best wireless solution for high altitude balloon

Wireless & IoT
1

Hi,

I am thinking of starting a high altitude balloon project with a camera that would take images every minute or so. I would really like to use an arduino for this project and I’m thinking of getting the [venus GPS. I think it would be a suitable GPS because it has an operational limit that is either 515m/s OR an altitude of 18km, and since the balloon cant go 515m/s the GPS should work at the high altitude (which would be about 30km or 100,000 feet). But I am not sure if the arduino can communicate with the GPS (yeah, im pretty new at this). And I was also wondering what the best way to communicate the GPS data would be. I would really like something cheap, because all I want is the GPS data to be sent.

Cheers](http://www.sparkfun.com/commerce/product_info.php?products_id=9133)

2

Do you intend for continous GPS updates to be sent from your balloon when it is at ‘high’ altitude?

3

Something to keep in mind, most of our stuff is only rated to work to 60,000 ft (including the venus)

4

100,000 ft. (19 miles) Line of sight to the receiver on the ground. Let’s do the math

Using the No. American 902-928MHz unlicensed band…

that’s about 120dB of path loss (attenuation).

take a 50mW (17dBm) radio like the XBee 900MHz teeny module

17 - 120 yields -102dBm received signal strength.

Compare that to a receiver spec of -100dBm for some reasonable bit error rate, assuming no interference.

We come up 2 dB short and no fade margin.

Add a directional antenna on the ground, but it has to be aimed.

That might be 6dB or so at 900MHz, for a practical size.

So we have 17 - 120 + 6 = -97dBm. Well, this is 3dB better than the receiver spec. But let’s go for 10dB of margin.

Find a radio that’s 100mW (20dBm)

Now we improve by 3dB and the received signal is about -94dBm. With the gain antenna.

Ideally, then, we’d use a 500mW or so transmitter and no directional antenna.

But this is a bit of a battery power hog. And $$$.

Digi and others make 1 Watt and more 900MHz modems. Pricey.

Ah, let’s try the unlicensed 434MHz band. That’s about half of 900MHz. Thus, the path loss improves by 6dB.

Hard to find 434MHz radios with 50-100mW. FCC limits on duty cycle, etc, are strict in this band.

Let’s try again using the unlicensed MURS frequency, 154MHz

The path loss at this freq. improves to 104dB rather than 120dB.

Problem then is to find a 100mW or more MURS transmitter/receiver that’s cheap.

Here’s a MURS band modem http://www.raveontech.com/rv_m3_m.html

Or get a ham license and use the 2m band which is about 150MHz.

Hope this gives you some food for thought on how to plan instead of trial and error. In line of sight, the math matches reality fairly well. Not so for clutter in terrestrial paths.

http://www.radio-electronics.com/info/p … uation.php

http://www.radio-electronics.com/info/p … uation.php

5

Not to rain on anyone’s parade, but unless you are in the boonies, their may be a hefty permitting process for these kinds of balloons, i.e. high altitude. Even in no-where-land, air-space is air-space and therefore regulated.

6

Yes!!! don’t let it hit my airliner!

7

The rules for high altitude ballooning are not that difficult to meet, and don’t require special permits, as long as you keep the payload below a certain weight. I assume you’re read the websites. If not, you’ll need to carefully go over the other HAB balloonists’ interpretations of the Part 101 sections related to HAB.

8

When I asked a similar question, somebody suggested these radios

http://search.digikey.com/scripts/DkSea … 0-1000M-ND

9

sylvie369:
The rules for high altitude ballooning are not that difficult to meet, and don’t require special permits, as long as you keep the payload below a certain weight. I assume you’re read the websites. If not, you’ll need to carefully go over the other HAB balloonists’ interpretations of the Part 101 sections related to HAB.

Pretty much, I too am also looking into doing this, even though I like to say “as long as its safe for all it could affect, noone has the right to permit me to experiment”

With that said, if you do a night launch there has to be a strobe light on it (more weight)

Day launches are easier on rules, bright colored, etc.

Look at the faa regulations, that will help you for the rules associated with it.

Its easy to do if you have a balloon some helium or an empty head and hydrogen.

Jack the local car lots for their balloons to get the helium, (I know you cant very well use those balloons) but the helium is helium. Get it where you can.

Thanks to the author for posting this question. I like the ham radio aspect, but would rather use a massive antenna and free-to-use spectra.

Hell, maybe hack an old satellite dish for the receiver end.

Good luck.

Or if you have a ham-radio licensed friend that would be cool.

10

There have been successful xbee balloons in the past (e.g. [this one with a 900 MHz one). We’re currently working on another one, with an 868 MHz module. Going straight up radios really get to do their job, balloons regularly fly with 25 mW or even less.

Get yourself a patch on the ground and aim it either with a tracker or manually, and something with a conical radiation pattern on the aerial segment and you’d get very reasonable link even from near-space.

edited: typo](http://www.davidankers.com/?p=11)

11

hey, just wanted to thank everyone for their reply. I am thinking of using two xbee modules as they would probably be the easiest to use. I got quite a few things to learn and your replies have given me quite some food for thought. I probably wont be able to do this very soon, but I hope to do it sometime this year.

12

nafis:
hey, just wanted to thank everyone for their reply. I am thinking of using two xbee modules as they would probably be the easiest to use. I got quite a few things to learn and your replies have given me quite some food for thought. I probably wont be able to do this very soon, but I hope to do it sometime this year.

The 40-mile or even the 16-mile 900MHz system would work, but not the lower powered models.

Or you can do what nasa does and what I am planning on doing, using a small transceiver on the balloon and a large dish on the ground.

Nasa contacts the deep space probes with massive antenna/arrays, and the satelite transceiver has a very small powered system.

But the idea is the same, just have the dish movable and trackable.

Enjoy.

13

Use MURS, 150MHz, unlicensed. Watts of power. A few modest cost uni- and bi-directional RF modems on the market.