft reception at say 8000 msl - aircraft to aircraft communication fizzles out about 60? miles. So the ducky isn't bad "transmission" range in direct line of sight situations. But it seems bad in reception. Yeah the current APRS catch is the HAM license. Wish somehow it was easier to get a tracker for GA use. APRS tracking can be a great safety factor. On Oct 31, 10:32 pm, Dave S wrote: wrote: 60 miles coverage on the ground? to what elevation of a receiving antenna? Details.. details.. As for APRS.. while I applaud it, the "catch" is that you have to have a HAM radio licence and ham radio equipment to utilize the existing VHF packet network. Dave |
#7
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ELT antenna in composite planes.
Why not install a "new" ELT that IS satellite tracked? As I stated in
an email way back when on this same topic, what if you are flying in an area with no APRS coverage? Also, is there just one APRS frequency used throughout the country? If not, it would require the pilot to change to an appropriate frequency at the appropriate time, based on his location. Scott N0EDV wrote: OK. I expected your reply quickly. On Oct 31, 1:00 pm, "RST Engineering" wrote: As you say, a ducky is nearly isotropic ... but equally poorly isotropic in all directions. If the ducky is well tuned it will radiate very well - I measured pretty low reflection on one I have. The radiation gain in larger antennas comes from directionality and not from nothing - it does not radiate more RF energy than the transmitter generates. I have a 5W APRS (VHF) tracking unit with a ducky in my aircraft and it reaches about 60 miles direct to my iGate. Not bad. As to the orientation of the dipole, if you can tell me how the airplane parts are going to come to rest in the incident, I'll tell you how to mount the antenna. Yeah, but that is the trick. Nobody knows how the plane will come to rest. And don't forget even in ideal situation (vertical) most radiation is against horizontal obstructions and not up - and neither 121.5 nor 243 will get help from repeaters. AND if the plane is mangled your seat mounted or whatever does not likely have survival rate as an a small attached ducky. ELT failure rate is about 25%. A tuned ducky for 121.5? Great. How do you radiate the 243.0 component since the antenna will be nearly anti-resonant at that frequency. The dual freq loss problem is true of any single ELT antenna. You can tune a ducky to 243, your choice - I understand 121.5 satellite tracking is being abandoned. Personally I prefer APRS tracking. You can see my today's track at http://aprs.he.fi/ - just enter N416 and then again at right in the box. For those who want more info about APRS see http://www.abri.com/sq2000/GPStrack.html Its fantastic for GA aircraft tracking. -- Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) |
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ELT antenna in composite planes.
wrote:
Personally I prefer APRS tracking. You can see my today's track at http://aprs.he.fi/ - just enter N416 and then again at right in the box. For those who want more info about APRS see http://www.abri.com/sq2000/GPStrack.html Its fantastic for GA aircraft tracking. The next version of PocketFMS will support FLARM: http://www.flarm.com/product/index_en.html http://www.pocketfms.com Inflight traffic for the masses... |
#9
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ELT antenna in composite planes.
On Nov 21, 11:42 pm, Darrel Toepfer wrote:
wrote: Personally I prefer APRS tracking..... The next version of PocketFMS will support FLARM:http://www.flarm.com/product/index_e....pocketfms.com Inflight traffic for the masses... What relevance is this device to general S&R tracking? It is a short range - aircraft to aircraft - collision warning device and not a tracking device. There are no ground based - or anything based - networks that store the information on internet for locating the aircraft by S&R agencies. APRS is working NOW with across the country network. |
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