#1 2016-08-10 04:24:56

jremington
Member
Registered: 2016-03-09
Posts: 2

MicroModem and Radiometrix HX1?

A number of people are using the HX1 VHF transmitter module from Radiometrix for high altitude balloon projects with APRS.

There is remarkably little information on the HX1 data sheet about the TX input of the module (appears to be analog 0-5 V for 3kHz FM deviation), so I'm wondering if the microModem output is directly compatible, or is a voltage amplifier/offset stage is required. Has anyone tried?

HX1 data sheet http://www.radiometrix.com/content/hx1

Application using HX1 as APRS transmitter: https://blog.adafruit.com/2011/07/10/tr … s-tracker/

On a related topic, the above Trackuino project uses fast (62.5 kHz) PWM to generate analog modulation waveforms for the HX1, but no low pass filter is used in the output stage. It is surprising to me that this works! Comments welcome.

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#2 2016-08-18 17:11:50

jremington
Member
Registered: 2016-03-09
Posts: 2

Re: MicroModem and Radiometrix HX1?

First question is moot.

I just noticed that there is a line-level audio output from MicroModem, as well as the "MIC" level audio output. The output voltage swing from the former should work well with the HX1, but if anyone has verified this (or found otherwise), please post!

Last edited by jremington (2016-08-18 17:13:45)

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