2013-05-20

The World's Oldest Ham Radio Beacon

OZ7IGY - Next Generation Beacons

The world's oldest beacon · OZ7IGY in JO55WM · 28 MHz to 24 GHz.

OZ7IGY goes all the way back to the International Geophysical Year in 1957. From its start on 144 MHz it has ever since been on air continuously and on ever more and more bands. Today OZ7IGY transmits on 28 MHz, 40 MHz, 50 MHz, 70 MHz, 144 MHz, 432 MHz, 1,3 GHz, 2,3 GHz, 3,4 GHz, 5,7 GHz, 10 GHz and 24 GHz. Most of the HF, VHF and UHF technology used by OZ7IGY is old(er) land mobile equipment modified for the purpose. For the microwave bands most of the technology is dedicated radio amateur beacon designs while power amplifiers are often surplus.

However, given the latest developments in digital modulation techniques and RF-circuits it is time also for OZ7IGY to take advantage of these technologies. On 30 October 2012 the first two Next Generation Beacons were put on air after thorough testing and burn-in periods. The Next Generation Beacons platform is open to others and the software can easily be adapted to other modulations and sequences. Furthermore, is the new platform frequency and time locked to GPS. Thus the frequency accuracy is better than 5 mHz.

The new beacons on 28 MHz to 432 MHz transmit in a 1 min sequence starting with PI4 (call and locator) then CW (call and locator) and finally a carrier until next cycle begins at the 00 second. Over time all the OZ7IGY beacons will use the Next Generation Beacons platform. During the Perseids, 8 to15 August, and Geminids,10 to 15 December, meteor showers the 2 m and 4 m beacons transmit FSK441 and the 6 m transmits JT6M the first 30 s every period instead of PI4.

Spotted decodes

Status

OZ7IGY goes all the way back to the International Geophysical Year in 1957. From its start on 144 MHz it has ever since been on air continuously and on ever more and more bands. Today OZ7IGY transmits on 28 MHz, 40 MHz, 50 MHz, 70 MHz, 144 MHz, 432 MHz, 1,3 GHz, 2,3 GHz, 3,4 GHz, 5,7 GHz, 10 GHz and 24 GHz. Most of the HF, VHF and UHF technology used by OZ7IGY is old(er) land mobile equipment modified for the purpose. For the microwave bands most of the technology is dedicated radio amateur beacon designs while power amplifiers are often surplus.

However, given the latest developments in digital modulation techniques and RF-circuits it is time also for OZ7IGY to take advantage of these technologies. On 30 October 2012 the first two Next Generation Beacons were put on air after thorough testing and burn-in periods. The Next Generation Beacons platform is open to others and the software can easily be adapted to other modulations and sequences. Furthermore, is the new platform frequency and time locked to GPS. Thus the frequency accuracy is better than 5 mHz.

Currently the new beacons on 2 m, 4 m and 6 m transmit in a 1 min sequence starting with PI4 (call and locator) then CW (call and locator) and finally a carrier until next cycle begins at the 00 second. Over time all the OZ7IGY beacons will use the Next Generation Beacons platform. During the Perseids, 8 to15 August, and Geminids,10 to 15 December, meteor showers the 2 m and 4 m beacons transmit FSK441 and the 6 m transmits JT6M the first 30 s every period instead of PI4.

Here is a number of OZ7IGY YouTube videos.

Decoding PI4

The OZ7IGY Next Generation Beacons transmit, in a 1 minute cycle starting at the full minute. The colored line below illustrates the mixed mode sequence where P indicate pauses. The CW is sent at 60 LPM/12 WPM.

Why PI4

The reason for using PI4 for the OZ7IGY beacons is related to the below requirements:

• The analog part of the identification must be frequent both to identify the beacon but also to "handle" QSB
• The beacon, must be readable even when the path is distorted i.e. by rain scatter, aurora etc. Who says we have finished detecting new propagation techniques? So the beacon must also be "forward compatible"
• It must be possible to decode the MGM part even if the receiver is not frequency locked
• Today most beacons identify themselves every 30-45 seconds. But waiting for the identification "always" seems to long. Like waiting in a telephone queue always seems to long. The perceived time when waiting always seems to be to long
• A 2 min sequence is to long and the shorter the better
• Identical sequence every minute
• It should be possible to calibrate to the beacon. Thus a carrier is needed to zero-beat on. Today this is specified to be about 20-30 seconds
• The analog identification should be readable by "all of us" not just the very high speed CW operators. Thus 12 WPM/60 LPM as already specified seems to make sense
• Must fit into the current 1 kHz beacon to beacon spacing structure
• The MGM must be transmittable via a class C amplifier to save power

PI4 is specifically designed with beacons and VUSHF propagations in mind. It is far more robust to path irregularities and equipment inaccuracies than e.g. WSPR and JT9 that both would require a long sequence. JT65, modes are in-between WSPR/JT9 and PI4, and JT4, when it comes to robustness but cannot fulfil an identical sequence every minute without other sacrifices unless using the JT65B2/C2 submodes. The JT4 submode JT4G has better path robustness than PI4 but takes about twice as long to transmit thus it will not fulfil the sequence requirements. PSK2K, FSK441, JT6M and ISCAT are "fast modes" but are not as sensitive as the other modes. Because of this is PI4 the MGM used by the OZ7IGY Next Generation Beacons.

Elevation and horizon maps

The OZ7IGY building is 85 mASL and the antennas are from 5-10 mAGL.

Elevation map 10 x 10 km. OZ7IGY is located at the black dot in the center of the map. Courtesy Radio Mobile and Uffe, PA5DD.

Elevation map 1000 x 1000 km. OZ7IGY is located at the red dot in the center of the map. Courtesy Radio Mobile and Uffe, PA5DD.

Visual horizon map. Courtesy Radio Mobile and Uffe, PA5DD.

Reports

We appreciate your feedback so please send it to Ivan, OZ7IS, at his_callsign @ yahoo dk.

For technical questions about the Next Generation Beacons platform please contact Bo, OZ2M, at his_callsign @ rudius net.

OZ7IGY, www.rudius.net/oz7igy