Open Research Institute RFBitBanger, 1 Mar 2023

Previous Meeting

Next Meeting

⏯

youtube image

►

From YouTube: RFBitBanger Demo

Description

Paul KB5MU demonstrates the user interface and mode capabilities of the first prototype of the RFBitBanger open source HF transceiver.

Info on RFBitBanger: https://github.com/profdc9/RFBitBanger

FlexRadio 6600M: https://www.flexradio.com/products/flex-6600m-signature-series-sdr-transceiver/

A

Welcome to this demonstration of the RF bit banger early prototype start by turning it on it's drawing about 90 milliamps in idle mode and displaying its default wake up screen, which is a frequency at 13.56, megahertz.

A

Normally I'd use the buttons here on the board. You can see them here, just above the display or I can plug in a PS2 keyboard and use that which is more convenient, especially for filming so I'm going to use the keyboard from now on, I'm going to cursor over to the frequency digits that I want to change and use up and down arrows to change them. I'm going to go to our frequency in the 10 meter band.

A

That's my happy frequency there I hit, enter and now I'm on that frequency.

A

If I want to transmit, if I can go into this transmit mode hit enter, it's warning me: I need to change the band module because I've changed bands I'll accept that and now I'll type a test message.

A

Put my call sign in there for good measure. In case it leaks out of my dummy load and I'll hit enter having hit enter I'll return. There is a little menu of different things that it can mean. I can clear the transmit buffer I can just quit out of this menu, I can go ahead and transmit or I can return to editing.

A

So there I'm back in the editor I can move around and change what I wanted to transmit if I so desire.

A

But what I really want to do is transmit and I want to see it happen over the air. So let's turn on a receiver.

A

Here we are looking at a Flex radio, 6600 M, as it happens tuned to that same frequency, I've, put a 60 DB attenuator between the receiver and the RF bit Banger, so as to be able to transmit safely directly into the radio.

A

Let's bring back the display up in the right hand corner so I can see. What's on the display, while I do this demonstration and now I'm going to go ahead and hit enter again, cursor up once to transmit and hit transmit.

A

You can see that it transmits what I said to transmit and the cursor follows along. So you can see where it is in. The transmission Spectrum you can see is not completely perfect. It's got a nice big peak right on frequency, but there are some other lumps you know. Maybe some room for improvement there.

A

Cw is not the only mode it can transmit. Of course, let's try a different mode. If I scroll up through this menu to the trm or transmit mode menu, it's all right set the CW right now the next choice is rtty.

A

Let's try that and set the mode and go back down to transmit same message is still there, I'll go ahead and accept it and let's transmit some rtty.

A

That works pretty good. Okay. What other modes have we got back up to the mode menu.

A

Here's a brand new Mode called Scamp. Now we can do FSK or on off keying, depending on what you want. This is FSK mode and with the default settings. So let's listen to that set the mode back to transmit mode, same old message, and here we go now you'll notice. It's way down at the bottom, so I'm going to tune up so I can hear it.

A

Okay, that's got a lot of FSK. Excuse me. A lot of FEC on top of the transmission so should be more robust, more reliable to listen to I'm, going to tune up a little bit. So that's not quite so shrill. Next time we listen to it and go back to the mode menu.

A

And try the same thing in oh okay, mode, on off keyed, so sort of like CW, like Morse code, but with a different code. So it's more robust! So here we go.

A

Cool we can also.

A

Try the same two modes in fast and slow, so here we are in FSK fast mode. Let's try that oops.

A

That's quite a bit quicker.

A

And here is FSK slow mode.

A

Yeah, that's quite a bit slower! Isn't it let's see what other modes I can try here, 's the on off key Aid mode in slow? This is gonna, be even slower.

A

A

A

And that's the last mode: let's go back to CW for a moment.

A

And let's think about receiving.

A

I've got the Flex radio set to transmit into a dummy load, so we'll get leakage into the the RF bit banger and I'm going to set it set the Flex radio into CW mode, and we need to be up here offset of 750 Hertz.

A

And now, if I transmit on the Flex radio, The irfit Banger should copy it, and you should see it on the display. There.

A

There we go a little bit of decoding delay there because of the way it's doing the decoding. Remember all the processing is being done on little bitty at Mega, the same processor as in an Arduino Uno, not very much processing horsepower.

A

While I'm in the receive mode, I can scroll back because I missed what I saw and see the whole message, there's some gibberish that was before I started transmitting and then there's the message that I transmitted cool, so we've got transmitting receiving.

A

We can choose any frequency anywhere in HF band down to one Hertz resolution using a synthesizer optionally. We can use a crystal and choose one frequency, but the synthesizer is relatively inexpensive and much more convenient and the Scamp mode with its FEC capabilities, should be quite robust compared to simple CW or rtty.

A

So that's where RF bit Banger is at today tune in later for more developments.