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spudgun range, are we falling short?

A place to ask general spud cannon related questions.
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Unread postAuthor: jackssmirkingrevenge » Sat May 04, 2013 3:31 am

POLAND_SPUD wrote:yeah it might be but bluetooth for something so simple is an overkill

AFAIK it can be as simple as a loop antenna
http://en.wikipedia.org/wiki/Radio_direction_finding

don't ask me how to build a transmiter but I am sure duane or technician can post a schematic or at least mention where to find one


Yeah but these are like 25 bucks a piece.
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Unread postAuthor: POLAND_SPUD » Sat May 04, 2013 5:18 am

the device is a class 2 device so the range is just 10 meters and that's assuming direct LOS between the devices... if the projectile penetrates the soil you're f#####


The only thing that I like about it is that you can use a smartphone for reception... you could use RSSI and GPS in a way similar to apps such as wigle wifi wardriving (rssi location estimation)... very cool stuff if you ask me - I personally use the app and it can physicly locate WIFI hotspots and cell towers with amazing precision
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Unread postAuthor: jackssmirkingrevenge » Sat May 04, 2013 5:30 am

POLAND_SPUD wrote:the device is a class 2 device so the range is just 10 meters and that's assuming direct LOS between the devices... if the projectile penetrates the soil you're f#####


According to the manufacturer, the range is approximately 100 feet or about 30 Meters.

A projectile could be designed for the tail to separate on impact.

If you shoot along a specific bearing and follow that line, I think the projectile will not deviate more than 30 metres left of right so you should be able to find it. Then again on an empty beach you could probably see it at that distance.

I think the ultimate solution is a device that beams its location in real time... something like this: http://www.ebay.com/itm/Vehicle-Car-Tra ... 19db7af97b

The problem is that it's pretty wide, the projectile would need to be around 1.5 inches diameter, so it would need a big bore launcher.
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Unread postAuthor: POLAND_SPUD » Sat May 04, 2013 5:42 am

heh your right I first read 100 feet then subconsciously converted that to 30 meters... then I assumed it's range in feet - so again conversion to metric units hence 10 meters :D


anyway if you have a smartphone with an fm receiver you might as well build your own transmiter and use the phone as the receiver... when the signal becomes stronger you're closer to the transmiter... the added advantage is that it forces you to build an electronic circuit :wink:
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Unread postAuthor: jackssmirkingrevenge » Sat May 04, 2013 6:04 am

I still have this unassembled on the shelf...
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Unread postAuthor: Technician1002 » Sat May 04, 2013 1:48 pm

FYI, Loop antennas are for much lower frequency than Bluetooth. Most loop antennas are for HF - VHF frequencies (3-30 MHZ and 30-300MHZ) Since Bluetooth is in the WiFi frequency band of 2.4 GHZ (2,400,000MHZ) the loop if you built one would be very small at less than 0.1 inches in diameter.

For more sensitivity, a small dish antenna or Yagi antenna would work well. The difficulty is getting a receiver to lock on and then display signal strength instead of the connected/not connected indication of most devices.

Your choice of receiver that can display signal strength is up to you.

An old satellite dish re purposed to hold a cell phone at the focal point could work very effectively by using the high gain to triangulate the position then walking into the target zone for a careful target zone search.

One trick to find your target if in brush is to use an attenuator. Don't shop online looking for one. Most anything you use will have a built in antenna so you can't insert an attenuator between the antenna and receiver. You can use an attenuator between the transmitter and receiver. Place your phone in a silver colored ESD anti static bag. Most of these will attenuate the signal. Try it. Place your cell phone in an old bag that enclosed your latest electronics purchase. The metallic shielding is a good attenuator for reducing the sensitivity to narrow the search area where the signal strength is full to a much smaller area.
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Unread postAuthor: jackssmirkingrevenge » Sun May 05, 2013 1:11 am

Technician1002 wrote:An old satellite dish re purposed to hold a cell phone at the focal point could work very effectively by using the high gain to triangulate the position then walking into the target zone for a careful target zone search


Interesting thought... simply placing it there?
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Unread postAuthor: Technician1002 » Sun May 05, 2013 11:07 am

Yes, remove the original satellite electronics and place the phone or other bluetooth device in the same place where the feedhorn was. This provides a long range narrow beam antenna.

Visit the web and find ones done using a USB WiFi adapter and a dish to get high gain in a narrow direction, often reaching several miles.

http://www.ab9il.net/wlan-projects/wifi3.html
http://www.ehow.com/how_6136334_build-usb-wifi-satellite-dish.html
http://technetz.com/index.php/2009/03/21/how-to-make-outdoor-wifi-antenna-using-satellite-dish-and-usb-wifi-adapter/

I pack an old sat dish with me in the motorhome. Use it when on the road to hit the nearest apartment complex, home on a hill or other out of range wifi. It takes a littel care to get it aimed and find an unsecured hotspot, but it beats no signal at all in many campgrounds.
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Unread postAuthor: POLAND_SPUD » Sun May 05, 2013 1:27 pm

well I don't really think there is any point in using bluetooth for that

I have a 2$ wireless bug that I could use for this - the range is close to 60 meters in LOS
I've never attempted locating it but I think a loop antena would be enough



anyway I think we have already established that for long range you should use a UAV plane :D
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Unread postAuthor: jackssmirkingrevenge » Mon May 06, 2013 1:25 am

POLAND_SPUD wrote:anyway I think we have already established that for long range you should use a UAV plane :D


:D
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Unread postAuthor: jackssmirkingrevenge » Sat Jul 13, 2013 10:41 am

http://www.bbc.co.uk/news/science-environment-23281423

And we're worried about tracking the projectile under a few inches of sand...
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Re: spudgun range, are we falling short?

Unread postAuthor: PeteS » Mon Nov 11, 2013 7:31 pm

Very interesting thread. I have enjoyed reading it.

Since I have reached my first big goal of breaking the sound barrier, I was thinking of going for a range related goal.

Since I do not have a land launch site option that will allow easy recovery of projectiles at the maximum range of my hybrid, I am thinking trying of another option, firing a streamlined floating projectile over water. I am thinking that a blinking LED in a floating projectile should be easy to find after it lands in the water. My kayak and GPS should allow recovery and reasonably accurate range measurements. Any reason that is a bad approach?
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Re: spudgun range, are we falling short?

Unread postAuthor: jackssmirkingrevenge » Mon Nov 11, 2013 8:01 pm

PeteS wrote:My kayak and GPS should allow recovery and reasonably accurate range measurements. Any reason that is a bad approach?


Sounds good, but presumably the projectile would have a float on a length of line to mark its position? Certainly a projectile sufficiently low in density to float on water would have a very poor ballistic coefficient and therefore be less impressive in terms of range, and in any case drift would negate the accuracy of any measurement.
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Re: spudgun range, are we falling short?

Unread postAuthor: Ragnarok » Mon Nov 11, 2013 9:19 pm

Reasons it's a bad approach? Well, as Jack says, "float =/= aerodynamic".

And if you go for properly aerodynamic, all of these projects are talking about kilometres of range and projectiles that can land anywhere inside hectare sized areas and still have enough energy to put themselves several feet underground. Not something achievable with kayak. Submarine, maybe.

I still think tracking down a projectile only really becomes plausible if you can both accurately predict its landing area AND reliably search an area equal to your margin of error. That either takes exceptional prediction or highly efficient searching - and we seem to be at a loss for many brilliant solutions to either.
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Re: spudgun range, are we falling short?

Unread postAuthor: POLAND_SPUD » Tue Nov 12, 2013 1:43 am

What do you think about using barometers ?? there are some fairly inexpensive and small parts but I am wondering if it even makes sense to use them... Wouldn't the readings be affected by air flowing around the projectile ?
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