Building a SatNOGS groundstation: Buying components I (mechanical)

1) Trackingbox case:

– Dimensions: 310x240x110mm (approx.)
– Sealing: IP55 (or above)

(A) ABB box

However it may be hard to find from some locations. You have to drill your own holes anyway so you can prefer a box without pre-drilled side holes!

Ideally you are looking for these MPN:

1SL0828A00(*)  / with pre-drilled wholes

1SL0858A00(*)  / without pre-drilled holes

1SL0878A00(*) / without pre-drilled holes, acrylic front

RS-Online: 20-30 € Ships worlwide, from EU
Walker Industries: 12.60$ Ships from US

 

(PDF) ABB low voltage enclosers overview (schematics page 11)

(PDF) ABB IP44 and IP55 junction boxes in thermoplastic material with press-on lid

00828c

00828a

00828b

(Copyright by ABB SACE)

 

(B) Alternatives

Based on discussions in the SatNOGS forum, here some other possibilities to source similar boxes.

  • Bud Industries NBF-32022 (Digikey): Inside 135mm sufficient, however needs to add spacer.
  • Ebay Noname 310mmx230mmx110mm: Inner dimension is 5 mm shorter, and requires adjustment.

 2) Stepper motors NEMA17

Stepper motor sizes are with 1.7 x 1.7 inch (43.2 x 43.2 mm) faceplate, which is NEMA17 size.

Shaft type: Single
Body Length: 47mm
Shaft Diameter: Φ5mm
Shaft Length: 19.5mm

Possible partnumber: 17HS19-2004S, 17HS6002-27B

The stepper motors provide 0.59 Nm (84 ounce inch).

After the gear 1:60 the total torque is 35.4 Nm.

1 Newton meter ≈ 141.61 ounce inch

1 Kilogram meter ≈ 0.1 Newton meter

Building a SatNOGS groundstation: Grounding and lightning protection

Dealing with grounding and lightning protection is obligatory when setting up a roof antenna. Bad grounding might cause not only damage to your antenna and equipment but even your complete home electronics or ignite fire.

Lightning is dangerous for two reasons. Direct lightning conduction can cause impulse voltages of higher than 20 Megavolts, whileas induced voltages can also reach up to 10 Kilovolts. Very interesting I found also this quote [1]:

A lightning has  an impulse voltage of > 20 Megavolts and an impulse current above 100.00 Ampere. Multiplying both numbers, the resulting yields a power that would instantaneosly vaporize any conductor. It does not, because the condctor does not actually conduct the energy of the lightning. The a cable with a diameter of 10mm alumium or 8mm copper only lays out a path, through which the surrounding air gets ionized, through which the actual charge surge current flows. This ionized stream will has a diameter of 2-5 cm and will not ignite anything, as the grounding conductor has a resistance <3 ohms.

Continue reading Building a SatNOGS groundstation: Grounding and lightning protection

Increasing WR703N flash memory with ExtRoot on OpenWRT 14.07 with usb stick(Easy way)

There are one million awesome things you can do with small router and an OpenWRT firmware on it. I have been surprised how mature, easy to use and community driven it has become.  The WR703N is an awsome device and I have probably never seen such a small device (smaller than a smartphone) with so many features, an USB, Ethernet, Wifi and Linux running for just under 25$.

However 4 Mb is very few, even to run OpenWrt, and you quickly run into flash memory limits. But you can easily work around this limitation using ExtRoot, which allows you to include external USB devices or even network mounts. However the collection of instructions on how to setup ExtRoot makes it look more complicated than it is, and it can be (almost) performed completely by LuCi, OpenWRTs GUI interface in the latest stable release (Breaking Barrier 14.07).

Continue reading Increasing WR703N flash memory with ExtRoot on OpenWRT 14.07 with usb stick(Easy way)

Students(DE): 45. IAF student conference call for papers (deadline 01.05.2015)

The 66. International Astronautical Federation (IAF) congress takes place from 12.10 – 16.10.2015 in Jerusalem/Israel. The DGLR supports up to two students to participate in the congress.

Undergraduate and graduate level students (no more than 28 years of age) present technical papers on any project in space sciences, industry or technology. These papers will represent the specific work of the author(s) (no more than two students). The students presenting in this session will compete in the 44th International Student Competition. This session is NOT for team projects. Team project papers should be submitted to session E2.3.French, German, US, British and Canadian students submitting abstracts for the sessions E2.1 and E2.2 should apply via the national coordinators: – for France: Benedicte Escudier at: benedicte.escudier@supaero.fr – for Germany: Marco Schmidt at: schmidt.marco@informatik.uni-wuerzburg.de – for USA: Stephen Brock at: stephenb@aiaa.org – for Great Britain: Chris Welch at: Welch@isu. isunet.edu – for Canada: Jason Clement: Jason.Clement@asc-csa.gc.ca The guidelines for the student competition will be distributed from the session chairs to the authors after abstract acceptance

Attachment: iaf-studenten-2015

Students: ESA and Google Summer of Code events (deadlines: 27.03 / 30.04)

is open for applications! Support an open-source project of your choice and receive grants of up to 4000 €uro. The funding is granted for selected open-source projects.

The Google Summer of code is very comparable and open for any kind of open-source project, not only space-related and is applicable worldwide.
The ESA Summer of Code in Space is applicable and open for more open projects including hardware, software and research projects. However it is limited to countries that are part of the ESA.

GSOC – Google summer of code (6000 USD)
Application date: 16-27 march 2015
Mentor organization:
https://www.google-melange.com/gsoc/org/list/public/google/gsoc2015

SOCIS – ESA Summer of Code in Space 2015 (4000€)
Application date: Until 30 april 2015
Mentor Organizations:
http://sophia.estec.esa.int/socis/?q=node/13

There is only few advertisment so far, so go for it !

Building a SatNOGS groundstation: Buying components I (electronics)

This page is a work in progress and will be updated on the way.

Last update: 2015-03-04

Overview of SatNOGS electrical components (1)
Part Comment Cost Am Source
Realtek RTL2832U Radio receiver 12-23 € 1 Amazon(DE)
Ebay
NooElec(US)
LM2596 Board Voltage regulator 2-6 € 1 Ebay(HK)
Arduino Micro Pro Microcontroller 12-20€ 1 Amazon(DE)
Sparkfun(US)
TP-Link WR703N Router 25€ 1  Ebay
Pololu A49888 Stepper motor driver 5€ 2 Pololu(US)
Ebay
NEMA 17 Stepper motor 15€ 2 Pololu(US) 
Ebay
Stepperonline
Sum 91-114€

Overview of SatNOGS electrical components (2)
Part Comment Cost Am Source
Connector
TCST2013 Optical Sensor
Resistors
http://www.reichelt.de/CNY-37/3/index.html?&ACTION=3&LA=446&ARTICLE=6682&artnr=CNY+37&SEARCH=gabellichtschranke
Sum 91-114€

The prices included are the prices I found for which you can buy these components new. Many of those parts are well known in the hacking world and you often find them overpriced, therefore you can take these prices as an orientation.

RTLSdr (RTL2832)

The software defined radio USB stick is basically just a hacked DVB stick. You can find those at cheap prices starting from 12 €uro everywhere. However, since this products is not intended for this purpose, some improvements can be made to the design, for instance a better crystal oscillator for better frequency stability or diodes for a smoother supply voltage. This improvements can have effect on your temperature stability and frequency offset. However those are not critical, but a nice feature to have for just a couple Euro more.

Further, the receiver comes with a variety of different (supported) tuners (E4000, R820T, R820T2 among those as the ones which are most commonly around).

The E4000 was the original tuner which is said to have better performance than the later R820T. However ever since the E4000 is now hardly available and prices have skyrocketed. Between the R820T and R820T2 a comparison shows a marginally better background noise and sensitivity is achieved by the R820T2.

LM2596 Voltage regulator

The LM2596 is a very small, however very powerful and efficient switching step-down voltage regulator. It creates a lower output voltage (as for instance 5V) from a higher supply voltage. They can supply up to 2-3 amps which is sufficient for most projects and have a very small footprint. To avoid designing the whole converter including inductors, capacitors etc. you can buy simple breakout boards for just several €uro. However be aware that there exist plenty different breakout boards of different sizes. Use the ones which have dimensions of about 41mmx21mm, e.g. the common small footprint without a voltage display.

The breakout boards you commonly find only have an 33μH as you can see on the pictures (inductor marking 330). According to the datasheet the inductance for 12V->5V would be best to have a higher inductance (68 μH), but for the currents required, less than 1 Ampere@5 Volts, is still highly sufficient. The 5 Volt line has to supply has to power the RTLSDR takes about ~300mAWR703N router about ~100mA, the Arduino usually at less than ~25mA.

TP-LINK WR703N

Although you could use any (old) router that supports the open-source firmware OpenWRT that has USB, the WR703N advantages are its very small size (57x57x18mm³), very low power consumption and price, and that it is well known to the OpenWRT community (which is worth a lot). Disadvantages generally speaking are the fact that it has no external Wifi antenna and in the lower range of ram and flash memory. (Although there are documented hacks to increase both). If you are willing to invest some Euro more you can probably go for other supported routers (e.g. tl-wr1043nd) but then you can quickly run into space problems inside the tracking box.

Be sure not to buy the WR702N, although very similar it has to few memory to run the linux distribution and is therefore absolutely unusable for this purpose.

You can get this one for instance on Ebay or Amazon for less than 25€.

Building a SatNOGS groundstation: Introduction

The project uses many well established hacks and combines them in a very clever way,  without needing to re-invent the wheel.
Software Defined Radio for instance using an inexpensive DVB-T receiver hack allows to receive radio communications with a very wide bandwidth for just around 20$.
The usage of a small router TL-WR703N, which has been also whichs hardware has been well explored by the open-source community running an very customizable open-source firmware, OpenWRT, which has been around for a long time already and can be used easily on productive.

3D printing has been around for several decades and hit consumer market just a couple of years ago. There are plenty of software and hardware tools available for little money, or even suppliers on the internet, that allow cheap manufacturing of prototype parts.

SatNOGS team currently is a group of people based in a hackerspace in Athen, Greece.

You can find an illustrated assembly instruction for the mechanical parts and electronical parts here: http://satnogs.dozuki.com/Guide.

Website: https://satnogs.org/

(c) SatNOGS
(c) SatNOGS