Tag Archives: GPS

Mar 5 2014

Galileo GPS closes down 23cm ATV Repeater DB0QI

AMSAT-UK Logo

AMSAT-UK Logo

The new Galileo GPS system that broadcasts across 1260-1300 MHz has resulted in the closure of a German ATV repeater.

The DARC report the Munich ATV repeater DB0QI has been closed down due to it jamming the Galileo Satnav Control Centre.

DB0QI was located 18 km from the Galileo GNSS receiver, another repeater that has been shut down is DB0ITV which was located 55 km from the receiver. It is believed both repeaters were running about 15 watts ERP.

DARC in Google English http://tinyurl.com/GermanyDARC

A 2006 Galileo GPS article by Peter Blair G3LTF highlighted the problems this system could cause, see
http://www.southgatearc.org/articles/galileo.htm

The Amateur Satellite Service has an important allocation at 1260-1270 MHz for Earth-to-Space (Uplink) communications. The Amateur Satellite Service has already seen its allocations at 2.4 and 5 GHz rendered unusable in urban areas due to WiFi and other licence exempt devices. The Amateur Satellite Service does not have any other global spectrum allocations in the key 915 MHz to 6 GHz region.

While the German announcement may relate to a single Galileo command station being used to test the initial satellites it clearly raises concerns about what will happen in a few years time when the full Galileo constellation is deployed and 1260-1300 MHz GPS units are in widespread use.

Jun 12 2012

Satpack: Arduino satellite tracking and doppler tuning

The Satpack is an ATmega328 controlled satellite tracker with doppler tuning. To calculate the position of the satellite, they use qrpTracker, which is an Arduino friendly program based on James Miller’s Pan-13. Next, the Arduino tunes the radio to listen to the transmitted Morse code. Amazing! It’s open source, so check out the link for a lot more information on building your own Satpack.

Here’s a video of the Satpack code tracking a few satellites. Note that the tone of the cubesat drifts a bit. The keps were a bit old, but in a addition, I just got a letter from James Miller, the author of Plan 13 who recommends some constants that are more in keeping with the earth model used in today’s GPS engines.

May 31 2012

23cm band covered by GNSS

An article in the May 2012 edition of the free publication Microwave Journal shows that all of 1240-1300 MHz except for two narrow gaps will be used by global navigation satellite systems (GNSS).

The article by Rachid El Assir, Rohde & Schwarz, conatin a chart that graphically illustrates where the GNSS systems will operate in 1240-1300 MHz band.

A gap of about 3 MHz occurs at 1240 and one of about a MHz at 1259 MHz.

Read Global Navigation Satellite Systems and Their Applications
http://www.microwavejournal.com/articles/17568-global-navigation-
satellite-systems-and-their-applications

Microwave Journal http://www.microwavejournal.com/publications/1

May 23 2012

UKube-1 is Taking Shape

UKube-1, the programme to launch the UK Space Agency’s first Cubesat mission, has reached an important milestone. Two payloads have now undergone pre-integration testing at Clyde Space’s facilities in Glasgow.

UKube-1. Credit: Clyde Space.

UKube-1. Credit: Clyde Space.

Miniature satellite UKube-1, is a collaboration between the UK Space Agency, industry and academia. Open University payload C3D and University of Bath payload TOPCAT were the first of the four payloads selected to be tested. These workshops provided the first opportunity to carry out physical and functional testing between the protoflight payloadsand platform subsystems.C3D imager. Credit: Clyde Space/Open University. (JPG, 2.7 Mb) 

The tests confirmed physical, electrical and operational interfaces between the subsystems. The tests represent the successful handover to flight integration and delivery from the interface emulator (supplied to payload teams by Clyde Space at the start of the program to facilitate rapid parallel development of subsystems).

C3D is a small imager which will take pictures of the earth and investigate radiation damage effects in space. It uses new sensor technology developed for space conditions.

TOPCAT (Topside Ionosphere Computer Assisted Tomography) will measure space weather conditions to inform users of the Global Positioning System (GPS) users using a dual-frequency GPS receiver designed especially for use in space.

With the remaining payloads due to be tested over the coming few weeks, the program continues confidently towards full integration in July.

UKube-1 will also take an educational subsystem called FUNcube, developed by the voluntary organisation AMSAT-UK, to encourage young people to learn about radio, space, physics and electronics. It contains a 1200 bps BPSK telemetry beacon and a 435/145 MHz linear transponder.

UKube-1 on BBC TV http://www.uk.amsat.org/5983

UKube-1 to launch in 2013 http://www.uk.amsat.org/5933