Tuesday, May 07, 2013

ESTcube: radio details

Technical Details: packet downlink

  • Frequency: 437.505 MHz
  • Frequency deviation: 3.5 kHz
  • Modulation: 2FSK
  • Output power: 0.5 W
  • Bitrate: 9600 bps
  • Callsign: ES5E-11
  • Packet format: AX.25 UI frames
  • Data payload per packet: up to 239 bytes
  • Active: during commisioning period - mainly over the Europe, later also periodically sending housekeeping data in bursts after every 3-4 minutes

Technical Details: CW beacon

  • Frequency: 437.250 MHz
  • Modulation: CW
  • Output power: 0.1 W
  • Bitrate: approximately 9 bps, 18 WPM
  • Callsign: ES5E/S
  • Sending period: 3 to 4 minutes
  • Sending format: mostly letter-coded HEX numbers (see conversion table below)

Groundstation requirements

While CW beacon can be received with very simple setup (even small handheld yagi will do) and either CW-capable transceiver or SDR receiver, for packet downlink requirements are more serious. Example minimal setup to receive successfully ESTCube-1 is given as following:
  • Yagi antenna with gain more than 16 dBi, preferably a crossyagi
  • Low noise preamplifier for 70cm band
  • Antenna rotator for both azimuth and elevation
  • Transceiver capable to receive 9600 bps packet
  • G3RUH-type TNC (e.g. Kantronics KPC-9216+) or SDR with appropriate software (e.g. based on https://www.cgran.org/wiki/ESTCube-1Receiver)
  • Packet data could be received also using a soundmodem program - AGWPE, MixW, Linux Soundmodem, MultimonNG etc

Orbit info

TLE-s will be available via NORAD: http://www.celestrak.com/NORAD/elements/
Preliminary TLE-s for ESTCube-1 are following:
1 00000U 00000    13127.17171296  .00000000  00000-0  10000-3 0 00005
2 00000 098.1390 205.7730 0134000 220.5400 211.2631 14.71982716000009

How to send reports to es5e@estcube.eu

When sending received data to given e-mail address, please add following information
  • Your name
  • Your callsign (if exists)
  • Skype contact (if desired)
  • Location in geographical coordinates or WWL locator
  • Time of acquisition of signal (UTC) (day:hour:minute:second)
  • Time of loss of signal (UTC) (day:hour:minute:second)
  • CW data as an ASCII string (if recieved)
  • Packet data as binary attachment or decoded AX.25 packets in ASCII HEX (if recieved)

Interesting and useful for us would be also additional information such as:
  • Short description of equipment
  • Signal to noise ratio interval (min-max dB) or
  • Signal strength interval (min-max S level)
  • Qualitative description of radio link (tumbling? abrupt losses?)
  • Other comments

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