How to Create a Linear Transponder using a RTL Dongle and HackRF with Gnu Radio.

How to Create a Linear Transponder using a RTL Dongle and HackRF with Gnu Radio.

I wanted to test the concept of a linear Transponder and how difficult would it be to build it with conventional components.

Hardware Configuration

Hardware required to build the Transponder.

1. SDR IQ demodulator with rtl dongle (RF In)
2. SDR IQ DSP processing system. Gnu Radio (DSP processing)
3. SDR IQ Modulator. HackRF (RF Out)
4. Background management system. (OBC) for additional telemetry.

Software required for Transponder.

1. SDR IQ demodulator. rtl dongle (RF In)
2. SDR IQ DSP processing system. Gnu Radio (DSP processing)
3. SDR IQ Modulator. HackRF (RF Out)
4. Background management system. (OBC)

Video of working Transponder.

Gnu Radio.

Transponder Block Diagram

RTL SDR Block.

RTL-SDR Source

Low Pass Filter Block.

 

Low Pass Filter Block

AGC Block.

AGC Block

Power Squelch.

Power Squelch

Osmocom Sink. (HackRF)

Osmocom Sink (HackRF)

FFT. (Spectrum View of input)

FFT Spectrum View

REF: Power point Slides at AMSAT SA

Ref:Source code is available on Github Version 4

After a wonderful day at the SA AMSAT satellite symposium I have learned the following.

After a wonderful day at the SA AMSAT satellite symposium I found the following very interesting. (24May2014)

http://www.amsatsa.org.za/

1. KLETSkous the 1U Cubesat build by volunteer Amateur Radio operators.

The planned payload for KLETSkous will be as follows.

• A Linear transponder (2m uplink and 70 cm downlink)bandwidth of 20 kHz
• Currently the frequencies in the 435.100 to 435.140 MHz range are considered for the uplink and 145.860 to 145.980 MHz for the downlink
• The scientific payload will be a experiment analysing "Worm Holes"  (This experiment will try and find the portholes between Sun and Earth).
• There was a live Transponder demo and a prototype of the space frame.

More information is available at http://www.amsatsa.org.za/

2) A presentation on the progress of the experiments on ZACube-1 was also very interesting.

ZACUBE-1 Cube sat Picture

• Very nice pictures were captured from the VGA cameras.
• Beacon TX power was also increased and should be easier to capture the signals.
• They are now slowly deploying the long wire HF antenna in the following few weeks to enable the HF experiments.

More info available at http://www.cput.ac.za/blogs/fsati/zacube-1/

3) A presentation on the experiments of a Satellite propulsion system (Vacuum Arc Thruster)

Vacuum Arc Thruster

• Vacuum arc thrusters are a potentially useful technology for use as microthrusters on microsats for the future.
• It is basically a spark plug that generate sparks in a vacuum to propel the satellite. by (Jonathan Lun PhD Student SANSA Space Science,University of the Witwatersrand)

New Satellite planed for Launch in January 2014 from ISS

LituanicaSAT-1 with amateur radio FM transponder to deploy from ISS.
( Launch at 1:32 pm EST on Wednesday, January 8 2014)
You should be able to here this satellite on the webSDR http://zr6aic.giga.co.za:8902

This satellite will be the first Lithuanian satellite.
Payload
1) VGA camera.
2) GPS receiver.
3) UHF CW beacon 100mW.
4) 9k6 AX25 FSK telemetry TX 2 watts.
5) FM Mode V/U transponder 150mW Voice Repeater.

• FM Transponder Uplink 145.950 MHz Downlink 435.180 MHz 
• AX25 Uplink 145.850 MHz AX25 Downlink 437.550 MHz 
• CW Beacon 437.275 MHz 

 Read more at http://amsat-uk.org/2013/04/12/lituanicasat-1/  , http://ly3h.epalete.com/?p=371 and here http://www.kosmonautai.lt/en/

Upcoming Satellites with transponders to look out for. FUNcube-1, FUNcube-2 on UKube-1, Delfi-n3Xt, FOX-1, FOX-2 and KletsKous

Upcoming Satellites with transponders to look out for.

FUNcube-1, FUNcube-2 on UKube-1, Delfi-n3Xt, FOX-1, FOX-2 and KletsKous (21 Nov 2013)

FUNcube-1 (1U CubeSAT) (More info available here http://www.batc.tv/vod/Funcube1.flv)
and here http://funcubetest2.files.wordpress.com/2010/11/funcube-handbook-en_v1.pdf
and https://warehouse.funcube.org.uk

Funcube-1

FUNcube-1 will launch from Yasny base located in Orenburg Region, Russia on a DNEPR.
Launch Date:expected to be late November  2013.(Also on this launch is tw

Day time mode (Education Mode) Telemetry mode.

• Beacon frequency: 1k2 BPSK 145.915Mhz
• Night time mode (Amateur Mode) Transponder mode.
• Transponder Up link 435.080 - 435.060 Mhz
• Transponder Down link 145.930 -145.950 Mhz

POD partners, ZAcube from South Africa and HiNCube from Norway
read more about it here http://zr6aic.blogspot.com/search/label/ZACUBE-1

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FUNcube-2 (3U CubeSAT) FUNcube-2 is a subsystem on the UKube-1 satellite.
More info available from http://amsat-uk.org/2012/10/20/funcube-2-boards-delivered-to-clyde-space/

Funcube-2 on  UKube-1 satellite

Communications systems:

• 1k2 or 9k6 BPSK Telemetry downlink 145.840 MHz
• FUNcube-2 1k2 BPSK Telemetry downlink 145.915 MHz
• FUNcube-2 Transponder SSB/CW uplink 435.080 – 435.060 MHz and downlink 145.930 -145.950 MHz
• S Band downlink 2401.0 MHz
• myPocketQub 437.425-437.525 MHz

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Triton-1 (3U cubesat) Launch  (21NOV2013)
ISIS-BV (Innovative Solutions In Space BV)

more details at http://www.isispace.nl/cms/index.php/projects/triton-missions

and http://www.southgatearc.org/news/january2012/triton_amateur_radio_cubesats.htm

• Main Downlink 145.815MHz & Backup Downlink 145.860MHz.
• 600-700 km sun-sync orbit.
• AIS (ship location service) radio science experiment.
• Two U/V FM to DSB (“AO-16 mode”) repeaters.
• Will be activated after 3 months (possibly both at once) 

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Delfi-n3Xt (3U Cubsat)
More info available from http://www.southgatearc.org/news/december2011/delfi_n3xt.htm

Communications systems:

• Downlink 145.870 MHz and 145.930 MHz
• Downlink 2405.00 MHz high speed
• Linear transponder Uplink 435.530 – 435.570 MHz Downlink145.880 – 145.920 MHz.

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FOX-1 (Fox-1 Assigned for launch in November 2014 on the ELaNa XII mission)
More info available from http://www.amsat.org/amsat-new/symposium/2012/2012_Symposium_Fox_Overview.pdf

Communications systems:

• FM analog transponder.
• Telemetry sent simultaneously with voice in sub-audio band as low-speed FSK.
• Data Mode FSK Digital data up to 9600 bps

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FOX-2
More info from http://www.southgatearc.org/news/december2011/delfi_n3xt.htm
Communications systems:

• Linear transponder.

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KletsKous (1U Cubesat)
More info available here http://www.amsatsa.org.za/KLETSkous2.htm and http://www.amsatsa.org.za/KLETSkous.htm


Communications systems:

• Linear transponder.  uplink 70cm  downlink 2 metre

TURKSAT 3USAT Satellite

TURKSAT 3USAT Satellite

You could listin to my websdr on Sat freq http://zr6aic.giga.co.za:8902/ (Egg Beater mark 2 Antenna)

Stats:

• Down-link 435.200 – 435.250 MHz Linear Transponder ("Tracking"mode "inverting")
• Up-link 145.940 – 145.990 MHz Linear Transponder.
• Beacon 437.225 MHz CW ( " YM2RTU "call sign)
• 680 km Low Earth Orbit (LEO)

Reception report submission page.  http://translate.googleusercontent.com/translate_c?depth=1&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=auto&tl=en&u=http://turksat3usat.tamsat.org.tr/info/&usg=ALkJrhgd6DgnRP57nAmSzIGxg5F8v5ufAQ

Here is the info regarding this satellite. http://amsat-uk.org/satellites/turksat-3usat/

Latest Kep's for TURKSAT 3USAT
New TLE info:  http://www.celestrak.com/NORAD/elements/tle-new.txt
Satellite 3USAT number: 2013-018C

Cube Bug-1 Satellite was launched on same rocket.