I'm attempting to transmit data over radio signals, but my receiving end is spitting out gibberish.The serial monitor shows,Start 0 0 1 0 0 0 16 5 (@) (!) 0 1 0 0 0 128 16 4 0 17 0 1 0 0 0 0 4 1 0 0 0 0 1 176 2 0 0 4 1 0 0 130 0 0 ( ) (") 0 0 0 0 0 4 1 0 0 1 16 0 (@) 0 0 0 0 4 1 0 0 0 (H) 0 0 0 0When it should be a legible message. On the signal out I have a radio transmitter with a Tx pin connected to serial 2 on an Arduino mega. The code just enables the transmitter, then does "Serial2.println("message");". Baud is 1200. Transmitter data sheet here (HX1)On the receiving end I'm using a library called SoftModem (SoftModem-005) to demodulate the signal. I'm pretty sure my code here is the reason the gibberish, I have almost no idea what I'm doing. Most of this code is from a tutorial I found. These are the settings I have in the .h file.#define SOFT_MODEM_BAUD_RATE (1200)#define SOFT_MODEM_LOW_FREQ (1200)#define SOFT_MODEM_HIGH_FREQ (2200)#define SOFT_MODEM_RX_BUF_SIZE (32)
I don't see anything here that indicates an AUDIO =>TTL or TTL => AUDIO interface in your system.Audio signals must be capacitively coupled and voltage biased to 2.5V to interface to an analog input.
I don't see any oscilloscope screenshots for inputs or outputs. (until later in your most recent posts)
You certainly get an "A" for AMBITION, but I would give lower marks for planning and execution because you are interfacing very different types of circuit blocks.
You probably think I am unfairly critical but that's because I am a professional electronics engineering technician and these kinds of projects are usually done with a lot more research in the commercial world so seeing this as a "hobby" project, it strikes as just "thrown together", rather than "carefully planned" and the forum posts strike me as sorely lacking in schematic reference detail.
I've seen the HX1 used in a number of high altitude balloon projects, like this one: http://www.sbszoo.com/bear/construction/traker/utrak1.3/utrak-V1-3.htmEvidently the HX1 has a digital input but the internal modulation generates the required audio tones in the matching receiver, HRX1. So, the microModem tone generation code is not needed. It appears that you still have to assemble packets with preamble, sync, data and checksum.To use the HX1, you need the matching receiver and to follow the manufacturer's or other people's advice on how to set up a functional communications system. I haven't done the research required in order to be of assistance.The microModem software is better suited to handheld radios intended for voice communications.
Note that you need a license to operate the HX1.
There is nothing on the HX1 product page or data sheet to indicate that it was "made for APRS" and nothing to suggest that the HX1 is intended for use with receivers other than those made by Radiometrix.APRS is listed as one of several possible applications.In order to use this transmitter for APRS, one would normally need quite a bit more information than is given in the HX1 data sheet. I'm certainly puzzled about how it is supposed to work!
Variants and ordering informationThe HX1 transmitter is manufactured in the following variants as standard:HX1-144.390-10 US APRSHX1-144.800-10 EU APRSHX1-169.4125-3 EU Meter Reading, Asset Tracing and Tracing
The HX1 DOES NOT generate the two-frequency AFSK tones - you need a modem eg the micromodem you linked to get these. You're wasting your time otherwise.
Screwing around, tossing stuff together that shouldn't fit, inconsistent progress, and dead ends. All part of the amature/hobbiest experience
The HX1 DOES NOT generate the two-frequency AFSK tones