BRB Gps combo and dh-72

[GrapeFire]

Does anyone have any experience with the brb gps and rf unit with this handheld. I'm wanting to know how easy it is to receive gps packets but also track the rf as a backup. Is it super easy, or would a different handheld be required?

 

[ksaves2]

Does anyone have any experience with the brb gps and rf unit with this handheld. I'm wanting to know how easy it is to receive gps packets but also track the rf as a backup. Is it super easy, or would a different handheld be required?

Now do you mean the Rf tracker or GPS tracker? For GPS it works fine. Interface to an old Garmin 60Cs or 60 CsX with the round serial port in the back and you will have a total navigation solution that will track and compute a navigation solution to a rocket in real time while in flight.


This is a total solution to find on a map. You can buy these used on Ebay and don't have to use Garmin maps or subscription. Open Source Maps are downloadable although the database for services aren't any good. Not a problem if
just wanting to find rockets: https://garmin.openstreetmap.nl/

Go to the Electronics forum here and there is a sticky on GPS tracking. https://www.rocketryforum.com/showthread.php?45080-Setting-up-the-VX-8GR-and-TH-D72-for-BeeLine-GPS

If you want to RDF get a Yagi antenna and an electronic attenuator. Arrow Antennas can set you up and Marvin West has an economical attenuator: https://www.west.net/~marvin/k0ov.htm

Marvin also has a nice 50mW RDF tracker on the 2 meter band:https://www.west.net/~marvin/microhnt.htm

He can customize the morse code message. I have mine that does the ID it's a rocket tracker and gives my email address and my callsign all in morse code. Kurt

 

[rms]

Does anyone have any experience with the brb gps and rf unit with this handheld. I'm wanting to know how easy it is to receive gps packets but also track the rf as a backup. Is it super easy, or would a different handheld be required?

I use the dh-72 interfaced with a handheld garmin using a serial cable. It works really well and super easy.
Basically your call sign embedded in gps packet shows up on the handheld, go to the interfaced garmin, find your call sign on the list of destinations (i think it is under destinations but will have to check) Only your call sign will be on the list unless others are using BRB gps that you receive packets for as well. Prompt the garmin to "Go To " your call sign destination and an arrow will show you the direction and straight line distance to the rockets location. Describing it is harder than doing it, once you get comfortable with the handheld and gps setup.
I have been able to locate many rockets using this setup. Some recovered up to three miles away through terrain varying from open to wooded to really thick 10'-12' high bushes that are hard as heck to even walk through.


The dh-72 can also be used for rdf as well. In fact I had a rocket land in a thick stand of trees and we were unable to pin point it as the gps is accurate to only approx 30-50 feet depending on satellite lock. This sounds like a non issue until you can hardly walk through the trees and bushes! I took the antenna off the dh-72 and was able to further pin point the rf signal by tuning off the transmitting frequency and go in the general direction of the stronger signal. We were able to pin it down to approx a 10' circle and then found it higher up in the trees.

Greg

 

[ksaves2]

If strapped for cash a Garmin Legend can do it: https://www.amazon.com/dp/B000058BCQ/?tag=skimlinks_replacement-20
but buy one for a lot cheaper off of Ebay and not at this link.
The cable is like this: https://www.gpsgeek.com/products/in...-aprs-to-garmin-etrex-emap-geko-gps-receivers

The Garmin 60's are a lot nicer and I believe there are a few more Garmin round serial port units out there also. Otherwise interfacing becomes much more
difficult.

As an aside, this type of tracking has been possible for 12+ years with a Garmin/Kenwood D7A but was very expensive to buy and there was the process of
getting a Ham license.

BTW, I don't recommend a second hand D7A or D7A(g). I have two of them and the oscillator has gone off spec on both of them and are deaf for APRS tracking now. Not practical or economical to fix plus the TNC's on these units can peter out with no warning. I think it's been around since 1998.

Since Kenwood released the D74A which could also be used, the D72A has had a substantial price drop. The 74 though is ~$700.00 and is too rich for me.
If you already own a 72 and a TH-F6A you already have access to most of the features on the 74 except you won't have Bluetooth or D-Star. Kurt

 

[GrapeFire]

I understand the differences in the handhelds and interfacing, and money wont be that big of an issue, considering i'm going to make this a universal system for all my rockets. What my understanding with the gps, if for some reason the gps looses connection, you can still track the "squelch" of the rf transmitter, correct?

 

[rms]

I understand the differences in the handhelds and interfacing, and money wont be that big of an issue, considering i'm going to make this a universal system for all my rockets. What my understanding with the gps, if for some reason the gps looses connection, you can still track the "squelch" of the rf transmitter, correct?

Yes you can track the rf of the transmitter if it is transmitting. For rdf tracking you want to turn the squelch off. This allow turning the receiver frequency away from the transmitted frequency so that you get a faint received signal allowing you to zero in on it.
My worry would be if the gps wasn't transmitting packets it wouldn't be transmitting. I guess not a problem if you had a back up rf beacon.
Greg

 

[ksaves2]

You can open the squelch and hear the "Brrrrrrrrraaaappp" of the signal buried in the noise. I don't worry about having to RDF the signal because with the
handheld map, I just continue to proceed to the last known packet and eventually I get close enough to receive an updated position.

Now conceivably with a real long range flight or perhaps with the GPS not sending out a valid position after touchdown due to the GPS antenna facing the
ground or what have you, one could plug in an attenuator with a Yagi get a bearing and RDF track. That's a good backup strategy to be prepared for but I don't believe the average flier would face that scenario very often. Kurt