09-08-2018, 04:19 PM
Hello list
I just found this list, so sorry for the late response. The topic of what should a beacon do is identical to what was discussed nine years ago in the group behind OZ7IGY that wanted to upgrade the beacons with digital modulation and referenced locked among other things.
However, before we started to design the new beacons we made a member and user survey as well as presenting the conceptual idea(s) on a handful of VUSHF meetings. This was done to collect the needs and ideas because the OZ7IGY beacons are made for the users not for the designers and builders. No one expressed any wishes for a non-continuously transmitting beacons – in fact quite the opposite. VUSHF propagation conditions can be short lived and thus not detected if the beacon signal is not present all the time. Furthermore, if the beacon signal is randomly on the air using the beacon for propagation studies and rig alignment becomes cumbersome if not impossible.
The concluding requirements to OZ7IGY were:
- The beacon should be readable without a computer. Therefore, a beacon should not be 100% digital (machine generated modulation - MGM) but either 100% analog or mixed mode
- The beacon, at least the analog part, 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"
- The analog part of the identification must be frequent both to identify the beacon but also to "handle" QSB
- Today most beacons identify themselves every 30-45 seconds. But waiting for the identification "always" seems to long
- 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
- 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
- When using the beacon for signal strength measurements, antenna pattern, receiver aligning etc., it is important that the envelope of the transmitted signal remains the same during the entire sequence
- For a mixed mode beacon the MGM should act as a "pre-human condition" detection, i.e. better than -10 S/N as well as automated monitoring. A very good CW operator can detect signals way down in the noise perhaps -10 dB S/N. But "all of us" may only go down to say -3 dB S/N
- Must fit into the current 1 kHz beacon to beacon spacing structure
- Low phase noise in order not to disturb nearby stations
- The MGM must be transmittable via a class C amplifier. Overall power consumption is a concern. OZ7IGY has 12 beacons on the air and uses 800 W DC continuously. The electricity bill is close to 4000 AUD annually and energy prices will continue to go up. For the same reason a group is busy with a renewable enerIGY project
But it is also worth noting that some users asked for:
- more carrier, less carrier, no carrier
- no MGM, only CW
- more power, less power
- EME training beacon
There is no one-size fits all. Likewise when it comes to the MGM. There are no free lunches when it comes to sensitivity, speed, robustness and flexibility. So the requirements were a good and robust general purpose sequence with equal offset tuning for all parts of the sequence AND just like any other CW beacon.
If I am to advice anyone on beacons it would be:
- what is the purpose of the beacon?
- who are the users? FM-stations, analog DXers, mixed mode DXers or digital DXers?
- what do the users/listeners want?
- don’t start backwards by looking at the S/W available – if any
I just found this list, so sorry for the late response. The topic of what should a beacon do is identical to what was discussed nine years ago in the group behind OZ7IGY that wanted to upgrade the beacons with digital modulation and referenced locked among other things.
However, before we started to design the new beacons we made a member and user survey as well as presenting the conceptual idea(s) on a handful of VUSHF meetings. This was done to collect the needs and ideas because the OZ7IGY beacons are made for the users not for the designers and builders. No one expressed any wishes for a non-continuously transmitting beacons – in fact quite the opposite. VUSHF propagation conditions can be short lived and thus not detected if the beacon signal is not present all the time. Furthermore, if the beacon signal is randomly on the air using the beacon for propagation studies and rig alignment becomes cumbersome if not impossible.
The concluding requirements to OZ7IGY were:
- The beacon should be readable without a computer. Therefore, a beacon should not be 100% digital (machine generated modulation - MGM) but either 100% analog or mixed mode
- The beacon, at least the analog part, 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"
- The analog part of the identification must be frequent both to identify the beacon but also to "handle" QSB
- Today most beacons identify themselves every 30-45 seconds. But waiting for the identification "always" seems to long
- 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
- 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
- When using the beacon for signal strength measurements, antenna pattern, receiver aligning etc., it is important that the envelope of the transmitted signal remains the same during the entire sequence
- For a mixed mode beacon the MGM should act as a "pre-human condition" detection, i.e. better than -10 S/N as well as automated monitoring. A very good CW operator can detect signals way down in the noise perhaps -10 dB S/N. But "all of us" may only go down to say -3 dB S/N
- Must fit into the current 1 kHz beacon to beacon spacing structure
- Low phase noise in order not to disturb nearby stations
- The MGM must be transmittable via a class C amplifier. Overall power consumption is a concern. OZ7IGY has 12 beacons on the air and uses 800 W DC continuously. The electricity bill is close to 4000 AUD annually and energy prices will continue to go up. For the same reason a group is busy with a renewable enerIGY project
But it is also worth noting that some users asked for:
- more carrier, less carrier, no carrier
- no MGM, only CW
- more power, less power
- EME training beacon
There is no one-size fits all. Likewise when it comes to the MGM. There are no free lunches when it comes to sensitivity, speed, robustness and flexibility. So the requirements were a good and robust general purpose sequence with equal offset tuning for all parts of the sequence AND just like any other CW beacon.
If I am to advice anyone on beacons it would be:
- what is the purpose of the beacon?
- who are the users? FM-stations, analog DXers, mixed mode DXers or digital DXers?
- what do the users/listeners want?
- don’t start backwards by looking at the S/W available – if any