GPS tracking - what's your preference?

eggtimer rocketry
the rocketry show
The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
PKMdotCOM said:
Any thoughts on the Garmin 320 "Astro"
Click to expand...

Way too much power to put them anywhere near an altimeter - I've done ground testing and verified that they will indeed bugger up an altimeter, and possibly cause them to fire, or not fire at all, depending on how the altimeter fails. Others have reported the same.

Not to mention, they're awfully expensive.

-Kevin
 
Anyone use the Real Flight Systems equip.? Looks pretty sophisticated.
 
What is the recommended antenna for a gps device like a Yaseu or a Kenwood? Do people use the standard whip or rubber antenna that comes with the unit? I get the last position in the air thing, but what do people do when the rocket is on the ground and the signal is lost? Do people use a long antenna on their vehicle to try to get some elevation? Just curious. Does a Yagi antenna have any use in gps telemetry, or is that only for direction finding of RDF signals.
 
The rubber duck antenna will work to decode APRS packets, but won't provide a lot of gain. That's when a Yagi can help, however it is a directional antenna so it needs to be pointed in the general vicinity of the transmitting antenna. I've flown with the 16 mW BRB GPS and used rubber duck antenna to flights in the 5000' range, I've used a 5 element Yagi with strong signals at 12,000'. I would expect both to be operational for much higher flights, and there's also a much stronger transmitter option BRB GPS available.

As the rocket approaches the ground, if it's far away, it's likely to lose signal. Where this will happen will depend local terrain effects. At Dairy Aire (alfalfa farms in central CA), I lost signal below 500' using the rubber duck at a distance of about 0.6 miles from the launch area. At Mudrock, we lost signal about 1700' up and nearly 1 mile from the launch area using the Yagi. In both cases, I had the last packet in the HT and proceeded along that heading. At Black Rock, I drove out toward the last coordinate with the Yagi sitting on the dash. At about 0.2 miles away, the HT re-acquired the signal and then we drove directly to the transmitter.

Should it not have acquired, I would have resorted to more drastic measures... drive out to the last coordinate, stand on top of the truck and then do a 360 degree scan with the Yagi. It would have more gain than the rubber duck, and that could help a lot at that point.

It's also possible to re-acquire with the Yagi a signal that isn't strong enough to fully decode the APRS packet. In that case, the Yagi can be used in traditional RDF techniques to locate a bearing to the transmitter. Note that all of this happens on FM, so a weak signal just means more static, not higher volume.
 
Last edited:
4kids49 said:
What is the recommended antenna for a gps device like a Yaseu or a Kenwood? Do people use the standard whip or rubber antenna that comes with the unit? I get the last position in the air thing, but what do people do when the rocket is on the ground and the signal is lost? Do people use a long antenna on their vehicle to try to get some elevation? Just curious. Does a Yagi antenna have any use in gps telemetry, or is that only for direction finding of RDF signals.
Click to expand...

Hi Chris. Your Space Cowboy had such a beautiful flight, it was a darn shame it was lost - out there at the launch console, I thought we had a pretty good bearing on it too :(

I use the Big Red Bee 100mW GPS unit (it is set to radiate at that power). My radio is the Yaesu VX-8GR. I've done a lot of experimenting with this out on the playa and found that:

With the stock Yaesu rubber antenna
With the transmitter on the playa surface, range is 1/4 to 1/3 mile - can't even hear a beep, no data
With the transmitter on top of the Black Rock, reception at the AeroPac launch site is superb - loud, clear, all data. This is ~12 miles.


With an external high gain mobile antenna
With the transmitter on the playa surface, range is 1/3 to 1/2 mile - can't even hear a beep, let alone data
With the transmitter on top of the Black Rock, reception at the AeroPac launch site is (also) superb - loud, clear, all data. This is ~12 miles.


As you will recall, the antennas we have on our RZR are about 6' off the ground. The antenna I use for the VX-8GR is a Diamond NR770, this has a gain of 5.5 dBi on the 70 cm band.

NR770.jpg

The NR770 antenna, 38 inches long, 5.5 dBi, mounted on the RZR. SWR is 1.6

I had installed this with the intention of being able to pull in a signal from the Big Red Bee while it was on the ground, or at least, pull it in from beyond visual range (1/2 mile in the heat of mid day). Ha ha. Incremental improvement at best...soooo....I generally use the stock rubber antenna. This has been fine for my current altitudes of ~25,000' and certainly picks up the signal & data throughout the flight, as well as very well during drougefall and under parachute.

The VX-8GR retains the last received packet, so even after when the signal is extinguished by the giant ground plane of the playa, it still displays the last GPS position of touchdown.

When using a 7-element Yagi on the Black Rock, results are pretty much the same as the NR770 - 1/3 to 1/2 mile when the BRB is on the ground. Yech. The place for a Yagi would be ultra-high altitude flights, or in instances when the flight portion has the Big Red Bee in a poor transmitting position (partially shielded, perhaps).

Summary: right now, as fairly typical L3 flyer on the Black Rock, I am happy with the stock rubber antenna. When I move to 2-stage, I will probably return to the external NR770 antenna.

Hope this helps.


All the best, James
 
Thanks Tim and James. Great stuff that you guys posted. I am learning a lot. I will get gps at some point. I read and ask a lot of questions. I learned a lot at Black Rock. There is a slight chance that the main could have come out at apogee. I ground tested one charge in the booster side and one in the nose cone side. But with backup charges, and two altimeters, who knows. If that happened, it could have drifted pretty far. Anyway, back to the thread, the BRB 70 cm seems like a good product. They all have pros and cons. It is nice to hear people talk about what they like and don't like about stuff. Thanks for all of the tips.
 
I typically use a 7 element Yagi, because it gives me a better signal when the rocket is low, or on the ground. The exception, of course, being radio tracking hell (Black Rock) where nothing provides much for range.

James is spot on about how to handle loss of signal - go to the last packet, and use that as a starting point.

-Kevin
 
Just curious, if one were to fly an UAV to a few thousand feet altitude, would it help pick up the signal from a rocket somewhere on playa surface?

This won't help RDF but will to APRS/GPS...

-Alex
 
4kids49 said:
What is the recommended antenna for a gps device like a Yaseu or a Kenwood? Do people use the standard whip or rubber antenna that comes with the unit? I get the last position in the air thing, but what do people do when the rocket is on the ground and the signal is lost? Do people use a long antenna on their vehicle to try to get some elevation? Just curious. Does a Yagi antenna have any use in gps telemetry, or is that only for direction finding of RDF signals.
Click to expand...

I went out last week for some range testing. I found a couple of hilltops 12.2km apart and tried a variety of antennas and radios. With a 16mW transmitter (TeleGPS), I was able to receive APRS and our digital telemetry using a 3 element Arrow yagi, but not with a Diamond SRH519 dual-band whip. With a 34mW transmitter (TeleMetrum), I was able to receive both APRS and digital telemetry using either the yagi or whip.

So, yes, the yagi will give you better range.
 
troj said:
I typically use a 7 element Yagi, because it gives me a better signal when the rocket is low, or on the ground. The exception, of course, being radio tracking hell (Black Rock) where nothing provides much for range.

James is spot on about how to handle loss of signal - go to the last packet, and use that as a starting point.

-Kevin
Click to expand...

Thanks Kevin. I can definitely see where having the last packet would be helpful, including knowing if the rocket is on the ground as opposed to have an RDF signal. I am also with you on the difficulties of switching to reading glasses all of the time. I followed my last ComSpec heading out to the end of driving and then hiked up into the dunes. I did a lot of the drive a half mile, stand on the car, search with binoculars and 360 sweep with ComSpec. The last gps position would have been helpful.
 
keithp said:
I went out last week for some range testing. I found a couple of hilltops 12.2km apart and tried a variety of antennas and radios. With a 16mW transmitter (TeleGPS), I was able to receive APRS and our digital telemetry using a 3 element Arrow yagi, but not with a Diamond SRH519 dual-band whip. With a 34mW transmitter (TeleMetrum), I was able to receive both APRS and digital telemetry using either the yagi or whip.

So, yes, the yagi will give you better range.
Click to expand...

Thanks Keith. I will have to look back into TeleMetrum and TeleGPS products. I agree with the statements that one gets a lot for the money. I also really like that your products are Apple compatible. Adding up a transmitter, Yaseu or Kenwood receiver, antenna, possible handheld gps, the price gets up there pretty fast. Having an integrated system like those in Altus Metrum producs is definitely worth looking into.
 
Chris, None of these systems are fool (not calling anyone or any product fools) proof. The rocket I found while out looking for yours had a TeleMetrum in it. I'm not sure why it became lost? I like and use radio Tx in most of my flights. I've gotten good at it over the years. I've also lost rockets with GPS and Tx in them. I did 2 flights at Mudroc 29 and 25K. recovered using Tx. Yes Black Rock will eat your radio signals close to the ground. I've lost GPS signals as high as 8K agl out there. Once on the ground it is really bad. Some of things I've earned over the years are...

The Arrow Anttenuator, anttenuates even when it's turned off! I leave it out of the system until I know my rocket has reached apogee and is not coming in hot. I then connect it into the system.

I use a cheap radio shack scanner with a 7 element yagi. I add attenuation and I'm into the squelch on the radio while I'm doing circular motions with the yagi. On the 25K flight my buddy spotted the rocket under main about 2 miles out. He was looking where I was "waving" the yagi..maybe in a 6 inch circle by that time.

I set my mains to 2500 - 3000 to give me time to dial in the rockets location. They come down pretty fast without a drogue.

Don't talk to or distract guys using a yagi!

If I'm really having a hard time hearing the signal inside the squelch..I'll close my eyes. It makes my hearing much better.

As the rocket gets close to the ground I'll take my foot and scratch a line in the dirt to the direction of the signal.

I also look for land marks in the mountain ranges past the signal.

I actively...actively meaning I won't stop tracking the rocket until it's on the ground!

It does take practice to get the knack to track rockets. If your at a launch with me come on over..I'm more then willing to have some help on my next rocket recovery adventure!

Tony
 
tfish said:
Chris, None of these systems are fool (not calling anyone or any product fools) proof. The rocket I found while out looking for yours had a TeleMetrum in it. I'm not sure why it became lost? I like and use radio Tx in most of my flights. I've gotten good at it over the years. I've also lost rockets with GPS and Tx in them. I did 2 flights at Mudroc 29 and 25K. recovered using Tx. Yes Black Rock will eat your radio signals close to the ground. I've lost GPS signals as high as 8K agl out there. Once on the ground it is really bad. Some of things I've earned over the years are...

The Arrow Anttenuator, anttenuates even when it's turned off! I leave it out of the system until I know my rocket has reached apogee and is not coming in hot. I then connect it into the system.

I use a cheap radio shack scanner with a 7 element yagi. I add attenuation and I'm into the squelch on the radio while I'm doing circular motions with the yagi. On the 25K flight my buddy spotted the rocket under main about 2 miles out. He was looking where I was "waving" the yagi..maybe in a 6 inch circle by that time.

I set my mains to 2500 - 3000 to give me time to dial in the rockets location. They come down pretty fast without a drogue.

Don't talk to or distract guys using a yagi!

If I'm really having a hard time hearing the signal inside the squelch..I'll close my eyes. It makes my hearing much better.

As the rocket gets close to the ground I'll take my foot and scratch a line in the dirt to the direction of the signal.

I also look for land marks in the mountain ranges past the signal.

I actively...actively meaning I won't stop tracking the rocket until it's on the ground!

It does take practice to get the knack to track rockets. If your at a launch with me come on over..I'm more then willing to have some help on my next rocket recovery adventure!

Tony
Click to expand...

Thanks Tony. Awesome stuff. I hope that people are learning as much in this thread as I am. Hopefully I am not derailing Bill's thread. In my case at Black Rock, I believe that the rocket was on the ground. That being said, I was not sure. In the future I would have to be aware of times from apogee, etc. I am sure that mine was not ballistic. I could have been derailed by something as simple as not having the battery secured well inside the protective case, possibly the exposed antenna could have been snapped on the ground. I put about 70 miles on my car in the playa. All part of the learning experience. I have learned a lot in this thread. Hopefully Bill will do well and tell us about his experiences.
 
4kids49 said:
Thanks Keith. I will have to look back into TeleMetrum and TeleGPS products. I agree with the statements that one gets a lot for the money. I also really like that your products are Apple compatible. Adding up a transmitter, Yaseu or Kenwood receiver, antenna, possible handheld gps, the price gets up there pretty fast. Having an integrated system like those in Altus Metrum producs is definitely worth looking into.
Click to expand...

Our new stuff works with APRS receivers as well, so you get choices, which is always nice. Note that we support Linux, Mac OS X, Windows and Android, but cannot support iOS because the bluetooth support in those products is locked down.
 
tfish said:
Chris, None of these systems are fool (not calling anyone or any product fools) proof. The rocket I found while out looking for yours had a TeleMetrum in it. I'm not sure why it became lost? I like and use radio Tx in most of my flights. I've gotten good at it over the years. I've also lost rockets with GPS and Tx in them. I did 2 flights at Mudroc 29 and 25K. recovered using Tx. Yes Black Rock will eat your radio signals close to the ground. I've lost GPS signals as high as 8K agl out there. Once on the ground it is really bad. Some of things I've earned over the years are...

The Arrow Anttenuator, anttenuates even when it's turned off! I leave it out of the system until I know my rocket has reached apogee and is not coming in hot. I then connect it into the system.

I use a cheap radio shack scanner with a 7 element yagi. I add attenuation and I'm into the squelch on the radio while I'm doing circular motions with the yagi. On the 25K flight my buddy spotted the rocket under main about 2 miles out. He was looking where I was "waving" the yagi..maybe in a 6 inch circle by that time.

I set my mains to 2500 - 3000 to give me time to dial in the rockets location. They come down pretty fast without a drogue.

Don't talk to or distract guys using a yagi!

If I'm really having a hard time hearing the signal inside the squelch..I'll close my eyes. It makes my hearing much better.

As the rocket gets close to the ground I'll take my foot and scratch a line in the dirt to the direction of the signal.

I also look for land marks in the mountain ranges past the signal.

I actively...actively meaning I won't stop tracking the rocket until it's on the ground!

It does take practice to get the knack to track rockets. If your at a launch with me come on over..I'm more then willing to have some help on my next rocket recovery adventure!

Tony
Click to expand...

Tony, thanks for the very useful insights. I particularly like the advice to set the mains to a higher altitude than I likely would have.

Also, good pointer on the Arrow attenuator. I would not have guessed that.
 
Worsaer said:
Ok, so I have a BRB GPS (70cm version) and a Kenwood TH-D7a(g) combo. Using the TNC it works great, displaying the GPS coordinates.

For actually trekking to the location, I was considering purchasing a handheld GPS unit. While I can buy a used unit on thEbay, they are still pricey.
So here's the decision I'm faciing...

I can purchase a used handheld GPS for $200 - $250, or a new unit for much more.

Or, with GPS units being relatively pricey, I could instead purchase a handheld radio with an integrated GPS, such as the Kenwood TH-D72a, or the Yaesu. It's bit more, yet it's one less thing to carry.



For those of you that do this, do the combo handheld radios with integrated GPS work well for navigating to the destination?
Or, do you prefer using a dedicated handheld GPS unit?
Click to expand...

I have the Yaesu with gps. I learned something about it today that I didn't know. Specifically, when you get the "last packet", the radio will continue to update the direction and distance as you move toward the rocket. I thought you had to get fresh packets for those updates. WooHoo! So, this is certainly one advantage for using the integrated gps radio. On the other hand, when it says your rocket is to the northeast, you have to know what direction northeast is. With the handheld gps, and ideally one with a compass, it will tell the directionally challenged which way to walk.

I prefer to use the handheld gps rather than rely on the radio (although now that I know how the radio actually works, it's a little more of a toss-up). However, I use my handheld much, much more often for the purpose of projecting a line. In short, I can input a line so that when I walk around something, like a stand of trees for example, I can find the line again. I have a procedure to do this, and if I take the time to set it up properly (maybe 30 minutes tops), I can put in a line that will be within 50 feet of a rocket at 3 miles out. I have found many rockets in this manner, and putting in a line is helpful even if the rocket has an RDF tracker in it. Not all gps handhelds have the features to easily "project a waypoint". The one I have is the Etrex Vista H. With two beneficial uses, the handheld wins for me.

Jim
 
tfish said:
It does take practice to get the knack to track rockets. If your at a launch with me come on over..I'm more then willing to have some help on my next rocket recovery adventure!
Click to expand...

If you've never done RDF, an offer like this is something you don't want to pass up.

The best time to learn to track is when you don't need it....not when you have no idea where $1500 worth of rocket is....

-Kevin
 
troj said:
If you've never done RDF, an offer like this is something you don't want to pass up.

The best time to learn to track is when you don't need it....not when you have no idea where $1500 worth of rocket is....

-Kevin
Click to expand...

Amen! I hope to play with my new equipment on a few lower altitude flights in a couple of weeks.
 
I have been using the CSI RF beacon for a couple of years now, and do pretty good with it. I did loose a rocket out at Lucerne last year, but after several people searched for it, we decided it had been stolen. Not the first time at a ROC event.
Now I'm using an Eggfinder. It's a whole nother ball game. Six flights and six easy recoveries.
My system consists of the transmitter with a rubber duckie antenna, a receiver with the same antenna and an HC-06 bluetooth module that sends the data to an Android phone with "Rocket Locator" app. that displays your current location, the rockets location, bearing and distance. Both the handheld units have belt clips, so it's all mobile with me. I just follow the arrow to the rocket, works every time.
Funny thing happened with a flight I made at ROCstock last month. Driving my Jeep to my rocket and another vehicle is heading in the same direction. Drove right up to my rocket and the truck stops about 100 yards away, when he sees me pick up "Jughead", he asks if I have seen another rocket around..... Just coincidence?
Being able to drive right to my rocket might have saved it...
 
Wayco said:
I have been using the CSI RF beacon for a couple of years now, and do pretty good with it.
Click to expand...


I lost a Cirrus Dart in the forest tonight, was a breeze to find if with my CSI system.
 
Area66 said:
I lost a Cirrus Dart in the forest tonight, was a breeze to find if with my CSI system.
Click to expand...

I have made dozens of successful recoveries with the CSI tracker beacon, but the dry lake playa is totally different than a forest, or the desert for that matter. I still put a beacon in all my rockets that it will fit in, but use it for a backup.
 
Fdog said:
With the stock Yaesu rubber antenna
With the transmitter on the playa surface, range is 1/4 to 1/3 mile - can't even hear a beep, no data
With the transmitter on top of the Black Rock, reception at the AeroPac launch site is superb - loud, clear, all data. This is ~12 miles.


With an external high gain mobile antenna
With the transmitter on the playa surface, range is 1/3 to 1/2 mile - can't even hear a beep, let alone data
With the transmitter on top of the Black Rock, reception at the AeroPac launch site is (also) superb - loud, clear, all data. This is ~12 miles.
Click to expand...

So here's perhaps an ignorant question... Understanding that the playa 'soaks' up the radio signal once the rocket is on the ground (acting as a huge ground plane), and knowing that you can still get decent reception at a higher elevation as described above, would it makes sense to set up a digipeater and rebroadcast the APRS traffic on another frequency, thereby allowing reception for greater distances across the playa?
 
Do not see the need when using GPS. Last location has always gotten me close enough to either see the rocket or reacquire the signal.


Sent from my iPad using Rocketry Forum
 
Worsaer said:
At some point I'll post some observations. I purchased a used Garmin 60csx and a cable to go with my Kenwood TH-D7. Additionally, I couldn't resist a recent an eBay auction for a TH-D72. So now, I have both rigs to play with. I realize it's probably a matter of personal preference rather than which is truly 'better'.

I'm hoping to fly a new 54mm minimum diameter rocket on one of the new CTI L265 'Mellow' reloads at Balls in September, and REALLY want to find it after the flight. (Considering all the components, it's easily the most expensive bird that I will have ever flown.) I have a vested interest in finding which combination of equipment works best for me.
Click to expand...

You have the best combination for portable APRS tracking. May sure the 60CsX is set for NMEA output and the D72A is set for use with an external GPS.
The rocket will be entered as a waypoint in the 60CsX directory and you can set the Garmin to "navigate to" the rocket/waypoint. Don't use metallic paint on the rocket as it will soak up Rf like a sponge. No range. Kurt
 
troj said:
Way too much power to put them anywhere near an altimeter - I've done ground testing and verified that they will indeed bugger up an altimeter, and possibly cause them to fire, or not fire at all, depending on how the altimeter fails. Others have reported the same.

Not to mention, they're awfully expensive.

-Kevin
Click to expand...

Yup,

Was an article in the NAR mag on the dog trackers. Some electronics get buggered up and do things like not work or blow on the pad.
For an example, look here:

https://tripolipeoria95.com/Pictures.html

Scroll down and look at that 16' 6" tall, 12" diameter behemoth. Then scroll to the bottom of the picture page and click on the photo links for OMG.jpg. (Incidentally, OMG stood for "O" motored girl, not the other obvious exclaimation.) :)

That rocket had a dog tracker in the "other side" of the ebay and shut down the two altimeters on the maiden flight.

People use dog trackers but they ride away from the altimeters and the deployment electronics are best served with some shielding if using them. Ground testing helps but may not be 100% in being certain they play well.

I had a pad deployment with a P6K and a 150mW non-directional beacon tracker. So be careful with Rf. The low powered Beeline GPS plays well with deployment electronics. Kurt
 
Over on the AERO-PAC mailing list, there was a discussion about GPS tracking, so my latest how-to article, co-authored with Ken Biba, is on that subject.
jcrocket.com/gps-tracking.shtml

And to address the question posed by the title of this post, the TL;DR answer:

flowchart1.svg
 
Last edited:
Worsaer said:
So here's perhaps an ignorant question... Understanding that the playa 'soaks' up the radio signal once the rocket is on the ground (acting as a huge ground plane), and knowing that you can still get decent reception at a higher elevation as described above, would it makes sense to set up a digipeater and rebroadcast the APRS traffic on another frequency, thereby allowing reception for greater distances across the playa?
Click to expand...

Bill, that's an excellent question!

My distance experiments have been limited to placing the BigRedBee on top of Black Rock Peak. At an altitude of roughly 600' above the playa, it nicely simulates a rocket a long distance away while under parachute (just before touchdown). This was approximately 12 miles away from the AeroPac camp, and folks back at camp heard the signal perfectly, with all the APRS data intact.

However, I've not done the experiment in reverse...with the VX-8GR at the top of Black Rock Peak, and the BigRedBee laying on the playa. I have a guess, but, lacking experimental evidence, I will decline to posit.

...Sounds like something to do on our next trip out there!


All the best, James
 
John, nicely done on the GPS tracking article.


All the best, James
 
JohnCoker said:
Over on the AERO-PAC mailing list, there was a discussion about GPS tracking, so my latest how-to article, co-authored with Ken Biba, is on that subject.
jcrocket.com/gps-tracking.shtml

And to address the question posed by the title of this post, the TL;DR answer:

flowchart1.svg
Click to expand...

Nice article, John! You might want to note that the TeleGPS can transmit APRS packets that are decodeable by any ham TNC including the ones built into the Kenwood and Yaesu handheld radios. So you don't absolutely have to use their dongle and a laptop.


Sent from my iPad using Rocketry Forum
 

Similar threads

P
Issues with new GPS modules
Replies
10
Views
3K
PhysicsGuy
P
plugger
Using a Software Defined Radio (SDR) to decode APRS packets
Replies
12
Views
7K
plugger
plugger
rocketgeek101
Best GPS tracking system?
2 3 4
Replies
112
Views
25K
manixFan
manixFan
BryRocket
Yaesu VX-8R or Kenwood TH-D7 or TH-D72 or similar radio with APRS/TNC capabilities.
Replies
9
Views
2K
manixFan
manixFan
ksaves2
GPS Map 78 on sale for APRS tracking
Replies
0
Views
630
ksaves2
ksaves2

Latest posts

Back
Top