Radio Cartridge: The Microlog AIR-1

6502dude · Post by **6502dude** » Mon Mar 07, 2005 9:08 am

I should be able to make it to the meeting on the 17th and will bring a radio.

brain · Post by **brain** » Sun Mar 13, 2005 4:40 pm

If you need more info on the use of it, let me know. I don't own one, but I am a ham.

Jim, KB8WYW

carlsson · Post by **carlsson** » Sun Mar 13, 2005 5:41 pm

brain wrote:I am a ham.

Akin to "I am the walrus"?

6502dude · Post by **6502dude** » Sun Mar 13, 2005 9:44 pm

brain wrote:If you need more info on the use of it, let me know. I don't own one, but I am a ham.

Jim, KB8WYW

Thanks Jim.

I likely will be bringing my Icom R71A receiver and figure we should be able to pick up something in 75 meter band.

Any suggestions of other bands to try for CW?

BTW, in the book 6502 Applications by Rodnay Zaks, there is an example of a routine in assembler for conversion of morse code to Ascii. This would provide a good start to anyone who wished to create their own decoder for the Vic-20.

I expect in the cartridge there is simply a ROM and and AF detector (with filters & comparator). I would like to have a look at schematic for cartridge, if anyone has it.

Schema · Post by **Schema** » Tue Apr 19, 2005 8:06 am

OK, I took the AIR1 cartridge and the VIC20 that came with it to the cottage last weekend. Set it all up with the B&W TV, and hooked it up to my father-in-law's Shortwave radio. This is just a desktop model with analog dials, nowhere near as fancy as 6502dude's unit.

Still, I was able to find half a dozen frequencies that were clearly data. For each one, I tried all the different modes and baud rates/WPM (Morse, RTTY, ASCII), inverted vs. non-inverted, etc.

I never did get anything coherent, but it was a lot of fun. In a few cases, I was able to get a pretty steady stream of gibberish flowing across the screen. My wife and friends who were along thought they were encrypted messages. Possible?

So is there any way to determine what the correct settings should be? Or does that just come with experience?

carlsson · Post by **carlsson** » Tue Apr 19, 2005 9:01 am

An idea: make a program to send out encrypted messages and call it VICnigma or EnVICma.

6502dude · Post by **6502dude** » Tue Apr 19, 2005 10:35 am

Schema wrote: So is there any way to determine what the correct settings should be? Or does that just come with experience?

I think getting the hang of this is "trial & error(s)"

Try dowloading this morse code trainer file:

www.bjlyons.com\ham\morse.zip

Then, hook up audio output from your PeeCee to the cart input. The program will generate test characters and will also allow you to vary speed and tone of dits & dahs.

Testing this out in this manner will give you a bit of an idea what MircoAir cartridge wishes to see for signal. After you have a sense of this, you are likely to find messages which have less gibberish.

Schema · Post by **Schema** » Tue Apr 19, 2005 1:20 pm

Thanks Brian! However, I left the AIR-1 at the cottage so I can try it again in the summer. I won't be able to try your program until then.

What about RTTY? The cartridge handles that as well.

6502dude · Post by **6502dude** » Tue Apr 19, 2005 7:34 pm

Although I have a filter for RTTY on my radio, I never got into it - I just can't think that quick

I think your docs on the MicroAir has a bit on RTTY and freqs are used for mark and space. I believe it is simple FSK.

Generally summer is poor for radio reception, especially dx. I'm moving in July and will be putting up a couple of decent antennas for the fall. Until then, I'll be busy packing.

I have a book "The Commodore Ham's Companion" by Jim Grubbs K9EI that you are welcome to borrow. It covers a few basics and is interesting to read given it was written in 1985 and C128 was not generally availability. There is even a reference to TPUG on page 105 of this book!