Difference between revisions of "Pico Trackers"
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|Name=Pico Trackers | |Name=Pico Trackers | ||
|Status=In progress | |Status=In progress | ||
− | |Contact=User: | + | |Contact=User:Bertrik_Sikken |
}} | }} | ||
+ | |||
+ | Current status: | ||
+ | * software is basically ready | ||
+ | * pico tracker boards still have to be populated with actual electronic components | ||
== Intro == | == Intro == | ||
This page is about a so-called tracker for use with small ("pico") balloons, | This page is about a so-called tracker for use with small ("pico") balloons, | ||
− | which is light-weight electronics board carried by a balloon | + | which is light-weight electronics board carried by a balloon and sends telemetry back to earth. |
− | + | == Software == | |
+ | The software of the payload tracker basically does the following: | ||
* get position data from the GPS receiver | * get position data from the GPS receiver | ||
− | * | + | * get temperature and battery voltage (optionally barometric pressure) |
* broadcast this data using a radio transmitter (RTTY, 70cm band, about 10 mW) | * broadcast this data using a radio transmitter (RTTY, 70cm band, about 10 mW) | ||
− | * repeat | + | * repeat until battery is exhausted ... |
+ | |||
+ | |||
+ | The source code can be found at | ||
+ | https://github.com/bertrik/picoballoon | ||
+ | |||
+ | It is based on the source of the pFalcon balloon by Nick Blommen. | ||
+ | |||
+ | Special features: | ||
+ | * (runs the GPS in low-power mode for extra battery savings) | ||
+ | * resets the RFM22 radio every 8 cycles, in case it goes weird because of low temperature | ||
== Hardware == | == Hardware == | ||
+ | The hardware consists of a custom PCB, a uBlox6G GPS receiver, an RFM22B transmitter, all controlled by an ATMega328. | ||
+ | |||
+ | === Power budget === | ||
+ | To reduce the power consumption as much as possible, the board runs at a low voltage, 1.8V. | ||
+ | The AVR clock frequency needs to be limited to 4 MHz, as this is the fastest the AVR can run at this voltage. | ||
+ | See [http://ava.upuaut.net/?p=383 here] for more information on running at low-voltage / low-frequency mode. | ||
+ | |||
+ | Current estimates: | ||
+ | {| class="wikitable" | ||
+ | |- | ||
+ | ! Component !! current !! Remark | ||
+ | |- | ||
+ | | RFM22B || 27 mA || 27 mA @ +11 dBm transmit | ||
+ | |- | ||
+ | | uBlox 6G || 12.2 mA || 22 mW @ 1.8 V Power Save Mode (1 Hz) | ||
+ | |- | ||
+ | | AVR || 1.7 || active current, 4 MHz, 3V | ||
+ | |- | ||
+ | | Total || 41 mA || current drawn from the 1.8V boosted voltage | ||
+ | |} | ||
+ | |||
+ | Assuming 1.2V average battery voltage and adjusting for step-up ratio (1.8V / 1.2V) and voltage converter efficiency (60%), this means about 103 mA average current draw from the battery. | ||
+ | An Energizer 1.5V primary lithium battery has a capacity of about 3000 mAh, so it is expected to last approximately 29 hours (3000 mAh / 103 mA). | ||
+ | |||
+ | === Weight budget === | ||
+ | Most commonly used for pico balloons seems to be the Qualatex 36 inch foil balloon, see [http://randomsolutions.co.uk/Random_Aerospace/Balloons.html]. | ||
+ | This balloon weighs about 37g and has a volume of about 100 liter. | ||
+ | See [http://ukhas.org.uk/projects:microballoons:data here] for a graph of reachable height vs payload weight and maximum free lift to reduce the chance of bursting. | ||
+ | |||
+ | A possible alternative balloon is a Qualatex 36 inch latex balloon, weighs about 35 gram and a volume of about 400 liter (fully inflated). | ||
+ | |||
+ | Rough weight estimates: | ||
+ | {| class="wikitable" | ||
+ | |- | ||
+ | ! Component !! weight !! Remark | ||
+ | |- | ||
+ | | Balloon || 37 g || assuming Qualatex 36 inch latex | ||
+ | |- | ||
+ | | Battery || 15 g || one 1.5V lithium AA (non-rechargable) | ||
+ | |- | ||
+ | | Enclosure || 10 g || insulation to reduce RFM22B drift, "rope", etc. | ||
+ | |- | ||
+ | | PCB + components || 5 g || rough guess | ||
+ | |- | ||
+ | | Miscellaneous || 5 g || battery holder, wiring, antenna, etc. | ||
+ | |- | ||
+ | | Total || 72 g || 35 g excluding balloon | ||
+ | |} | ||
+ | |||
+ | === Schematic === | ||
Schematics: | Schematics: | ||
* [[File:Picofalcon - Power.pdf|power-circuit]] | * [[File:Picofalcon - Power.pdf|power-circuit]] |
Revision as of 21:17, 20 March 2014
Project Pico Trackers | |
---|---|
Status | In progress |
Contact | User:Bertrik_Sikken |
Last Update | 2014-03-20 |
Current status:
- software is basically ready
- pico tracker boards still have to be populated with actual electronic components
Intro
This page is about a so-called tracker for use with small ("pico") balloons, which is light-weight electronics board carried by a balloon and sends telemetry back to earth.
Software
The software of the payload tracker basically does the following:
- get position data from the GPS receiver
- get temperature and battery voltage (optionally barometric pressure)
- broadcast this data using a radio transmitter (RTTY, 70cm band, about 10 mW)
- repeat until battery is exhausted ...
The source code can be found at
https://github.com/bertrik/picoballoon
It is based on the source of the pFalcon balloon by Nick Blommen.
Special features:
- (runs the GPS in low-power mode for extra battery savings)
- resets the RFM22 radio every 8 cycles, in case it goes weird because of low temperature
Hardware
The hardware consists of a custom PCB, a uBlox6G GPS receiver, an RFM22B transmitter, all controlled by an ATMega328.
Power budget
To reduce the power consumption as much as possible, the board runs at a low voltage, 1.8V. The AVR clock frequency needs to be limited to 4 MHz, as this is the fastest the AVR can run at this voltage. See here for more information on running at low-voltage / low-frequency mode.
Current estimates:
Component | current | Remark |
---|---|---|
RFM22B | 27 mA | 27 mA @ +11 dBm transmit |
uBlox 6G | 12.2 mA | 22 mW @ 1.8 V Power Save Mode (1 Hz) |
AVR | 1.7 | active current, 4 MHz, 3V |
Total | 41 mA | current drawn from the 1.8V boosted voltage |
Assuming 1.2V average battery voltage and adjusting for step-up ratio (1.8V / 1.2V) and voltage converter efficiency (60%), this means about 103 mA average current draw from the battery. An Energizer 1.5V primary lithium battery has a capacity of about 3000 mAh, so it is expected to last approximately 29 hours (3000 mAh / 103 mA).
Weight budget
Most commonly used for pico balloons seems to be the Qualatex 36 inch foil balloon, see [1]. This balloon weighs about 37g and has a volume of about 100 liter. See here for a graph of reachable height vs payload weight and maximum free lift to reduce the chance of bursting.
A possible alternative balloon is a Qualatex 36 inch latex balloon, weighs about 35 gram and a volume of about 400 liter (fully inflated).
Rough weight estimates:
Component | weight | Remark |
---|---|---|
Balloon | 37 g | assuming Qualatex 36 inch latex |
Battery | 15 g | one 1.5V lithium AA (non-rechargable) |
Enclosure | 10 g | insulation to reduce RFM22B drift, "rope", etc. |
PCB + components | 5 g | rough guess |
Miscellaneous | 5 g | battery holder, wiring, antenna, etc. |
Total | 72 g | 35 g excluding balloon |
Schematic
Schematics:
Andere benodigde onderdelen
Designator | Description | Manufacturer | Manufacturer Part Number | Manufacturer series | Package | Value |
ANT1 | ANTENNA | Johanson Technology Inc | 1575AT43A0040 | GPS ANTENNA | ||
C1 | Capacitor - non polarized | 0805 | 0.1uF | |||
C2 | Capacitor - non polarized | 0805 | 0.1uF | |||
C3 | Capacitor - non polarized | 0805 | 0.1uF | |||
C4 | Capacitor - non polarized | 0805 | 0.1uF | |||
C5 | Capacitor - non polarized | 0805 | 18pF | |||
C6 | Capacitor - non polarized | 0805 | 18pF | |||
C7 | Capacitor - non polarized | 0805 | 0.1uF | |||
C8 | Capacitor - non polarized | 0805 | 0.1uF | |||
C9 | Capacitor - non polarized | 1210 | 10uF | |||
C10 | Capacitor - non polarized | 1210 | 10uF | |||
C11 | Capacitor - non polarized | 0805 | 0.1uF | |||
C12 | Capacitor - non polarized | 0805 | 1uF | |||
CON2 | 6 pin 2.54mm Dual Row Pin Header | |||||
CON3 | SMA | Emerson | 142-0701-801 | SMA (End-Launch) | ||
CON4 | CON JST BOX 2P | JST | JST 2P | |||
CON5 | 3 pin 2.54mm Pin Header | |||||
FB1 | Ferrite Bead 0805 | Murata | BLM21BD102SN1D | EMIFIL | FB1 | |
L1 | SMD Shielded Tiny Power Inductor WE-TPC, L=2.5µH | Wurth | 744031002 | WE-TPC 3816 | 2.5 µH | |
LED1 | Led | 0603 | 2mA - 1.8V | |||
LED2 | Led | 0603 | 2mA - 1.8V | |||
R1 | resistor | 0805 | 2K2 | |||
R2 | resistor | 0805 | 2K2 | |||
R3 | resistor | 0805 | 10K | |||
R4 | resistor | 0805 | 10K | |||
R5 | resistor | 0805 | 1K6 | |||
R6 | resistor | 0805 | 1K6 | |||
R7 | resistor | 0805 | 10K | |||
R8 | resistor | 0805 | 475K | |||
R9 | resistor | 0805 | 182K | |||
U1 | GPS | UBlox | MAX-6G | |||
U2 | uC | Atmel | ATmega328P of [2] | ATMEGA328P-AU | ||
U3 | Tranceiver | HopeRF | RFM22B | |||
U4 | Pressure Sensor | Bosch | BMP085 | |||
U5 | DC/DC Regulator | TI | TPS61200 | tps61200drct | ||
XTAL1 | 4Mhz Crystal | TXC CORPORATION | AT-4.000MAGE-T | HC49/US | 4MHz |
Parts Pricing
Upu's store
- Zo'n €33,- per setje (gps+antenne, 434MHz zender)
Farnell
- Om van alles één te hebben is het ongeveer 7,87 euro.