Northeast Missouri Amateur Radio Club

Serving Adair County and the Surrounding Area

440 Digital Net info

What is the 440 digital net?

In order for more usage for our 70cm repeater it has been proposed to use it at least some of the time for digital keyboard to keyboard coms.

We will be using the free fldigi software in MFSK64 mode for the communications.

What Do I need to participate in the net?

You will need at minimum a 70cm radio that has been setup to use our repeater that is

a frequency of 442.525MHz + offset and a tone of 156.7Hz

You will also need a PC or raspberry pi and an interface to go between the radio and PC

That could be one of several options

Either a signalink

Or a digirig

These are the 2 easiest solutions as they supply ready made cables for many radios.

click on the pictures for a link where to buy

For an option that may take a bit of soldering of cables you could use

A usb sound dongle

and use vox to key the radio, or on a pi one of the gpio pins can be setup as a ptt circuit

There are also pi hats to do this sort of thing.

Finally if you are lucky enough to have a radio with built in a usb port then you have all you need except for a usb cable.

More about the fldigi software

The FLdigi software will need to be setup with your sound device. the following screens show how this is done.
First you will need to open the config dialog

Then once there, click the plus next to sound card and click devices to setup your audio in and outs.

Another thing to keep in mind is some interface ports on the various radios do not engage the radio's squelch.
Fortunately fldigi has that covered
see the arrows pointing to the squelch toggle and slider. Set the slider just above green column when radio is not recieving a signal to keep garbage text
from filling the yellow area.

QSO principles

The following images illistrates several features.

1st. You can see recieved text shows up in the yellow area the blue area is where you type in free text to send.
Once you click TX> it shows as red text in the yellow window as it is being transmitted. If using that far left TX> button after all text is sent it should put the radio back in recieve mode. The text you typed in the blue window disapears as it is transmitted.

2nd. note that I have highlighted the call sign in a transmission I recieved. If I then right click on the call I can click on callsign in the menu and that sets the callsign in the software for the QSO.

3rd. note I have highlighted the macro buttons.
These buttons are usefull for sending canned text. You can right click on these buttons to edit them or left click to send out the canned text.
The first one calls CQ the second one is for answering the CQ (after you set the callsign as above)
Brag sends a bit of info about your shack. WX is a special one for sending a weather report. I added that to my software. I will show how later on.
The kn macro is used like the word over in voice modes sk is analogous to goodbye

I strongly encourage you to look through the fldigi manual available from
http://www.w1hkj.com/files/fldigi/fldigi_help.pdf

Using the waterfall

In the picture above notice the waterfall area at the bottom. this will show you recieved signals and allow you to tune them in.
the red vertical lines are a bracket showing where you are tuned. If you hover your mouse over the waterfall you will also see
3 vertical yellow lines this is how you tune. Click the left mouse button to set. For using the repeater I suggest centering on 1500 on the waterfall.
I also sugget turning off AFC at bottom right and clicking the Lk button to lock your waterfall.
You may find that when you are set to tx at 1500 center frequency on the waterfall that you cannot decode others and they cannot decode you
This is because your soundcard needs to be calibrated for fldigi. see the WWV codec measurement section of the fldigi user manual for this procedure.
Since most 2 meter radios dont tune wwv frequencies you can ask a friend to put his fldigi in wwv tx mode and provide you with a signal to calibrate to.

Selecting an operating mode

We will be using MFSK 64 mode on the repeater. To select theis mode click on the operating mode text in the menu
hover over MFSK and then click MFSK-64
You can confirm you are in that mode as it will be displayed at extreme lower left of the fldigi window.

Defining a Weather Macro

You will notice one of the macro buttons is blank in a stock fldigi install
This is for you to define a custom macro of your choosing.
I set mine up to give the weather for my area as that functionality is available in fldigi.
right click the macro to edit and fill out the left side like I have done in this picture.

Make sure to also label the button text at the bottom.
Next you need to go into the config dialog open up the Web section and under WX put in your location's identifier and select what you want to be displayed.