News Page 12

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SARCNET Goes Digital

We had been listening for weeks on 40m, looking for regular digital teletype-mode traffic (i.e. Where stations can type messages to each other, using a computer, and send them over the air, using an HF transceiver. However, not like FT-8, where messages just contain call signs, signal reports and locations. We also explored JS8Call - which was too slow, and VarAC - which was not free and had too much TX activity). While digital teletype-modes are common on 20m, to our surprise, there was no regular traffic on 40m! We were looking specifically for any QSOs using the Olivia digital mode, which utilises forward error detection and correction, providing virtually error-free communications on very weak signals. An Internet search of suitable Olivia frequencies helped, but only one frequency was found to be relatively free of WSPR traffic and other QRM.

So, in September 2022, we started a regular digital version of SARCNET on 7072.500 kHz USB using Olivia 8/250. It operates in the evenings, Melbourne, Australia time. Our motto for the net is: "Kiss the Donkey", a phrase of dubious origin made famous in the movie "Battleship". Why: Olivia transmissions begin and end with a characteristic Hee-Haw, donkey-like, sound as the highest and lowest tones are sent twice.

"Kiss the Donkey"

The settings for FLDIGI are: Dial Frequency (QRG) 7071.000 kHz and Cursor Frequency 1500 Hz, giving a Centre Frequency of 7072.500 kHz, Op Mode Olivia | OL 8-250. Note: The cursor frequency is traditionally set to 1500Hz, which is at the centre of your radio's 3000Hz bandwidth, allowing the widest bandwidths to be used. The settings for your HF transceiver are: Mode USB; TX/RX filters, if you have them, 1350Hz to 1650Hz i.e. a 300Hz BPF centered on 1500Hz. The settings are shown below.

FLDIGI Settings

HF Transceiver Settings

The purpose of the net is just to increase digital tty-mode usage on the 40m band. As the net grows in popularity it means that stations will not have to wait around for hours looking for a digital QSO. We are still experimenting with how to run a digital net on HF. Here are some hints and tips for stations joining our net (Note: Some are only applicable to using FLDIGI):

Centre Frequency: 7072500 Hz (i.e. 7071000 Hz Dial frequency and 1500 Hz Cursor frequency)
Alternate Centre Frequencies: 7072200 Hz and 7072800 Hz if the above channel is in use.
Rig Mode: USB
Digital Mode: Olivia 8/250
Time: 0700-1300 UTC

Power levels: Generally use low power (QRP), say less than 30W. Indeed, we have made 3000 km QSOs on 0.5W. Note that if you can see a station on the waterfall, or even hear it, it is using more power than is strictly necessary for a reliable Olivia QSO! Each station can call CQ regularly to see if others wish to join the net. All stations may like to increase power if a DX station is present on the net.
Audio Levels: Adjust the audio levels using a combination of rig configuration and audio device properties. Increase the TX audio level to just below the pre-set rig TX output power level. Check that there is no ALC action on the rig. Set the RX audio level to achieve a salt-and-pepper display on the FLDIGI waterfall.
Filters: If you have TX and RX filters use them! These provide an excellent improvement in RX SNR and TX adjacent channel interference. Use 300Hz bandwidth on both TX and RX.
Squelch: Use the minimum FLDIGI squelch level necessary to avoid the display of random characters, or off for weak stations. Having the squelch set too high is the usual reason why you can't decode anything. It is easy to forget.
IDs: Encode TxIDs decode RxIDs (turn RxID and TxID on) so newcomers can see what frequency and mode to use. However configure your software not allow RxIDs to automatically change your TX frequency.
Spotting: Configure Misc/PSK reporter and turn spotting on (and click the spot button on the top menu bar). This will automatically send received callsigns to PSKreporter.
Cursor: Do not change your cursor frequency to centre stations that are not quite on frequency. Use your rig's RIT. Keep your TX frequency constant.
Messages: Short, single line sentences are easier to read. Avoid any unnecessary verbosity. In a group, no more than six (6) single line sentences per QSO will ensure that everyone gets a turn.
Macros: Try not to use Macros. Except maybe ANS and KN. Macros are BORING and impersonal. Let your fingers do the talking. Press <CTRL-T> to transmit and <CTRL-R> to receive.

QSOs: Double click on the other station's callsign and press the QRZ button to get the details. Provide callsigns at the start (use ANS) and end (use SK) of a QSO, and only every so often while in a QSO (use KN).
Overs: When it is your turn to send: After the other station's final "Hee-Haw", press <CTRL-T>, press <Enter>, type in your sentences, press <Enter> <Enter> <CTRL-R>. Note: You can pre-fill the FLDIGI blue message window with text to send while you are receiving, but avoid any lengthy delay in starting your transmissions. At the end of your over send BTU or callsigns and KN.
Text Cursor: FLDIGI only sends up to the text cursor in the blue message window. If you reposition it, or hide it by switching to a different app, FLDIGI will stop sending and just enter a "TX holding pattern".
Backspace: With FLDIGI you can use backspace if you make a mistake!
Signal Reports: RST and SNR reports are of little value. Report the percentage correctly received. E.G. "90% copy".
Signing Off: Be brief: "73, GL".

More information about Olivia: Olivia Digital Mode Radioteletype on HF group

Station List: Joe VK3TET, Mike VK2DJP, Skip KL7NN, Oscar VK3TX, Keith VK3MKE, Chris VK3IK, Tim VK1TTY, Adrian VK5AW, Andrew ZL1COP, Geoff VK2XGB, Greg WA5IEK, Stephen ZL1ANY, Jim AJ8S, Matthew VK6QS, Rob VK2ARL, Felix VK3FAR, Dick VK7DIK, Karl VK3KRL, Justin VK5LAN, Paul VK2AMT, Mike W4ISB, Charles VK1CM, Colin VK2LCT, Ken JA1RZD, Alan VK4AAN, Simon VK4XP, Daryl VK3AWA, Rob VK6WHO, Gavan VK4GAV, Scott VK1PWE, Ralph VK3ZZC, Milan VK2PP, John N7TIN, Paul VE6FEX, John VK5PO, Mickey W2C, Robert VK4APF, Anthony VK3YSA, Armin VK2GAS, David VK4DPP, Dave VK2NA, Tom VK3TZT, Nigel ZL1AI, Steven VK2KDX, Erwin VK3ERW, Paul VK2EX, Ian VK1HF, Mark VK1MK, Judd VK1STL, Mick N3OJP, Glenn W8BVI, Tomas NW7US, Bob NR4U, John KC4LZN, Gary WW8O, Paul VE3EEI, Wayne KN2Z, Jim VK1RF, Peter VK6YSF, Dave KZ1O, Robert K6SQA, Arthur VK5AI, Bob AB5N, John W0MPM, Bob K8EAC, Mike WA7IJV, Murray VK2LAT, Gary WD4NKA, Graham VK4GTR, Mike VK6TX, John V63JB/KH6DLK, Bob VK2YQA.

Here is an actual record of a small group session from 15 September 2022. Note: FLDIGI shows transmissions from your own station in red:

CQ SARCNET de VK3SRC

VK3SRC de VK2DJP good evening Joe. Can't stay long dinner is in the oven.

Hi Mike,

Could you decode that other station?

He's on regularly but won't QSO.

VK2DJP de VK3SRC

VK3SRC de VK2DJP no I could not decode him.

I noticed that FLDIGI automatically changed mode when you transmitted in Feld.

Yeah I don't like that. I click "Notify Only".

I suppose its OK when there are lots of modes present on the frequency.

VK2DJP de VK3SRC

VK3SRC de VK2DJP

Had a QSO with Ian VK3AXH earlier this evening so there are some other active stations… Build it and they will come!

Yes. That's good.

Have a nice dinner Mike.

73 VK2DJP de VK3SRC

Thanks Joe, Maybe catch you later this evening.

TNX fer QSO Joe, 73

VK3SRC de VK2DJP sk

73 Mike. VK2DJP de VK3SRC

CQ SARCNET de VK3SRC

Good evening Joe and Mike.

QRZ de VK3SRC

Sorry, my laptop was playing up. de VK3TX

Hi Oscar,

How are you this evening?

VK3TX de VK3SRC

Hi Joe, all good in general.

Feeling a bit worse than yesterday but I hope this sickness will finish up soon.

VK3SRC de VK3TX

Yes it is terrible.

Hope you get better quick.

Lots of static crashes.

Doesn’t worry Olivia, though.

She is pretty good at decoding!

VK3TX de VK3SRC

Many thanks Joe.

I noticed today during the whole afternoon the same on 20m, sometimes also the receiver overloading a bit.

I just wanted to say hello today but, I won't be long here. I may try to sleep early,

VK3SRC de VK3TX

That's OK.

We don't have to get on every day, or stay long.

We just need to make a noise to say that we are here.

There is a link on my QRZ page to a page about this net.

Still trying to work out the details.

73, Good Luck VK3TX de VK3SRC

Looks like for me it is a must. LOL.

I'm really enjoying this, something different.

Always listening for something different but took me 7 years to find someone else interested!

Thanks for the check in today.

Cheers Oscar. GET BETTER mate. 73 VK3TX de VK3SRC

Before I go, you've neen spotted in the cluster! 73 de VK3TX

Oh no. I better keep my head down, hi hi. VK3TX de VK3SRC

CQ SARCNET de VK3SRC

VK3SRC de VK3MKE Good evening Joe.

Hi Keith,

How are you?

VK3MKE de VK3SRC

Yes very good. All under control.

I saw your sig so I thought I should say hello.

Also to VK3TX I could see both sigs very well. Btu

Very good.

Mike was on earlier too.

Well this is a lot of fun!

I wonder if anyone else can hear us?

QRZ de VK3SRC

Good, starting to make a presence felt.

Im using another old Codan tonight a 8525 abt 25W this one has fixed channels but its going okay.

Tried a few calls on 20m this arvo but had no responses. Could see some PSK31 sigs as well.

VK3SRC de VK3MKEQ

VK3SRC and the group de VK3IK.

Just a quick call in.

I am running the club net at 2030. I will be listening .... watching.....LOL.

Enjoy. 73 de VK3IK

VK3IK de VK3SRC

Hi Chris. Thanks for calling in.

Over to you Keith.

VK3MKE de VK3SRC

Good evening Chris solid signal.

Great to hear from you.

I'm sure many people would use Olivia if there was some more activity.

Anyway I'll try during the day to call on 40m, this frequency, even tried 15m today too.

Btu Joe

Yes anything we can do to resurrect the activity would be good.

Have been on 7105 LSB mostly today.

VK3MKE de VK3SRC

Yes I hear you sometimes on 7105, I was going to call on 17m today but I was unsure about

the frequency. Suggested was 18.101, I think, but that is really close to the FT8 so I didn't bother.

btu VK3SRC de VK3MKE

Yes well FT8 is only 1.5kHz above us here.

I guess no one will be listening if there has been no activity.

Better do my job:

CQ SARCNET de VK3SRC

No one else there.

Yes very quiet.

On 17m FT8 is 18.100 so it could get ugly.

I can see some SSB just below us too. I just checked power out 15W.

I hoped Adrian VK5AW might call in tonight. I let him know the details.

btu VK3SRC de VK3MKE

Not sure if VK5 is in range.

I have had VK4 and VK6.

Amazed that 40m is open locally to Qlivia all night.

It is a whole new ball game.

We have to find out what she is capable of.

VK3MKE de VK3SRC

de VK2DJP

Hi Mike VK2DJP de VK3SRC

Good evening again Joe and hello Keith.

Will put it to Keith.

VK3MKE de VK2DJP

Yes that may well be, forgot about that. It certainly is a new ball game for me.

Good evening, Mike nice to hear you again.

There is a website I found that has lots of info on the various modes I'll find it again and mention it.

VK3SRC de VK3MKE in the group

VK3MKE de VK3SRC

Yes we need all the info we can get.

QRX Mike...

CQ SARCNET de VK3SRC

nothing heard VK3MKE de VK3SRC

I guess I'll take it now hi hi.

I'm looking forward to seeing just how weak signals can get before Olivia loses them,

I'm running 10 watts at the moment.

Both of your signals are S9 with me.

VK3MKE de VK2DJP

de VK3MKE The website is W1HKJ.com there is lots of stuff there.

Yes that would be interesting Mike, I'm running abt 15W.

I could reduce it a bit further I guess.

I don't know how to express a signal report in this mode but I can copy both of you readable 5 so that's all we need.

VK3SRC de VK3MKE

The s/n is on the bottom line of FLDIGI. UR 22.5dB Keith.

Great website Keith. What's my s/n Mike?

VK2DJP de VK3SRC

UR s/n is 22.5 Joe.

Will give Keith his next over.

Running 5W now.

Hope u still copy

VK3MKE de VK2DJP es the SARCNET group

VK2DJP de VK3MKE Thanks Mike,

Yes can still copy.

Joe your s/n varies a bit. UnsurePwhat@to give you.

Just xhduced power to awc%5W too.

btu MK3SRC de VK3MKE

Keith UR 18-20dB and only 90% copy on 5W now.

Looks like that is the limit here - It varies of course.

VK2DJP de VK3SRC

Keith 100% copy here with ur 5W

S/N was +8.5 then dropped to -4.9

I think....can't see the plus or minus sign because of task bar

Can't remember how to get rid of it hi hi

VK3MKE de VK2DJP

Very good Mike yr signal was as high as 5.5dB.

Joe yrs was 8.8db at th peak.

Just went back to 12W again.

The task bar... can you minimise FLDIGI and then adjust it back maybe VK3SRC de VK3MKE

I don't understand the + and -.

My meter says: s/n: 24.8 dB for you Keith. 30.2 for Mike.

Anyway we are still learning.

VK2DJP de VK3SRC

Keith thanks for the tip

Trying to minimise made everything on FLDIGI come into view.

Joe, when there is no signal the S/N here is something like -15dB.

Signals for the most part are positive.

But they can become negative as the signals weaken and approach the noise floor

VK3MKE de VK2DJP

Well done Mike.

Yes I don't really get the s/n

I agree about the s/n meter, same here.

If you can copy everything 100% that's ok.

Until I found the cursor needed to be at the end of the text...

I’ll stay for one more round then I'll be going.

btu VK3SRC de VK3MKE

The displayed s/n depends on your RX filter BW.

I have set my RX and TX filters to 850Hz Lo and 1150Hz Hi.

My s/n is between 20-30dB for you guys.

When I set a SSB 3kHz BW it drops to -5dB to +5dB

We can't all set our TX and RX BW so s/n won't be very useful.

Yes I am going QRT on the next too.

Cheers and 73.

VK2DJP de VK3SRC

Kinda like how long is a piece of string Joe hi hi

It all boils down to being able to decode the signals

Tonight, you two gentlemen have been 100% copy with me all the time

Yes, it's a good time to pull the plug for me to.

Thanks for being in my shack tonight

73 Joe and Keith, it's been fun again

VK3MKE de VK2DJP sk sk

Yes the old piece of string, 100% copy here too.

I don't have any adjustment on the Codan, except power out.

It's been a pleasure.

Thanks Joe and Mike really enjoyed the chat.

73 cheers VK3SRC de VK3MKE going QRT sk

73 Keith and Mike. VK3MKE de VK3SRC sk

Donkey graphic Pixta licence no. 23630864

SARCNET @ Warrnambool Hamfest

At the kind invitation of Mark VK3UA, Julie VK3FOWL and Joe VK3YSP, attended the Warrnambool Hamfest. The inaugural event was a joint event by the Warrnambool District Amateur Radio Group and the Portland and South West Radio Group.

Mark said: "It came about from a desire of hams in the Western District to get something happening post lockdown. With restrictions easing, we felt it was the time to organise a local event. With active operator numbers growing in the district, we now have the manpower and enthusiasm to take on an event like this. We hope to provide everyone a good fun radio day."

To support the event, SARCNET donated raffle prizes including an LCD Soldering iron, USB soldering iron and an Electronics Prototyping Kit, valued at $55. It was a great, well-organised, event and good to see so many oeprators attend.

Warrnambool Hamfest

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