Balloon Release Saturday 25th October 2014

Balloon scheduled to release Saturday 25th of October at 10:30am Location Ancona near Bonnie Doon Vic.

Frequency UHF FM 434.650 25 mw

Modes:  Thor  Telemetry, 1200 FEC Telemetry and SSDV, Olivia  Telemetry, 4800  Telemetry and SSDV, 9600  Telemetry

Latest Prediction


Hi all,

Just a few tips on decoding for Saturday 25th October 2014 based on observation and testing.


Olivia and Thor (Use FLDIGI)

The payload has a function that sends out a mode identifier (called RSID). For this to work on FLDIGI, you need to click on the RX RSID button top right panel of FLDIGI. This will AutoDetect the Oliva and Thor modes and configure FLDIGI.

Also, there is another configuration item in FLDIGI that searches the entire passband in FLDIGI for the RSID signal. What this means is that, if you have incorrectly set where the frequency of the tones are going to be decoded from, it will automatically detect this and move the decoder where it needs to be. If you do not click on this configuration item, it will not search the entire passband.

The balloon has been registered with HAB and will appear as MTG002. You can download the balloon parameters of the flight (you need to be using the HAB version of FLDIGI)

1200, 4800,and 9600 FEC

To decode this you need the TNCEMULATOR program. With higher baud rates, (especially 4800 and 9600) you need to come out of the discriminator of the radio (or use a dongle like FUNCUBE). 1200 will work from an audio out but the discriminator is still better. With these modes, you need to turn off any extra sound card settings around AGC/ALC enhancements etc. All of these will add distortion to the data signal (audio will sound find, but the data waveform will be corrupted). Also, it is not recommended to use VAC for the higher speeds. This is because they sometimes insert pops and clicks which can wipe out a perfectly good data  packet. You will need to adjust audio input levels so that it’s not too loud or too soft going into the application. Red bar about 1/2 to 3/4.


There is a button to reverse the phase called “reverse”. If you are coming out of the discriminator and you are not decoding the packets, then, tick this check box.


There is a mode that has been setup called SSDV. On this payload, images will be transmitted using 1200 baud and 4800 baud. All you need to do is select SSDV RX.

General notes

With both programs, you will need to set the call sign and lat,long (decimal degrees) and enable logging. In the TNC program it’s the enable web logging checkbox. In FLDIGI it’s in the configuration item.




Thor           Telemetry

1200 FEC Telemetry and SSDV

Olivia         Telemetry

4800          Telemetry and SSDV

9600          Telemetry


Above all, have fun on the day ! Cheers /DD VK3TBC


New Module FM mode

After lots of development and testing our new FMPSB module has been performing fantastic!

FMPSB output test

FMPSB output level and deviation test

Our new FMPSB  module is driven by a Teensy 3.1 ARM Processor using  a Radiometrix NTX2 that transmits Thor 16 and FEC 1200, 4800, and 9600 FEC based on FX25, additionally the FMPSB can transmit APRS and SSDV.

One of the reason to develop a payload on FM is to enable anyone with a scanner receivers to  be able to participate with the tracking without having to use a SSB receiver. I think we will also find some advantage in being able to quote a stationary frequency in order to detect the payload unlike the drifting we had with SSB. High altitude tests are still to take place to see how stable this frequency will be.

We are hoping to involve enthusiast with tracking that are not necessarily radio hams.

FMPSB 13.67gm


Top side of FMPSB with the 25mw Radiometrix module and power inverter under side.

GPS is a uBLOX MAX-7 Pico Breakout with Chip Scale Antenna




UHF Antenna is a 1/4 vertical. Payload is shown upside down



Payload with one Saft Li-SOCl2 Lithium Battery


QuadCopter Payload Test


QuadCopter Payload Test

Hovering at only 500 meters AGL our payload could be heard more than 70 klm away from Romsey Victoria over into the Melbourne South Eastern Suburbs. Not bad for 25mw FM




Happy New Year – PSB-6 and PSB-7

PSB-6 and PSB-7 will be our first HAB releases of the year over the weekend of 18-19/1/2014, when we will launch two balloons from Southern NSW.

The first balloon will have SSDV, RTTY, APRS and spread spectrum on VHF/UHF. The second one will have THOR4, JT65 and WSPR on HF, and SSDV on UHF. We are expecting 30,000m altitude on both balloons.

Spread spectrum transmission will be on our new tracker, using Zachary Manchester implementation for project KickSat ( See here for project details ). The binary 0s and 1s are modulated with two 511-bit Gold sequences before transmitted at 64kbps using MSK. As confirmed by Zac, this will be how the Sprite spacecrafts will transmit after launch. Our payload telemetry will alternate between RTTY and Gold codes on 434.075Mhz.

This will be the first flight for our new pico tracker:

Reception of the Gold codes will require GNURadio, and a supported SDR receiver (RTL or Funcube should work). Zac has some instructions on installation here. He is in transition from using Gnuradio 3.6 to 3.7 so the installation script will require some tweaking. If you are familiar with Linux or have used GNUradio this should be straight forward.

The HF transmissions will be time-scheduled as previously done on PSB-5, minus 40m band.

Screen Shot 2014 01 01 at 8 03 38 AM

Transmissions in the first half of the hour (minute 0-29) will be on 30m, and 20m on the second half of the hour (minute 30-59). In each 10 minute block the sequence will be THOR4 (5 minutes), JT65 (2 minutes) and WSPR (2 minutes).

We will have test transmissions from Melbourne on HF and UHF from time to time in the next few weeks, and would appreciate any test reports or comments. Please include your location in the test reports, and send them to

Hope to see you on the launch days :)

PSB-5 launched

PSB-5 was released and recovered yesterday.


The flight lasted 5 hours, gaining maximum altitude of 18,914m.

We were able to test HF telemetry on multi bands and multi protocols with hams and non-hams around Australia. Telemetry was received from as far as WA 2,500km away.

THOR4 was very good with HF noise, and was easy to use with dl-fldigi. It would make a good choice for HF telemetry.

JT65 was solid, however some work will need to be done to integrate it with tracking site. With the limitation of 13 characters of free-text per message, it would be ideal for an extension of the JT65/9 family of protocols to be developed for telemetry. The time-synced start of transmission is also not optimal for mobile telemetry tracking.

WSPR was working well, we had 26 WSPR spots on all bands, the majority was on 30m. The main advantages of WSPR for us is the reliability, and number of existing receiving stations. Like JT65, extension to the protocol would be required to make it useful for HF tracking.

Most of the initial HF telemetry was received on 30m at the time of launch, and we could see 40m and 20m coverage coming in at the end of the flight. For future flights we probably will use only 30m and 20m for telemetry.

The star of the experiment however was the Raspberry Pi computer that was multi-tasking all HF protocol encoding and transmission, and house-keeping tasks, including GPS sync for time and frequency, RF generation, SSDV image encoding, communicating with GPS tracker, under extreme conditions that saw the ambient temperature rising to 66 degree Celsius (payload insulation was working too well!), and constant payload movement.

The complex payload could not have been developed and tested in such a short time for us without the versatile linux environment on the Pi. It does have limitations but we managed to address many of them for the flight. Still more work to do, but the Raspberry Pi has proven to be a very versatile and mature platform for ham radio and HAB experimenting.

A big thank-you to everyone for assistance with tracking, and testing before the launch.

Credits also goes to various people that contributed to the softwares and protocols associated with the experiment, such as Joe Taylor K1JT, Oliver Mattos and Oskar Weigl who implemented PiFM, MD1CLV, PE1NNZ for coding WSPR on the Pi, who gave us the idea of implementing other protocols on the Pi, and Philip Heron for SSDV codes.

SSDV photos

2013 11 16 01 11 36 PSBPI 61F

2013 11 16 02 58 05 PSBPI 624

Payload landing site

2013 11 16 07 28 05 PSBPI 62B


PSB-5 will be launched from Bendigo on 16th November 2013.

We are sending away a Raspberry Pi with high-def Pi-Cam camera, interfacing to our standard tracker.


One main objective of the flight is to test HF tracking. DominoEX8 THOR4, JT65 and WSPR will be the three transmission protocols, beside the usual RTTY/SSDV on UHF.

DominoEX8 was chosen as one of the protocols to be tested on the flight, but initial tests showed that without Forward Error Correction (FEC), it was lagging far behind JT65, at least in our intended application of telemetry tracking on HF.

Thanks to a suggestion by Mark VK5QI, we replaced DominoEX8 with THOR4 at the last minutes, and that looks much better. THOR4 uses the same modulation scheme as DominoEX8 (incremental FSK) but with FEC.

The predicted path should be something like this, but we will need to run the prediction closer to the date.

Untitled 9

The payload will send back SSDV images and telemetry on UHF until it is beyond radio line-of-sight. After that HF will be the only way of getting telemetry from the payload, assuming we can keep it afloat until then :)

To assist with tuning, the HF transmissions will be assigned different time slots, which are just the number of minutes in the hour.

Untitled 2

Basically it is transmitting on 20m band in the first 20 minutes of the hour, 30m band in the second 20 minutes and 40m band in the last 20 minutes. Please note the JT65 frequencies are not standard JT65 QSO frequencies.

In each 20 minute interval there will be 8 minutes of THOR4, 8 minutes of JT65, and 4 minutes of WSPR.

On UHF it will be 434.650MHz, RTTY 300baud, 8 None 1, 450Hz shift.

dl-fldigi can be used to decode RTTY/SSDV and THOR4. The data format for THOR4 is the same as normal RTTY telemetry, ie. sentences with call sign, sequence number, time, coordinates, altitude, speed, satellites, GPS status and battery voltage as can be seen in this fldigi decode for DominoEX8.

IMG 1299

Check here for instruction on RTTY/SSDV decoding:

With JT65, we will need to use WSJTX software from Joe Taylor

The existing JT65 protocol has a limitation of 13 characters per message, so our telemetry data will be sent as two JT65 packets:
Packet #1: VK3YT+Altitude(4 digits)+Satellite(2 digits)+Temperature(2 digits)
Packet #2: Lat+Long without decimal point+temperature sign (-/+)

Untitled 6

In the screen capture, the two lines of test telemetry are:
VK3YT00110725 & -37480144846

This translates to:
- Altitude = 0011 * 100 = 1100m
- Number of Satellites = 07
- Temperature = 25C
- Lat = -37.480
- Long= 144.845

If you receive JT65 telemetry from the payload, please send a screen capture or the two lines to and we will manually upload that to If JT65 proves to be viable for long range telemetry we will look at integrating the decoding software with

WSPR can be decoded using WSPR software

You can check the WSPR spots (received transmissions from a WSPR beacon) here

WSPR propagation map can be found here

When looking for the signals, the HF frequency should be quite accurate as that is GPS compensated. You will need to check the transmission timeslot table, and look for the signals either audibly or visually.

This is spectrum sample for a THOR4 signal.

Untitled 3

This is spectrum sample for a JT65 signal. Note the very narrow bandwidth of less than 400Hz. Each JT65 transmission starts on the second second of the minute and completes in 46 seconds. Therefore time on the computer has to be accurate within 1 second of UTC time. Please consider syncing the time with internet time servers

PastedGraphic 1

Actual RF spectrum from the Pi after a LPF


Tracking data will be uploaded on the day to

Initial testing looks promising, this is a WSPR transmission received from the payload. The distance is 16,000km.