# Has anyone tried "Light Aprs" or PicoAPRS-Lite Trackers?

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#### DaveW6DPS

##### Well-Known Member
I have been looking at these, since they are popular with the ARHAB crowd. Since we have much higher weight budget, it seems like they would be a great APRS tracker choice for rocketry.

QRP Labs Light APRS.

PicoAPRS-Lite

Both are very light, with fairly modest power requirements, and are very inexpensive.

#### FMarvinS

##### Well-Known Member
Hi Dave,

A few members of the local ham club are into HAB and use the pico with good success. For about the same price, one can get a Byonics MT 2001 2 watt 2 meter transmitter for $99 and with accompanying GPS unit (60,000 feet=$64 or 270,000 feet = \$74). You can add a SparkFun open logger to record NMEA and later place in google earth for flight trajectory plot.
If you'd like, I can ask the HAB hams what their overall impression of the Pico is. Send me a pm with your questions.

Regards,
Fred, L2
ICBM, Camden, S.C.
KG4YGP

#### DaveW6DPS

##### Well-Known Member
If you'd like, I can ask the HAB hams what their overall impression of the Pico is. Send me a pm with your questions.
Thanks, but I was looking for experience using these in rockets.
I use Byonics and/or Big Red Bee for HAB.

#### WillMarchant

##### Well-Known Member
I have a PicoAPRS and it is a fun little gizmo. I haven't tried the Lite.

You’re specifically looking for 2m transmitters?

#### Stable1

##### Well-Known Member
I've used the QRP Labs Light APRS on two occasions with a pico balloon. For those unfamiliar with a pico balloon, it is a small super pressure balloon used for extended hi altitude flights -- some have circumvented the globe numerous times. Regular latex weather balloon will burst at 80 - 100,000 ft but the super pressure balloon will stay intact and float at around 30 - 40,000 ft. If you make it into the jet stream it can reach speeds of 100+ MPH. These boards are very light and require very little power. Mine flies on a 4.8, 50ma solar cell using two super-capacitors. The output frequency is fixed at 146.39Mhz in the US and has a 1 watt output. Here's a picture of my payload ready for it's next flight -- Just waiting for my hydrogen.

#### plugger

##### Well-Known Member
I have been looking at these, since they are popular with the ARHAB crowd. Since we have much higher weight budget, it seems like they would be a great APRS tracker choice for rocketry.

QRP Labs Light APRS.

PicoAPRS-Lite

Both are very light, with fairly modest power requirements, and are very inexpensive.
Hi Dave,

I had a quick look at these units and while they do look good from a pricing perspective there are some questions I'd have and comments I'd make before using them for rocketry. First off, will the GPS antenna "stand up" to our requirements? I don't think I've ever seen that type of antenna used for rocketry. Second question is around data logging. While they seem configurable to 5 second beaconing (which is what we want) but does either of the units store the flight log on-board? I'd want that as my primary reasons for flying GPS are A) assisting in recovery of the rocket and B) have a log of my GPS track for post flight review. If a solution can't do this I'm not that interested.

Historically I've stayed away from 2M hardware due to the antenna requirements. A 1/4 whip would need to be nearly 20 inches in length for this unit, correct? That would be my main gripe when compared to 70cm offerings.

#### DaveW6DPS

##### Well-Known Member
I have a PicoAPRS and it is a fun little gizmo. I haven't tried the Lite.

You’re specifically looking for 2m transmitters?
Not specifically 2 meters. I am mainly looing for inexpensive, light, and ready to go equipment. Just needing power and antennas makes these pretty ready to go.

I have also thought about the full PicoAPRS, since it would fit in the rocket easily and be useful for other applications.

#### DaveW6DPS

##### Well-Known Member
Historically I've stayed away from 2M hardware due to the antenna requirements. A 1/4 whip would need to be nearly 20 inches in length for this unit, correct? That would be my main gripe when compared to 70cm offerings.
I am looking at a 54mm minimum diameter (Mad Cow Go Devil) so there is plenty of length for an antenna; even a twinlead j-pole.

I am looking for just tracking, so datalogging is not a criterion.

Good point about the GPS antenna durability. With a K250 I don't expect really extreme g-forces, but I don't know if these are designed for much. Balloons are pretty gentle.

#### Stable1

##### Well-Known Member
Hi Dave,

I had a quick look at these units and while they do look good from a pricing perspective there are some questions I'd have and comments I'd make before using them for rocketry. First off, will the GPS antenna "stand up" to our requirements? I don't think I've ever seen that type of antenna used for rocketry. Second question is around data logging. While they seem configurable to 5 second beaconing (which is what we want) but does either of the units store the flight log on-board? I'd want that as my primary reasons for flying GPS are A) assisting in recovery of the rocket and B) have a log of my GPS track for post flight review. If a solution can't do this I'm not that interested.

Historically I've stayed away from 2M hardware due to the antenna requirements. A 1/4 whip would need to be nearly 20 inches in length for this unit, correct? That would be my main gripe when compared to 70cm offerings.
The antenna for the QRP Labs Light APRS is a small patch antenna. I had some difficulties getting a satellite lock in the house but worked OK outside. I think it would handle a "K" motor flight as long as it was protected. There is no on board storage it only beacons it's position.

#### elpis

##### New Member
I've used the QRP Labs Light APRS on two occasions with a pico balloon. For those unfamiliar with a pico balloon, it is a small super pressure balloon used for extended hi altitude flights -- some have circumvented the globe numerous times. Regular latex weather balloon will burst at 80 - 100,000 ft but the super pressure balloon will stay intact and float at around 30 - 40,000 ft. If you make it into the jet stream it can reach speeds of 100+ MPH. These boards are very light and require very little power. Mine flies on a 4.8, 50ma solar cell using two super-capacitors. The output frequency is fixed at 146.39Mhz in the US and has a 1 watt output. Here's a picture of my payload ready for it's next flight -- Just waiting for my hydrogen.

View attachment 417236

hello sir I have recently purchased 2 light a aprs for hight altitude balloons and I have a few questions

there is a line on the code that says

 //boolean GpsFirstFix=false;
boolean ublox_high_alt_mode = false;

should I change this true ?

#### Stable1

##### Well-Known Member
hello sir I have recently purchased 2 light a aprs for hight altitude balloons and I have a few questions

there is a line on the code that says

 //boolean GpsFirstFix=false;
boolean ublox_high_alt_mode = false;

should I change this true ?

boolean GpsFirstFix=false;
boolean ublox_high_alt_mode_enabled = false; //do not change this. ( My Emphasis )

It looks like this is part of an initialization routing. The value changes to true above 12,00ft. I flew this transmitter without any code changes except for my identification info in lines 37 - 45. Circumnavigated the globe 3 1/2 times. Last seen over China

#### plugger

##### Well-Known Member
I have been looking at these, since they are popular with the ARHAB crowd. Since we have much higher weight budget, it seems like they would be a great APRS tracker choice for rocketry.

QRP Labs Light APRS.

PicoAPRS-Lite

Both are very light, with fairly modest power requirements, and are very inexpensive.
Hi Dave, just wanted to chime back in and say since my initial response I've had some experience with the MediaTek 3333 GPS chipsets (Quectel L70 on the WiMo PicoAPRS unit) and they're garbage for rocketry related work. Same with the MediaTek 3339 chipped (Quectel L80). Out of the two units you linked to initially I'd go for the QRP Labs unit given it's using a Ublox-8 chipset which is a known good unit for our use case.

#### OverTheTop

##### Well-Known Member
With the GNSS antenna cantilevered out of the board like that I would just be adding some support to stiffen it up and/or damp it out a bit. As long as flexing there doesn't break any solder joints it should still work, but it needs something given the thrust pulsations that the solid motors make. Mabye a G10 rib on the rear side of the PCB?