New VK3RGL 2m Beacon under construction. Ideas please.

[VK3YE]

Why is GL an obvious abbreviation for Geelong?

Partly due to local radio history. Eg http://www.radioheritage.net/Story242.asp

[VK3ALB]

Hi Everyone,

I'm pleased to announce that the new GPS locked VK3RGL beacon is now on air. Reports are welcome and we'd be very interested to hear from anyone that can do accurate off air frequency measurements - sorry no prizes.

Beacon and 10MHz reference on air.

[VK3AUU]

If the key down frequency is GPS locked to the assigned frequency the serious listener will know for sure whether what they are listening to is VK3RGL and not a birdie so that an ident every 10 minutes to conform to the regulations should be all that is necessary.
David

[VK3TU]

...an ident every 10 minutes to conform to the regulations should be all that is necessary.
David

And for the casual listener that just wants a quick check and move on, a confidence call-sign every minute is useful.

Bert
VK3TU

[VK3PY]

Good work Bert & Lou.

Bert - it would be useful if you could post the beacon's actual identification cycle here for listeners. I assume the beacon is set for 20W into each yagi, which is a significant increase over the old beacon's 7.5W.

I would also be interested in reports of signal cleanliness (never mind the quality - feel the width!), especially from those who cop a fair whack of signal from it.

Chas
VK3PY

[VK3MEG]

i didnt mind the fsk id b4 and could get a good decode. no decode of ident here with pre amp on of or even attenuator turned on and the tone drives me nuts sorry . i understand the reasons for it. but i'm just up the road from it.
cheers

[VK3TU]

...Bert - it would be useful if you could post the beacon's actual identification cycle here for listeners.

Chas
VK3PY

Under normal conditions when the beacon and external reference are healthy, the ident cycle is:

"VK3RGL MT ANAKIE QF22DC" (@ ~16wpm) then 5 repeats of ~1 minute key down then "VK3RGL" (@ ~22wpm) then entire cycle repeats

In the event that the GPSDO oven reports low temp, the cycle falls back to:

"VK3RGL GPSDO OVEN FAIL" (@ ~10wpm) then ~1 minute key down then repeats

In the event that the GPSDO reports a loss of satellite lock, the cycle falls back to:

"VK3RGL GPSDO LOCK FAIL" (@ ~10wpm) then ~1 minute key down then repeats

In the event that the TX reports a loss of the external reference and reverts to the internal TCXO, the cycle falls back to:

"VK3RGL EXT REF FAIL" (@ ~10wpm) then ~1 minute key down then repeats

The controller also monitors the TX synthesizer lock and will shut the TX down in the event of an unlocked condition.

I included the last three messages as remote diagnostic indicators of the beacon system's health for the benefit of the people who have to maintain the beacon more than anything else. Hopefully, we'll never hear them. The short cycle and slow CW shouldn't bother the WSPRers because if you hear any of these cycles, the beacon isn't locked any more and we'd like to know if we have a problem. It should also be noted that the controller is an Arduino without a real-time clock. To keep things simple, we don't decode the NMEA sentences either, so the times indicated above are approximate.

Power is 40W at the TX into the splitter that runs the original 2 antennas at N-E & W. Frequency is as near as I can measure (with my antediluvian equipment) to 144.530MHz key down with ~400Hz negative FSK with key up.

Beret
VK3TU

[VK3HZ]

Great work. It's about 40 over 9 here, so about normal!

I make it about 19.9 Hz low. Or is my GPS Ref battery flat?

Regards,
Dave
VK3HZ

[VK3DXE]

Nice clean and stable signal for me at home. Also around S9+40

I'm not locked yet, but I measured close to 20Hz low by comparing my frequency at the time of measurement against other known locked stations on 2m WSPR.

[VK3ALB]

Thanks Alan and David.

I'll let Chas or Bert comment on the frequency accuracy. Chas did mention that there were some limitation on absolute frequency due to PLL programming. I'd be more interested to learn how stable it is. David, could you please take some comparison measurements over the next few days?

The 10MHz reference is a BG7TBL unit found on Ebay.

[VK3TU]

Thanks for dobbing me in Lou

Clearly, the Galilean Pendulum I use for measuring frequency here is a bit imprecise.

There's been a couple of people who have mentioned a figure around -20Hz now. Perhaps in a few days we'll have a consensus on the frequency error.

The control software for the RFI-148 TX has a facility for applying up to + or - 3KHz of offset to the programmed carrier frequency in 1Hz increments. That means we should be able to "bump" the frequency up on our next trip up the hill simply by adding whatever the consensus settles on.

Bert
VK3TU

[VK3HZ]

It seems quite stable at -19.9 Hz. So, I'd reckon an adjustment of +20Hz would be just what Goldilocks ordered

Regards,
Dave
VK3HZ

[VK3PY]

VK3MEG wrote:

no decode of ident here with pre amp on

Steve: Note that the previous beacon's FSK was arranged with "key up" on its assigned frequency, whereas the new beacon has "key down" on its assigned frequency, as is the more common practice. This might be the reason for your inability to achieve CW decodes.

Bert: Your reference to the Galilean pendulum reminded me that just the other day I was standing under the very chandelier in the cathedral of Pisa which Galileo observed swinging in the breeze, and which led him to formulate the physics of pendulums. It is not GPS-locked. In fact, it wasn't even swinging. It does, however, boast electric lighting, something which the old man would have thought miraculous.

Chas
VK3PY

[VK3QI]

Lou,

I have been monitoring it for the last 48 hours - absolutely no noticeable drift on steady carrier. It sits at about one bees dick below -20hz.

When it is keying the ident, I can occasionally hear a 1 hz beat against my GPS locked sig gen, suggesting an ever so slight drift of less than 1 hz under keying to -19hz.

Cheers

Peter VK3QI

[VK7JG]

Hello Lou.

With my rough GPS setup
I make it 20.4 hz low and RGI 5.15High .

Good work.

73
Joe VK7JG

[VK3ALB]

Hi Everyone,

Thanks for your reports, I've been advised by Alan that the beacon meets the criteria set out by the WIA. Thanks to those that posted reports both here on the logger and elsewhere. Of course, I'm just the messenger and the real thanks for the implementation of this new beacon must go to Chas VK3PY for the configuration and preparation of the transmitter and Bert VK3TU for learning Arduino speak and building in all the extra diagnostics into the controller. Hopefully we never get to hear those diagnostic messages.

Well done chaps.

[VK3PY]

Actually, Bert did pretty much all the work to get this beacon up and running, including sourcing the new transmitter and reverse-engineering some of its secrets. My involvement was minimal.

Chas
VK3PY

[VK3TU]

...and not forgetting the good tutelage of Lee, VK3PK without whose patience and advice I would have struggled to make the Arduino sing and dance like it does.

There were many brains trusts, tutors, and advisors who had a some investment in this project. All in all, a good group effort. The focus now is on doing the same for 70cm then upwards from there.

Bert
VK3TU

[ADMIN]

Speaking of ideas relating to beacons: Seeking input from users: http://www.vklogger.com/forum/viewtopic ... 725#p54725

[VK3MEG]

chas all good now the 1 min quick high speed ident is much better.