Now that the VHF FM receiver part is almost done, nothing like giving it a little "professional" touch...said that, on to make a "packet" dedicated output, also know as discriminator out...
Basically this output is a low pass filter from the recovered audio of the MC3361. The same signal goes to the speaker amplifier, so it's just a matter of filtering and preserving the signal in it's more pure form.
I add an amplifier because the sound card wasn't liking the very low output of the MC3361. The "filter" part is just the 5k6 resistor and the 4.7nF capacitor.
Before making the amplifier I tested for some time with the my PIC aprs decoder but not even one packet was decoded (it's working/well connected since I get the boot message and the blinking led...)
Then I proceeded to "multimon" software, now with the amplifier working, had limited success, about 20% of all packets were decoded (remember, I am using a peace of wire as antenna inside the shack). By this time the TM-D700 was decoding around 95% (I was beaten by a kitchen electronics manufacture).
Bellow, "multimom" decoding:
Also tested with "soundmodem" software but no success. I didn't proceeded with further testing since I installed and tested "multimon" and "soundmodem" today for the first time. Could be my mistake in the configurations.
Hope to get better results in the future with the outside antenna.
I also tweaked the IF frequency a little bit and the quad coil to try improving reception but not much success.
Incidentally I found a PIC aprs decoder project with an LCD that migh work a litle bit better since is based on the MX614 chip, unfortunately is very hard to find the MX614, so for now I will put on standby this project. Here's one of the links:
http://www.ke4nyv.com/peekpack.htm
Further reading:
* http://www.xastir.org/wiki/HowTo:SoundModem
not in documentation but port on "Xastir" should be configured at 4800 and probably you need to "chmod" a+rw /dev/pts/"whateveryours"
* http://www.baycom.org/~tom/ham/linux/multimon.html
Download link for "multimon" is at the bottom!
* http://www.discriminator.nl/
3 comments:
Boas há um conjunto de assuntos interessantes no seu blog daí comentar conforme vou descobrindo. Eu já consegui ter um discriminador num VHF maritimo a trabalhar conseguido através do site que publicou, o NL. Era um uniden unimetrics. Não funcionava a 100%,culpa do radio e penso que acabava por bloquear ao fim de 15 a 20 minutos e era preciso andar a afinar a placa de som do pc, mas o que é certo é que funcionava. Ando agora a ver se aplico o FLDIGI ao meu Debeg... se percebesse mais de softwer e de como trabalhar ao PC. Faz-se o que se pode. Ob.
need more about mc3361 perhaps alba 01 tranciever use mc3361
Hello Rachmanbobo,
Have a look on mc3361 datasheet: https://www.nxp.com/docs/en/data-sheet/MC3361C.pdf you will find more info there.
Post a Comment