Mini Morse decoder using Nokia 5110 graphics LCD.

S

srnet

Senior Member
I was looking for a way to make a small, portable, decoder for the Morse audio that the GPS locator beacons I have made can transmit. You can decode morse audio with a PC of course, but I dont like the idea of carrying one around in the field.

Most of the small LCD displays are graphic based and I found some posted code from Hippy that used a 20X2 to drive one as a character display;

http://www.picaxeforum.co.uk/showth...l-LCD-module-from-mobile&highlight=Nokia+5110

5110 displays are cheap, I got 5 from eBay for £10.

So I took this code, stripped out the stuff I did not need, added a 08M2 to decode the morse and a NE567 to detect the audio and the result is the PCB shown.

The morse bits can be left off the PCB, and the display unit will plug on top of the telemetry ground station receiver shown in another post.

Code to follow, once I have added the comments before I forget.
 

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Circuit diagram of the combined 20X2 5110 display driver and the 08M2\NE567 Morse decoder.

The PCB included a PIC programmer header connection for using a 18F14K22 in case the PICAXE proved not to be up to the task. The 20X2 seems to cope well enough running at 64Mhz and the incoming serial is 9600 Baud.

It ought to be possible to control the contrast with the pot on pin c.3, but this is not yet working so do not fit the pot.
 

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It is rather cute.

The display part is designed to be plugged onto the top of the GPS Locator receiver shown in the other thread. It then displays the Latitude and Longtitude from the matching transmitter, this is a lot more compact than the trailing AXE133 LCD display.

What hope to do is use the Morse decoder as an ultra portable Morse decoder (that does not need a PC) and use it to decode Morse from a very long distance. There is a ready made test transmitter in orbit, ITUPSAT1, which transmits a 100mW FM beacon, the same as the GPS locator beacon I built . I have heard this satellite by ear from as far 2000kM away (its at an altitude of 720kM), and decoded fragments of the Morse on a PC from about 500kM away. I have built a UHF pre-amd which should bring the Morse audio up to the S2\3 the Morse decoder needs for reliable decode. Sad thing is I cant now find the built up amp PCB, so looks like I will need to order another one.
 
@srnet...
And I thought I was the only one unable to find things that I "know" I have. Worse part, is the list of things to find keeps growing longer! The good part is that occasionally I do find something on the lost list, so I think that statistically the list is not infinitely extendable. Or said another way, the more one loses, the quicker should be the rate of recovery - therefore, equilibrium must exist... have faith. In my experience, I usually find something about the time the replacement arrives :D

- Ray
 
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