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CAP Talk  |  Operations  |  Tools of the trade  |  Topic: Inexpensive 406 Mhz Decoder/tracker system
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Author Topic: Inexpensive 406 Mhz Decoder/tracker system  (Read 1581 times)
GZCP31
Recruit

Posts: 34
Unit: Somewhere

« on: February 08, 2018, 04:56:49 PM »

While looking at options for ELT tracking options that are available today, I have run across an inexpensive way to receive and decode 406Mhz ELT transmissions.
This requires a Laptop, USB Stick, Software and an antenna.
The Laptop needs to be running Windows.
The Additional Software is a program called Multipsk. It was written by a Ham radio operator in France. (License is $40) http://f6cte.free.fr/index_anglais.htm
The USB Stick is an RTL-SDR. This is a Software Defined Radio  that is based on the DVB-T stick. (available on Amazon for $20.00) https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2
The Antenna I am using is a hand held Ham YAGI antenna that is tuned to the 440 Ham band. This is close enough for testing. (Cost $20.00 to build)
For information on getting it all to work, I found this BLOG. http://www.bytebang.at/Blog/ELT+Testing+with+rtl-sdr

I hope to do testing on this soon.
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Former OK Wing DCL/DCA Mid 90s, Rejoined after 17 years out.
1LT. Communications-Master
Squadron Deputy Commander, Emergency Services Training Officer,  Professional Development Officer,  Administration Officer, Personnel Officer, Communications Officer and Aerospace Education Officer
GZCP31
Recruit

Posts: 34
Unit: Somewhere

« Reply #1 on: February 08, 2018, 05:10:00 PM »

It looks like there may be a similar setup for Android. http://giammaiot.blogspot.com/2017/03/test-on-android-decoder-epirb-distress.html
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Former OK Wing DCL/DCA Mid 90s, Rejoined after 17 years out.
1LT. Communications-Master
Squadron Deputy Commander, Emergency Services Training Officer,  Professional Development Officer,  Administration Officer, Personnel Officer, Communications Officer and Aerospace Education Officer
Live2Learn
Salty & Seasoned Contributor

Posts: 625

« Reply #2 on: February 08, 2018, 06:45:33 PM »

Interesting tool.  What exactly does "inexpensive" mean in today's nominal currency?
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SarDragon
Global Moderator

Posts: 10,342
Unit: NAVAIRPAC

« Reply #3 on: February 08, 2018, 07:16:21 PM »

IMHO, inexpensive means anything that can be paid for with a single currency note - $100 or less.
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Dave Bowles
Maj, CAP
AT1, USN Retired
Mitchell Award (unnumbered)
C/WO, CAP, Ret
GZCP31
Recruit

Posts: 34
Unit: Somewhere

« Reply #4 on: February 08, 2018, 10:09:05 PM »

Interesting tool.  What exactly does "inexpensive" mean in today's nominal currency?
Better than the thousands of dollars I have seen.
Logged
Former OK Wing DCL/DCA Mid 90s, Rejoined after 17 years out.
1LT. Communications-Master
Squadron Deputy Commander, Emergency Services Training Officer,  Professional Development Officer,  Administration Officer, Personnel Officer, Communications Officer and Aerospace Education Officer
Live2Learn
Salty & Seasoned Contributor

Posts: 625

« Reply #5 on: February 09, 2018, 02:19:29 PM »

Interesting tool.  What exactly does "inexpensive" mean in today's nominal currency?
Better than the thousands of dollars I have seen.

so, maybe multiples of that "single currency note" mentioned above.  maybe lotsa multiples??   :)
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jthomsenrn
Newbie

Posts: 1
Unit: Kingston

« Reply #6 on: February 09, 2018, 10:17:28 PM »

While looking at options for ELT tracking options that are available today, I have run across an inexpensive way to receive and decode 406Mhz ELT transmissions.
This requires a Laptop, USB Stick, Software and an antenna.
The Laptop needs to be running Windows.
The Additional Software is a program called Multipsk. It was written by a Ham radio operator in France. (License is $40) http://f6cte.free.fr/index_anglais.htm
The USB Stick is an RTL-SDR. This is a Software Defined Radio  that is based on the DVB-T stick. (available on Amazon for $20.00) https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2
The Antenna I am using is a hand held Ham YAGI antenna that is tuned to the 440 Ham band. This is close enough for testing. (Cost $20.00 to build)
For information on getting it all to work, I found this BLOG. http://www.bytebang.at/Blog/ELT+Testing+with+rtl-sdr

I hope to do testing on this soon.
Post how it goes


Sent from my E6810 using Tapatalk

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GZCP31
Recruit

Posts: 34
Unit: Somewhere

« Reply #7 on: February 10, 2018, 04:49:17 PM »

Testing today went well. We used a 433.6 Mhz Ham band transmitter and a 121.775 ELT.

The Antenna I used was for 440mhz so the 121.775 did not pick up until I was within 100ft. I will build a 121mhz/243mhz antenna for the next testing.

The 433.6 testing went great. I had a 1 second pulse every 5 seconds. The Transmitter was hidden at an airfield in the door jam of a hanger 500 yards from my starting point. I had no idea where it was on the field. We took our initial direction heading and then proceeded 50 yards then repeated the procedure. All headings were very close to the previous ones.
We found the transmitter within 10 minutes on the opposite side of a hanger from the starting point.

We did not have a 406 Mhz ELT to test with, but the 433.6 was close enough for proof of concept. I have also tested using APRS data and that worked well also for reading location. I hope to have access to an actual 406 ELT to make sure it reads the data correctly soon.
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Former OK Wing DCL/DCA Mid 90s, Rejoined after 17 years out.
1LT. Communications-Master
Squadron Deputy Commander, Emergency Services Training Officer,  Professional Development Officer,  Administration Officer, Personnel Officer, Communications Officer and Aerospace Education Officer
sardak
Salty & Seasoned Contributor

Posts: 1,190

« Reply #8 on: February 10, 2018, 07:14:48 PM »

While you're waiting for the 406 beacon, which should be one of the 406 practice beacons CAP has distributed, adjust your test pulse, if you can, to 1/2 second every 50 seconds. That's the interval on 406 beacons.

Mike
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GZCP31
Recruit

Posts: 34
Unit: Somewhere

« Reply #9 on: February 10, 2018, 08:22:26 PM »

That  is what I was going to do. BTW the transmitter I am using is the Beeline transmitter. http://www.bigredbee.com/BeeLine.htm I had it set to 4mw during the test. I was able to show the Cadets and our squadron commander that the little L-Per is not our only option. We used a $50 bearcat scanner, and this setup to show possibilities.

Once it is working effectively, I will have to start working on a PICO-ITX system to make it more "Ground team" Friendly. I might even have to play with Windows mobile to see if it is possible to make this a viable option to what is on the market.
I will see if I have the time. No promises.
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Former OK Wing DCL/DCA Mid 90s, Rejoined after 17 years out.
1LT. Communications-Master
Squadron Deputy Commander, Emergency Services Training Officer,  Professional Development Officer,  Administration Officer, Personnel Officer, Communications Officer and Aerospace Education Officer
GZCP31
Recruit

Posts: 34
Unit: Somewhere

« Reply #10 on: March 19, 2018, 07:32:31 PM »

This weekend was the state SAREX. I was able to do real world testing of the system. We started out with the RTL-SDR connected to a Samsung TAB 2 and an Omni-directional antenna for 121.775. When we got within 1.5 miles of the ELT we began picking up a weak signal. We continued sown the road until we had several peaks (It was hilly) and notated each peak. We then stopped where we had the strongest peak. We then switched from the TAB2 and Omni antenna to a Android Cell phone and 4 element Yagi. We also had our LL-16 to compare.
The LL16 had issue. It kept pointing from left to center while we did our 360. Never to the right. (It will be getting repaired). The SDR system gave us the general direction using the peak strength. We had no issue tracking the ELT even though it was about 1700 ft off of the road.

We then had a 406 mission as our 2nd sortie. Since we did not have an actual 406 ELT available, they used the Beeline transmitter set at 150MW with a 1.5 second pulse every 45 seconds. This was a Ramp check. We had the cadets running the new system. At first they were looking at the back side strengths and went the wrong way. After 30 minutes we were pointed in the correct direction. We had the Transmitter in had within an hour. (Keep in mind we did not have the 121 MHz secondary transmitter on this sortie).

We impressed group and other squadrons with the capabilities of the new system.

 One problem during the first sortie was the Aircraft was given return to base  due to ceiling. We were not informed until they were landing. We also would have liked to know where the AC was while we were out. As part of the tool kit we have now added an ADS-B tracking software (Xradio ADS-B Receiver Pro ) to the tablet, a second RTL_SDR and a 1090 Mhz antenna. This way we can map out where the AC is on a separate system.

With this system being able to not only track the ELT, adding in the ADS-B will help teams be more efficient for a very low cost on equipment.
« Last Edit: March 19, 2018, 07:43:35 PM by GZCP31 » Logged
Former OK Wing DCL/DCA Mid 90s, Rejoined after 17 years out.
1LT. Communications-Master
Squadron Deputy Commander, Emergency Services Training Officer,  Professional Development Officer,  Administration Officer, Personnel Officer, Communications Officer and Aerospace Education Officer
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CAP Talk  |  Operations  |  Tools of the trade  |  Topic: Inexpensive 406 Mhz Decoder/tracker system
 


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