Clueless on Rocket finding, GPS or RF

I am mechanically minded. That at least for me means I am clueless when it comes to all things electrical. Not sure why but thats the way this brain works.

I want to start putting a finding solution into my rockets as they are starting to get larger and go higher. I have a few basic questions as I jump head first into this.

There is another thread in this section about a cheap handheld that will receive GPS information from the BRB transmitters. I am concerned about lost signal once the rocket is on the ground. Is it possible to direction find without an s-meter? If it is, what equipment do you need and how do you do it? I read an article, forget by who (female), about direction finding and only using the ear and closing her eyes to determine strong signal and direction. Is this truly possible? I am looking for simple and cost effective. I must be in the minority when it comes to rocketry but I do not have the funds for equipment that other people seem to buy as just another rocket purchase. hundreds of dollars it a lot of money for me. So I want something that works, is reliable and easy to use. The BRB/handheld seems to be a pretty elegant solution. Again I am mechanical so I can build just about anything including antennas if that helps cut costs.
Thanks for the help.

Welcome on board! Do you fly with a club? See if they already have tracking gear you can borrow. Or see if a fellow flyer has gear you can borrow.

And 2nd hand receiver shopping at a local amateur radio "hamfest" may turn up a deal.

That assumes you're willing/able to get your ham radio license.

BrAdam said:

I read an article, forget by who (female), about direction finding and only using the ear and closing her eyes to determine strong signal and direction. Is this truly possible?

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Yes, this is perfectly possible with the right receiver; I never look at the meter on a Com-spec. YMMV on cheaper receivers and FM versus CW.

The article (by Sue McMurray) is at https://www.privatedata.com/byb/rocketry/rocket_electronics/walston.html

The cheapest RDF option is a Big Red Bee transmitter, a scanner or cheap HT, and a homemade Yagi antenna.

And, as Will mentions, you have to have a ham license to be legal.

I fly at Bong in Wisconsin either at TWA launches or Woosh launches. I am sure there are people who will help at the launches (both groups are very friendly bunches) but I like to be self sufficient when it comes to equipment. I would hate to break or loose somebody else's stuff. I plan on studying for the license test and have that taken care of before springtime launches and LDRS this summer. I will have to look around for clubs. Based on listings on the web there are plenty to contact and I am sure they must have swap meets.

Can you use the GPS BRB transmitter and RDF it when it is on the ground? Or if you are getting a signal you are always getting GPS coordinates?

I have experience using BRB RDF trackers. I use a Yaesu handheld, Vx-3 model and a 7 element yagi from Arrow Antennas. You asked about tracking without a s-meter. In my opinion it is NOT possible, even remotely, to track without an s-meter on this equipment at the ranges I'm used to (approx 1 mile max).

At the outer edge of that range, it's possible to track by "does it break the squelch". When you get to a point where the signal opens the squelch on its own and does so in nearly every direction, the beep is a beep is a beep. I can't distinguish between them. Can you do it for a bit by listening to how much background noise there is? Yeah, sort of.

My take is use the s-meter. Program your beeps to be longer than the stock setting. This gives you a little wiggle room while it's transmitting. At some point the transmitter will overpower the shielding in the case of the receiver, or start getting into the coax wire. You get a full power signal in a large area (nearly 180 degrees, sometimes more--- but you're in a corn field and 40 yards away might as well be a mile) so install an Arrow Antenna offset attenuator. S-meter, yagi, some triangulating, and at the end, the attenuator. This will put you within about 10 feet.

You can RDF on the GPS / APRS signal but it's very short. RDFing a quick beep is harder than a longer one. A longer beep... you can swing the antenna a few degrees while it's transmitting. A short beep goes like: point and wait.. point a few degrees off and wait.. point and wait. Harder to do and slower.

Edit: Receiver in FM mode.

Nat

BrAdam said:

Can you use the GPS BRB transmitter and RDF it when it is on the ground? Or if you are getting a signal you are always getting GPS coordinates?

Click to expand...

Yes, you can DF the 2m and 70cm BRB stuff.

I haven't used the 900MHz stuff but expect it would be a challenge if it is spread spectrum. If it is a discrete 900MHz frequency you could probably DF it with a scanner and Yagi antenna.

You should get a GPS fix almost to the ground. Once you get to the location of the last fix you'll probably be able to decode packets again. You'll probably want a Yagi and a beeper to help with the "last 100 feet" issues.

Wingarcher said:

I have experience using BRB RDF trackers. I use a Yaesu handheld, Vx-3 model and a 7 element yagi from Arrow Antennas. You asked about tracking without a s-meter. In my opinion it is NOT possible, even remotely, to track without an s-meter on this equipment at the ranges I'm used to (approx 1 mile max).

Click to expand...

When I do RDF, I never use the meter. Instead, I rely on signal clarity and volume.

I own an offset attenuator, but never use it. Instead, I've learned to knock the radio off-frequency, change the antenna orientation, and shield the antenna.

To the OP, the single most important thing to learn about tracking is that it's more art than it is science.

-Kevin

troj said:

To the OP, the single most important thing to learn about tracking is that it's more art than it is science. -Kevin

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i.e. It requires practice in a controlled setting.

Wingarcher said:

I have experience using BRB RDF trackers. I use a Yaesu handheld, Vx-3 model and a 7 element yagi from Arrow Antennas... In my opinion it is NOT possible, even remotely, to track without an s-meter on this equipment at the ranges I'm used to (approx 1 mile max).

Click to expand...

Huh. All of my experience is with the Com-spec, which is 2-meter CW instead of 70-cm FM. The Com-spec is highly directional and I've had no problems tracking using audio only at ranges of at least a mile. I set out once with zero signal but a rough bearing and found a rocket 3+ miles away hidden in fairly dense scrub.

I've never used an FM system personally but your experience doesn't speak well for them relative to CW. Maybe the Com-spec is worth the extra expense. The BRB will do 70-cm CW but very few receivers can receive in that mode AFAIK.

The Yaesu will do CW, haven't tried it. Maybe there is a significant difference in CW vs FM and how the tones come out through the speaker with varying distance and antenna orientation. FM has been working nicely for me.

I feel that for the un-initated, the equipment I use and the way I use it makes it pretty much fool proof. Anyone can understand the goal of "find the highest signal strength on the scale" vs trying to get a sense for "was that beep stronger than the last?". Experience makes the second method viable and apparently reliable but using a meter makes the learning curve shorter and the "quick success, found it, got it, that was awesome, glad I bought the radio gear" feeling stronger for the beginner. Then it's learning the strategies to shorten up the walk- triangulation especially.

Kevin- try the offset attenuator.... strong directionality at 10 feet without playing games is awesome!!

I like the fact that the Beeline 70cm equipment fits in a 24mm tube. That means it goes for a ride in EVERYTHING I fly (I don't do LPR) in a modular, swappable pod system protected in the nosecone.

We did a 3.5 mile recovery with a Beeline from the MARS field. Had an oops on a L3 cert deployment and it was off to the races. Got to a point where we said.. dammit, we must be under it..... we were. ;-)

N

BrAdam said:

I fly at Bong in Wisconsin either at TWA launches or Woosh launches. I am sure there are people who will help at the launches (both groups are very friendly bunches) but I like to be self sufficient when it comes to equipment. I would hate to break or loose somebody else's stuff.

Click to expand...

I agree with you , I like to own my stuff, but if some have receivers at club you will not broke anything as you will use your transmitter in the rocket, you can start by purchasing a transmitter, use it at the club and later purchase a receiver , it's good to have the same equipment as the other.

mikec said:

Huh. All of my experience is with the Com-spec, which is 2-meter CW instead of 70-cm FM. The Com-spec is highly directional and I've had no problems tracking using audio only at ranges of at least a mile. I set out once with zero signal but a rough bearing and found a rocket 3+ miles away hidden in fairly dense scrub.

I've never used an FM system personally but your experience doesn't speak well for them relative to CW. Maybe the Com-spec is worth the extra expense. The BRB will do 70-cm CW but very few receivers can receive in that mode AFAIK.

Click to expand...

The Com-Spec is the same as a Big Red Bee with an offset attenuator. The challenge without the attenuator is that the BRB's signal is so strong that at 200 feet, the radio will receive the signal even with the radio's antenna removed.

The offset attenuator lets you set the radio to a frequency offset from where the transmitter is, so the radio is no longer directly picking up the signal. Instead, it all has to come through the antenna, then the attenuator, which offsets the frequency to what the radio is set to. In addition, the signal gets attenuated (reduced in strength) based on what the dial is set to.

So, BRB + Ham + offset attenuator = Com-Spec equivalent.

Where some of the packaged stuff really shines is in size -- the Com-Spec transmitters are more bulky than a Big Red Bee, but the L&L transmitters are tiny. An L&L transmitter will fit in a BT5!

-Kevin

BrAdam said:

I am mechanically minded. That at least for me means I am clueless when it comes to all things electrical. Not sure why but thats the way this brain works.

I want to start putting a finding solution into my rockets as they are starting to get larger and go higher. I have a few basic questions as I jump head first into this.

There is another thread in this section about a cheap handheld that will receive GPS information from the BRB transmitters. I am concerned about lost signal once the rocket is on the ground. Is it possible to direction find without an s-meter? If it is, what equipment do you need and how do you do it? I read an article, forget by who (female), about direction finding and only using the ear and closing her eyes to determine strong signal and direction. Is this truly possible? I am looking for simple and cost effective. I must be in the minority when it comes to rocketry but I do not have the funds for equipment that other people seem to buy as just another rocket purchase. hundreds of dollars it a lot of money for me. So I want something that works, is reliable and easy to use. The BRB/handheld seems to be a pretty elegant solution. Again I am mechanical so I can build just about anything including antennas if that helps cut costs.
Thanks for the help.

Click to expand...

Your preference - GPS or RDF - can be dictated by your local flying area and your flying habits.

RDF is easier to set-up and move from rocket to rocket than most (or all) GPS set-ups. With RDF you can track a really weak signal once the rocket has landed whereas GPS will suffer.

If you have a good track on your rocket, usually the last GPS position will get you back in a place where you can pick it up again and walk right to the rocket.

RDF transmitters are cheaper than GPS. This gap has narrowed, but it is still true.

I am not very experienced with GPS (two flights) but I have watched many GPS tracked flights. For extreme altitude flights, GPS is the bees knees. For routine/casual flying, i.e. 3 or 4 rockets in a day that stay below about 15,000' or so, RDF makes sense for me because of the easy set-up.

At Argonia, we can get up to about 1.5 miles or so LOS tracking via RDF depending upon the landing spot of the rocket. If it lays down in a low spot, that may be reduced to 3/4 mile or slightly less. This means you can virtually always get a track on an RDF transmitter from a road and then walk in. Almost all of the 'regulars' here use RDF on a consistent basis and unless the rocket meets its demise in some manner, we always find them.

Tracking takes practice. Many of us use the F&L set-ups and I use the S-meter extensively. The receiver has a built-in attenuator that lets us walk right to the transmitter while keeping the S-meter within a specific range. I couldn't do it with audible levels only.

One final tidbit, we have gone out to Black Rock twice and had an interesting discovery regarding tracking, that being: The playa attenuates radio transmissions. At BR, GPS tracking is best for rockets that you will lose visual track on. A long distance final position can be obtained, but you have to get pretty close to reacquire the signal. With GPS you have a reasonable idea where to go. With RDF, if you don't get a really good directional fix, you can look a really long time for a rocket because you don't know the distance. It can take some time to get close enough to reacquire the RDF signal. I experienced attenuation down to just over 1/4 mile - much less than we experience at Argonia.

Final word, RDF or GPS is an investment you make for your entire fleet. I almost NEVER fly without an RDF transmitter in a rocket. RDF finds rockets and there are always weeds or crops or long distances that can make finding rockets a challenge. That said, don't cheat yourself and your enjoyment of the hobby by cutting corners on your tracking investment. It will serve you well.

--Lance.

Join WOOSH. We have two Rocket Hunter receivers for club member use. There are one or two transmitters available for use as well, obviously must be replaced if lost.

Plan on joining Woosh but was waiting till the new year. I have a rotating work schedule so I don't make it to a ton of launches and have more time at home to practice.

my 2 cents on this thread.

If you're tracking FM signals, a signal strength meter is really, really helpful. I always use mine in addition to some of the other techniques mentioned above.

CW tracking is a different animal, and is easier done by listening to the quality of the signal. I have a CW capable radio, but use FM most of the time since I'm more comfortable with that setup.

In both cases, an attenuator can be extremely helpful, especially when close to, or using a powerful (100mw) transmitter.

The 70cm and 2 Meter APRS units can be heard (and tracked) just like any other FM beacon, but typically their transmissions are spaced further apart then how I set up my beacons. I've never had to resort to this except when my GPS fell out of it's payload bay and fell into the sage.

You can *not* DF the 900 Mhz spread spectrum radios -- at least I've never been able to "hear" them on my amateur radio receivers.

Greg

To add to Lance's comments about Black Rock....based on talking to people with way more radio knowledge than I, Black Rock is a combination of two things: It's almost perfectly flat, and the composition of the lake bed absorbs signals even more than most places do.

As an example, I flew a rocket to roughly 14K when I was there; we lost it on the way up, and didn't see it on the way down. But, due to GPS, we knew where it had last been in the air, on the way down, and started driving that way. We could see it again on the ground about the same time we could start picking up APRS packets again.

-Kevin